[Show abstract][Hide abstract] ABSTRACT: In this study, we aimed to develop polyelectrolyte multilayered films that could be absorbed onto a silicone rubber substrate; this composite material was then tested for its ability to inhibit bacterial adhesion. Polyacrylic acid (PAA) grafting onto the silicone rubber substrate was confirmed by attenuated total reflectance-infrared spectroscopy and the surface roughness of multilayered films was measured using an atomic force microscope and scanning electron microscopy. Immobilization of PAA, chitosan (CS) and heparin (HEP) films conferred antibacterial activity against Escherichia coli and Staphylococcus Aureus. The adhesion of both E. coli and S. aureus on PAA-CS-HEP multilayer film was reduced when compared to pristine, PAA, and PAA-CS films; this was due to effective complex formation between polyelectrolytes and cell adhesion proteins. Moreover, immobilization of HEP on the PAA-CS composite was efficiently reduced cell adhesion.
Journal of Polymer Research 07/2015; 22(7). DOI:10.1007/s10965-015-0767-6 · 1.90 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this study, we synthesized a water-soluble poly(amic acid-co-imide) (PA-I) from ethylenediaminetetraacetic dianhydride (EDTA) and 2,2'-(ethylenedioxy)bis(ethylamine) that possesses comparable transfection efficiency to that of polyethylenimine (PEI), when prepared in combination with divalent calcium cations. The polycondensation of monomers afforded poly(amic acid) (PA) precursors, and subsequent thermal imidization resulted in the formation of PA-I. At a polymer/DNA ratio (indicated by the molar ratio of nitrogen in the polymer to phosphate in DNA) of 40, complete retardation of the DNA band was observed by gel electrophoresis, indicating the strong association of DNA with PA-I. A zeta potential of -22 mV was recorded for the PA-I polymer solution, and no apparent cytotoxicity was observed at concentrations up to 500 μg·mL(-1). In the presence of divalent Ca(2+), the transfection efficiency of PA-I was higher than that of PA, due to the formation of a copolymer/Ca(2+)/DNA polyplex and the reduction in negative charge due to thermal cyclization. Interestingly, a synergistic effect of Ca(2+) and the synthesized copolymer on DNA transfection was observed. The use of Ca(2+) or copolymer alone resulted in unsatisfactory delivery, whereas the formation of three-component polyplexes synergistically increased DNA transfection. Our findings demonstrated that a PA-I/Ca(2+)/DNA polyplex could serve as a promising candidate for gene delivery.
International Journal of Nanomedicine 02/2015; 10:1637-1647. DOI:10.2147/IJN.S76502 · 4.38 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Carbon nanorice has been prepared by the hydrothermal carbonization of heparin in a Nafion solution at a mild temperature of approximately 100 °C. Through transmission electron microscopy, the individual grains of this nanorice were found to have a diameter in the range of 100 nm and a length of approximately 500 nm. The mechanism of formation for this nanoscale rice-like structure is suggested to be a self-assembling process; wherein charring of the heparin causes desulfation followed by carbonization, ultimately forming 5-hydroxylmethyl furfural in the presence of a Nafion membrane. This is confirmed through Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, with this method also shown to produce a much greater number of carbon structures than other synthesis methods. Moreover, this new method results in carbon nanorice that exhibits fluorescence, which is of great interest for potential biomedical or optoelectronic applications.
[Show abstract][Hide abstract] ABSTRACT: Successful application of biodegradable implants in the gastrointestinal tract requires intensive research to understand their degradation behavior. We studied biodegradable poly(epsilon-caprolactone) (PCL) films in several digestive glands using films formed from a solution of PCL in dichloromethane and ether. Examination of the film morphology showed that solvent evaporation resulted in the formation of a smooth and flat surface. In addition, our results revealed that the PCL films degraded very differently in different digestive glands while they continued to undergo hydrolysis. There was also significant weight loss in the PCL films in saliva and gastric juice, which indicates that the degradation was sensitive to protein enzymes. Deconstruction of the PCL film was first discovered when it was incubated with saliva for 6 weeks. These results indicate that the degradation by saliva was mainly responsible for the enzymatic erosion of the film, which was confirmed by scanning electron microscopy.
[Show abstract][Hide abstract] ABSTRACT: In this work, we reported the synthesis of water soluble MoS2 quantum dots from the monolayer nanosheets of MoS2, using thioglycolic acid (TGA) with sonication method. The gaps of MoS2 layers were enlarged by the stirring process. Meanwhile TGA molecules strongly binding to the defect sites of MoS2 would reduce the Vander Waals force between the MoS2 layers through sonication. This led to the improved dispersion of MoS2 monolayers in water. The addition of TGA molecules not only exfoliated the bulk of MoS2, but also modified the surface of MoS2 with carboxylic acid groups. As a result, highly concentrated MoS2 nanosheets were produced in water. Subsequently, heavy metal-free MoS2 quantum dots with sustained fluorescence emission, which were fabricated from hydrothermal treatment of MoS2 mono-layers, can be utilized as cell biomarker.
[Show abstract][Hide abstract] ABSTRACT: The purpose of this study was to develop and evaluate thermally responsive copolymers, which contain temperature- and pH-sensitive segments that are either alternating in or grafted onto the main chain, and to exploit their temperature-sensitive properties for ophthalmic drug delivery. Accordingly, two types of thermoresponsive copolymers—a linear poly(acrylic acid-co-N-isopropylacrylamide) random copolymer (PAAc-co-PNIPAAm) and a poly(acrylic acid-g-N-isopropylacrylamide) graft copolymer (PAAc-g-PNIPAAm)—were investigated for their thermosensitive in situ gel formation and potential applications for ophthalmic drug delivery. All the PAAc-g-PNIPAAm graft copolymers, and the linear PAAc-co-PNIPAAm copolymer with low acrylic acid contents, have an LCST of 34 °C; this is close to the surface temperature of the eye and can therefore be utilized for ophthalmic drug delivery. In addition, the PAAc-g-PNIPAAm graft copolymers showed a higher water content than the linear random copolymer; this is due to the high water adsorption ability of PAAc. The drug release dynamics of [3H]-epinephrine as a model showed that the linear random copolymer has a faster drug release, while the graft copolymers showed a more sustained release profile. The Ritger–Peppas model was used to account for the release of the epinephrine diffusion exponent ‘n’ which was in between 0.5 and 0.6. The release of the drug is considered mainly dependent on diffusion but other factors cannot be excluded. We suspected that the dynamics of drug release are determined by the water adsorption ability because high water content results in the formation of a larger capillary network in the polymer matrix, which promotes drug diffusion into the copolymer. The results suggest that PAAc-g-PNIPAAm graft copolymers are potential thermosensitive in situ gel-forming materials for ophthalmic drug delivery.
[Show abstract][Hide abstract] ABSTRACT: A sol-gel reaction was used to prepare core-shell nanoparticles of 5,10,15,20-tetrakis(pentafluorophenyl)-21H,23H-porphine (PF6) with titania (TiO2) coating. PF6 molecules would self-assemble to form dispersed PF6 nanoparticles in water during dialysis. The resulting PF6-TiO2 core-shell nanoparticle was characterized using several methods, revealing a thin TiO2 layer coated on the surface of the PF6 nanoparticles and confirming the chemical composition of the core-shell structures. The absorption spectrum of the PF6-TiO2 core-shell nanoparticle was extended to 300-500 nm, which greatly enhanced the photocatalytic efficiency in the visible light spectrum compared to that of bare TiO2.
[Show abstract][Hide abstract] ABSTRACT: In this study, three types of hybrid nanotubes (NTs), ie, oxidized multiwalled carbon NTs (COOH MWCNTs), heparin (Hep)-conjugated MWCNTs (Hep MWCNTs), and diblock copolymer polyglycolic acid (PGA)-co-heparin conjugated to MWCNTs (PGA MWCNTs), were synthesized with improved biocompatibility and drug-loading capacity. Hydrophilic Hep substituents on MWCNTs improved biocompatibility and acted as nucleus-sensitive segments on the CNT carrier, whereas the addition of PGA enhanced drug-loading capacity. In the PGA MWCNT system, the amphiphilic copolymer (PGA-Hep) formed micelles on the side walls of CNTs, as confirmed by electron microscopy. The PGA system encapsulated the hydrophobic drug with high efficiency compared to the COOH MWCNT and Hep MWCNT systems. This is because the drug was loaded onto the PGA MWCNTs through hydrophobic forces and onto the CNTs by π-π stacking interactions. Additionally, most of the current drug-carrier designs that target cancer cells release the drug in the lysosome or cytoplasm. However, nuclear-targeted drug release is expected to kill cancer cells more directly and efficiently. In our study, PGA MWCNT carriers effectively delivered the active anticancer drug doxorubicin into targeted nuclei. This study may provide an effective strategy for the development of carbon-based drug carriers for nuclear-targeted drug delivery.
International Journal of Nanomedicine 11/2013; 8:4427-40. DOI:10.2147/IJN.S53636 · 4.38 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Hydrogels have been developed as artificial extracellular matrixes (ECMs) to mimic native tissue microenvironments for various applications. Unfortunately, poly(N-isopropylacrylamide) (PNIPAAM)-based hydrogels are not suitable for cell culturing and cell sheet preparation. Carbon nanotubes (CNTs), with their mechanical strength and electrical conductivity, have been considered as additives to increase the applicability of hydrogels to cell encapsulation and advance cardiac electrophysiological functions. A simple method for fabrication of PNIPAAM hydrogels interpenetrated with multiwalled CNTs (MWCNTs) as substrates for cell sheet preparation is reported. The results demonstrate that PNIPAAM hydrogels with interpenetrating MWCNTs still exhibit thermosensitive behavior. It is also found that epithelial Madin-Darby canine kidney (MDCK) cells can only attach and proliferate on MWCNT-interpenetrated PNIPAAM hydrogels. Furthermore, the PNIPAAM hydrogels with MWCNTs possess higher elastic moduli and hydrophobicities than those without MWCNTs, suggesting these two characteristics are necessary for the cells to attach to the hydrogel surfaces. Moreover, cell sheets can only be harvested from PNIPAAM hydrogels with MWCNTs because of their high ratio of cell attachment. Thus, this simple method provides sufficient mechanical strength to PNIPAAM hydrogels so that anchorage-dependent cells can be cultivated and provides a superior system for preparing cell sheets.
[Show abstract][Hide abstract] ABSTRACT: The kinetics of the curing of sulfone epoxy (SEP) monomers using aromatic and aliphatic amine curing agents was studied via differential scanning calorimetry (DSC). SEP curing is a two-stage process involving SEP/electron donation and electron donation to either aliphatic or aromatic curing agents. The SEP/electron donation curing process occurred readily since semi-electron-withdrawing curing agents are induced by nucleophilic substitution in the first stage. In the second stage, SEP is cured by the semi-electron-withdrawing curing agents. The kinetic parameters of the curing process were determined using a conversional method derived from Ozawa’s and Kissinger’s methods, which are typically used for kinetic analysis of data for thermal treatments. The higher melting points and steric bulk of the aromatic curing agents resulted in higher curing activation energies than for the aliphatic curing agents. The aliphatic curing agents also increased the activation energy of the curing process due to their electron-withdrawing and cross-linking properties as well as the viscosity of the epoxy/amine curing system. Cured SEP/aromatic curing agent materials possessed higher glass transition temperatures than cured SEP/aliphatic curing agent materials.
[Show abstract][Hide abstract] ABSTRACT: The purpose of this study was to evaluate the use of the biodegradable poly(l-lactide) (PLLA) as a gastro-jejunal tube anchored in the duodenum for duodenal exclusion. PLLA film was fabricated using a hot melting process to a thickness of around 40–50 μm and was then immersed in human gastric juice to estimate the in vitro biodegradability behavior. PLLA film was more biodegradable in human gastric juice than in HCl and PBS. Measurements of weight loss indicated that 60% of original the PLLA was lost after 42 days of incubation. Surface functional group characterization, thermal stability, and surface morphology of the degraded PLLA film in human gastric juice showed that the decomposed sections of the PLLA film were primarily from the amorphous region. The degradation of the PLLA film in human gastric juice began with the erosion of continuous nanocavities in the range of 100–200 nm on the PLLA surface over the course of 21 days. The PLLA film collapsed and spiral PLLA fiber was obtained after 42 days of decomposing in human gastric juice.
[Show abstract][Hide abstract] ABSTRACT: An optimized, biodegradable, dual temperature- and pH-responsive micelle system conjugated with functional group Cy5.5 was prepared in order to enhance tumor accumulation. The Dynamic light scattering (DLS) measurements showed that these diblock copolymers form micelle in PBS buffer with a size of around 50 nm by heating of an aqueous polymer solution from below to above the cloud point (CP). Anticancer drug, doxorubicin was incorporated into the inner core of micelle by hot shock protocol. The size and stability of the micelle were controlled by the copolymer composition and is fine tuned to extracellular pH of tumor. The mechanism then caused pH change and at body temperature which induce doxorubicin release from micelles and have strong effects on the viability of HeLa, ZR-75-1, MCF-7 and H661 cancer cells. Our in vivo results revealed a clear distribution of Doxorubicin-loaded mixed micelle (Dox-micelle) and efficiency targeting tumor site with particles increasing size in the tumor interstitial space, and the particles could not diffuse throughout the tumor matrix. In vivo tumor growth inhibition showed that Dox-micelle exhibited excellent antitumor activity and a high rate of anticancer drug in cancer cells by this strategy.
[Show abstract][Hide abstract] ABSTRACT: A two-photon excitation difluoroboron dye activated in the near infrared region for biological image analysis was synthesized in this study. Cell affinity, membrane interaction, and the endocytosis pathway of PAMAM dendrons were investigated using only covalent two-photon dyes (TPD) at the periphery of the PAMAM dendrons. Generation 3 TPD-labeled PAMAM dendrons (BG3) exhibited multivalency binding on the HeLa cell membranes from the cell affinity study in the fixation of HeLa cells. Photo-stimulation on the membrane of the living HeLa cell was observed by confocal optical imaging in situ, using the two-photon model, when incubated with BG3. Analyses of cell membrane integrity via lactate dehydrogenase (LDH) assay confirmed membrane damage at two photon excitation model. However, no variation in the cell was observed using the one-photon excitation model. These results indicated a high degree of dendrons uptake by cells through binding to the cell membrane following the endocytotic pathway. Furthermore, the wide excitation fluorescence spectrum of difluoroboron dye provides dual imaging with which to study the endocytosis of TPD-labeled PAMAM dendrons using a single near infrared laser.
Journal of Biomedical Materials Research Part A 03/2012; 100(3):746-56. DOI:10.1002/jbm.a.33283 · 3.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The sterically polymer-based liposomal complexes (SPLexes) were formed by cationic polymeric liposomes and pH-sensitive diblock copolymer were studied for their capabilities in improving the stability with high efficiency of siRNA delivery. The SPLexes were formed a dual-shelled structure and uniform size distribution. The PEGylated outer shell could mitigate the phagocytosis and reduce the cytotoxicity. Moreover, the folated SPLexes improved 42.9× accumulation in vitro and 1.7× tumor uptake in vivo in contrast with nonfolated SPLexes. The protonated copolymer at low pH would improve the siRNA released into cytoplasm following SPLexes fusion with the endo/lysosome membrane and inhibited the protein expression to 75.6 ± 4.5% efficiently. Results of this study significantly contribute to efforts to develop lipoplexes based siRNA delivery systems.
[Show abstract][Hide abstract] ABSTRACT: To understand the effect of photosensitizer (PS) release from graft copolymer based micelles in photodynamic therapy (PDT), the two pH-sensitive and non-pH-sensitive graft copolymers, (poly(N-vinyly caprolactam)-g-poly(D,L-lactide) and poly(N-vinyly caprolactam-co-N-vinyl imidazole)-g-poly(D,L-lactide)), were synthesized and utilized for the encapsulation of protoporphyrin IX (PPIX) for in vitro and in vivo PDT studies. Photochemical internalization (PCI) was utilized to study the localization of pH- and non-pH-sensitive micelles uptake in the lysosome. After non-toxic light treatment, PPIX was found in the nucleus with pH-sensitive micelles, while PPIX was still localized in the lysosomal organism with the non-pH-sensitive micelles, as observed by confocal microscopy. Because the formation of singlet oxygen was observed for the block and graft micelles, dramatic differences in the cell viability could be ascribed to the damage occurring at the region where the PPIX was located. An in vivo study revealed that PPIX-loaded graft and diblock micelles presented prolonged blood circulation and enhanced tumor targeting ability. The PPIX released from g-CIM micelles on tumor site was further proved by ex vivo confocal image. In addition, non-pH-sensitive micelle-treated mice showed a better repression of tumor growth than PPIX-treated mice, which was likely due to the larger amount of PS localized in the tumor region still exhibiting therapeutic effects. Finally, effective PDT-induced inhibition of tumor growth was found in pH-sensitive micelle-treated mice. This work provides insight into PS-loaded graft and diblock micelles for the PDT of tumors.
[Show abstract][Hide abstract] ABSTRACT: This paper develops a non-spherical polymeric micelle using an amphiphilic block copolymer and a porphyrin crystalline structure. The nanoscale polymer micelles were characterized by transmission electron microscopy (TEM) and atomic force microscopy (AFM), revealing particle sizes of approximately 150 nm with a particular shape in the hexagonal lattice. The shape shows the selective uptake efficacy for the HeLa and macrophage cells, and inhibits phagocytosis against the macrophage. A hexagonal lattice in nanoscale was constructed by an amphiphilic block copolymer and a porphyrin crystalline structure developed in this study. The shape shows selective uptake efficacy for the HeLa and macrophage cells after 24h incubation. We expect that targeting efficiency of drug could be improved by modified the shaped with hexagonal lattice.
[Show abstract][Hide abstract] ABSTRACT: Target geometry for mitigating phagocytosis has garnered considerable attention recently in the drug delivery field. This study examined nanoparticles (NPs) with same volume but different shapes, namely, spherical NPs (SNPs) and hexagonal nanoprisms (HNPs), and analyzed their behaviors in vitro and in vivo. These NPs were constructed with a multifunctional block copolymer component, mPEG-b-P(HEMA-co-histidine-PLA). Geometry of SNPs and HNPs was controlled by adjusting copolymer properties and particle size was controlled by adjusting formulation parameters. Nanoparticle morphology had no effect in mitigating phagocytosis when NP size was 70 nm; however, morphology had a significant effect when NP size was 120 nm. The radioactivity-time curves for (99m)Tc-labeled NPs, fitted by the two-compartment pharmacokinetic model, show that the prolonged plasma distribution half-life of HNPs is indicative in the bloodstream. The in vitro and in vivo studies reveal that dual stealth characteristics, pegylation and hexagonal prism structure, of nanocarriers can be adopted in clinical application for safe and efficient delivery of cancer therapy.
[Show abstract][Hide abstract] ABSTRACT: This article reports a flexible hollow nanoparticles, self-assembling from poly(N-vinylimidazole-co-N-vinylpyrrolidone)-g-poly(d,l-lactide) graft copolymers and methoxyl/functionalized-PEG-PLA diblock copolymers, as an anticancer drug doxorubicin (Dox) carrier for cancer targeting, imaging, and cancer therapy. This multifunctional hollow nanoparticle exhibited a specific on-off switch drug release behavior, owning to the pH-sensitive structure of imidazole, to release Dox in acidic surroundings (intracellular endosomes) and to capsulate Dox in neutral surroundings (blood circulation or extracellular matrix). Imaging by SPECT/CT shows that nanoparticle conjugated with folic acids ensures a high intratumoral accumulation due to the folate-binding protein (FBP)-binding effect. In vivo tumor growth inhibition shows that nanoparticles exhibited excellent antitumor activity and a high rate of apoptosis in cancer cells. After 80-day treatment course of nanoparticles, it did not appreciably cause heart, liver and kidney damage by inactive Dox or polymeric materials. The results indicate that the flexible carriers with an on-off switched drug release may be allowed to accurately deliver to targeted tumors for cancer therapy.
[Show abstract][Hide abstract] ABSTRACT: In poled electro-optical (E-O) polymer systems, the relaxation of oriented chromophores is maintained by either introducing the guest chromophores into host polymers with high glass transition temperatures, or by confining the chromophores in polymer networks. Various highly stable NLO polymers have been prepared by grafting NLO-active chromophores onto aromatic polyimide backbones. The pendent chromophores of side chain polyimides can be stabilized at low temperature because they have rigid rod-like structures. However, the orientation decays quickly at elevated temperatures because the local free volumes that surround the chromophores increase. Taking advantage of the multifunctional characteristics of carbazole along with rational molecular design, a new NLO-active lambda-shape main-chain polyimide that comprises the two-dimensional carbazole chromophore was synthesized. This polyimide exhibits high thermal and temporal stability. it can endure as high as 240 °C in a transient time and maintain large SH signal at 100 °C for a long time. The high-glass transition polyimide as a matrix and embedding the two-dimensional chromophore into the polymer backbone are the major reasons that effectively restrict randomization of the oriented dipole.