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Folate-mediated poly(3-hydroxybutyrate-co-3-hydroxyoctanoate) nanoparticles for targeting drug delivery
Abstract
A novel targeting drug delivery system (TDDS) has been developed. Such a TDDS was prepared by W(1)/O/W(2) solvent extraction/evaporation method, adopting poly(3-hydroxybutyrate-co-3-hydroxyoctanoate) [P(HB-HO)] as the drug carrier, folic acid (FA) as the targeting ligand, and doxorubicin (DOX) as the model anticancer drug. The average size, drug loading capacity and encapsulation efficiency of the prepared DOX-loaded, folate-mediated P(HB-HO) nanoparticles (DOX/FA-PEG-P(HB-HO) NPs) were found to be around 240 nm, 29.6% and 83.5%. The in vitro release profile displayed that nearly 50% DOX was released in the first 5 days. The intracellular uptake tests of the nanoparticles (NPs) in vitro showed that the DOX/FA-PEG-P(HB-HO) NPs were more efficiently taken up by HeLa cells compared to non-folate-mediated P(HB-HO) NPs. In addition, DOX/FA-PEG-P(HB-HO) NPs (IC(50)=0.87 microM) showed greater cytotoxicity to HeLa cells than other treated groups. In vivo anti-tumor activity of the DOX/FA-PEG-P(HB-HO) NPs showed a much better therapeutic efficacy in inhibiting tumor growth, and the final mean tumor volume was 178.91+/-17.43 mm(3), significantly smaller than normal saline control group (542.58+/-45.19 mm(3)). All these results have illustrated that our techniques for the preparing of DOX/FA-PEG-P(HB-HO) NPs developed in present work are feasible and these NPs are effective in selective delivery of anticancer drug to the folate receptor-overexpressed cancer cells. The new TDDS may be a competent candidate in application in targeting treatment of cancers.
... Natural polymers such as polyhydroxyalkanoates (PHAs), as well as synthetic polymers like PLGA, have been studied for targeted drug delivery applications paired with anticancer agents like paclitaxel [70,94], doxorubicin [95,96], and cisplatin [97,98]. These studies were tested in vivo and there are some that have been used in preclinical trials on mice [99]. ...
... It was observed that the functionalized nanoparticles showed improved efficiency compared to the unfunctionalized nanoparticles, because of their altered surface and specific targeted delivery [71]. Folic acid coupled with poly(3-hydroxybutyrate-co-3-hydroxyoctanoate) and loaded with doxorubicin presented a drug encapsulation performance of above 80% [96]. ...
... Furthermore, in vitro assays exhibited a release profile of the anticancer drug of approximately 50% in the first five days, and in vivo assays showed that the system displayed enhanced therapeutic efficiency in limiting the tumor growth when compared to controls [96]. Additionally, PLGA nanoparticles loaded with methotrexate-transferrin conjugates and coated with Polysorbate 80, a water-soluble surfactant, were investigated as vehicles for brain cancer treatment. ...
Cancer is among the leading causes of death worldwide. Therefore, timely diagnosis and appropriate treatment are very important. There are many disadvantages that come with traditional cancer treatments, such as chemotherapy and radiotherapy. In these treatments, the specific drug concentration affects not only the tumor site but also healthy tissues or organs. One of the foremost promising uses of nanotechnology is in the field of medical technology and specific site targeting can be achieved due to manipulation of materials at a nanometric scale. Nanotechnology offers specific benefits in terms of cancer therapy by enhancing it and reducing its adverse effects by guiding drugs to selectively target cancer cells. In addition, the use of minute amounts of medicine can lead to cost savings. Furthermore, nanoparticles can also be used as imaging agents to improve cancer diagnostics, therapeutics, and treatment management. Thus, this review has focused on the different types of nanoparticles used in cancer therapy, their action mechanisms, and their benefits and applications in diagnosis, imaging, and treatment. This review sums up the parameters that need to be considered when designing systems for cancer therapy while considering the desired characteristics of the nanoparticles from the biological point of view.
... Similar to other colloidal systems, PHA nanoparticles also suffer the disadvantage of poor drug loading [38]. For instance, a drug loading of less than 30% has been reported in various studies [30,35,[39][40][41][42][43]. As a solution, the strategies reported for other polymers such as PLGA can be used as a guideline to increase the drug loading of PHA-based nanoparticles. ...
... In another study, doxorubicin (DOX)-loaded FA-conjugated poly(3-hydroxybutyrate-co-3-hydroxyoctanoate) [P(HB-co-HO)] nanoparticles (DOX/FA PHB-co-HO-NPs) were significantly more cytotoxic towards HeLa cells compared to non-FA NPs. The IC 50 of DOX/FA PHB-co-HO-NPs and non-FA NPs were 0.87 µM and 27.53 µM, respectively, which demonstrated that the potency of killing HeLa cells increased thirtyfold when an active targeting ligand was added [42]. A prolonged drug release pattern was noticed whereby almost 50% of DOX was released after 5 days. ...
... In another study, Sasikumar and Ayyasamy also observed that the release behaviour of DOX encapsulated within PHB nanoparticles using a nanoprecipitation technique followed a slow, sustained release curve [65]. Owing to the sustained DOX release, selective cancer targeting, and higher internalization rate, the reduction of tumour volume for HeLa bearing BALB/c nude mice was comparably higher for DOX/FA PHB-co-HO-NPs (final tumour volume: 178.91 ± 17.43 mm 3 ) compared to a normal saline group (542.58 ± 45.19 mm 3 ) [42]. ...
Polyhydroxyalkanoates (PHAs) are natural polymers produced under specific conditions by certain organisms, primarily bacteria, as a source of energy. These up-and-coming bioplastics are an undeniable asset in enhancing the effectiveness of drug delivery systems, which demand characteristics like non-immunogenicity, a sustained and controlled drug release, targeted delivery, as well as a high drug loading capacity. Given their biocompatibility, biodegradability, modifiability, and compatibility with hydrophobic drugs, PHAs often provide a superior alternative to free drug therapy or treatments using other polymeric nanocarriers. The many formulation methods of existing PHA nanocarriers, such as emulsion solvent evaporation, nanoprecipitation, dialysis, and in situ polymerization, are explained in this review. Due to their flexibility that allows for a vessel tailormade to its intended application, PHA nanocarriers have found their place in diverse therapy options like anticancer and anti-infective treatments, which are among the applications of PHA nanocarriers discussed in this article. Despite their many positive attributes, the advancement of PHA nanocarriers to clinical trials of drug delivery applications has been stunted due to the polymers’ natural hydrophobicity, controversial production materials, and high production costs, among others. These challenges are explored in this review, alongside their existing solutions and alternatives.
... Their use for controlled and sustained drug delivery to wounds improves the efficiency of therapeutic molecules with minimal side effects. For example, silicone, which has been frequently used to encapsulate hydrophobic drugs, must be replaced as it is carcinogenic [97,98]. Dendrimers are produced from 3HB monomers. ...
... P(3HB)-based spherical polymeric nanocomposites with a higher anticancer drug (docetaxel) loading capacity (>17%) showed enhanced (>43%) encapsulation efficiency [125]. The information regarding the applications of PHAs in drug carriers and delivery has been presented in Table 2. P(3HB-3HO) (10 mol% HO) Sinorhizobium fredii PHA-PEG-Folic acid with Doxorubicin kills 3-fold higher HeLa cells [97] To develop the wound dressing necessary for healing defects in the skin of Wistar rats, the copolymer P(3HB-4HB) was used. PHA-based membranes loaded with fibroblasts from mesenchymal stem cells facilitated the release of fibroblast-secreted matrix proteins. ...
Polyhydroxyalkanoates (PHA) are biodegradable plastic. Numerous bacteria produce PHAs under environmental stress conditions, such as excess carbon-rich organic matter and limitations of other nutritional elements such as potassium, magnesium, oxygen, phosphorus, and nitrogen. In addition to having physicochemical properties similar to fossil-fuel-based plastics, PHAs have unique features that make them ideal for medical devices, such as easy sterilization without damaging the material itself and easy dissolution following use. PHAs can replace traditional plastic materials used in the biomedical sector. PHAs can be used in a variety of biomedical applications, including medical devices, implants, drug delivery devices, wound dressings, artificial ligaments and tendons, and bone grafts. Unlike plastics, PHAs are not manufactured from petroleum products or fossil fuels and are, therefore, environment-friendly. In this review, a recent overview of applications of PHAs with special emphasis on biomedical sectors, including drug delivery, wound healing, tissue engineering, and biocontrols, are discussed.
... anticancer drugs to the folate receptor-overexpressed cancer cells [320]. Sulperaz loaded P(3HB-co-3HV) was employed for an in vitro antibiotic release [321]. ...
... In another study, a new nanocarrier was formulated with folic acid (FA) and doxorubicin (DOX) as the targeting ligand and anticancer drug, respectively. This nanocarrier was found to be a potential candidate for the targeted delivery of anticancer drugs to the folate receptor-overexpressed cancer cells [320]. Sulperazone-loaded P(3HB-co-3HV) was employed for an in vitro antibiotic release [321]. ...
Nanoparticles (NPs) have remarkable properties for delivering therapeutic drugs to the body’s targeted cells. NPs have shown to be significantly more efficient as drug delivery carriers than micron-sized particles, which are quickly eliminated by the immune system. Biopolymer-based polymeric nanoparticles (PNPs) are colloidal systems composed of either natural or synthetic polymers and can be synthesized by the direct polymerization of monomers (e.g., emulsion polymerization, surfactant-free emulsion polymerization, mini-emulsion polymerization, micro-emulsion polymerization, and microbial polymerization) or by the dispersion of preformed polymers (e.g., nanoprecipitation, emulsification solvent evaporation, emulsification solvent diffusion, and salting-out). The desired characteristics of NPs and their target applications are determining factors in the choice of method used for their production. This review article aims to shed light on the different methods employed for the production of PNPs and to discuss the effect of experimental parameters on the physicochemical properties of PNPs. Thus, this review highlights specific properties of PNPs that can be tailored to be employed as drug carriers, especially in hospitals for point-of-care diagnostics for targeted therapies.
... A sharp peak at 1598 cm −1 shows the presence of aromatic ring [26]. A small bend at 1635 cm −1 (Fig. 1d) indicates amide bond formation between the amine group of PEG-diamine and the carboxyl group of FA [38]. The bands at 2831 and 2924 cm −1 in Fig. 1c(i) suggest the presence of symmetric and asymmetric CH 2 vibration of the PEG group. ...
... The bands at 2831 and 2924 cm −1 in Fig. 1c(i) suggest the presence of symmetric and asymmetric CH 2 vibration of the PEG group. Presence of broadband around 3010-3500 cm −1 indicates stretching vibration of OH group and NH 2 group [38,39]. Further, the vibrational band at 532 cm −1 correspond to Fe-O vibration indicating the formation of magnetite phase [39]. ...
Effective and targeted delivery of the antitumour drugs towards the specific cancer spot is the major motive of drug delivery. In this direction, suitably functionalised magnetic iron oxide nanoparticles (NPs) have been utilised as a theranostic agent for imaging, hyperthermia and drug delivery applications. Herein, the authors reported the preparation of multifunctional polyethyleneglycol-diamine functionalised mesoporous superparamagnetic iron oxide NPs (SPION) prepared by a facile solvothermal method for biomedical applications. To endow targeting ability towards tumour site, folic acid (FA) is attached to the amine groups which are present on the NPs surface by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride/N-hydroxysuccinimide chemistry. FA attached SPION shows good colloidal stability and possesses high drug-loading efficiency of ∼ 96% owing to its mesoporous nature and the electrostatic attachment of daunosamine (NH3 +) group of doxorubicin (DOX) towards the negative surface charge of carboxyl and hydroxyl group. The NPs possess superior magnetic properties in result endowed with high hyperthermic ability under alternating magnetic field reaching the hyperthermic temperature of 43°C within 223 s at NP's concentration of 1 mg/ml. The functionalised NPs possess non-appreciable toxicity in breast cancer cells (MCF-7) which is triggered under DOX-loaded SPION.
... Natural polymers such as polyhydroxyalkanoates (PHAs), as well as synthetic, poly-lactide-co-glycolide (PLGA) have been investigated in this regard. Coupled with anti-cancer agents such as paclitaxel [56,57], doxorubicin [58,59], cisplatin [60,61], and many others, these systems have been tested in vivo, and some have even been used in preclinical trials on mice [62]. ...
... Moreover, in vitro assays showed a release profile of the anti-cancer agent of almost 50% in the first five days. In vivo testing revealed that the system exhibited enhanced therapeutic efficiency in restraining the growth of the tumor, when compared to controls [58]. ...
The disadvantages that come with traditional cancer treatments, such as chemotherapy and radiotherapy, generated a research shift toward nanotechnology. However, even with the important advancements regarding cancer therapy, there are still serious stepping stones that need to be addressed. The use of both nanotechnology and nanomedicine has generated significant improvements in nano-sized materials development and their use as therapeutic, diagnosis, and imaging agents. The biological barriers that come from the healthy body, as well from the tumorous sites, are important parameters that need to be taken into consideration when designing drug delivery systems. There are several aspects of extreme importance such as the tumor microenvironment and vasculature, the reticuloendothelial system, the blood–brain barrier, the blood–tumor barrier, and the renal system. In order to achieve an effective system for cancer therapy, several characteristics of the nanoparticles have been outlined. Moreover, this review has also focused on the different types of nanoparticles that have been studied over the years as potential candidates for cancer therapy.
... They also implied that the receptor-ligand complex can be induced to internalize via endocytosis, enhancing cellular uptake of nanoparticles which may facilitate the delivery of drugs [56]. The similar result is also found in the investigation of Zhang et al. (2010). Regarding their results, the overexpression of FRs on the HeLa cells may significantly improve the uptake of the targeted nanoparticles via FR-mediated endocytosis and consequently result in higher cytotoxicity [57]. ...
... The similar result is also found in the investigation of Zhang et al. (2010). Regarding their results, the overexpression of FRs on the HeLa cells may significantly improve the uptake of the targeted nanoparticles via FR-mediated endocytosis and consequently result in higher cytotoxicity [57]. ...
The aim of this study was to develop and characterize 5-Fluorouracil (5FU) containing targeted liposomes in order to enhance the efficacy and safety of the drug. Folic acid (FA) was used as a targeting ligand. The in vitro cytotoxicity of formulation against HT-29, Caco-2, CT26, HeLa and MCF-7 cell lines was evaluated using MTT assay. Mechanism of cell death induced by targeted liposomes was further investigated via the production of
reactive oxygen species (ROS), change in mitochondrial membrane potential (ΔΨm), release of cytochrome c and activity of caspase 3/7. The in vivo tumor inhibition study was also performed after administration of drug and targeted 5FU liposome. The encapsulation efficiency (EE%) of the optimized formulation was 39.71%. Particle
size of liposomes was around 174 nm and the nanoparticles were found to be spherical in shape. Differential Scanning Calorimetry (DSC) results indicated that the drug remained in an amorphous state in liposomes. According to the MTT results, targeted liposomes exhibited higher cytotoxicity than 5FU and liposomal 5FU. Targeted liposomes were found to trigger necrosis in HT-29 cells; while, in HeLa cells, targeted liposomes activated apoptotic pathway by collapse of ΔΨm, increased activity of cytochrome c as well as caspases activity. in vivo results showed that targeted liposomes reduced tumor volume significantly in comparison with 5FU (169.00 mm 3 tumor volume vs326.40 mm ). From these findings, it can be concluded that folic acid targeted liposomes may provide a new platform for selective delivery of drugs to cancer cells.
... Silicone, as an organic compound, is widely used to encapsulate hydrophobic drugs, but recent studies have shown that silicone has the potential to cause cancer. 121,122 In recent decades, researchers have shown great interest in developing biodegradable polymeric materials from natural sources as drug delivery materials and have achieved positive results. Due to their good biocompatibility and biodegradability, PHAs have attracted great attention in drug delivery systems. ...
Infection and rejection in musculoskeletal trauma often pose challenges for natural healing, prompting the exploration of biomimetic organ and tissue transplantation as a common alternative solution. Polyhydroxyalkanoates (PHAs) are a large family of biopolyesters synthesised in microorganism, demonstrating excellent biocompatibility and controllable biodegradability for tissue remodelling and drug delivery. With different monomer-combination and polymer-types, multi-mechanical properties of PHAs making them have great application prospects in medical devices with stretching, compression, twist in long time, especially in musculoskeletal tissue engineering. This review systematically summarises the applications of PHAs in multiple tissues repair and drug release, encompassing areas such as bone, cartilage, joint, skin, tendons, ligament, cardiovascular tissue, and nervous tissue. It also discusses challenges encountered in their application, including high production costs, potential cytotoxicity, and uncontrollable particle size distribution. In conclusion, PHAs offer a compelling avenue for musculoskeletal system applications, striking a balance between biocompatibility and mechanical performance. However, addressing challenges in their production and application requires further research to unleash their full potential in tackling the complexities of musculoskeletal regeneration.
... In another study, only 30% of PTX was successfully loaded in transferrin-coated PLGA nanoparticles (Shah et al., 2009). There are success reports with the use of members of the PHA family such as PHB, PHBV, and poly(3-hydroxybutyrateco-3-hydroxyoctanoate) nanoparticles for controlled release of drug molecules (Masood et al., 2013;Perveen et al., 2020;Zhang et al., 2010). Recently, Lee et al. (2022) developed hybrid nanoparticles based on PHA and PLGA for the delivery of PTX. ...
Paclitaxel (PTX) is a potent anticancer drug. In the present study, PTX was loaded in poly-3-hydroxybutyrate-co-3-hydroxyvalarate (PHBV) to fabricate the PTX/PHBV (drug-loaded) nanoparticles via the nanoprecipitation method. Blank PHBV nanoparticles were also prepared. The drug-encapsulation efficiency of PTX/PHBV nanoparticles was 45±0.4%. The PTX/PHBV nanoparticles exhibited a pH-sensitive release profile and followed a quasi-Fickian diffusion mechanism. Cytotoxic properties of PHBV and PTX/PHBV nanoparticles were checked against the MCF-7 and Caco-2 cell lines. The PHBV nanoparticle did not inhibit the proliferation of MCF-7 and Caco-2 cell lines, thus depicting their non-toxic and biocompatible nature. On the other hand, the PTX/PHBV nanoparticles demonstrated 1.03-fold higher cytotoxicity and 1.61-fold enhanced apoptosis after treatment with the PTX/PHBV nanoparticles versus free PTX. In summary, the PHBV nanoparticles could be a potential candidate for the delivery of PTX for cancer treatment.
... A high antitumor activity of P(3HB-co-3HHx) nanoparticles with folic acid was demonstrated in HeLa cell culture [124]. The P(3HVco-4HB)-bmPEG copolymer PHA-polyethylene glycol particles enhanced the apoptotic activity of encapsulated cisplatin on the DU145 prostate cancer cell line [131]. The drug efficiency of P(3HB-co-PEG) nanoparticles loaded with an antisense oligonucleotide were effective in suppressing cancer cell line A549 [132]. ...
The development of controlled drug delivery systems, in the form of microparticles, is an important area of experimental pharmacology. The success of the design and the quality of the obtained microparticles are determined by the method of manufacture and the properties of the material used as a carrier. The goal is to obtain and characterize microparticles depending on their method of preparation, the chemical composition of the polymer and the load of the drugs. To obtain microparticles, four types of degradable PHAs, differing in their chemical compositions, degrees of crystallinity, molecular weights and temperature characteristics, were used (poly-3-hydroxybutyrate and copolymers 3-hydroxybutyric-co-3-hydroxyvaleric acid, 3-hydroxybutyric-co-4-hydroxybutyric acid, and 3-hydroxybutyric-co-3-hydroxyhexanoic acid). The characteristics of microparticles from PHAs were studied. Good-quality particles with an average particle diameter from 0.8 to 65.0 μm, having satisfactory ζ potential values (from −18 to −50 mV), were obtained. The drug loading content, encapsulation efficiency and in vitro release were characterized. Composite microparticles based on PHAs with additives of polyethylene glycol and polylactide-co-glycolide, and loaded with ceftriaxone and 5-fluorouracil, showed antibacterial and antitumor effects in E. coli and HeLa cultures. The results indicate the high potential of PHAs for the design of modern and efficient drug delivery systems.
... Ellipticine Emulsification/Solvent evaporation in vitro [61,62] Cisplatin Emulsification/Solvent evaporation in vitro [63] Thymoquinone Emulsification/Solvent evaporation in vitro [64] Paclitaxel Double emulsification/Solvent evaporation in vitro [65] 5-Fluorouracil Double emulsification/Solvent evaporation in vitro [66] Etoposide Solvent evaporation in vitro [67] Doxorubicin Double emulsification/Solvent evaporation in vitro [68] Rhodamine B isothiocyanate (RBITC) ...
Latterly, the development of green synthesized polymeric nanoparticles with anticancer studies has been an emerging field in academia, and in the pharmaceutical and chemical industry. Vegetable oils are potential substitutes for petroleum derivatives, as they present themselves as a clean and environmentally friendly alternative and are available in high quantities at relatively low prices. Biomass-derived chemicals can be converted into monomers with unique structures, generating materials with new properties for the synthesis of sustainable monomers and polymers. In this way, the production of bio-based polymeric nanoparticles appears as a great application of green chemistry for biomedical uses. There is an increasing demand for biocompatible and biodegradable materials for specific applications in biomedical as cancer therapy, encouraging scientists in working on research towards designing polymers, with enhanced properties and clean processes, containing oncology active pharmaceutical ingredients (APIs). The nanoencapsulation of these APIs in bio-based polymeric nanoparticles can control the release of the substances, increase bioavailability, reduce problems with volatility and degradation, reduce side effects, and increase treatment efficiency. Thus, this review aims to discuss the use of green chemistry for bio-based nanoparticle production and its application in anticancer medicine. The use of vegetable oils for the production of renewable monomers and polymers will be discussed, bringing castor oil as an ideal candidate for such application, as well as more suitable methods for the production of bio-based nanoparticles and some oncology APIs available for anticancer application.
... These cells' multiplication and metabolic activity increased, significantly impacting tissue engineering (Masaeli et al. 2014). PHA nanoparticles mediated by floats have been investigated for medication delivery targeting (Zhang et al. 2010). Protein immobilisation has also been described using PHA as nanobeads (Rehm 2003). ...
Bioplastics replace synthetic plastics of petrochemical origin, which contributes challenge to both polymer quality and
economics. Novel polyhydroxyalkanoates (PHA)-composite materials, with desirable product quality, could be developed,
thus targeting the global plastics market, in the coming years. It is possible that PHA can be a greener substitute for their
petroleum-based competitors since they are simply decomposed, which may lessen the pressure on municipal and industrial
waste management systems. PHA production has proven to be the bottleneck in industrial application and commercialization
because of the high price of carbon substrates and downstream processes required to achieve reliability. Bacterial PHA
production by these municipal and industrial wastes, which act as a cheap, renewable carbon substrate, eliminates waste
management hassles and acts as an efficient substitute for synthetic plastics. In the present review, challenges and opportunities
related to the commercialization of polyhydroxyalkanoates are discussed and presented. Moreover, it discusses critical steps
of their production process, feedstock evaluation, optimization strategies, and downstream processes. This information may
provide us the complete utilization of bacterial PHA during possible applications in packaging, nutrition, medicine, and
pharmaceuticals.
... In recent years, an important trend in biocompatible polyesters modification has been the obtaining of their oligomers for further use in several fields [7]. In particular, such oligomers can be used in chain elongation reactions or for copolymerization with oligomers of a different nature to obtain new polymers [8][9][10] or for the addition of low molecular weight compounds [11]. Thus, for the formation of microparticles that can be used for controlled drug delivery, it is desirable to use polymers with relatively low molecular weight (around thousands of Da) [12]. ...
The degradation pattern of bacterial poly-3-hydroxybutyrate (PHB) in dimethylformamide (DMF) and dioxane solutions at 100 °C assisted by ethylenediamine, 1,4-diaminobutane and monoaminoethanol was studied. When diamines were introduced into the PHB solution in DMF in the amount of 1 mol of the reagent to 5 or 10 mol of PHB monomers, a rapid decrease in the molecular weight of the polymer was observed. The initial value of the weight average molecular weight (Mw) 840 kDa had decreased by 20–30 times within the first 10–20 min of the experiment, followed by its gradual decrease to several thousand Da. When a similar molar quantity of aminoethanol was added, the molecular weight decreased slower. PHB had been degrading much slower in the dioxane solution than in DMF. By varying the number of reagents, it was possible to reach stabilization of the Mw at 1000–3000 Da when using diamines and 8000–20,000 Da using aminoethanol. 1H NMR analysis of the oligomers revealed of amino and amido groups forming in their structure. From the opposite end of the polymer chain, residues of 3-hydroxybutyric, crotonic and isocrotonic acids were formed during degradation. Differential scanning calorimetry indicated that after oligomerization there was a decrease in the melting point from 178 °C to 140–170 °C depending on the decrease in the molecular weight. The method proposed can be used for obtaining aminated PHB oligomers.
... This is in accordance with previous report, in which the uptake of nile red-and GFP-loaded PHB NPs in MDA-MB-231 breast cancer cells were demonstrated [19]. A similar study reported the uptake of doxorubicin-loaded [P (HB-HO) nanoparticles coated with folate in the cytoplasm [38]. The advantage of the present study relies on the efficient uptake of PHB NPs at very low concentration (200 ng/ml). ...
Ursolic acid (UA), a pentacyclic triterpenoid and a phytochemical, is a potent inhibitory agent against proliferation of various tumors. Polyhydroxybutyrate nanoparticles (PHB NPs) are preferred in therapeutics due to their drug-stabilizing property and enhanced biological activity. In this study, PHB NPs were utilized to deliver and enhance the bioavailability of UA against cancer cells (HeLa). Further, molecular docking and dynamic studies were conducted to calculate the binding affinity and stability of UA at the active site of target protein (epidermal growth factor receptor-EGFR). The PHB NPs revealed the average size as 150–200 nm in TEM, which were used in subsequent experiments. The cytoplasmic uptake of nanoparticles was confirmed by florescent microscopy. The encapsulation potential of PHB NPs with UA was assessed by UV–visible spectrophotometer as 54%. Besides, the drug release behavior, cytotoxicity and the regulation of apoptosis were investigated in vitro. The cytotoxicity results revealed that the maximum efficiency of drug delivery was at 96th hour.
... Nanodevices. For the release of molecular drugs like anticancer drugs, hormones, antibiotics and immuno-modulatory agents that can cross the intracellular membrane, PHB or its copolymers have been used to construct nanodevices (Fig. 3) [172]. The biopolymer like P3HB4HB, PHBV and PHB have been used in the manufacture of biodegradable, implantable rods/discs for the local delivery of antibiotics in chronic osteomyelitis therapy for the prevention of post-operative and implant-related infections [174]. ...
Biological polyesters of hydroxyacids are known as polyhydroxyalkanoates (PHA). They have proved to be an alternative, environmentally friendly and attractive candidate for the replacement of petroleum-based plastics in many applications. Many bacteria synthesize these compounds as an intracellular carbon and energy compound usually under unbalanced growth conditions. Biodegradability and biocompatibility of different PHA has been studied in cell culture systems or in an animal host during the last few decades. Such investigations have proposed that PHA can be used as biomaterials for applications in conventional medical devices such as sutures, patches, meshes, implants, and tissue engineering scaffolds as well. Moreover, findings related to encapsulation capability and degradation kinetics of some PHA polymers has paved their way for development of controlled drug delivery systems. The present review discusses about bio-plastics, their characteristics, examines the key findings and recent advances highlighting the usage of bio-plastics in different medical devices. The patents concerning to PHA application in biomedical field have been also enlisted that will provide a brief overview of the status of research in bio-plastic. This would help medical researchers and practitioners to replace the synthetic plastics aids that are currently being used. Simultaneously, it could also prove to be a strong step in reducing the plastic pollution that surged abruptly due to the COVID-19 medical waste.
... Developments in drug delivery systems have made steady progress. However, there is a need to replace silicone used for encapsulating hydrophobic drugs because it is carcinogenic (Pramual et al., 2016;Zhang et al., 2010) (Table 5). Electrospun fibers made from PHB and PEO, along with 1% chlorhexidine (CHX), were effective in the higher release of CHX. ...
Plastics are an integral part of most of the daily requirements. Indiscriminate usage and disposal have led to the accumulation of massive quantities of waste. Their non-biodegradable nature makes it increasingly difficult to manage and dispose them. To counter this impending disaster, biodegradable polymers, especially polyhydroxy-alkanoates (PHAs), have been envisaged as potential alternatives. Owing to their unique physicochemical characteristics, PHAs are gaining importance for versatile applications in the agricultural and medical sectors. Applications in the medical sector are more promising because of their commercial viability and sustainability. Despite such potential, their production and commercialization are significant challenges. The major limitations are their poor mechanical strength, production in small quantities, costly feed, and lack of facilities for industrial production. This article provides an overview of the contemporary progress in the field, to attract researchers and stakeholders to further exploit these renewable resources to produce biodegradable plastics on a commercial scale.
... Since the regulation of kinase expression is one of the key targets in the prevention of the cell proliferation of malignant tumours, the aforementioned approach is particularly interesting. A modification of pegylated PHA-based DDS was reported wherein folic acid was conjugated to the system [93]. Folate receptor has shown its ubiquitous presence on the surface of cancer cells and it has therefore been regarded as a therapeutic target in the fight against tumour progression. ...
The success of oil-based plastics and the continued growth of production and utilisation can be attributed to their cost, durability, strength to weight ratio, and eight contributions to the ease of everyday life. However, their mainly single use, durability and recalcitrant nature have led to a substantial increase of plastics as a fraction of municipal solid waste. The need to substitute single use products that are not easy to collect has inspired a lot of research towards finding sustainable replacements for oil-based plastics. In addition, specific physicochemical, biological, and degradation properties of biodegradable polymers have made them attractive materials for biomedical applications. This review summarises the advances in drug delivery systems, specifically design of nanoparticles based on the biodegradable polymers. We also discuss the research performed in the area of biophotonics and challenges and opportunities brought by the design and application of biodegradable polymers in tissue engineering. We then discuss state-of-the-art research in the design and application of biodegradable polymers in packaging and emphasise the advances in smart packaging development. Finally, we provide an overview of the biodegradation of these polymers and composites in managed and unmanaged environments.
... Poly(3-hydroxybutyrate-co-3-hydroxyoctanoate) [P(HB-HO)] was used as a carrier in a system of targeted drug delivery (Zhang et al., 2010). Folic acid (FA) and doxorubicin (DOX) were respectively employed as targeting ligand and anticancer drug. ...
Polymers are of tremendous importance in the delivery of drugs to the site of action. Natural polymers are preferable to synthetic ones because they are biocompatible and biodegradable. Polyhydroxyalkanoates (PHAs) are polyesters of various hydroxyalkanoate monomers accumulated by a wide range of bacterial strains in the form of intracellular granules, under unbalanced growth and excess carbon conditions. Polyhydroxyalkanoates have been tipped as a potential replacement for synthetic polymers due to their superior biocompatibility, biodegradability and controllable retarding properties. However, the cost of production of PHA compared to the synthetic polymers they are envisioned to replace is high. Studies have been done to reduce cost by employing cheap and renewable carbon sources. This review article presents an overview of PHA production from these sources as well as the use of PHA in the delivery of drugs
Polihidroksialkanoatların İlaç Dağılımında Uygulamaları ÖZ Polimerler, ilaçların etki yerlerine ulaştırılmasında çok önemlidir. Doğal polimerler, biyouyumlu ve biyolojik olarak parçalanabilir olmaları nedeniyle sentetik olanlara tercih edilir. Polihidroksial kanoatlar (PHA'lar), çok çeşitli bakteri suşları tarafından denge siz büyüme ve aşırı karbon şartları altında hücre içi granül for munda akümüle edilen çeşitli hidroksialkananoat monomerlerin poliesterleridir. Polihidroksialkanoatlar, üstün biyouyumluluk, biyobozunurluk ve kontrol edilebilir geciktirici özellikleri nedeniy le sentetik polimerlerin potansiyel olarak yerine geçebilir. Ancak, PHA üretim maliyeti, sentetik polimerlerle değiştirilmeleri ile karşılaştırıldığında yüksek olduğu öngörülmektedir. Ucuz ve ye nilenebilir karbon kaynakları kullanarak maliyeti düşürmek için çalışamalar yapılmıştır. Bu derleme makalesinde kaynaklardan PHA üretimi yanında PHA'nın ilaç dağılımında kullanımına genel bir bakış sunulmaktadır. Anahtar kelimeler: Biyopolimer, ilaç dağılımı, polihidroksial kanoat üretimi, yenilenebilir polimerler, polihidroksialkanoat 148 Balogun-Agbaje, Odeniyi, Odeniyi
... In addition to its functions in numerous metabolic pathways for one carbon transfer reactions, the use of FA during pregnancy has been related to a significant reduction of the risk of birth of children with neural tube defects [15]. Due to the high affinity of FA for folate receptors [16], broadly present on cancer cell surfaces [17,18], and the role that FA in the proliferation and growth of cells, this compound has been extensively used in drug delivery systems as a targeting biomolecule [19][20][21][22]. The strategy of using FA and other biomolecules that present targeting function, onto the surfaces of drug carriers is a promising alternative for the reduction of possible collateral effects by the enhancement of the selectivity of nanocarriers by the target tissue [23,24]. ...
Surface-enhanced Raman scattering (SERS) spectroscopy was used in the investigation of the adsorption of folic acid (FA) on the surface of gold nanoparticles (AuNPs) in the absence and presence of surface modifiers hydrochloride acid (HCl) and 1-mercaptoethanol (ME). The proposal for the chemical interactions of FA with the metallic surface was based on vibrational assignment supported by Density Functional Theory (DFT) calculations. In the absence of surface modifiers, FA interacts with the gold surface through the pteridine moiety in a tilted geometry. In the presence of ME, the molecule of FA is anchored through hydrogen bonds with the surface modifier. The presence of HCl induced ion-pair interactions involving chloride ions, adsorbed on gold surfaces, and both the nitrogen N1 of the pteridine ring and the γ-carboxylic acid of the glutamic acid moiety. In this condition, keto-enol equilibrium can be evidenced by a remarkable enhancement of marker bands in the SERS spectra.
... PHB or its copolymers based nanodevices have been often used for the release of molecular drugs able to cross intracellular membranesi.e. anticancer drugs, hormones, antibiotics and immunomodulatory agents [76]. Alternatively, PHBV rods and discs have been tested as drug-eluting implants, being able to release antibiotics to prevent post-operative and implant-related infections [77]. ...
Introduction: The applications of naturally obtained polymers are tremendously increased due to them being biocompatible, biodegradable, environmentally friendly and renewable in nature. Among them, polyhydroxyalkanoates are widely studied and the can be utilized in many areas of human life research such as drug delivery, tissue engineering, and other medical applications.
Areas Covered: This review provides an overview of the polyhydroxyalkanoates biosynthesis and their possible application in drug delivery in the range of micro- and nano-size. Moreover, the possible applications in tissue engineering are covered considering macro- and micro-porous scaffolds and extracellular matrix analogs
Expert Commentary: The majority of synthetic plastics are non-biodegradable so, in the last years, a renewed interest is growing to develop alternative processes to produce biologically derived polymers. Among them, PHAs present good properties such as high immunotolerance, low toxicity, biodegradability, so, they are promisingly using as biomaterials in biomedical applications.
... As a complimentary strategy to EPR, ligand-functionalised nanoparticles offer the potential to further augment the efficacy of nanotherapeutics in treating diseases. Although there have been multiple studies reporting the enhanced uptake by FR-positive cells following folate conjugation to liposomes carrying the therapeutic payload [33,[38][39][40], research that focuses on determining the optimal spacer length for FA conjugation on liposomal physicochemical characteristics, inhibitory potency, and in vitro performance on cervical cancer cells with differing HPV status cannot be found. The aim of this study was to assess the effect of ligand spacer length on cellular uptake and inhibitory potency against HPV-positive cervical cancer cells in vitro and to identify the most suitable liposomal formulation for delivering ATO to cervical cancer cells. ...
High-risk human papilloma virus (HPV) infection is directly associated with cervical cancer development. Arsenic trioxide (ATO), despite inducing apoptosis in HPV-infected cervical cancer cells in vitro, has been compromised by toxicity and poor pharmacokinetics in clinical trials. Therefore, to improve ATO’s therapeutic profile for HPV-related cancers, this study aims to explore the effects of length of ligand spacers of folate-targeted liposomes on the efficiency of ATO delivery to HPV-infected cells. Fluorescent ATO encapsulated liposomes with folic acid (FA) conjugated to two different PEG lengths (2000 Da and 5000 Da) were synthesised, and their cellular uptake was examined for HPV-positive HeLa and KB and HPV-negative HT-3 cells using confocal microscopy, flow cytometry, and spectrophotometer readings. Cellular arsenic quantification and anti-tumour efficacy was evaluated through inductively coupled plasma-mass spectrometry (ICP-MS) and cytotoxicity studies, respectively. Results showed that liposomes with a longer folic acid-polyethylene glycol (FA-PEG) spacer (5000 Da) displayed a higher efficiency in targeting folate receptor (FR) + HPV-infected cells without increasing any inherent cytotoxicity. Targeted liposomally delivered ATO also displayed superior selectivity and efficiency in inducing higher cell apoptosis in HPV-positive cells per unit of arsenic taken up than free ATO, in contrast to HT-3. These findings may hold promise in improving the management of HPV-associated cancers.
... The cytotoxicity was high, and the in vitro assay has shown the intracellular uptake of the nano particles were efficient with the HeLa cells. The in vivo studies on mice having the HeLa tumors xenograft exhibited similar activity with minimal side effects (Zhang et al. 2010). In a study, the chemotherapeutic drug etoposide (ETO) was delivered with the P(3HB-co-3HHx) conjugated with the folate(FA). ...
Polyhydroxyalkanoates (PHAs) are the biodegradable polyesters synthesized from the bacterial origin with high therapeutic importance due to their major biopolymer properties like biodegradability, biocompatibility, non-toxicity and thermo-plasticity. These hypotheses make the PHAs as one of the drug carrier or nanovehicles for therapeutic drug delivery. Drug delivery is one of the emerging fields in biological science, which gives application of delivering the promising drug molecules in the desired drug target, with increasing dissolution rate and bioavailability. Understanding the drug-polymer interactions and controlled release makes the combo of the perfect drug molecule and the biopolymer, and in this, the PHA is reported to be a better natural origin drug carrier. Several reports suggest that, chemical entities of PHA show enhanced activity and used as one of the promising nanocarrier. Experimental test by several assays shows PHA’s as one of the compatible biopolymers in tissues. This chapter comes up with various applications related to PHAs like medical implants, adhesion barriers, drug carriers, tissue engineering, Nano based targeted delivery. Overall, this chapter will provide a perfect base for studies on PHA related to drug carrier studies.
... where a lower content of nanofiller facilitated the production of an exfoliated morphology with good dispersion. PHA/folate ligand nanocomposite particles were shown to carry doxorubicin for anticancer therapy [151][152][153]. Shape memory polymer nanocomposites are of great interest as they are able to revert to their original shape after being deformed. ...
A wide variety of bacteria are found to be the tiny factories in the production of polyhydroxyalkanoate (PHA) biopolymer. PHA is the polyesters of 3-hydroxyalkanoic acids which occur in bacteria when the bacteria is subjected to nutrient limitation and simultaneously fed with an excess amount of carbon. This unfavorable condition forces the bacteria to store carbon in the form of resorbable cellular inclusions called PHA. Biosynthesized PHA has the ability to replace the currently feasible harmful petroleum based plastics to biobased plastics. PHA research is being focused mainly on two facts - bulk production of environment friendly low-cost PHA and functional group modification for multiple applications to mankind. Many companies are already producing PHA with highly tunable properties and are looking into economically feasible technologies for mass production of PHA. The core focus of PHA research includes a selection of potential PHA producers and low to zero cost carbon sources such as carbon containing wastages of household, farms and industries. This challenge of “trash to treasure” still remains to attain. Tunable properties of PHA have made them a more interesting biomaterial to blend with suitable biopolymers including bioactive compounds. Under precise physiological environment, PHA blends can deliver promising mechanical properties, acting as effective drug carriers and showing time bound degradation. Perhaps desirably tuned PHA may address many health issues including orthopedics - load bearing cartilage, artificial membranes for kidneys, heart and wound management. PHA has high immunotolerance, low toxicity and sustained biodegradability, which have attracted diverse scientist with many medical advancements such as bioabsorbable sutures and 3D structures. In the near future, it is expected to derive many smart auto controllable products from PHA such as microsphere, which could be utilised for a range of applications much more than just drug delivery. Furthermore, naturally produced hybrid PHA will be an interesting candidate as they possess essential properties for targeted applications without further artificial blending or incorporating any components.
In this study, salicylic acid (SA) dopped into poly(3-hydroxybutyrate) (PHB) and prepared nanoparticles (NPs) to increase encapsulation efficiency, anti-cancer activity of caffeic acid (Caff), and folic acid (FA) for breast cancer treatment. NPs were prepared by solvent evaporation method and characterised by FTIR, DSC, SEM, and entrapment-loading efficiencies. The mean diameter, polydispersity index (PDI), and zeta potential (ZP) were evaluated by dynamic light scattering (DLS). In vitro release and stability studies were done via eppendorf method. The cytotoxicity, cell dead and internalisation of NPs were shown by MTT, fluorescein and confocal microscopy. The diameter and ZP of NPs were 172 ± 7 nm and -29 ± 0.38 mV. The entrapment efficiencies of 5 and 10 Caff NPs were 79 ± 0.23% and 70 ± 0.42%. NPs showed good stability within 30 d and sustained release over 25 d. FA-5Caff NPs showed 37 ± 0.3% viability on MCF-7. FA-Caff NPs were identified as promising carrier system for breast cancer therapy.
Timely diagnosis and appropriate antitumoral treatments remain of utmost importance, since cancer remains a leading cause of death worldwide. Within this context, nanotechnology offers specific benefits in terms of cancer therapy by reducing its adverse effects and guiding drugs to selectively target cancer cells. In this comprehensive review, we have summarized the most relevant novel outcomes in the range of 2010–2023, covering the design and application of nanosystems for cancer therapy. We have established the general requirements for nanoparticles to be used in drug delivery and strategies for their uptake in tumor microenvironment and vasculature, including the reticuloendothelial system uptake and surface functionalization with protein corona. After a brief review of the classes of nanovectors, we have covered different classes of nanoparticles used in cancer therapies. First, the advances in the encapsulation of drugs (such as paclitaxel and fisetin) into nanoliposomes and nanoemulsions are described, as well as their relevance in current clinical trials. Then, polymeric nanoparticles are presented, namely the ones comprising poly lactic-co-glycolic acid, polyethylene glycol (and PEG dilemma) and dendrimers. The relevance of quantum dots in bioimaging is also covered, namely the systems with zinc sulfide and indium phosphide. Afterwards, we have reviewed gold nanoparticles (spheres and anisotropic) and their application in plasmon-induced photothermal therapy. The clinical relevance of iron oxide nanoparticles, such as magnetite and maghemite, has been analyzed in different fields, namely for magnetic resonance imaging, immunotherapy, hyperthermia, and drug delivery. Lastly, we have covered the recent advances in the systems using carbon nanomaterials, namely graphene oxide, carbon nanotubes, fullerenes, and carbon dots. Finally, we have compared the strategies of passive and active targeting of nanoparticles and their relevance in cancer theranostics. This review aims to be a (nano)mark on the ongoing journey towards realizing the remarkable potential of different nanoparticles in the realm of cancer therapeutics.
The development of green synthesized polymeric nanoparticles with anticancer studies has been an emerging field in academia and the pharmaceutical and chemical industries. Vegetable oils are potential substitutes for petroleum derivatives, as they present a clean and environmentally friendly alternative and are available in abundance at relatively low prices. Biomass-derived chemicals can be converted into monomers with a unique structure, generating materials with new properties for the synthesis of sustainable monomers and polymers. The production of bio-based polymeric nanoparticles is a promising application of green chemistry for biomedical uses. There is an increasing demand for biocompatible and biodegradable materials for specific applications in the biomedical area, such as cancer therapy. This is encouraging scientists to work on research toward designing polymers with enhanced properties and clean processes, containing oncology active pharmaceutical ingredients (APIs). The nanoencapsulation of these APIs in bio-based polymeric nanoparticles can control the release of the substances, increase bioavailability, reduce problems of volatility and degradation, reduce side effects, and increase treatment efficiency. This review discusses the use of green chemistry for bio-based nanoparticle production and its application in anticancer medicine. The use of castor oil for the production of renewable monomers and polymers is proposed as an ideal candidate for such applications, as well as more suitable methods for the production of bio-based nanoparticles and some oncology APIs available for anticancer application.
Polyhydroxyalkanoates (PHAs) are a family of natural microbial biopolyesters with the same basic chemical structure and diverse side chain groups. Based on their excellent biodegradability, biocompatibility, thermoplastic properties and diversity, PHAs are highly promising medical biomaterials and elements of medical devices for applications in tissue engineering and drug delivery. However, due to the high cost of biotechnological production, most PHAs have yet to be applied in the clinic and have only been studied at laboratory scale. This review focuses on the biosynthesis, diversity, physical properties, biodegradability and biosafety of PHAs. We also discuss optimization strategies for improved microbial production of commercial PHAs via novel synthetic biology tools. Moreover, we also systematically summarize various medical devices based on PHAs and related design approaches for medical applications, including tissue repair and drug delivery. The main degradation product of PHAs, 3-hydroxybutyrate (3HB), is recognized as a new functional molecule for cancer therapy and immune regulation. Although PHAs still account for only a small percentage of medical polymers, up-and-coming novel medical PHA devices will enter the clinical translation stage in the next few years.
Polyhydroxyalkanoates (PHAs) are polyesters synthetized by microorganisms or a chemical synthetic route with inherent chemical and physical properties comparable to conventional non-biodegradable polymers but a less environmental impact. Furthermore, the new generations of PHAs have found engineering and specialties applications in biotechnological sector, biomedical for tissue engineering, drug delivery, etc. Similarly, synthesis, processing and recycle of PHAs involves processes that helps to change until a circular and green economy. Nevertheless, the low cost-effectiveness associated with fermentation and downstream processing for recovery and purification of PHAs after biopolymerization are one of the issues that remains. Additionally, PHAs offer several mechanical behaviors from hard to elastic due to partial crystallinity, wide values in glass transition temperature, variety of structures of repeating units, as well as several additives and fillers to design tailor-made properties. Moreover, PHAs are usually blended with other biodegradable polymers searching synergistic interactions (e.g., in mechanical, biodegradability, barrier properties, etc.) through miscibility modification and microdomains interactions for the diversification of their applications. Eventually, single use products of PHAs for packing could improve the managing plastics waste through reach short times of biodegradation, a carbon neutrality and the use of some residues and contaminants sources as raw materials for PHAs synthesis.
Chitin is a bio-based and biodegradable polymer since it is the second most abundant natural polysaccharide on earth after cellulose. It is composed of N-acetyl-d-glucosamine, and it is found in different organisms such as in the exoskeleton of crustacean, insects, annelids, mollusks, plants, and some microorganisms. On the other hand, Chitosan is generally obtained by the controlled deacetylation of chitin in the presence of alkali, composed of randomly distributed β-(1–4) linked d-glucosamine (deacetylated unit) and N-acetyl-d-glucosamine (acetylated unit). Chitin and chitosan are different based on the degree of deacetylation. These polysaccharides possess different physicochemical and biological properties which has been modified and/or improved thanks to the development of chitin and chitosan nanocomposites. There are various methods for the development of chitin and chitosan-based nanocomposites, including solvent casting, spray coating, layer-by-layer, and extrusion. Also, it has been combined with different nano compounds to obtain these nano composites. This chapter summarizes some of the most important technologies involved in synthesizing chitin and chitosan nanocomposites, as well as the study of its physicochemical and biological properties, its production costs and ending in the analysis and discussion of the applications that these materials have in various fields.
Regenerative medicine has sought new alternatives of materials capable of being used in humans for different purposes, with low or no cytotoxicity, ability to adapt to the body and mainly biodegradation. In this sense, polymeric nanocomposites based on biodegradable polymers have shown a high level of acceptance for this application. Among the most promising biodegradable polymers are polylactic acid (PLA), polyvinyl alcohol (PVA), polyhydroxybutyrate (PHB), polyhydroxyalkanoates (PHAs); which have served as a support or matrix, nevertheless, they lack molecular signals to respond to stimuli from the receiving organism, due to this, different biopolymers have been used such as chitosan, chitin, cellulose, collagen, alginate and combinations of them, to improve the biological response and generate a synergy effect. Biodegradable nanocomposites have been a sensitive topic due to the implications involved in the incorporation and subsequent release of by-products of the degradation of the polymeric material, therefore, it is of great interest to study the possible mechanisms of biodegradation in in vitro and in vivo environments and the response at the cellular level due to the presence of metabolites from the biodegradation of the support matrix, on the immune response within the organism.
Nanofibers have attracted significant interest due to their unique properties such as high specific surface area, high aspect ratio, and spatial interconnectivity. Nanofibers can exhibit multifunctional properties and unique opportunities for promising applications in a wide variety of fields. Hierarchical design strategies are being used to prescribe the internal structure of nanofibers, such as core-sheath, concentric layers, particles distributed randomly or on a lattice, and co-continuous network phases. This review presents a comprehensive overview of design strategies being used to produce the next generation of nanofiber systems. It includes a description of nanofiber processing methods and their effects on the nano- and microstructure. Physico-chemical effects, such as self-assembly and phase separation, on the ultimate morphology of fibers made from designed emulsions, polymer blends, and block copolymers, are then described. This review concludes with perspectives on existing challenges and future directions for hierarchical design strategies to produce internally structured nanofibers.
The utilization of biomaterials in the human body was first practiced several years ago to restore normal functional activities by replacing the impaired organs with bio-inspired materials without devastating the cells and tissues. Today, many advanced technologies are reported to be worthwhile to effectively prepare different categories of biomaterials with amplified properties and characteristics for therapeutic applications. When considering the prosperous aspects of biomaterials, keratin has proved to be a fascinating material and has allured many researchers in various novel scientific studies, especially in drug delivery systems. Keratin is a naturally derived fibrous protein with cysteine, proline, serine, and glycine as the main amino acid constituents and has been found to have remarkable properties. Although keratin exhibits excellence and loss of distinction, it is utilized effectively in drug delivery for treating various diseases. Certainly, keratin nanoparticles (KNPs) showed remarkable features, such as optimistic surface area, good encapsulation efficiency, and controlled release of drugs. However, there is a need for more research to know about the cell interaction with keratin nanoparticles in novel drug delivery management. Indeed, certain biological and mechanical factors in alpha and beta keratins are still ambiguous, and higher attentiveness is required. The major purpose of this review is to assess the prospective utility and outstanding features of keratin nanoparticles in drug delivery systems. Keratin types, source of extraction, and properties are reviewed in this article. The characteristics and development of KNP are highlighted. Furthermore, the importance of nanoparticles in drug delivery, drug release mechanisms, challenges, and the need for future research are discussed.
Targeted drug delivery systems that selectively deliver anticancer drugs to tumour cells have always been a field of interest to reduce side effects associated with chemotherapy in cancer patients. Cancer cells require nutrients for their multiplication; folic acid is one such nutrient. Expression of folate receptors is negligible in normal cells, whereas they are overexpressed in a variety of cancer cells. A number of studies have shown that selective targeting of folate receptors in cancer is a beneficial approach, as folate targeted anticancer conjugates are selective towards cancer cells, thereby sparing non-cancerous cells. In this review, we have discussed folate receptor, folic acid as a cancer targeting moiety, different folate targeted anticancer drug conjugates, and different folate conjugated nanodelivery systems. This summarized information may turn out to be valuable for researchers to design novel folate targeted anticancer drug delivery systems having the potential to reduce the drawbacks associated with conventional cancer therapeutics.
For the past few years, nanotechnology applications play an emerging field in various sectors like agricultural, electronics, textile, biomedical and drug delivery, etc. Developing nanoparticle drug therapy in cancer treatment is a new generation capable of therapy to be used with the other biological, biophysical, and biomedical barriers that the body stages against a standard intervention. In general, nanoparticles are defined as small microparticles that range between 1 and 100 nm. Nanotechnology is a developing area that has gained tremendous interest in the medical field. Nanotechnology may also lead to detect diseases like cancer much earlier than ever imaginable. This attention to developing nanodrug delivery systems is already in medical treatment, especially in cancer therapy. The expansion of nanoparticles drug delivery at a constant rate into cancer cells may deliver better efficiency and less toxicity in primary and advanced cancer tumors treatment. Because of its small size and modifiability, nanoparticles showed more potential in cancer therapy by selectively gaining access to tumors. The preparation of nanoparticles takes benefit in basic cancer morphology and development methods such as the rapid proliferation of cells, antigen expression, and leaky tumor vasculature. In cancer therapy and detection, the nanoparticles aid the several targeted functions in thermotherapy, immunotherapy, chemotherapy, photodynamic therapy, radiotherapy, antiangiogenesis, and immunodetection. In tumor targeting and supporting to cross the biophysical barriers such as the blood-brain barrier, decreasing peripheral effects and developing the absolute quantity of drug reaching in the brain. This chapter highlights the various classes of targeting nanoparticles for detection, analysis, and cancer treatment. We also reviewed the emerging technologies and available nanodrugs for cancer therapy in the present market and discussed the advances and drawbacks of passive and targeted delivery.
Quantum dots are the most innovative molecules created in the modern era. These molecules are of nano-size ranged from 1-10 nm with unique photoluminescence characteristics. The unique properties of luminescence madethem an excellent candidate for cellular labelling and detection markers. The fabrication by conjugating with a library of biomolecules opened the gates for various innovative bioimaging and diagnostic protocols and drugdelivery systems. Having these versatile properties, QDs are originating as next-generation bio-nanotechnological tools for mankind to answer many biomedical issues in the fields of diagnosis and treatment. In this book chapter, a comprehensive discussion was made on the QDs, and their critical physico-optical characteristics, and their application in bioimaging, diagnosis, and drug targeting. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.
Because of their biodegradability, compostability, compatibility and flexible structures, biodegradable polymers such as polyhydroxyalkanoates (PHA) are an important class of biopolymers with various industrial and biological uses. PHAs are thermoplastic polyesters with a limited processability due to their low heat resistance. Furthermore, due to their high crystallinity, some PHAs are stiff and brittle. These features result sometimes in very poor mechanical characteristics with low extension at break values which limit the application range of some natural PHAs. Several in vivo approaches for PHA copolymer modifications range from polymer production to enhance PHA-based material performance after synthesis. The methods for enzymatic and chemical polymer modifications are aiming at modifying the structures of the polyesters and thereby their characteristics while retaining the biodegradability. This survey illustrates the efficient use of enzymes and chemicals in post-synthetic PHA modifications, offering insights on these green techniques for modifying and improving polymer performance. Important studies in this sector will be reviewed, as well as chances and obstacles for their stability and hyper-production.
Polyhydroxyalkanoates (PHAs) are storage granules found in bacteria that are essentially hydroxy fatty acid polyesters. PHA molecules appear in variety of structures, and amongst all types of PHAs, polyhydroxybutyrate (PHB) is used in versatile fields as it is a biodegradable, biocompatible, and ecologically safe thermoplastic. The unique physicochemical characteristics of these PHAs have made them applicable in nanotechnology, tissue engineering, and other biomedical applications. In this review, the optimization, extraction, and characterization of PHAs are described. Their production and application in nanotechnology are also portrayed in this review, and the precise and various production methods of PHA-based nanoparticles, such as emulsion solvent diffusion, nanoprecipitation, and dialysis are discussed. The characterization techniques such as UV-Vis, FTIR, SEM, Zeta Potential, and XRD are also elaborated.
There is much interest in biodegradable polymers for different uses and polyhydroxyalkanoates (PHAs) have potential applications in a broad range of areas from food packaging to biomedical applications. The book will provide a comprehensive overview of the recent accomplishments in the area of polyhydroxyalkanoates providing a resource that helps find solutions to both fundamental and applied problems.
The book introduces polyhydroxyalkanoates including their biosynthesis, recovery and extraction followed by specific chapters on blends, composites and nanocomposites. The book finishes with the applications of the materials including additives in paints, adhesives, production of plastics as well as tissue engineering and drug delivery.
The book provides a reference for students and researchers in chemistry, polymer science, materials science, biotechnology and life sciences working in the field of bio-based and biodegradable polymers and composites as well as those interested in its applications.
There is much interest in biodegradable polymers for different uses and polyhydroxyalkanoates (PHAs) have potential applications in a broad range of areas from food packaging to biomedical applications. The book will provide a comprehensive overview of the recent accomplishments in the area of polyhydroxyalkanoates providing a resource that helps find solutions to both fundamental and applied problems.
The book introduces polyhydroxyalkanoates including their biosynthesis, recovery and extraction followed by specific chapters on blends, composites and nanocomposites. The book finishes with the applications of the materials including additives in paints, adhesives, production of plastics as well as tissue engineering and drug delivery.
The book provides a reference for students and researchers in chemistry, polymer science, materials science, biotechnology and life sciences working in the field of bio-based and biodegradable polymers and composites as well as those interested in its applications.
Molecularly imprinted membranes that demonstrated high selectivity for celecoxib were synthesized using N-vinylcaprolactam and 2-Hydroxyethyl methacrylate functional monomers, crosslinking with the ethylene glycol dimethacrylate and, 2,2′-azobisisobutyronitrile as the initiator. The obtained polymeric membrane was characterized using attenuated total reflection Fourier transmission infrared spectroscopy technique and scanning electron microscopy and was employed as a solid-phase extraction medium for extraction of celecoxib from biological and pharmaceutical samples. The effects of pH, contact time on the sorption, capacity of polymeric sorbent, and interfering drugs were investigated as critical analytical parameters. Several models, including Longmuir, Temkin, Freundlich, and Redlich-Peterson, were used to study the equilibrium adsorption data of celecoxib on the polymeric sorbent. The developed method was utilized to determine the concentration of celecoxib in pharmaceutical and biological samples. The results of extraction recoveries for celecoxib in urine, plasma, and drug matrix were more than 93.3%, 90.7%, and 87.2%, respectively. The analytical determination revealed that the limit of detection and limit of quantification of celecoxib were 0.9 and 3.0 ng mL-1, respectively. Accordingly, the experiments indicated that the proposed molecularly imprinted membranes showed high selectivity to celecoxib and can be used for sensing the presence of celecoxib in biological samples.
Requisite of contriving strategies for mitigating polymeric waste generated in Nature via synthetic polymers has conceded in development of biopolymers like poly(hydroxybutyrate) (PHB), poly(hydroxyvalerate) (PHV), poly(lactic acid) (PLA) etc. Amongst all these biopolymers, PHB and its assorted homologues have sought more attention from scientific researchers due to their non-toxic nature coupled with their intrinsic biodegradability as well as biocompatibility. Concurrently, they also demonstrate ease of production via microbial fermentation and closely analogous physical traits against their synthetic counterparts utilized in biomedical sector. Researchers have extensively exploited PHB and its amalgams for an array of biomedical functions extending from carriers for drug delivery to scaffolds in tissue engineering to resorbable medical devices like cardiovascular grafts and so on. Additionally, advancement of science and technology in recent times has realized in utilization of PHB and its various derivatives as chemoembolizing agents as well as carriers of encapsulated drugs in nanomedicine sector for cancer treatment functions. PHB and its derivative polymeric systems have been extensively explored and probed, however, no amalgamated information on their effective utilization in cancer treatment applications is available as such. Within this review, we consolidate and discuss current progress and strategies of PHB and its copious amalgams from available literature, while concurrently outlining their future potential for implementation in cancer treatment as nano-carriers for therapeutic agents.
Molecularly imprinted polymers have exhibited good performance as carriers on drug loading and sustained release. In this paper, vinblastine (VBL) loaded polymeric nanoparticles (VBL-NPs) were prepared by one-step molecular imprinting process, avoiding the waste and incomplete removal of template, and evaluated as targeting carriers for VBL delivery after modification. Using acryloyl amino acid co-monomers and disulfide cross-linkers, VBL-NPs were synthesized and then conjugated with polyethylene glycol-folate. The dynamic size of obtained VBL-NPs-PEG-FA was 258.3nm (PDI=0.250), and the encapsulation efficiency was 45.82±1.45%. The nanoparticles of VBL-NPs-PEG-FA were able to completely release VBL during 48h under mimic tumor intracellular condition (pH4.5, 10mM glutathione (GSH)), displaying significant redox responsiveness, while the release rates were much slower in mimic body liquid (pH7.4, 2μM GSH) and tumor extracellular environment (pH6.5, 2μM GSH). Furthermore, the carriers NPs-PEG-FA, prepared without VBL, showed the satisfactory intrinsic haemocompatibility, cellular compatibility and tumor targeting properties: it could rapidly and efficiently accumulate to folate receptor (FR) positive Hela cells and then internalized via receptor-mediated endocytosis, and the retention in tumor tissues could last for over 48h. Interestingly, VBL-NPs-PEG-FA could evidently increase the accumulation of VBL in tumor tissue while decrease the distribution of VBL in organs, exert the similar anticancer efficacy against Hela tumors in xenograft model of nude mice to VBL injection, and significantly improve the abnormality of liver and spleen observed in VBL injection. VBL-NPs-PEG-FA is potential to be delivery carrier for VBL with enhancing tumor targeting efficacy of VBL and decreasing toxicity to normal tissues.
Production of polyhydroxyalkanoates (PHA) by bacteria isolated from spent engine oil (SEO) contaminated soils was investigated using nitrogen limitation in the production medium. Out of ten isolates, three were selected as the best based on their ability to metabolize SEO effectively and fluoresce orange when stained with Nile Blue A dye. Fourier Transform Infrared spectrophometer was used as a confirmatory test for PHA detection by tracking the carbonyl bands on the spectra. Optimum growth of the isolates occurred at 1% (v/v) SEO, pH 7, 37°C for K1+VE and Kar5+VE1 while for Kar5+VE2 was at 1% (v/v) SEO, PH 7, 40°C and 150 RPM. Sequencing of 16S rDNA partial genes grouped the isolates into 6 different genera: Ochrobactrum, Pseudoxanthomonas, Bodetella, Achromobacter, Alcaligenes and Acinetobacter species. Isolate K1+VE, identified as an Ochrobactrum produced Poly (3-hydroxyheptanoate) 46% (w/w), isolate Kar5+VE1, identified as Achromobacter spp. produced poly (3-hydroxybutyrate) 20% (w/w)) while isolate Kar5+VE2, identified as an Alcaligenes spp. produced a co-polymer poly-3-(3-hydroxybutyrate-Co-3-hydroxyoctanoate) 45% (w/w). Orthoxylene and ethylbenzene were the major hydrocarbons in spent engine oil before degradation while ethylhexanol was the major degradation product as identified by Gas Chromatography-Mass Spectrophotometry. The isolates were able to degrade hydrocarbons as well as produce polyhydroxyalkanoates.
Drug delivery systems based on biodegradable biomaterials have proved attractive to improve their efficacy. Biopolymers such as Polyhydroxyalkanoates (PHAs) have the potential to be used as materials for preparing nanoparticles as drug carriers. This review describes the recent developments in drug delivery systems based on PHAs derived from microbial fermentations. Various strategies for the synthesis of microspheres, encapsulations, nano-constructs, have been presented, with their potential applications in medical domain.
Flutamide (FLU) loaded onto functionalized magnetite iron oxide nanoparticles were prepared and characterized with scanning electron microscopy, elemental analysis, thermogravimetric analysis, Fourier transform infrared spectroscopy, and energy dispersive spectroscopy techniques. In addition, the effects of parameters of pH, temperature, contact time, and concentration on the adsorption capacity of nanoparticles were evaluated and optimized. The adsorption data were fitted to the Langmuir isotherm and the relevant parameters were inferred. Findings of the study suggested that N-vinylcaprolactam-allylimidazole copolymer coated MNPs are promising carrier for FLU delivery. The solid phase extraction technique was investigated for biological samples. Urine extraction recovery obtained about 91%.
The concept of targeted drugs is not new, but dates back to 1906 when Ehrlich1 first postulated the ‘magic bullet’. The durability of this concept is a strong indication of its appeal, but the ‘magic bullet’ continues to be a challenge to implement in the clinic. The challenge has been on three fronts: finding the proper target for a particular disease state; finding a drug that effectively treats this disease; and finding a means of carrying the drug in a stable form to specific sites while avoiding the immunogenic and nonspecific interactions that efficiently clear foreign material from the body. Nanoparticles are potentially useful as carriers of active drugs and, when coupled with targeting ligands, may fulfill many attributes of a ‘magic bullet’. This review focuses on targeted drug delivery using nanoparticles as a modality that couples a ligand to a nanosized, drug-loaded vehicle as a potential means to achieve increased efficacy of a drug at the site of interest.
The folate receptor is overexpressed in a broad spectrum of malignant tumors and represents an attractive target for selective delivery of anticancer agents to folate receptor-expressing tumors. This study examines folate-lipid conjugates as a means of enhancing the tumor selectivity of liposome-encapsulated drugs in a mouse lymphoma model. Folate-derivatized polyethylene glycol (PEG3350)-distearoyl-phosphatidylethanolamine was post-loaded at various concentrations into the following preparations: radiolabeled PEGylated liposomes, PEGylated liposomes labeled in the aqueous compartment with dextran fluorescein, and PEGylated liposomal doxorubicin (PLD, Doxil). We incubated folate-targeted radiolabeled or fluorescent liposomes with mouse J6456 lymphoma cells up-regulated for their folate receptors (J6456-FR) to determine the optimal ligand concentration required in the lipid bilayer for liposomal cell association, and to examine whether folate-targeted liposomes are internalized by J6456-FR cells in suspension. Liposomal association with cells was quantified based on radioactivity and fluorescence-activated cell sorting analysis, and internalization was assessed by confocal fluorescence microscopy. We found an optimal ligand molar concentration of approximately 0.5% using our ligand. A substantial lipid dose-dependent increase in cell-associated fluorescence was found in folate-targeted liposomes compared with nontargeted liposomes. Confocal depth scanning showed that a substantial amount of the folate-targeted liposomes are internalized by J6456-FR cells. Binding and uptake of folate-targeted PLD by J6456-FR cells were also observed in vivo after i.p. injection of folate-targeted PLD in mice bearing ascitic J6456-FR tumors. The drug levels in ascitic tumor cells were increased by 17-fold, whereas those in plasma were decreased by 14-fold when folate-targeted PLD were compared with nontargeted PLD in the i.p. model. Folate-targeted liposomes represent an attractive approach for the intracellular delivery of drugs to folate receptor-expressing lymphoma cells and seem to be a promising tool for in vivo intracavitary drug targeting.
The porous P (HB-HO) scaffold materials were prepared with particle-leaching/freeze-drying method and were evaluated by SEM observation, porosity and mechanical assessment, degradability in vitro and cellular compatibility. The results showed that P (HB-HO) scaffold had a good pore interconnectivity with porosity 50%-90% and compressive strength 1.7-6.2MPa. Its degradation rate reached about 20% until the 12th week. MC3T3-E1 could adhere to the surface and inner walls of it, proliferated well. It was demonstrated that the new porous P (HB-HO) had superordinary physico-chemical properties and cellular compatibility, and so it is promising to be a bone tissue engineering scaffold with clinical value.
The biocompatibility of poly(3-hydroxybutyrate-co-hydroxyocatanoate) [P(HB-HO)], a new biodegradable co-polymer scaffold, was evaluated with a series of tests, including cytotoxicity test, acute systemic toxicity test, hemolysis test, pyrogen test, genetic toxicity test, intracutaneous stimulation test and subcutaneous implantation test. The results indicated that, P(HB-HO) and its leaching liquor co-cultured with mouse osteoblasts was nontoxic, the growth and morphology of the cultured cells were well, and the cell number was increased; No acute systemic toxicity was observed; Hematolysis rate was 1.67%, which was in accordance with the standard of ISO (<5%); No pyrogen reaction occurred after the injection into auricular vein of the rabbits; There was no skin irritantation reaction found in rabbits after intracutaneous injection; Tail vein injection in mice did not induce genetic toxicity; The P(HB-HO) implanted in mice subcutaneously for 12 weeks did not cause inflammation reactions. These results all reveal the good biocompatibility of P(HB-HO).
A novel synthetic gene transfer vector system is developed based on targeting to the folate receptor. The folate receptor is a cellular marker overexpressed in over 90% of ovarian carcinomas and large percentages of other human tumors. Folic acid is a high affinity ligand for the folate receptor that retains its binding affinity upon derivatization at its gamma carboxyl. Folate conjugation, therefore, presents a novel strategy for tumor-specific targeted drug delivery. In the current study, we investigated novel folate conjugates of the cationic polymer polyethylenimine (PEI), for potential applications in receptor-mediated gene delivery. Unmodified PEI (M.W. 25,000) forms charge complexes with plasmid DNA carrying the luciferase reporter gene and was capable of cellular transfection, the efficiency of which depends on charge ratio (N/P ratio). Folate directly attached to PEI did not alter the transfection activity of its DNA complex compared to unmodified PEI. Modification of PEI by polyethyleneglycol (PEG) partially inhibited gene delivery. Attaching a folate to the distal terminus of PEG-modified PEI greatly increased the transfection activity in cultured folate receptor-positive human oral carcinoma KB cells at all N/P ratios. This increase was partially blocked by coincubation with 200 μM free folic acid, suggesting the involvement of folate receptor in gene transfer. Targeted synthetic vectors based on cationic polymer-folate conjugate may be useful in the tumor-specific delivery of therapeutic genes.
In vitro degradation of three-dimensional composite scaffolds made from poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and wollastonite has been investigated up to 15 weeks in phosphate buffered saline (PBS) solution at 37°C. Weight loss, water absorption, pH of the PBS and molecular weight measurements were used to monitor the degradation of the scaffolds. The results showed that the addition of wollastonite into PHBV scaffolds resulted in an increase of the water absorption and weight loss as compared to that of the pure PHBV scaffolds. However, the polymer molecular weight in the pure PHBV scaffolds was found to decrease more rapidly than that of the PHBV in the composite scaffolds. This delayed degradation in the composite scaffolds was caused probably by the dissolution of alkaline ions from the wollastonite, which resulted in a buffering effect to the acidification of the PBS due to the acid degradation products of PHBV. These results suggested that the addition of wollastonite into polymer might be a useful method to adjust the degradation rate of the composite scaffolds for special applications in tissue engineering.
Injectable blood persistent particulate carriers have important therapeutic application in site-specific drug delivery or medical imaging. However, injected particles are generally eliminated by the reticulo-endothelial system within minutes after administration and accumulate in the liver and spleen. To obtain a coating that might prevent opsonization and subsequent recognition by the macrophages, sterically stabilized nanospheres were developed using amphiphilic diblock or multiblock copolymers. The nanospheres are composed of a hydrophilic polyethylene glycol coating and a biodegradable core in which various drugs were encapsulated. Hydrophobic drugs, such as lidocaine, were entrapped up to 45 wt% and the release kinetics were governed by the polymer physico-chemical characteristics. Plasma protein adsorption was drastically reduced on PEG-coated particles compared to non-coated ones. Relative protein amounts were time-dependent. The nanospheres exhibited increased blood circulation times and reduced liver accumulation, depending on the coating polyethylene glycol molecular weight and surface density. They could be freeze-dried and redispersed in aqueous solutions and possess good shelf stability. It may be possible to tailor "optimal" polymers for given therapeutic applications.
Nanoparticles of Poly(L-glutamic acid) (PG) conjugated to the anticancer drug paclitaxel and targeted moiety folic acid (FA) were synthesized and characterized in vitro. The nanoparticles were designed to take advantage of FA targeting to folate receptor (FR) positive cancer cells. The chemical composition of the conjugate was characterized by 1 H-NMR, FTIR and UV/vis spectroscopy. The selective cytotoxicity of the FA-PG-paclitaxel con-jugates was evaluated in FR positive cancer cells. The interaction of the conjugate was visualized by fluorescence microscopy with results confirming the successful preparation of the conjugate and the production of nanoparticles of about 200-300 nm in diameter. The amount of paclitaxel conjugated to FA-PG was 25% by weight. Cellular uptake of the conjugate was FA dependent, and the conjugate uptake was mediated specifically by the folate receptor. These results demonstrate the improved selective toxicity and effective delivery of an anticancer drug into FR bearing cells in vitro.
Receptors for the vitamin folic acid are frequently overexpressed on epithelial cancer cells. To examine whether this overexpression might be exploited to specifically deliver liposome-encapsulated drug molecules in vitro, folate-targeted liposomes were prepared by incorporating 0.1 mol% of a folate-polyethyleneglycol-distearoylphosphatidylethanolamine (folate-PEG-DSPE) construct into the lipid bilayer, and were loaded with doxorubicin (DOX), an anti-cancer drug. Uptake of folate-PEG-liposomal DOX by KB cells was 45-fold higher than that of non-targeted liposomal DOX, and 1.6-times higher than that of free DOX, while the cytotoxicity was 86 and 2.7-times higher, respectively. Folate-targeting is fully compatible with PEG-coating of the liposomes, since incorporation of 4 mol% PEG2000-DSPE does not reduce the uptake or cytotoxicity of folate-PEG-liposomal DOX. Uptake of folate-PEG-liposomes was inhibited by 1 mM free folic acid but was unaffected by physiological concentrations of folate. In HeLa/W138 co-cultures, folate-PEG-liposomes encapsulating calcein, a fluorescent dye, were found to be almost exclusively internalized by the HeLa cells which overexpress the folate receptors. We suggest that folate targeting constitutes a possible mechanism for improving the specificity of PEG-coated liposomes for cancer cells.
A system of nanoparticles of mixed lipid monolayer shell and biodegradable polymer core was developed for targeted delivery of anticancer drugs with Docetaxel as a model drug, which provide targeting versatility with a quantitative control of the targeting effect by adjusting the lipid component ratio of the mixed lipid monolayer, and combine the advantages and avoid disadvantages of polymeric nanoparticles and liposomes in drug delivery. X-ray photoelectron spectroscopy (XPS) confirmed the coating of the mixed lipid monolayer on the polymeric core. Fluorescent microscopy proved the targeting efficacy of the folic acid conjugated on the mixed lipid monolayer for the cancer cells of over expression of folate receptors. The folic acid conjugated nanoparticles of mixed lipid monolayer shell and biodegradable polymer core were proved to possess sustainable, controlled and targeted delivery of anticancer drugs with Docetaxel as a model drug, which may provide a drug delivery system of precise control of the targeting effect.
Doxorubicin (DOX) is an anthracycline antibiotic widely used in cancer chemotherapy. Its use is limited by cardiac toxicity and drug resistance. Hyperthermia can aid the functionality of DOX, but current hyperthermia delivery methods are hard to apply selectively and locally. The slow temperature increase associated with the external heating may lead to thermal tolerance in cancer cells. The FDA approved dye indocynine green (ICG) has been demonstrated to absorb near-infrared (NIR) light at 808 nm (ideal for tissue penetration) and emit the energy as heat, making it an ideal agent for localized hyperthermia with a rapid rate of temperature increase. The purpose of this study was to investigate the in vitro cytotoxic effect of combined chemotherapy and hyperthermia to a DOX resistant ovarian cancer cell line (SKOV-3). The effect of two different heating methods, ICG induced rapid rate heating and an incubator induced slow rate heating, were compared. All the experiments were conducted in 96-well plates. Cells were subjected to different concentrations of DOX and 60 min 43 °C incubation or 5 μM of ICG with 1 min 808 nm NIR laser. SRB assay was used to measure cell proliferation. ICG itself without laser irradiation was not toxic to SKOV-3 cells. The two types of hyperthermia individually produced similar cytotoxicity. DOX by itself was toxic with an IC50 value of about 5 μM. Hyperthermia in combination with DOX achieved significantly greater cell killing/growth inhibition at all DOX concentrations compared to DOX alone. A subadditive cytotoxic effect was observed by combining DOX and 60 min 43 °C incubation which lead to a lowered DOX IC50 value of about 1 μM. This value was even lower with 1 min laser-ICG photothermotherapy (0.1 μM) and, though not statistically significant, a synergistic effect may exist between DOX and laser-ICG photothermotherapy. The rate of heating may have an effect on chemotherapy–hyperthermia interaction. In conclusion, the combination of photothermal therapy and chemotherapy may provide a valuable tool for cancer treatment with minimized side effect.
RNA interference (RNAi) is a sequence-specific gene-silencing mechanism triggered by synthetic small interfering RNA (siRNA), and is utilized in a wide range of fields including cancer gene therapy by down-regulating a specific target protein. In this study, for tumor-targeted siRNA delivery, we developed a folate-linked nanoparticle (NP-F), and evaluated the potential of NP-F-mediated tumor gene therapy in human nasopharyngeal KB cells, which overexpressed folate receptor (FR). NP-F was composed of cholesteryl-3beta-carboxyamidoethylene-N-hydroxyethylamine (OH-Chol), Tween 80 and folate-poly(ethylene glycol)-distearoylphosphatidylethanolamine conjugate (f-PEG(2000)-DSPE), and NP-P was substituted f-PEG(2000)-DSPE in NP-F PEG(2000)-DSPE for a non-targeting nanoparticle. The NP-F and siRNA complex (nanoplex) formed at a charge ratio (+/-) of 2/1 in the presence of 5mM NaCl was injectable size and increased transfection efficiency in the cells. NP-F showed a significantly higher intracellular amount of siRNA and stronger localization of siRNA in the cytoplasm than NP-P. When Her-2 siRNA was transfected into cells by NP-F and NP-P, NP-F significantly inhibited tumor growth, and selectively suppressed Her-2 protein expression more than NP-P. In in vivo gene therapy, a NP-F nanoplex of Her-2 siRNA by intratumoral injection significantly inhibited tumor growth of KB xenografts compared with control siRNA, but a NP-P nanoplex did not. These results of the experiments have provided optimal conditions to form folate-linked nanoparticle complexes with siRNA for folate-targeted gene therapy.
The purpose of this study was to develop polymeric nano-carriers of doxorubicin (DOX) that can increase the therapeutic efficacy of DOX for sensitive and resistant cancers. Towards this goal, two polymeric DOX nano-conjugates were developed, for which the design was based on the use of multi-functionalized poly(ethylene oxide)-block-poly(epsilon-caprolactone) (PEO-b-PCL) micelles decorated with alphavbeta3 integrin-targeting ligand (i.e. RGD4C) on the micellar surface. In the first formulation, DOX was conjugated to the degradable PEO-b-PCL core using the pH-sensitive hydrazone bonds, namely RGD4C-PEO-b-P(CL-Hyd-DOX). In the second formulation, DOX was conjugated to the core using the more stable amide bonds, namely RGD4C-PEO-b-P(CL-Ami-DOX). The pH-triggered drug release, cellular uptake, intracellular distribution, and cytotoxicity against MDA-435/LCC6(WT) (a DOX-sensitive cancer cell line) and MDA-435/LCC6(MDR) (a DOX-resistant clone expressing a high level of P-glycoprotein) were evaluated. Following earlier in vitro results, SCID mice bearing MDA-435/LCC6(WT) and MDA-435/LCC6(MDR) tumors were treated with RGD4C-PEO-b-P(CL-Hyd-DOX) and RGD4C-PEO-b-P(CL-Ami-DOX), respectively. In both formulations, surface decoration with RGD4C significantly increased the cellular uptake of DOX in MDA-435/LCC6(WT) and MDA-435/LCC6(MDR) cells. In MDA-435/LCC6(WT), the best cytotoxic response was achieved using RGD4C-PEO-b-P(CL-Hyd-DOX), that correlated with the highest cellular uptake and preferential nuclear accumulation of DOX. In MDA-435/LCC6(MDR), RGD4C-PEO-b-P(CL-Ami-DOX) was the most cytotoxic, and this effect correlated with the accumulation of DOX in the mitochondria. Studies using a xenograft mouse model yielded results parallel to those of the in vitro studies. Our study showed that RGD4C-decorated PEO-b-P(CL-Hyd-DOX) and PEO-b-P(CL-Ami-DOX) can effectively improve the therapeutic efficacy of DOX in human MDA-435/LCC6 sensitive and resistant cancer, respectively, pointing to the potential of these polymeric micelles as the custom-designed drug carriers for clinical cancer therapy.
A major obstacle in the development of polymeric nanoparticles (NPs) as effective drug delivery vesicles is the rapid clearance from blood. In order to realize a significant prolongation in blood circulation, a combinatorial design, covalent attachment of polyethylene glycol (PEG) to polylactic acid (PLA) and physical adsorption of water-soluble chitosan (WSC) to particle surface, has been developed for surface modification of PLA NPs. Two types of WSC, cationic partially deacetylated chitin (PDC) and anionic N-carboxy propionyl chitosan sodium (CPCTS) were investigated. All the NPs formulated in the size range of 100-200nm were prepared by a modified w/o/w technique and physicochemically characterized. In vitro phagocytosis by mouse peritoneal macrophage (MPM), in vivo blood clearance and biodistribution following intravenous administration in mice, of these NPs labeled with 6-coumarin, were evaluated. The presence of WSC, whether alone or with PEG, highly improved the surface hydrophilicity as well as suspension stability of NPs. Their surface charge was greatly affected by the WSC coating, being close to neutrality for PEG/PDC NPs and highly negative in the case of PEG/CPCTS NPs. In comparison to NPs treated with PEG or WSC alone, the synergistic action of PEG and WSC strongly inhibited the macrophage uptake and extended the circulation half-life (t(1/2)) with concomitant reduced liver sequestration. Particularly, PEG/PDC NPs showed the most striking result with regard to their performance in vitro and in vivo. Calculated t(1/2) of PEG/PDC NPs and PEG/CPCTS NPs was 63.5h and 7.1h, respectively, much longer than that of control PEG/PVA NPs (1.1h). More WSC materials need to be evaluated, but the present data suggest that, a combinatorial coating of PEG and PDC greatly prolongs the systemic circulation of NPs and represents a significant step in the development of long-circulating drug delivery carriers.
We developed a new strategy to prepare folate-decorated nanoparticles of biodegradable polymers for Quantum dots (QDs) formulation for targeted and sustained imaging for cancer diagnosis at its early stage. Poly(lactide)-vitamin E TPGS (PLA-TPGS) copolymer and vitamin E TPGS-carboxyl (TPGS-COOH) copolymer were synthesized. Their blend at various weight ratio was used to prepare folate-decorated nanoparticles (NPs) for QDs formulation to improve their imaging effects and reduce their side effects. The TPGS-COOH on the NP surface was designed to conjugate folate-NH(2) with advantage to make the targeting effect adjustable. The size of such NPs was found in the range of 280-300nm. In vitro cellular uptakes of such NPs were investigated with confocal laser scanning microscopy (CLSM), which demonstrated much higher internalization of the folate-decorated QDs-loaded PLA-TPGS/TPGS-COOH NPs by MCF-7 breast cancer cells which are of over-expression of folate receptors than the cellular uptake by NIH 3T3 fibroblast cells which are of low expression of folate receptors. Compared with the free QDs, the QDs formulated in the PLA-TPGS/TPGS-COOH NPs showed lower in vitro cytotoxicity for both of MCF-7 cells and NIH 3T3 cells. Additionally, our findings indicated that under same conditions, cytotoxicity of QDs formulated in the PLA-TPGS/TPGS-COOH NPs is lower for normal cells such as NIH 3T3 cells than that for breast cancer such as MCF-7 breast cancer cells due to folate targeting effect. Targeted imaging by QDs formulated in folate-decorated PLA-TPGS/TPGS-COOH nanoparticles with better effects and less side effects is feasible.
The capacity of doxorubicin to inhibit topoisomerase II in the MCF-7 breast tumor cell line is supported by the induction of protein-associated single-strand breaks in DNA, as well as by interference with the decatenation activity of nuclear extracts. Doxorubicin also produces non-protein-associated DNA strand breaks (at a supraclinical concentration of 5 microM), which may indicate damage mediated via the generation of free radicals. However, no strand breaks are detected in DNA of MCF-7 cells at the IC50 for doxorubicin (approximately 0.1 microM). At doxorubicin concentrations of 0.05, 0.1, and 0.5 microM, at which growth is inhibited by approximately 15, 50, and 75%, respectively, doxorubicin interferes with radiation-induced unwinding of DNA; doxorubicin also produces a concentration-dependent inhibition of DNA synthesis that corresponds closely to growth inhibition. These studies suggest that DNA strand breaks fail to fully account for the antiproliferative activity of doxorubicin in the MCF-7 breast tumor cell line. Compromised DNA synthesis associated with interference with DNA unwinding may contribute to growth inhibition in MCF-7 cells exposed to doxorubicin.
Epidermal growth factor (EGF)-labeled cationic liposomes (EGF-liposomes) were prepared for efficient gene transfer vector to EGF receptor expressing cells. Transfection activity of EGF-liposomes associating plasmid PGV-C which encodes luciferase showed a 2-fold increase in EGF receptor expressing cells, HEC-1-A, compared to that of EGF-non-labeled liposomes (N-liposomes). In EGF receptor deficient HRA cells, however, both EGF- and N-liposomes exhibited low transfection efficiency and no difference was observed between them. Furthermore, by the addition of anti EGF receptor antibody, transfection efficiency of EGF-liposomes was suppressed, suggesting EGF receptor-mediated endocytosis of EGF-liposomes. Transfection activity of EGF-liposomes was strongly dependent on the concentrations of fusogenic lipid, dioleoylphospha-tidylethanolamine in liposomes. By X-gal staining 6-8% of GCH-1(m) cells which also had EGF receptor expressed beta-galactosidase activity following the transfection by EGF-liposomes associating pSV-beta-galactosidase. These findings indicate that EGF-liposomes could be a preferable vector for EGF-receptor expressing cells.
The receptor for the vitamin, folic acid, is overexpressed on a number of human tumors, including cancers of the ovary, kidney, uterus, testis, brain, colon, lung, and myelocytic blood cells. Conjugates of folic acid linked via its gamma-carboxyl to either a single drug molecule or assembly of molecules can bind to and enter receptor-expressing cancer cells via folate receptor-mediated endocytosis. Because the affinity of folate conjugates for cell surface folate receptors is high (KD approximately 10(-10) M), folic acid derivatization allows the selective delivery of diagnostic and therapeutic agents to cancer cells in the presence of normal cells. This review will summarize studies aimed at folate-mediated targeting of protein toxins, imaging agents, antisense oligodeoxynucleotides, genes, and liposomes specifically to cancer cells in vitro and in vivo.
Poly(DL-lactide co-glycolide) microparticles below 5 microm in size and containing ovalbumin (OVA), were prepared using the water-in oil-in water (w/o/w) technique with either polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP) as stabilisers in the external aqueous phase. PVP-stabilised microparticles exhibited higher protein loading (8.2%, w/w relative to 4.0% for PVA stabilised microparticles) and increased core loading (encapsulation) of protein (70% vs. 30% for the PVA system). The use of PVP instead of PVA to prepare microparticles also resulted in reduction in the initial burst release of OVA, together with sustained protein release over 28 days and an increase in the protein delivery capacity from 35 to 45 microg/mg particles. The changes in protein loading and delivery characteristics are considered to arise in part from an increase in the viscosity of the droplets of polymer solution, constituting the primary water-in oil emulsion, by diffusion of PVP from the external aqueous phase. Variation of the external aqueous phase surfactant provides a promising approach for improving the loading of therapeutic proteins and vaccine antigens within biodegradable microparticles and for modulating their release pattern.
Cationic lipids are being used increasingly as reagents for gene delivery both in vitro and in vivo. One of the limitations to the application of cationic lipid-DNA complexes (lipoplexes) in vivo is the inhibition of gene delivery by serum. In this study, we have shown that transferrin (Tf)-lipoplexes, which had transferrin adsorbed at their surface via electrostatic interactions, are much more effective than plain lipoplexes in transfecting cells in the presence of relatively high concentrations (up to 60%) of fetal bovine serum (FBS). Serum even enhanced transfection by Tf-lipoplexes composed of 1,2-dioleoyl-3-(trimethylammonium) propane (DOTAP)/dioleoylphosphatidylethanolamine (DOPE)/pCMVLacZ at high lipid/DNA (+/-) charge ratios, and inhibited lipofection for those with low charge ratios when they were added to the cells immediately after the preparation of complexes. The effect of serum on lipofection was dose-dependent. Preincubation of the complexes at 20 degrees C for 6 h led to serum resistance, even for the negatively charged transferrin-lipoplexes. A similar tendency was observed for DOTAP/cholesterol and DOTAP/DOPE/cholesterol liposomes. The percentage of cells transfected, measured by beta-galactosidase expression, also increased with the serum concentration. Cell viability was not affected significantly when the cells were incubated with the complexes for 4 h at 37 degrees C, followed by a 48-h incubation. Our findings extend the scope of previous studies where transferrin-lipoplexes were used to introduce DNA into cells, rendering these complexes and their future derivatives potential alternatives to viral vectors for gene delivery in vivo.
The folate receptor is a highly selective tumor marker overexpressed in greater than 90% of ovarian carcinomas. Two general strategies have been developed for the targeted delivery of drugs to folate receptor-positive tumor cells: by coupling to a monoclonal antibody against the receptor and by coupling to a high affinity ligand, folic acid. First, antibodies against the folate receptor, including their fragments and derivatives, have been evaluated for tumor imaging and immunotherapy clinically and have shown significant targeting efficacy in ovarian cancer patients. Folic acid, a high affinity ligand of the folate receptor, retains its receptor binding properties when derivatized via its gamma-carboxyl. Folate conjugation, therefore, presents an alternative method of targeting the folate receptor. This second strategy has been successfully applied in vitro for the receptor-specific delivery of protein toxins, anti-T-cell receptor antibodies, interleukin-2, chemotherapy agents, gamma-emitting radiopharmaceuticals, magnetic resonance imaging contrast agents, liposomal drug carriers, and gene transfer vectors. Low molecular weight radiopharmaceuticals based on folate conjugates showed much more favorable pharmacokinetic properties than radiolabeled antibodies and greater tumor selectivity in folate receptor-positive animal tumor models. The small size, convenient availability, simple conjugation chemistry, and presumed lack of immunogenicity of folic acid make it an ideal ligand for targeted delivery to tumors.
The aim of this paper was to evaluate the potential of chitosan nanoparticles as carriers for the anthracycline drug, doxorubicin (DOX). The challenge was to entrap a cationic, hydrophilic molecule into nanoparticles formed by ionic gelation of the positively charged polysaccharide chitosan. To achieve this objective, we attempted to mask the positive charge of DOX by complexing it with the polyanion, dextran sulfate. This modification doubled DOX encapsulation efficiency relative to controls and enabled real loadings up to 4.0 wt.% DOX. Separately, we investigated the possibility of forming a complex between chitosan and DOX prior to the formation of the particles. Despite the low complexation efficiency, no dissociation of the complex was observed upon formation of the nanoparticles. Fluorimetric analysis of the drug released in vitro showed an initial release phase, the intensity of which was dependent on the association mode, followed by a very slow release. The evaluation of the activity of DOX-loaded nanoparticles in cell cultures indicated that those containing dextran sulfate were able to maintain cytostatic activity relative to free DOX, while DOX complexed to chitosan before nanoparticle formation showed slightly decreased activity. Additionally, confocal studies showed that DOX was not released in the cell culture medium but entered the cells while remaining associated to the nanoparticles. In conclusion, these preliminary studies showed the feasibility of chitosan nanoparticles to entrap the basic drug DOX and to deliver it into the cells in its active form.
The blood vessels of individual tissues are biochemically distinct, and pathological lesions put their own signature on the vasculature. In tumors, both blood and lymphatic vessels differ from normal vessels. New methods, such as in vivo screening of phage libraries, have provided peptides and antibodies that recognize these vascular signatures and can be used in targeted delivery of therapeutic agents. Targeting a therapy to the diseased tissue enhances the efficacy of the treatment while reducing the side effects in mouse experiments. Results from drug delivery to tumor vessels have been particularly encouraging.
The objective of this study was to target drug delivery to radiation-induced neoantigens, which include activated receptors within the tumor vasculature. These responses include posttranslational changes in pre-existing proteins, which can be discovered by phage-displayed peptide libraries administered to mice bearing irradiated tumors. Phage-displayed peptides recovered from irradiated tumors included the amino acid sequence RGDGSSV. This peptide binds to integrins within the tumor microvasculature. Immunohistochemical staining of irradiated tumors showed accumulation of fibrinogen receptor alpha(2b)beta(3) integrin. We studied tumor targeting efficiency of ligands to radiation-induced alpha(2b)beta(3). Radiopharmaceuticals were localized to irradiated tumors by use of alpha(2b)beta(3) ligands conjugated to nanoparticles and liposomes. Fibrinogen-conjugated nanoparticles bind to the radiation-activated receptor, obliterate tumor blood flow, and significantly increase regression and growth delay in irradiated tumors. Radiation-guided drug delivery to tumor blood vessels is a novel paradigm for targeted drug delivery.
Differential expression of folate receptor has been exploited to target liposomes to tumors. Astrogliomas express low folate receptor levels and are typically surrounded by normal cells expressing little or no folate receptors. While targeting cells with high over-expression of folate receptor (KB and HeLa) has been demonstrated, it is unclear whether targeting tumors expressing low levels of folate receptor is possible. In this study, it was demonstrated that optimizing the number of targeting ligands (folic acid) enables differential liposomal doxorubicin uptake in C6 glioma while sparing healthy cortical cells. By micellization of folate conjugates and their controlled insertion into pre-formed liposomes, tight control over the number of targeting ligands per liposome was demonstrated. Doxorubicin uptake in KB and C6 cells was dependent on the number of targeting ligands, while cortical cells showed increasing non-specific uptake with ligand number. Co-culture of C6 glioma with cortical cells confirmed preferential uptake in C6 glioma relative to cortical cells. A cell kill experiment showed that folate-targeted liposomal doxorubicin is cytotoxic and slows proliferation of KB and C6 cells with minimal effect on cortical cells. Therefore modulation of targeting ligand number enables significant differential uptake of doxorubicin in cells with low levels of folate receptor.
Biodegradable polymeric micelles, self-assembled from a di-block copolymer of poly(D,L-lactic-co-glycolic acid) (PLGA) and poly(ethylene glycol) (PEG), were prepared to achieve folate receptor targeted delivery of doxorubicin (DOX). In the di-block copolymer structure of PLGA-b-PEG, DOX was chemically conjugated to a terminal end of PLGA to produce DOX-PLGA-mPEG, and folate was separately conjugated to a terminal end of PEG to produce PLGA-PEG-FOL. The two di-block copolymers with different functional moieties at their chains ends were physically mixed with free base DOX in an aqueous solution to form mixed micelles. It was expected that folate moieties were exposed on the micellar surface, while DOX was physically and chemically entrapped in the core of micelles. Flow cytometry and confocal image analysis revealed that folate conjugated mixed micelles exhibited far greater extent of cellular uptake than folate unconjugated micelles against KB cells over-expressing folate receptors on the surface. They also showed higher cytotoxicity than DOX, suggesting that folate receptor medicated endocytosis of the micelles played an important role in transporting an increased amount of DOX within cells. In vivo animal experiments, using a nude mice xenograft model, demonstrated that when systemically administered, tumor volume was significantly regressed. Biodistribution studies also indicated that an increased amount of DOX was accumulated in the tumor tissue.
The vitamin, folic acid, has become a useful ligand for targeted cancer therapies because it binds to a tumor-associated antigen known as the folate receptor (FR). By linking folic acid to therapeutic agents, folate-targeted cancer therapies can deliver therapeutic drugs specifically to FR-positive tumor cells. This chapter provides a summary of a specific application of folate-targeted therapies whereby folic acid is exploited to carry an attached hapten (a highly antigenic molecule) to the surfaces of tumor cells for the purpose of rendering the tumors more immunogenic. The basic strategy is to (i) saturate (label) the surface of FR-positive tumor cells with a folate-hapten conjugate against which the cancer-bearing host already has a pre-existing or induced immunity, (ii) allow the surface bound haptens to attract anti-hapten antibodies to the tumor cell surface, and (iii) stimulate Fc receptor-bearing immune cells to mount an antitumor response against the anti-hapten antibody opsonized tumor cells. In immune competent murine tumor models, hapten-marked cancer cells have been shown to be quickly recognized by antibodies and the associated Fc receptor-expressing immune cells dedicated to eliminating antibody-coated target cells. Given the need for cancer cells to escape immune surveillance in order to proliferate and survive in vivo, folate-targeted immunotherapies that mark an otherwise immunologically "invisible" cancer cell as distinctively "non-self" may provide a key strategy for combating malignant disease.
The folate receptor (FR) is a confirmed tumor-associated antigen that binds folate and folate-drug conjugates with very high affinity and shuttles these bound molecules inside cells via an endocytic mechanism. Using folate (or an analog thereof) as the ligand, a wide variety of drug payloads can be delivered to FR-positive cells, ranging from small radioactive imaging agents up to large DNA-containing formulations. For therapeutic purposes, attachment of small molecular weight, highly potent agents to folate is a novel approach. As such, this review will outline the manner in which folate-drug conjugates are screened preclinically, it will summarize published activity data of various conjugates, and it will also highlight some newly emerging animal data from novel compounds that are currently under preclinical investigation.
Liposomes are one of the most promising systems for selective cellular targeting via introduction of specific ligands for cell-surface receptors. After being taken up by the cells, these liposomes usually follow intracellular pathways of receptor-mediated endocytosis. Control of intracellular trafficking is required for optimized drug delivery. In this study, we elucidated the intracellular fate of transferrin-modified liposomes and succeeded in altering it by introducing the pH-sensitive fusogenic peptide, GALA (WEAALAEALAEALAEHLAEALAEALEALAA). Transferrins that are chemically attached to a liposomal surface (Tf-L) were internalized via receptor-mediated endocytosis more slowly than unmodified transferrins. In contrast to the recyclable nature of transferrin, liposome-attached transferrins together with encapsulated rhodamines were retained in vesicular compartments. When GALA was introduced into liposomal membranes using a cholesteryl moiety for anchoring (Chol-GALA), rhodamines were efficiently released and diffused into the cytosol. The addition of GALA to the Tf-L-containing medium or the encapsulation of GALA in Tf-L did not induce similar effects. These results clearly indicate that GALA must be present on the surface of liposomes to exert its function. In vitro energy transfer and dynamic light scattering experiments suggested that the endosomal escape of the encapsulates in Tf-L equipped with Chol-GALA can be attributed to pH-dependent membrane fusion. With GALA present on the surface, intracellular trafficking of liposomes after receptor-mediated endocytosis could be successfully controlled.
Cell membrane-associated folate receptors are selectively overexpressed in certain human tumors. The high affinity of folic acid for folate receptors provides a unique opportunity to use folic acid as a targeting ligand to deliver chemotherapeutic agents to cancer cells. Folate-tethered liposomes bearing pteroyl-gamma-glutamate-cysteine-polyethylene glycol (PEG)-distearoylphosphatidylethanolamine (DSPE) as the targeting component are under investigation as mediators of drug and gene delivery to cancer cells that overexpress folate receptors. Pteroyl-gamma-glutamate-cysteine synthesis is one of the crucial starting steps in the preparation of pteroyl-gamma-glutamate-cysteine-PEG-DSPE. However, published methods for the synthesis of pteroyl-gamma-glutamate-cysteine provide low yields and are not easily reproducible. Therefore, we developed a modified synthetic method for the removal of the N(10)-trifluoroacetyl group after cleavage/deprotection that is reliable, is easily reproducible, and has high yield (38%) compared with an unreliable yield of 3-20% with the earlier methods. Folate-tethered liposomes containing calcein or doxorubicin were prepared using pteroyl-gamma-glutamate-cysteine-PEG-DSPE as the targeting component along with nontargeted liposomes with PEG-DSPE. The results of the uptake of calcein and cytotoxicity of doxorubicin in human cervical cancer HeLa-IU(1) cells and human colon cancer Caco-2 cells demonstrated that folate-tethered liposomes were efficient in selective delivery to cancer cells overexpressing folate receptors. The improvement in yield of the targeting component can significantly facilitate "scale up" of folate receptor-mediated liposomal cancer therapy to the preclinical and clinical levels of investigations.
The present studies were designed to test the hypothesis that neuronal‐specific protein kinase C γ (PKC γ ) plays a critical role in acute ethanol withdrawal hyper‐responsiveness in spinal cord.
Patch‐clamp studies were carried out in motor neurons in neonatal rat spinal cord slices. Postsynaptic currents were evoked by brief pulses of 2 m M N ‐methyl‐ D ‐aspartic acid (NMDA) in the presence of bicuculline methiodide 10 μ M ; strychnine 5 μ M and tetrodotoxin 0.5 μ M .
Both ethanol depression and withdrawal hyper‐responsiveness of NMDA‐evoked currents are dependent on increases in intracellular Ca ²⁺ . Blocking intracellular increase in Ca ²⁺ by 30 m M 1,2‐bis(2‐aminophenoxy)‐ethane‐ N , N , N ′, N ′‐tetraacetic acid (BAPTA) not only decreased the ethanol‐induced depression of NMDA‐evoked currents (33±5% in control vs 20±3% in BAPTA, P <0.05) but also eliminated acute ethanol withdrawal hyper‐responsiveness.
Immunohistochemistry studies revealed that neonatal spinal cord motor neurons contain an abundance of nuclear PKC γ .
Exposure to ethanol (100 m M ) induced PKC γ translocation from the nucleus to cytoplasm in motor neurons. Pretreatment with the γ ‐isozyme‐specific peptide PKC inhibitor, γ V5‐3, blocked ethanol‐induced translocation and also blocked withdrawal hyper‐responsiveness.
The results show that PKC γ mediates ethanol withdrawal hyper‐responsiveness in spinal motor neurons; the results may be relevant to some symptoms of ethanol withdrawal in vivo .
British Journal of Pharmacology (2005) 144 , 301–307. doi: 10.1038/sj.bjp.0706033
Traditional cancer chemotherapy relies on the premise that rapidly proliferating cancer cells are more likely to be a killed by cytotoxic agent. In reality, however, cytotoxic agents have very little or no specificity, which leads to systemic toxicity, causing severe undesirable side effects. Therefore, various drug delivery protocols and systems have been explored in the last three decades. Tumor cells overexpress many receptors and biomarkers, which can be used as targets to deliver cytotoxic agents into tumors. In general, a tumor-targeting drug delivery system consists of a tumor recognition moiety and a cytotoxic warhead connected directly or through a suitable linker to form a conjugate. The conjugate, which can be regarded as 'prodrug', should be systemically non-toxic. This means that the linker must be stable in circulation. Upon internalization into the cancer cell the conjugate should be readily cleaved to regenerate the active cytotoxic agent. Tumor-targeting conjugates bearing cytotoxic agents can be classified into several groups based on the type of cancer recognition moieties. This review describes recent advances in tumor-targeting drug conjugates including monoclonal antibodies, polyunsaturated fatty acids, folic acid, hyaluronic acid, and oligopeptides as tumor-targeting moieties.
Composite microspheres have been prepared from bioactive wollastonite (W) and biodegradable poly (hydroxybutyrate-polyhydroxyvalerate) (PHBV) in the present study. Gentamicin was encapsulated into the microspheres by the absorption method and the in vitro release of the gentamicin from the microspheres was performed in distilled water, modified simulated body fluid (SBF) and phosphate buffered saline (PBS) at 37 degrees C for 22 days, respectively. The results showed that the release behavior of gentamicin from PHBV/W composite microspheres was similar to that from the pure PHBV microspheres when the experiment was performed in distilled water. However, in the PBS and SBF solutions, gentamicin released from the PHBV/W composite microspheres at a relatively lower rate as compared to that of the pure PHBV microspheres and 90% of the total amount of gentamicin released from the composite microspheres after soaking for 22 days, which was much longer than that for the release of the same amount gentamicin from the pure PHBV microspheres (8 days). Scanning electron microscopy (SEM) and energy-dispersive spectrometer (EDS) analysis on the microspheres after release in SBF and PBS revealed that a microporous apatite layer was formed on the composite microspheres surface, which resulted in a controlled release behavior of the gentamicin from the PHBV/W composite microspheres. All of these results provided the possibility that the PHBV/W composite microspheres could be applied as alternative drug controlled release systems, especially as bone fillings for bone repair due to their advantages of controlled releasing antibiotics and apatite-formation ability, through which the implanted microspheres could chemically bond to the surrounding tissue in vivo.
Amphiphilic block copolymers composed of methoxy poly(ethylene glycol) (MPEG) and poly(epsilon-caprolactone) (PCL) were synthesized and then conjugated with folic acid to produce a folate-receptor-targeted drug carrier for tumor-specific drug delivery. Folate-conjugated MPEG/PCL micelles containing the anticancer drug paclitaxel were prepared by micelle formation in aqueous medium. The size of the folate-conjugated MPEG/PCL micelles formed was about 50-130 nm, depending on the molecular weight of block copolymers, and was maintained at less than 150 nm even after loading with paclitaxel. The in vitro release profile of the paclitaxel from the MPEG/PCL micelles exhibited no initial burst release and showed sustained release. Paclitaxel-loaded folate-conjugated MPEG/PCL micelles (PFOL50) exhibited much higher cytotoxicity for cancer cells, such as MCF-7 and HeLa cells, than MPEG/PCL micelles without the folate group (PMEP50). Confocal image analysis revealed that fluorescent paclitaxel-loaded PFOL50 micelles were endocytosed into MCF-7 cells through the interaction with overexpressed folate receptors on the surface of the cancer cells.
The potential of a Sinorhizobium fredii strain to produce a copolymer from glucose and sodium dodecanoate substrates was investigated.
Using an orthogonal design in a flask-shaker culture system, the vital regulation conditions for copolymer synthesis were optimized. These optimal results were applied to further studies in a two-stage fed-batch fermentation with a 10-l fermentor. When the biomass approached 33.5 g l(-1) dry cells at 35 h, 7 mmol l(-1) sodium dodecanoate was added into the broth to trigger the copolymer synthesis. After further culturing for 3 h, the copolymer product could be 17.14 g l(-1). The molecular structure of the copolymer was determined to be a poly (3-hydroxybutyrate-co-3-hydroxyoctanoate) [P (HB-HO)] by nuclear magnetic resonance. The content of HB and HO in P (HB-HO) was 79.2% (w/w) and 20.8% (w/w) respectively. The molecular weight of the P (HB-HO) was measured as 1.85 x 10(5) Da by a viscosity method.
The results demonstrated that the S. fredii strain used could be a potential candidate for the industrial production of the copolymer.
Some basic fermentation parameters were acquired through the fed-batch culturing experiments and they should be applicable in developing large-scale fermentation technologies for producing the P (HB-HO) copolymers.
Doxorubicin-loaded nanoparticles (NPs) of vitamin E TPGS-folate (TPGS-FOL) conjugate and doxorubicin-poly(lactide-co-glycolide)-vitamin E TPGS (DOX-PLGA-TPGS) conjugate were prepared by the solvent extraction/evaporation method for targeted chemotherapy of folate-receptor rich tumors. X-ray photoelectron spectroscopy demonstrated that folate was distributed on the NP surface while the drug molecules were entrapped in the NP matrix. The NPs were found of approximately 350nm diameter and exhibited a biphasic pattern of in vitro drug release. The cell uptake of the fluorescent NPs and the cell viability of the drug formulated in the NPs were quantitatively investigated, which were found dependent on the content of targeting TPGS-FOL conjugate. The NPs of 50% TPGS-FOL showed cellular uptake by MCF-7 cells 1.5 times higher and by C6 cells 1.7 times higher than the NPs with no TPGS-FOL component after 30min incubation. The MCF-7 cell viability was found decreased significantly from 50.8% for the drug-loaded NPs of no TPGS-FOL to 8.2% for those of 50% TPGS-FOL after incubation at 100microug concentration at 37 degrees C. The latter NPs also exhibited much lower IC(50) value than the DOX after 24h incubation, i.e., 19.4 vs. 43.7micror MCF-7 cells and 3.3 vs. >100micror C6 cells.
Folate or folic acid has been employed as a targeting moiety of various anticancer agents to increase their cellular uptake within target cells since folate receptors are vastly overexpressed in several human tumors. In this study, a biodegradable polymer poly(d,l-lactide-co-glycolide)-poly(ethylene glycol)-folate (PLGA-PEG-FOL) was used to form micelles for encapsulating anticancer drug doxorubicin (DOX). The drug loading content, encapsulation efficiency and in vitro release were characterized. To evaluate the targeting ability of the folate conjugated micelles, the cytotoxicity and cellular uptake of DOX-loaded micelles on three cancer cell lines with different amount of folate receptors (KB, MATB III, C6) and normal fibroblast cells (CCL-110) were compared. The cytotoxicity of PLGA-PEG-FOL micelles to cancer cells was found to be much higher than that of normal fibroblast cells, demonstrating that the folate conjugated micelles has the ability to selectively target to cancer cells. For normal cells, the cellular uptake of PLGA-PEG-FOL micelles was similar to PLGA-PEG micelles without folate conjugation, and was substantially lower than that of cancer cells. In addition, the cell cycle analysis showed that the apoptotic percentage of normal fibroblasts was substantially lower compared with the cancer cells after exposing to DOX-loaded PLGA-PEG-FOL micelles. An optimal folate amount of approximately 40-65% on the micelles was found to be able to kill cancer cells but, at the same time, to have very low effect to normal cells.
Quantum dots (QDs) are fluorescent semiconductor nanocrystals with superior optical properties compared to organic dyes currently undergoing rapid development for biological applications, particularly in fluorescence imaging. The folate receptor, overexpressed in a broad spectrum of malignant tumors, is an attractive target for selective delivery of imaging agents to tumor cells. This study examines nanoparticles containing QDs entrapped in a lipid shell, and post-loaded with a folate-lipid conjugate for targeting to mouse and human tumor cells expressing the folate receptor. Hydrophobic QDs were mixed with 1,2 dipalmitoyl-sn-glycero-3 phosphocholine and methoxy-polyethylene-glycol-distearoyl-phosphatidyl-ethanolamine (mPEG-DSPE) generating a nanoparticle referred to as lipodot, with a mean diameter size of approximately 100 nm. Folate-derivatized PEG-DSPE was post-loaded into the lipodots at 0.5% lipid molar concentration. Mouse J6456 lymphoma cells (J6456-FR) and human head and neck KB cancer cells (KB-FR), up-regulated for their folate receptors, were incubated with folate-targeted and non-targeted lipodots in vitro. Using fluorescence microscopy, it was found that only folate-targeted lipodots were taken up by tumor cells. Confocal depth scanning showed substantial internalization. Confirming the specificity of folate-targeted lipodots, binding and internalization were inhibited by free folate, and no uptake was found in a folate-receptor negative cell line. Selective binding and uptake of folate-targeted lipodots by J6456-FR cells was also observed in vivo after intra-peritoneal injection in mice bearing ascitic J6456-FR tumors based on FACS analysis and confocal imaging of harvested cells from the peritoneal cavity. Folate-targeted lipodots represent an attractive approach for tumor cell labeling both in vitro and in vivo.
Folic acid, conjugated to poly(ethylene glycol)-distearoylphosphatidylethanolamine (folate-PEG-DSPE), was used to target emulsions of all-trans retinoic acid (ATRA) to folate receptor-overexpressing tumor cells. Two kinds of ATRA-incorporated folate-tethered emulsions (ATRA-FTE 2000/3400) were prepared using soybean oil, egg phosphatidylcholine and folate-PEG-DSPE with different PEG length. As a control, ATRA-incorporated non-tethered emulsion (ATRA-NTE) was prepared by using PEG2000-DSPE without folate instead of using folate-PEG-DSPE. The mean particle diameters of ATRA-FTE 2000/3400 were about 100-130 nm. The cellular uptake in KB cells of fluorescence-labeled ATRA-FTE 3400 was determined with HPLC (for ATRA) and confocal microscopy (for lipid emulsion). The growth inhibitory activity of ATRA was evaluated by MTT assay. The folate ligands in emulsion increased the cellular uptake of ATRA about 3-fold and 1.6-fold in ATRA-FTE 3400 and ATRA-FTE 2000, respectively. Growth inhibitory activity of ATRA-FTE 3400 in KB cells was higher than that of ATRA-NTE at the same dose. Whereas the growth inhibitory effect in MCF-7 cells of ATRA was similar between ATRA-NTE and ATRA-FTE 3400. The addition of free folate significantly reduced the uptake of ATRA regardless of the length of PEG attached to folate. Folate-tethered lipid emulsion showed effective and selective delivery to the folate receptor-abundant carcinomas, suggesting a potential for targeted delivery of anticancer agents.
Folate receptors (FRs) have been identified as cellular surface markers for cancer and leukemia. Liposomes containing lipophilic derivatives of folate have been shown to effectively target FR-expressing cells. Here, we report the synthesis of a novel lipophilic folate derivative, folate-polyethylene glycol-cholesterol hemisuccinate (F-PEG-CHEMS), and its evaluation as a targeting ligand for liposomal doxorubicin (L-DOX) in FR-expressing cells. Liposomes containing F-PEG-CHEMS, with a mean diameter of 120+/-20 nm, were synthesized by polycarbonate membrane extrusion and were shown to have excellent colloidal stability. The liposomes were taken up selectively by KB cells, which overexpress FR-alpha. Compared to folate-PEG-cholesterol (F-PEG-Chol), which contains a carbamate linkage, F-PEG-CHEMS better retained its FR-targeting activity during prolonged storage. In addition, F-PEG-CHEMS containing liposomes loaded with DOX (F-L-DOX) showed greater cytotoxicity (IC(50)=10.0muM) than non-targeted control L-DOX (IC(50)=57.5 microM) in KB cells. In ICR mice, both targeted and non-targeted liposomes exhibited long circulation properties, although F-L-DOX (t(1/2)=12.34 h) showed more rapid plasma clearance than L-DOX (t(1/2)=17.10h). These results suggest that F-PEG-CHEMS is effective as a novel ligand for the synthesis of FR-targeted liposomes.
To compare the in vivo tissue distribution of folate-targeted liposomes (FTLs) injected i.v. in mice bearing folate receptor (FR)-overexpressing tumors (mouse M109 and human KB carcinomas, and mouse J6456 lymphoma) to that of nontargeted liposomes (NTLs) of similar composition.
A small fraction of a folate-polyethylene-glycol (PEG)-distearoyl-phosphatidylethanolamine conjugate was incorporated in FTLs. Both FTLs and NTLs were PEGylated with a PEG-distearoyl-phosphatidylethanolamine conjugate to prolong circulation time. Liposomes were labeled with [(3)H]cholesterol hexadecyl ether with or without doxorubicin loading. Liposome levels in plasma, tissues, or ascites were assessed by the number of [(3)H] counts. For doxorubicin-loaded formulations, we also determined the tissue doxorubicin levels by fluorimetry. To estimate the amount of liposomes directly associated with tumor cells in vivo, we determined the [(3)H]radiolabel counts in washed pellets of ascitic tumor cells using the ascitic J6456 lymphoma
FTLs retained the folate ligand in vivo, as demonstrated by their ability to bind ex vivo to FR-expressing cells after prolonged circulation and extravasation into malignant ascitic fluid. In comparison with NTLs, FTLs were cleared faster from circulation as a result of greater liver uptake. Despite the lower plasma levels, tumor levels of FTL-injected mice were not significantly different from those of NTL-injected mice. When NTLs and FTLs were loaded with doxorubicin, liver uptake decreased because of liver blockade, and uptake by spleen and tumor increased. When tumor-to-tissue liposome uptake ratios were analyzed, the targeting profile of FTLs was characterized by higher tumor:skin, and tumor:kidney ratios but lower tumor:liver ratio than NTLs. After a concomitant dose of free folic acid, FTLs (but not NTLs) plasma clearance and liver uptake were inhibited, indicating that accelerated clearance was mediated by the folate ligand. Surprisingly tumor uptake was not significantly affected by a codose of folic acid. In the J6456 ascitic tumor model, tumor cell-associated liposome levels were significantly greater for FTL-injected mice than for NTL-injected mice, despite slightly higher levels of the latter in whole ascites.
Whereas folate targeting does not enhance overall liposome deposition in tumors, the targeting profile of tumor versus other tissues is substantially different and intratumor liposome distribution in ascitic tumors is affected favorably with a selective shift toward liposome association with FR-expressing cells.
We synthesized nanoparticles (NPs) of the blend of two-component copolymers for targeted chemotherapy with paclitaxel used as model drug. One component is poly(lactide)-D-alpha-tocopheryl polyethylene glycol succinate (PLA-TPGS), which is of desired hydrophobic-lipophilic balance, and another is TPGS-COOH, which facilitates the folate conjugation for targeting. The nanoparticles of the two-copolymer blend at various component ratio were prepared by the solvent extraction/evaporation single emulsion method and then decorated by folate, which were characterized by laser light scattering (LLS) for particles' size and size distribution, zeta potential analyzer for surface charge, and X-ray photoelectron spectroscopy (XPS) for surface chemistry. The drug encapsulation efficiency (EE) and in vitro drug release were measured by high performance liquid chromatography (HPLC). The targeting effect was investigated in vitro by cancer cell uptake of coumarin-6-loaded NPs and further confirmed by cytotoxicity of cancer cells treated with the drug formulated in the NPs. We showed that the NP formulation has great advantages vs the pristine drug in achieving better therapeutic effect, which increased 8.68% for MCF-7 breast cancer cells, and that the folate-decoration can significantly promote targeted delivery of the drug into the corresponding cancer cells and thus enhance its therapeutic effect, which increased 24.4% for the NP formulation of 16.7% TPGS-COOH component and 31.1% for the NP formulation of 33.3% TPGS-COOH component after 24h treatment at the same 25 microg/ml paclitaxel concentration. The experiments on C6 glioma cells further confirmed these advantages.
Targeted drug delivery via the folate receptor
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