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Construction, application and biosafety of silver nanocrystalline chitosan wound dressing
Abstract
A novel wound dressing composed of nano-silver and chitosan was fabricated using a nanometer and self-assembly technology. Sterility and pyrogen testing assessed biosafety, and efficacy was evaluated using Sprague-Dawley rats with deep partial-thickness wounds. Silver sulfadiazine and chitosan film dressings were used as controls. At intervals wound areas were measured, wound tissues biopsied and blood samples taken. Compared with the controls, the silver nanocrystalline chitosan dressing significantly (p<0.01) increased the rate of wound healing and was associated with silver levels in blood and tissues lower than levels associated with the silver sulfadiazine dressing (p<0.01). Sterility and pyrogen tests of the silver nanocrystalline chitosan dressing were negative. Thus this dressing should have wide application in clinical settings.
... The nanomedicines provide a new alternative opportunity for postoperative therapy 388 . For instance, Lu et al 389 . constructed a wound nano-silver/chitosan dressing through nanometer and self-assembly technology. ...
... constructed a wound nano-silver/chitosan dressing through nanometer and self-assembly technology. The wound dressing significantly increased the wound healing efficacy and improved the assessed biosafety 389 . Another study reported a nanoemulsion complex constructed using propolis and vitamin C, significantly promoting wound healing in the oral mucosa 390 . ...
Owing to the inherent shortcomings of traditional therapeutic drugs in terms of inadequate therapeutic efficacy and toxicity in clinical treatment, nanomedicine designs have received widespread attention with significantly improved efficacy and reduced non-target side effects. Nanomedicines hold tremendous theranostic potential for treating, monitoring, diagnosing, and controlling various diseases and are attracting an unfathomable amount of input of research resources. Against the backdrop of an exponentially growing number of publications, it is imperative to help the audience get a panorama image of the research activities in the field of nanomedicines. Herein, this review elaborates on the development trends of nanomedicines, emerging nanocarriers, in vivo fate and safety of nanomedicines, and their extensive applications. Moreover, the potential challenges and the obstacles hindering the clinical translation of nanomedicines are also discussed. The elaboration on various aspects of the research trends of nanomedicines may help enlighten the readers and set the route for future endeavors.
... Silver sulfadiazine has been considered the gold standard for the treatment of local burns, but subsequent studies have found that it delays the wound healing process and is accompanied by severe cytotoxicity (Russell and Hugo, 1994a;Atiyeh et al., 2007). Actually, ideal wound dressing should meet the following requirements: good mechanical strength and breathability, excellent exudate absorption, blood and cell compatibility, etc. AgNPscontaining antibacterial wound dressings prepared by electrostatic spinning and in situ reduction of surface silver ions using biocompatible macromolecules such as polymers (Hong et al., 2006;GhavamiNejad et al., 2015;GhavamiNejad et al., 2016;Unnithan et al., 2016;Augustine et al., 2018) and biomacromolecules (Lu et al., 2008;Madhumathi et al., 2010;Singh and Singh, 2014;Biswas et al., 2018;Wu et al., 2018) as substrates can achieve good therapeutic effects. For example, a wound dressing consisting of AgNPs and chitosan was prepared by self-assembly, which passed sterility and pyrogenic safety evaluations in tests with deeper thick wound Sprague-Dawley rat model (Lu et al., 2008). ...
... Actually, ideal wound dressing should meet the following requirements: good mechanical strength and breathability, excellent exudate absorption, blood and cell compatibility, etc. AgNPscontaining antibacterial wound dressings prepared by electrostatic spinning and in situ reduction of surface silver ions using biocompatible macromolecules such as polymers (Hong et al., 2006;GhavamiNejad et al., 2015;GhavamiNejad et al., 2016;Unnithan et al., 2016;Augustine et al., 2018) and biomacromolecules (Lu et al., 2008;Madhumathi et al., 2010;Singh and Singh, 2014;Biswas et al., 2018;Wu et al., 2018) as substrates can achieve good therapeutic effects. For example, a wound dressing consisting of AgNPs and chitosan was prepared by self-assembly, which passed sterility and pyrogenic safety evaluations in tests with deeper thick wound Sprague-Dawley rat model (Lu et al., 2008). Further, MADO-AgNPs prepared by coating AgNPs on a novel electrospun nanofiber material, poly (methyl methacrylate-dopamine methacrylamide, MADO), exhibited good antibacterial activity in vitro and good wound healing ability in vivo ( Figure 6) (GhavamiNejad et al., 2015). ...
Antibacterial resistance is by far one of the greatest challenges to global health. Many pharmaceutical or material strategies have been explored to overcome this dilemma. Of these, silver nanoparticles (AgNPs) are known to have a non-specific antibacterial mechanism that renders it difficult to engender silver-resistant bacteria, enabling them to be more powerful antibacterial agents than conventional antibiotics. AgNPs have shown promising antibacterial effects in both Gram-positive and Gram-negative bacteria. The aim of this review is to summarize the green synthesis of AgNPs as antibacterial agents, while other AgNPs-related insights (e.g., antibacterial mechanisms, potential toxicity, and medical applications) are also reviewed.
... Current treatments for burns are based on antibiotic therapy methods and plastic surgery. Silver sulfadiazine is an effective and widely used antibiotic for burn injuries in humans [4][5][6][7]. ...
... It has also been confirmed that CS confers considerable antibacterial activity against a broad spectrum of bacteria [35][36][37]. Lu et al. used self-assembly technology for a novel wound dressing based on CS and nano silver an dreported an increase in the rate of wound healing while a decrease in the infection rate [7]. In another study by Shu-Huei Yu et al.,CS/alginate hydrogel membranes containing AgSD were prepared as a wound dressing.The controlled antibacterial release of AgSD against Pseudomonas aeruginosa and Staphylococcus aureus suggests that this dressing is effective in suppressing bacterial proliferation and keeping the wounds away from bacterial invasion [39]. ...
Chitosan/polyethylene oxide (CS/PEO) nanofiber containing silver sulfadiazine (AgSD) was successfully prepared and analyzed in the present study. CS nanofiber mats with antibacterial activity against some common bacteria found on burn wounds were provided from a 70% aqueous acetic acid solution containing a different ratio of CS/PEO and AgSD, as a potential antibacterial agent. Several parameters were investigated to optimize the fiber diameter, including polymer concentration, CS to PEO ratio, applied voltage, and needle to collector distance. The obtained nanofibers were analyzed by scanning electron microscopy, transmission electron microscopy, and ultraviolet-visible spectroscopy. The spectroscopy results showed the presence of AgSD in nanofiber mats. The drug release behavior of electrospun nanofiber mats was investigated in phosphate buffer saline (PBS, pH = 7.4) at 37 °C. In all tested nanofiber mats, a burst release of the drug was observed after 4hoursof incubation in PBS. The most AgSD released from nanofibrous mats were observed after 40 hours of releasing and it was 76.74%. The results indicated that the new type of CS wound dressing incorporated with AgSD can be a high potential candidate in the treatment ofinfected wounds.
... Silver nanoparticles (AgNP) (typically 1 to 100 nm diameter) enhance this physicochemical antimicrobial action through a high surface to volume ratio and can further gain access within cells to exert intracellular antiviral activity via interactions with viral genomes (DNA or RNA) (Galdiero et al., 2011;Greulich et al., 2011;Morris et al., 2019). Silver nanoparticles are currently used in human medical care, e.g. in wound dressings, surgical sutures, cardiovascular implants, catheters, or bone cement (Alt et al., 2004;Andara et al., 2006;Gallo et al., 2016;Lackner et al., 2008;Leaper, 2006;Lu et al., 2008). In vitro studies have shown that AgNP can inhibit the replication of human respiratory viruses, e.g. ...
Viruses can be involved in respiratory disorders in horses, with limited therapeutic options. Citrate-complexed silver nanoparticles (C-AgNP) have shown bactericidal properties after in vitro nebulization. The aim of the present study was to assess the virucidal activity of C-AgNP after in vitro instillation or nebulization on equine herpesvirus-1 (EHV-1) and murine norovirus (MNV), the latter used as surrogate for small non-enveloped viruses. Both viruses were instilled or nebulized with C-AgNP of increasing concentrations, and titres were determined via TCID50 method. We demonstrated efficient inactivation of enveloped EHV-1 following instillation and nebulization of C-AgNP (infectivity losses of ≥ three orders of magnitude). While tenacious MNV was inactivated via 2000 ppm C-AgNP instillation, nebulized C-AgNP did not lead to reduction in MNV titres. Nebulization of C-AgNP may represent a novel virucidal therapeutic approach in horses. Further investigations are needed to assess its safety and effective concentrations for in vivo use.
... for Membracel ® group only on the thirteenth day. The results were very similar or superior to the results observed by most works involving chitosan films, despite having different active ingredients and different dressing addition techniques (Arockianathan et al., 2012;Hirose et al., 2007;Kofuji et al., 2010;Lu et al., 2008;Xu et al., 2007). ...
Chitosan films are commonly used for wound dressing, provided that this polymer has healing, mucoadhesiveness and antimicrobial properties. These properties can be further reinforced by the combination of chitosan with polysaccharides and glycoproteins present in aloe vera, together with copaiba oleoresin's pharmacological activity attributed to sesquiterpenes. In this work, we developed chitosan films containing either aloe vera, copaiba oil or both, by casting technique, and evaluated their microbial permeation, antimicrobial activity, cytotoxicity, and in vivo healing potential in female adult rats. None of the developed chitosan films promoted microbial permeation, while the cytotoxicity in Balb/c 3T3 clone A31 cell line revealed no toxicity of films produced with 2% of chitosan and up to 1% of aloe vera and copaiba oleoresin. Films obtained with either 0.5% chitosan or 0.5% copaiba oleoresin induced cell proliferation which anticipate their potential for closure of wound and for the healing process. The in vivo results confirmed that tested films (0.5% copaiba-loaded chitosan film and 0.5% aloe vera-loaded chitosan film) were superior to a commercial dressing film. For all tested groups, a fully formed epithelium was seen, while neoformation of vessels seemed to be greater in formulations-treated groups than those treated with the control. Our work confirms the added value of combining chitosan with aloe vera and copaiba oil in the healing process of wounds.
... Hybrid nanofibers obtained from chitosan and PEO via electrospinning are also recognised as good carriers for various biomedical products [80]. Silver NPs (AgNPs) and chitosan have been used for the development of a wound dressing material that enhances the rate of wound healing [86]. Ultrafine fibres were derived through electrospinning which showed excellent anti-bacterial activity against Escherichia coli. ...
Effective wound care is a major concern as many conventional wound healing methods and materials have failed in facilitating proper healing which disrupts the overall healing process, leading to the development of chronic wounds. Advancement in tissue engineering has led to the development of scaffolds; a 3D construct which can be utilized as a template for cell growth and regeneration while preventing infection along with acceleration of the wound healing process. Natural and synthetic polymers are used extensively for scaffold production and hybrid scaffolds are also introduced which constitutes a combination of natural and synthetic polymers. This review highlights the production of scaffolds using different kinds of polymers for skin tissue engineering.
... Nanoparticles are commercial used as antibacterial and antifugal agents and they have potential application in the fields of medical, such as dental cements [121], healing of burns and wound care [122], skin therapy and crucial in cosmetics [123], reconstructive orthopedic surgery and bone cements [124], medical devices and plastic catheters [125], target drug delivery [126], medical imaging, biolabeling and detection [127], cancer therapy [128], coating of hospital textiles such as face mask surgicals [129], gowns, coating of breath mask patient and ultrasonic detection [130], coating of implants for joint replacement [131], orthopedic and orthopedic fixations and implants [132]. AgNPs exhibits antiviral activity against human immunodeficiency virus-1, influenza virus (HIV-1), Herpes Simplex Virus HSV-2, monkey pox virus, hepatitis B, HSV-1 and respiratory syncytial virus [133]. ...
Silver nanoparticles has gain great attention in the research field in the recent years. It is due to their size, eco-friendly, cost effective, chemical stability, availability, biocompatibility, antimicrobial activity, antiviral activity, anticancer activity and many more therapeutic applications. Especially the green synthesis of nanoparticles has been most popular due to their high efficiency, non-pollutant and cost effective approach which helps in stabilizing the silver nanoparticles for vast applications. Their therapeutic applications have got a great advantage in the field due to the potential usage of phytochemicals in order to reduce and use them as antimicrobial and anticancer agents. This review provides an insight into the plant mediated synthesis of nanoparticles, methods of plant extract preparation, stabilization and characterization of nanoparticles, antibacterial and anticancer activities followed by their applications.
... 78 Mi et al. 79 designed a type of bilayer chitosan wound dressing, including a dense upper layer (skin layer) and a sponge-like lower layer, which is very suitable for application as a modern delivery of silver sulfadiazine for the control of injury infections. Lu et al. 80 fabricated a new wound dressing composed of nano-silver and chitosan using a nanometer and self-assembly technology. This dressing should have wide utilization in clinical settings. ...
One of the most significant factors affecting the rapid and effective healing of wounds is the application of appropriate wound dressings. In the present study, novel antibacterial wound dressings are fabricated that consist of Chitosan (CS)/Polyvinyl alcohol (PVA)/Sodium Alginate (SA), which are all biocompatible, functionalized with mesoporous Ag2O/SiO2 and curcumin nanoparticles as reinforcements. In this research nanocomposites are fabricated (0 wt%, 5 wt%, 10 wt%, 15 wt%, and 20 wt% of Ag2O/SiO2). After the composition of nanocomposites using the cross-linked technique, Fourier Transform Infrared (FT-IR) spectroscopy is performed to confirm the functional groups that are added to the polymer at each step. X-ray diffraction (XRD) is done to show the crystallinity of Ag2O/SiO2. Field emission scanning electron microscopy (FE-SEM) studies are performed to demonstrate the morphology of the structure, Energy-dispersive X-ray spectroscopy (EDS) is done to examine the elements in the wound dressing and atomic force microscopy (AFM) study is performed to show surface roughness and pores. Then the nanocomposites with different weight percentages are cultured in three bacteria called Acinetobacter baumannii, Staphylococcus epidermidis, and Proteus mirabilis, all three of which cause skin infections. Finally, by performing the tensile test, the results related to the tensile strength of the wound dressings are examined. The results show that with the increase of Ag2O/SiO2, the mechanical properties, as well as the healing properties of the wound dressing, have increased significantly. Fabricating these nanocomposites helps a lot in treating skin infections.
... Many different inorganic nanomaterials have been studied to fight the coronavirus; the most effective are AGNPs, which act as potential antiviral agents as well as drug carriers [49]. They have biological activities and antibacterial, antifungal, and anti-cancer effects [50][51][52] and catalytic properties [16,17]; non-toxic nature and high quantum efficiency [18,53]; disinfectant capacity [54,55]; stability [56]; water purification properties [57]. Silver-based nanomaterials have antimicrobial and antiseptic effects by producing reactive oxygen species (ROS) and are currently used to treat COVID-19 patients [6]. ...
Many aspects of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its disease, COVID-19, have been studied to determine its properties, transmission mechanisms, and pathology. These efforts are aimed at identifying potential approaches to control or treat the disease. Early treatment of novel SARS-CoV-2 infection to minimize symptom progression has minimal evidence; however, many researchers and firms are working on vaccines, and only a few vaccines exist. COVID-19 is affected by several heavy metals and their nanoparticles. We investigated the effects of heavy metals and heavy metal nanoparticles on SARS-CoV-2 and their roles in COVID-19 pathogenesis. AgNPs, AuNPs, gold-silver hybrid NPs, copper nanoparticles, zinc oxide, vanadium, gallium, bismuth, titanium, palladium, silver grafted graphene oxide, and some quantum dots were tested to see if they could minimize the severity or duration of symptoms in patients with SARS-CoV-2 infection when compared to standard therapy.
... Another report on chitosan-nanocrystalline silver-based wound dressing displayed an excellent healing rate in comparison with the silver sulfadiazine and chitosan film dressing. It also demonstrated that the silver nanoparticles loaded dressing materials are non-toxic and exclude the possibilities of argyria and argyremia formation [13]. However, the synthesis of silver nanoparticles by chemical route provides an instability condition due to the high aggregation and oxidation, which significantly affects the functionalities [14]. ...
Hydrogel-based drug delivery systems have emerged as a promising platform for chronic tissue defects owing to their inherent ability to inhibit pathogenic infection and accelerate rapid tissue regeneration. Here, we fabricated a stable bio-hybrid hydrogel system comprising collagen, aminated xanthan gum, bio-capped silver nanoparticles and melatonin with antimicrobial, antioxidant and anti-inflammatory properties. Highly colloidal bio-capped silver nanoparticles were synthesized using collagen as a reducing cum stabilizing agent for the first time while aminated xanthan gum was synthesized using ethylenediamine treatment on xanthan gum. The synthesized bio-hybrid hydrogel exhibits better gelation, surface morphology, rheology and degelation properties. In vitro assessment of bio-hybrid hydrogel demonstrates excellent bactericidal efficiency against both common wound and multidrug-resistant pathogens and biocompatibility properties. In vivo animal studies demonstrate rapid tissue regeneration, collagen deposition and angiogenesis at the wound site predominantly due to the synergistic effect of silver nanoparticles and melatonin in the hydrogel. This study paves the way for developing biologically functional bio-nano hydrogel systems for promoting effective care for various ailments, including infected chronic wounds.
... After that it was oven-dried at a constant temperature of 40°C over a period of 24 h. Sterile chitosan films were immersed in nano-silver solution at 4 ° C for 12 h, then, they were washed extensively with distilled water (Lu et al., 2008). Ag-N bonding produced the dressing at a concentration ranged between 0.69 and 1.64 mg/cm² (Rigo et al., 2013). ...
... Further studies produced a remedy, which was formulated by the combination of AgNPs and chitosan polymer. This antimicrobial bandaid with low tissue absorbance was used to heal deep wounds [192]. AgNPs have shown a cytocompatibility with tested cell lines. ...
Published studies indicate that virtually any kind of botanical material can be exploited to make biocompatible, safe, and cost-effective silver nanoparticles. This hypothesis is supported by the fact that plants possess active bio-ingredients that function as powerful reducing and coating agents for Ag+. In this respect, a phytomediation method provides favourable monodisperse, crystalline, and spherical particles that can be easily purified by ultra-centrifugation. However, the characteristics of the particles depend on the reaction conditions. Optimal reaction conditions observed in different experiments were 70-95 °C and pH 5.5-8.0. Green silver nanoparticles (AgNPs) have remarkable physical, chemical, optical, and biological properties. Research findings revealed the versatility of silver particles, ranging from exploitation in topical antimicrobial ointments to in vivo prosthetic/organ implants. Advances in research on biogenic silver nanoparticles have led to the development of sophisticated optical and electronic materials with improved efficiency in a compact configuration. So far, eco-toxicity of these nanoparticles is a big challenge, and no reliable method to improve the toxicity has been reported. Therefore, there is a need for reliable models to evaluate the effect of these nanoparticles on living organisms.
... 11 Chitosan is produced by the de-acetylation of chitin. Chitosan is called the 'sixth life element' in nature, 12 and is abundant in nature. Chitosan has various physiological and biochemical properties such as being bacteriostatic, anti-tumorogenic, lowering blood pressure, regulating blood lipids and regulating immunity, and hence is used in livestock and poultry production, medical and health, textile industry and food antibacterial packaging. ...
BACKGROUD
With the development of modern industry, the task of replacing ordinary plastic products with environmentally friendly antibacterial materials is a high priority. In this study, natural cellulose from sugarcane was compounded with glycerin and chitosan to prepare a cellulose/glycerin/chitosan (CGC) degradable composite membrane with antibacterial properties. The physical and chemical structure of the CGC composite film was characterized by X‐ray diffraction, scanning electron microscopy, thermogravimetric analysis and mechanical testing. Then antibacterial properties of CGC composite membranes were measured.
RESULTS
The data showed that the raw materials used in the composite film had interacted showing the compatibility of the three components. The addition of chitosan and glycerin can improve the toughness of cellulose‐based membranes. The samples CGC‐5/2, CGC‐10/2 and CGC‐15/2 showed four‐, three‐ and 2.7‐fold greater elongation at break, respectively, than with the cellulose membrane. Hygroscopic and water solubility test showed that the higher the chitosan content, the greater the water absorption of the composite membrane and the weaker the water solubility. However, the higher the glycerin content, the weaker the hygroscopicity of the CGC composite membrane and the greater its water solubility. Additionally, the antibacterial performance of the CGC composite membrane was significantly improved and the glycerin:chitosan ratio affects its antibacterial ability against different bacteria.
CONCLUSIONS
This research provides a low‐cost and green method for preparing antibacterial film, which can be applied to environmentally friendly packaging films, medical films and electronic product encapsulation films. © 2020 Society of Chemical Industry (SCI)
... The science of nanotechnology is a branch of science that focuses on the manipulation of atoms and molecules in the nanometer size range (mostly, 100 nm or less) [1][2][3][4][5][6][7][8]. Nanoparticles (NPs) become a remarkable in the research field of textiles and fibers [9], forensic science [10], electronics [11], space [12], agriculture [13,14], and mainly in medical applications, because they involve the capability to deliver a vast range of drugs to altering the body areas for fixed interval of time. ...
... The silver sulfadiazine group develops no epithelial lamina, while the use of chitosan film leads to patchy epithelial lamina with a few sebaceous glands. Overall, the nanosilver impregnated nanocrystalline chitosan wound dressing can promote wound healing and combat infection (Lu et al., 2008). ...
Over the past decade, functional biomaterials research has received great interest due to the versatility of biomaterials used in regenerative medicines. The main goal of tissue engineering and use of regenerative medicines is to assemble functional constructs that restore, maintain or improve damaged tissues or whole organs. Biodegradable polymeric materials and their composites have been widely explored for the said purpose. Chitosan is a polyelectrolyte with reactive functional groups, gel‐forming capability and high adsorption capacity. It exhibits outstanding properties, likely structural similarity to glycosaminoglycan, innately biocompatible and non‐toxic to living tissues as well as having antibacterial, antifungal and antitumor activity. In recent years, considerable attention has been given to chitosan for its applications in the field of tissue engineering and tissue regeneration due to its minimal foreign body reactions and suitability for cell ingrowth. Composite materials based on combination of biodegradable polymers and inorganic materials exhibit tailored physical, biological and mechanical properties as well as predictable degradation behavior. In this chapter, chitosan and chitosan composites for skin tissue engineering and regeneration applications are discussed.
... First cardiovascular machine encrusted with Ag ingredient was prosthetic silicone heart regulator to moderate the happening of endocarditic [151][152][153][154][155][156][157][158][159][160][161][162][163][164][165][166] . This operation of Ag was wished-for to steer clear of bacterial corruption on the silicone valve and condense the irritation response of heart. ...
... Moreover, they have no unfavorable impacts on the biological balance of human skin microflora [23]. It was also found that the utilization of wound dressings with silver even accelerates the wound healing [24] and prevents the postoperative diseases [25]. The aim of this investigation is to elaborate on the presence of silver nanoparticles in bactericidal, antifungal fibers, textile biomaterials and its products, as well as to study their structural, physico-chemical and bactericidal properties. ...
Stable silver nanoparticles in solutions of sodium-carboxymethylcellulose (Na-CMC) were synthesized and their structure and physico-chemical properties were evaluated. The form and sizes of silver nanoparticles formed in solutions of CMC and cotton fabrics were studied using UV-VIS spectroscopy, atomic force microscopy and transmission electron microscopy methods. It was found that silver nitrate concentration increase in sodium carboxymethylcellulose solutions, as well as photoirradiation of the hydrogel lead to the changes of the silver nanoparticles size and shape. Investigations have also shown that spherical silver nanoparticles with sizes of 5-35 nm and content of 0.0086 mass% in cotton fabrics possess high bactericidal activity. Stabilization of silver nanoparticles has preserved bactericidal and bacteriostatic activities during the washing of cotton fabrics and textiles on their base.
... Chitosan is a biopolymer derived from partial deacetylation of chitin. It is considered as extremely suitable for biomedical applications due to its superior affinity to proteins, high biocompatibility, biodegradability, non-antigenicity and non-toxicity, antibacterial and blood coagulation properties [13][14][15][16][17].A lot of research groups have published their experimental research of the broad application of chitosan in medicine [18][19][20][21][22][23][24]. Composites combining these degradable polymers with bioceramics are of particular interest as tissue engineering scaffolds as the desirable mechanical, physical and biological, properties can be achieved [3,[25][26][27][28].Chitosan composites containing calcium phosphates such as β-tricalcium phosphate (β-TCP) and hydroxyapatite Hap (Ca 10 (PO 4 ) 6 (OH) 2 ) have been widely investigated as they meet the above-mentioned requirements for successful platforms for bone and dental tissue repair and engineering [29][30][31][32][33][34][35][36][37]. ...
Reconstruction of dental tissue defects is a major challenge facing dentistry. Temporary “platforms” materials for seeding different types of cells and their adhesion and proliferation has been extensively researched. Composites comprising zirconia and natural polymers are used as biomaterials as they meet the requirements for successful platforms for dental tissue repair. The fabrication of defined patterns, smaller than 100 µm, is difficult due to the brittleness of ceramic materials. In the recent years femtosecond laser microprocessing have been applied to modify surface of medical implants. In this study we have demonstrated surface texturing of chitosan, chitosan/ ceramics blends and bulk ceramic from Alumina toughened Zirconia (ATZ) with 150fs and 400 fs laser pulses at 800nm and 1040 nm wavelength. A comparative experimental study was performed to evaluate different modes of processing of biopolymer/ceramic material. The results obtained from biopolymers, biopolymer/ceramic composites, ATZ bulk ceramic demonstrate selectively structured morphologies with outstanding topographical properties. Furthermore, the formation of a laser induced microstructures, on all the examined specimens, demonstrate tunability, which strongly depends from the variation of scanning velocity, overlap percentage and laser fluence. Using femtosecond laser pulses, surface structures less than 100 µm were established on bio -polymer/ceramic surfaces. The microstructured scaffolds were investigated by SEM, EDX, AFM, XRD analyses. The X-ray diffraction analysis demonstrated preservation of the tetragonal phase of Zr ceramics for a specific fs laser treatment conditions namely N<5. The AFM results showed that femtosecond laser processing influence the surface roughness (Sa), by altering the depth of the structures which is related to the scanning velocity. In this paper, we found a method for optimization of Sa parameter, by increasing the scanning velocity and obtaining an Sa values in the nanometer range, simultaneously keeping the surface integrity of zirconia ceramic. The acquired experimental results demonstrate a path to optimize surface properties which affects cell–material interaction.
... In addition, they have no adverse effects on the ecological balance of healthy human skin microfl ora [23]. It was also found that the use of wound dressings with Ag even accelerates wound healing [24] and prevents postoperative infections [25]. ...
... In addition, they have no adverse effects on the ecological balance of healthy human skin microfl ora [23]. It was also found that the use of wound dressings with Ag even accelerates wound healing [24] and prevents postoperative infections [25]. ...
Citation: Yunusov KHE, Mullajonova SV, Sarymsakov АА, Jalilov JZ, Turakulov FM, et al. (2019) Antibacterial effect of cotton fabric treated with silver nanoparticles of different sizes and shapes. Int J Nanomater Nanotechnol Nanomed 5(2): 016-023.
... In addition, they have no adverse effects on the ecological balance of healthy human skin microfl ora [23]. It was also found that the use of wound dressings with Ag even accelerates wound healing [24] and prevents postoperative infections [25]. ...
... The antibacterial and antifungal properties of these polysaccharides are pertinent to their adhesive nature. The oxygen permeability property is attributed to the use of these biomaterials in the treatment of wound and burn injuries(Jayakumar, Prabaharan, Kumar, Nair, & Tamura, 2011).Lu and his team (S.Lu, Gao, & Gu, 2008), constructed an Ag nanocrystalline/chitosan(AgNC-Cs) composite by self-assembly. The prepared composite can promote wound healing and combat infections. ...
Wound healing is a dynamic and complex process which affects the quality of life in patients and annually causes high costs for the health system, worldwide. Polymers from natural origins such as polysaccharides have gained particular interest between researchers for wound dressing applications due to their abundance in nature, biocompatibility with human tissues, and ideal physicochemical properties. Aside from their supportive effect in wound care, polysaccharides and their derivatives can actively contribute to the healing process. Silver nanoparticles are widely used noble metal nanoparticles incorporated in wound dressings due to their low toxicity for human cells, naturally availability, and strong antimicrobial effects. In the present study, we will review the most frequently used polysaccharides in wound dressing procedure with silver or silver nanoparticles accommodated. The methods of synthesis, physicochemical properties, healing efficiencies, toxicity against human tissues, antibacterial and antifungal effects of each material will also be discussed.
... Chitosan is pointed out for treatment of wounds due to its beneficial biological properties, specifically hemostatic action, hydrating effect, anti-inflammatory characteristics, and angiogenic activity. It accelerates dermal regeneration and re-epithelization of skin promoting wound healing [57][58][59]. In addition, chitosan has been proved to be non-toxic, non-immunogenic, non-carcinogenic, biodegradable, biocompatible, bioadherent and blocks nerve endings to reduce pain [60][61][62][63][64]. ...
Film-forming emulsions and films, prepared by incorporating different concentrations of clove essential oil (CEO) and melaleuca essential oil (MEO) into chitosan (CS) were obtained and their properties were evaluated. Film-forming emulsions were characterized in terms of qualitative assessment, hydrogen potential and in vitro antibacterial activity, that was carried by the agar diffusion method, and the growth inhibition effects were tested on the Gram-positive microorganism of Staphylococcus aureus, Gram-negative microorganisms of Escherichia coli, and against isolated fungi such as Candida albicans. In order to study the impact of the incorporation of CEO and MEO into the CS matrix, the appearance and thickness of the films were evaluated. Furthermore, Fourier transform infrared spectroscopy (FTIR), contact angle measurements, a swelling test, scanning electron microscopy and a tensile test were carried out. Results showed that the film-forming emulsions had translucent aspect with cloudy milky appearance and showed antimicrobial properties. The CEO had the highest inhibition against the three strains studied. As regards the films’ properties, the coloration of the films was affected by the type and concentration of bioactive used. The chitosan/CEO films showed an intense yellowish coloration while the chitosan/MEO films presented a slightly yellowish coloration, but in general, all chitosan/EOs films presented good transparency in visible light besides flexibility, mechanical resistance when touched, smaller thicknesses than the dermis and higher wettability than chitosan films, in both distilled water and phosphate-buffered saline (PBS). The interactions between the chitosan and EOs were confirmed by. The chitosan/EOs films presented morphologies with rough appearance and with EOs droplets in varying shapes and sizes, well distributed along the surface of the films, and the tensile properties were compatible to be applied as wound dressings. These results revealed that the CEO and MEO have a good potential to be incorporated into chitosan to make films for wound-healing applications.
... In topical wound care, AgSD is primarily used in a hydrophilic cream base (Cream-AgSD) or dressing and applied to burn and other surface wounds [16]. Recently, transparent film dressings [17] composed of polyurethane or co-polyester, and hydrogels such as alginates [18], chitosan [19] and hyaluronic acid [20] based biomaterials containing AgSD formulations, have been used as carriers. These dressings possess a unique micromorphology with distinguished physical and mechanical properties that aid in the delivery of antibiotic agents to the wound surface [21,22]. ...
The delivery of antimicrobial agents to surface wounds has been shown to be of central importance to the wound healing process. In this work, we prepared film forming wound care formulations containing 3 polymers (FTP) that provide broad-spectrum antimicrobial protection for prolonged periods. FTP formulations comprises of a smart gel matrix comprising of pH-degradable and temperature responsive polyacetals (smart polymer) which allow for the FTP films to be hydrophobic at room temperature, preventing accidental rubbing off, and hydrophilic at lower temperatures, allowing for easy removal. Two FTP smart-antimicrobial films were evaluated in this work: FTP-AgSD (Silver sulfadiazine actives), and FTP-NP (Neosporin actives). The in vitro and ex vivo antimicrobial efficacy studies show that FTP-AgSD films are significantly more effective for longer durations against Staphylococcus aureus (3 days), Candida albicans (9 days) and Pseudomonas aeruginosa (4 days) when compared to the cream formulations containing antimicrobials. FTP-NP films showed significantly improved antimicrobial activity for a minimum of 3 days for all pathogens tested. Moreover, when tested ex vivo in porcine skin, FTP-AgSD and FTP-NP showed average improvements of 0.89 log10 and 1.66 log10 respectively over standard cream counterparts. Dermal toxicity studies were carried out in a rat skin excision model which showed a similar wound healing pattern to that in rats treated with standard cream formulations as represented by reduction in wound size, and increase in wound healing markers.
... Several membranes based on chitosan have been prepared for potential tissue engineering applications. [89][90][91][92][93][94] Scaffolds and composite scaffolds have also been used for skin tissue engineering applications. These scaffolds are designed in such a way that they can mimic the stratified microstructure of the skin tissue and provide a temporary porous ECM for cell infiltration and vascularization. ...
Tissue engineering is a multidisciplinary field of research which focuses on biological and bioactive substitutes. Chitosan is a naturally occurring polysaccharide demonstrating excellent biocompatibility, biodegradability along with antioxidant, antibacterial, and wound healing properties. The presence of amino and hydroxyl groups also allows various chemical and physical modifications in order to achieve a broad range of materials with diverse structures and applications. Therefore, the structure–property relationship of chitosan derivatives can be designed by chemical modifications,
blending, and physical and chemical cross-linking methodologies. Three-dimensional structures of chitosan such as hydrogels and porous scaffolds are able to accommodate cells for tissue engineering purposes. Moreover, chitosan allows the loading of various biological molecules such as growth factors, which are applicable in the regeneration of tissues such as skin, cartilage, and bone. In addition, chitosan has the potential to be processed into various forms of films, membranes, nanofibrous mats, and porous sponges for wound dressing applications. Wound healing properties of chitosan and its derivatives have resulted in the generation of various forms of versatile dressings with tunable properties. Several therapeutics such as antibiotics, antimicrobials, and growth factors are integrated with chitosan dressings in order to make the wound healing process more rapid and efficient.
... Another desirable property of the Ag nanoparticles is their aesthetic appeal, as there was less hypertrophic scarring and the hair growth on the wound surface was reported to be almost normal. To achieve a controlled and sustained therapy, Ag nanoparticles may also be incorporated into dressings based on chitosan or gelatin nanofiber mats prepared through electrospinning (Lu et al., 2008;Rujitanaroj et al., 2008). These kinds of formulations imbibe the beneficial effects of providing a moist, warm, and nutritious environment for wound healing, as contributed by the dressings. ...
The fusion of nanotechnology with medicine has offered a plethora of opportunity to control, manipulate, study, and manufacture structures and devices at the nanometer size range for biomedical applications, including drug delivery. Encapsulation of drugs into nanoparticles offers a great opportunity to improve the standard care and prognosis for challenging healthcare issues such as impaired wound healing. In fact, the use of nanoparticulate drug delivery vehicles for wound healing has been predicted to revolutionize the future of diabetic therapy. The slow and sustained release of the encapsulated drug from the nanoparticle can increase the safety of the drug for topical delivery, as the whole amount of the encapsulated drug is never in direct contact with the skin at one time. Controlled-release wound healing formulations are also highly beneficial in management of chronic wounds, as they eliminate the need for frequent dressing changes thus increasing patient compliance. Reduced dose, along with higher localized concentration and prolonged delivery at the wounds, can be achieved avoiding high dose, systemic exposure to the drugs. In addition, susceptible drugs such as growth factors can also be delivered safely while there is also a scope for tailoring their release profiles
Infection treatment plays a crucial role in aiding the body in wound healing. To that end, we developed a library of antimicrobial polymers based on segmented shape memory polyurethanes with nondrug-based antimicrobials (i.e., honey-based phenolic acids (PAs)) using both chemical and physical incorporation approaches. The antimicrobial shape memory polymers (SMPs) have high transition temperatures (>55 °C) to enable maintenance of temporary, programmed shapes in physiological conditions unless a specific external stimulus is present. Polymers showed tunable mechanical and shape memory properties by changing the ratio, chemistry, and incorporation method of PAs. Cytocompatible (∼100% cell viability) synthesized polymers inhibited growth rates of Staphylococcus aureus (∼100% with physically incorporated PAs and >80% with chemically incorporated PAs) and Escherichia coli (∼100% for samples with cinnamic acid (physical and chemical)). Crystal violet assays showed that all formulations inhibit biofilm formation in surrounding solutions, and chemically incorporated samples showed surface antibiofilm properties with S. aureus. Molecular dynamics simulations confirm that PAs have higher levels of interactions with S. aureus cell membranes than E. coli. Long-term antimicrobial properties were measured after storage of the sample in aqueous conditions; the polymers retained their antimicrobial properties against E. coli after up to 20 days. As a proof of concept, magnetic particles were incorporated into the polymer to trigger user-defined shape recovery by applying an external magnetic field. Shape recovery disrupted preformed S. aureus biofilms on polymer surfaces. This antimicrobial biomaterial platform could enable user- or environmentally controlled shape change and/or antimicrobial release to enhance infection treatment efforts.
The repair and remodeling of injured tissues, known as wound healing, is a multifaceted process. The use of nanotechnology to speed up the healing process of wounds by promoting the right kind of mobility through different mechanisms has shown a lot of promise. Several nanotechnologies with novel properties have emerged in recent years, each of which targets a different issue associated with wound-healing processes. Through their antibacterial, anti-inflammatory, and angiogenic actions, nanomaterials may alter the wound microenvironment from a non-healing to a healing state. Wound dressings including hydrogels, gelatin sponges, films, and bandages may all benefit from the use of nanoparticles (NPs) to keep harmful microbes out. The addition of bioactive substances like antibiotics, NPs, and growth factors to certain dressings may further boost their efficacy. In conclusion, this review sheds light on wound healing that may be aided by the special features of materials based on nanotechnology. Although nanomater-ials for wound healing show great promise, further study is needed before this promising area can convert its findings into consumer-friendly solutions.
Taking care of wounds costs a lot of money. A significant medical problem is the treatment of burns, surgical and trauma wounds and skin wounds, with current therapies primarily emphasizing supportive care techniques. Coagulation, inflammation, angiogenesis, new tissue creation and extracellular matrix modification are necessary processes for successful wound healing. Metal oxides (Titanium, Silver, Zinc, Copper, Magnesium, Nickel) with potent antibacterial and healing characteristics can be employed as nanomaterials in dressings. Metal oxide nanoparticles (MeO-NPs) have a wide range of physicochemical properties that allow them to function as antimicrobial agents through a variety of mechanisms. The treatment of lethal infectious diseases will be impacted by the enormous variety of features demonstrated by MeO-NPs. This study covers the antibacterial mechanisms of common MeO-NPs, factors affecting their antibacterial activity and their role in accelerating wound healing.
This work aims to statistically assess the biocompatibility and the biodegradability of hydrogels which synthesized to different conditions for the wound-dressing applications. The present work also focuses on providing information about the synthesis of chitosan and gelatine by using a cross-linker. Experiments were designed by using Box-Behnken experimental design method. Effects of chitosan amount, gelatin amount and glutaraldehyde amount on biocompatibility and biodegradability of hydrogels have been statistically investigated. This parameters optimized by the response surface methodology in order to maximize responses as swelling, porosity, in vitro degradation and in vitro enzymatic degradation. Structural analysis of hydrogels was performed by FTIR spectroscopy. Analysis of variance was performed to assess statistically significant differences between the parameters on the biocompatibility and the biodegradability of hydrogels by using the Design Expert 13 statistical program. Mathematical model was found for each response variable, and the optimum values of the parameters were determined. The maximum percentage swelling, porosity, in vitro degradation and in vitro enzymatic degradation were obtained 470%, 92%, 83% and 86%, respectively, under conditions that 0.2 g chitosan, 0.8 g gelatin and 0.5 mL cross-linker. The limitations due to the use of glutaraldehyde are related to its high cytotoxicity. 1-(3-Dimethylaminopropyl)-3-ethyl-carbodimide (EDC) does not form toxic aldehydes. Therefore, EDC was used in hydrogel synthesis in our study for comparison against glutaraldehyde. In this optimum conditions, the effect of the molecular weight of chitosan, cross-linker type (glutaraldehyde and EDC) and ambient pH on biocompatibility (swelling, porosity analysis) and biodegradability was determined. In this study, to improve wound healing, it is thought that the results of the statistical evaluation of the effect of the simultaneous changes of the parameters on the properties of the biomaterial in obtaining the optimum condition hydrogels will contribute to biomedical applications.
Previous studies using monotypic nerve cell cultures have shown that nanoparticles induced neurotoxic effects on nerve cells. Interactions between neurons and Schwann cells may protect against the neurotoxicity of nanoparticles. In this study, we developed a co-culture model consisting of immortalized rat dorsal root ganglion (DRG) neurons and rat Schwann cells and employed it to investigate our hypothesis that co-culturing DRG neurons with Schwann cells imparts protection on them against neurotoxicity induced by silver or gold nanoparticles. Our results indicated that neurons survived better in co-cultures when they were exposed to these nanoparticles at the higher concentrations compared to when they were exposed to these nanoparticles at the same concentrations in monotypic cultures. Synapsin I expression was increased in DRG neurons when they were co-cultured with Schwann cells and treated with or without nanoparticles. Glial fibrillary acidic protein (GFAP) expression was increased in Schwann cells when they were co-cultured with DRG neurons and treated with nanoparticles. Furthermore, we found co-culturing with Schwann cells stimulated neurofilament polymerization in DRG neurons and produced the morphological differentiation. Silver nanoparticles induced morphological disorganization in monotypic cultures. However, there were more cells displaying normal morphology in co-cultures than in monotypic cultures. All of these results suggested that co-culturing DRG neurons with Schwann cells imparted some protection on them against neurotoxicity induced by silver or gold nanoparticles, and altering the expression of neurofilament-L, synapsin I, and GFAP could account for the phenomenon of protection in co-cultures.
Current diabetic wound treatments remain difficult in clinical due to bacterial infection and excessive reactive oxygen species (ROS). An ideal wound dressing should have prominent antibacterial and ROS scavenging abilities. In this work, a conveniently multifunctional hydrogel wound dressing (abbreviated as CuTA/SG) was constructed by incorporating copper/tannic acid nanosheets into a dynamic cross-linking network composed of oxidized sodium alginate, gelatin, and Ca²⁺. The resulting CuTA/SG hydrogel had excellent exudate absorption, adjustable photothermal antibacterial, and ROS scavenging features. Furthermore, CuTA/SG hydrogel was injectable that possessed excellent adaptability to adapt to the wound defects due to its appropriate physical cross-linking. Astonishingly, CuTA/SG hydrogel showed good hemostasis, antibacterial, anti-inflammation, and even hair regeneration capabilities, which can significantly promote diabetic wound healing in the full-thickness skin defect model in rats through reducing inflammation, guiding wound repair, and restoring skin physiological functions. Therefore, this study develops a simple and effective strategy for fabricating highly effective hydrogel dressing, which might provide new options for clinical wound management.
In recent times, metallic and metal oxide nanoparticles have found significant applications in the field of biomedical and pharmaceutical research. Silver nanoparticles have been tremendously used in therapeutics, especially in personalized healthcare practice. Ag NPs are widely used in antimicrobial therapy, drug delivery, diagnosis, therapeutics, and tissue regeneration. Gold nanoparticles (GNPs) have been extensively used in various biomedical applications, including bioimaging, targeted drug delivery, and cancer diagnosis and therapy. They are easy to synthesize and conjugate with different molecular and chemical entities. They are relatively less cytotoxic with higher rates of penetration in comparison to other metal particles, such as silver nanoparticles. These properties of GNPs make them a perfect material of choice for biomedicine. ZnO nanomaterials have low toxicity and biodegradability. Zn2 + is an indispensable trace element for adults, and it is involved in various metabolic pathways. Within this chapter, we focus on the potential bioapplications of various nanoparticles, such as Ag NPs, Au NPs, and ZnO NPs, in antimicrobial therapy, drug delivery, wound repair, and cancer therapy.
The healing of defected skin tissue is a complex process, especially for chronic wounds. Poor healing of these wounds may cause extensive suffering and high cost for patients. Traditional wound dressings are typically designed for a single function and they cannot satisfy all requirements for the whole process of wound healing. Therefore, it is necessary to develop new types of wound dressings with multiple functions for wound healing. In particular, adding an antibacterial function has been shown to be of great benefit during tissue repair. Nano‑silver is widely used in wound treatment because of various advantages, such as its wide antibacterial spectrum and lower drug resistance. Therefore, wound dressings loaded with nano‑silver have attracted widespread attention in wound healing. Naturally derived polysaccharides hold great potential as wound dressings, because of their abundant availability, low prices and good biocompatibility. In this review, nano‑silver functionalized polysaccharide-based wound dressings are systematically reviewed, including their preparation methods, antibacterial performances and classification of nano‑silver wound dressings. Moreover, the toxicity of nano‑silver based wound dressings is discussed and the prospective research direction is elaborated. This review aims to provide readers with an overview of the latest developments in silver nanotechnology, and to provide a little guidance for the research of nano‑silver functionalized polysaccharide-based wound dressings.
Natural and synthetic biopolymers represent the most diverse class of engineered biomaterials. The variety of chemical constituents, modification strategies, processing methods, and functionalities, while overwhelming at first glance, are linked by common uses in drug delivery and tissue engineering. This chapter intends to highlight the main features of biopolymers for such use by surveying the last decade of publications on natural and synthetic polypeptides and polysaccharides. Particular focus is devoted to the development of systems for the delivery of anticancer therapeutics, the engineering of tissue grafts, and in vivo regeneration. For peptides, we present numerous examples of self‐assembling sequences as drug delivery vehicles and tissue scaffolds, as well as cell‐binding and tissue‐penetrating sequences that promote targeted delivery and tissue integration. We then retrace the same applications, with the leading role being played by polysaccharides, in particular dextran, chitosan, hyaluronate, and cellulose. The similarities in processing and utilizing polypeptides and polysaccharides across these applications bring the “parallel lives” of these materials out of the massive body of literature to the full fruition of the reader.
The main obstacle for brain drug delivery after systemic administration is the presence of the blood-brain barrier (BBB). The use of drug nanocarriers to overcome this selective barrier that isolates the central nervous system (CNS) has been widely studied in recent years. Among the different nanoparticles described in literature, inorganic nanoparticles such as gold, iron oxide, carbon, silver, and others have been studied for brain drug delivery. Here, we describe the strategies employed with different inorganic nanoparticles to reach the CNS, which in general used targeting molecules that can facilitate the transport across the BBB through transport mechanisms such as adsorptive-mediated transcytosis and receptor-mediated transport or the use of peptide vectors. Throughout this chapter, examples of diverse nanosystems will be given, highlighting the main research objectives, their characteristics, and the results obtained.
Since the identification of the first human coronavirus in the 1960s, a total of six coronaviruses that are known to affect humans have been identified: 229E, OC43, severe acute respiratory syndrome coronavirus (SARS-CoV), NL63, HKU1, and Middle East respiratory syndrome coronavirus (MERS-CoV). Presently, the human world is affected by a novel version of the coronavirus family known as SARS-CoV-2, which has an extremely high contagion rate. Although the infection fatality rate (IFR) of this rapidly spreading virus is not high (ranging from 0.00% to 1.54% across 51 different locations), the increasing number of infections and deaths has created a worldwide pandemic situation. To provide therapy to severely infected patients, instant therapeutic support is urgently needed and the repurposing of already approved drugs is presently in progress. In this regard, the development of nanoparticles as effective transporters for therapeutic drugs or as alternative medicines is highly encouraged and currently needed. The size range of the viruses is within 60-140 nm, which is slightly larger than the diameters of nanoparticles, making nanomaterials efficacious tools with antiviral properties. Silver-based nanomaterials (AgNMs) demonstrate antimicrobial and disinfectant effects mostly by generating reactive oxygen species (ROS) and are presently considered as a versatile tool for the treatment of COVID-19 patients. Other metal-based nanoparticles have been primarily reported as delivery agents or surface modifying agents, vaccine adjuvant against coronavirus. The present review summarizes and discusses the possible effectiveness of various surface-modified AgNMs against animal corona-viruses and presents a concept for AgNM-based therapeutic treatment of SARS-CoV-2 in the near future.
Although it is still worth to use silver nanoparticles as antimicrobial agents, silver nanoparticles can also be dangerous to human body, when they used directly to the wound sites. One strategy for avoiding this problem is to embed the nanoparticles in matrices such as hydrogels, polymers, or composites; however, most methods have limitations in terms of nanoparticle loading efficiency and/or pre- or post-treatment required in the manufacturing process. Herein, we introduce two in-situ synthetic methods in which silver nanoparticles are directly synthesized inside silver citrate nanorods that are antimicrobial materials composed of silver and citrate ions. The silver nanoparticles embedded antimicrobial silver citrate nanorods are expected to exhibit a synergistic, long―lasting, and sustainable antimicrobial effect. In addition, this study shows that a large number of nanoparticles can be formed inside silver citrate nanorods with no additional reagents not only at temperatures much lower (as low as 25 °C) than those usually required but also rapidly via electron beam irradiation. The fundamental principles of the proposed efficient syntheses are discussed in terms of the catalytic effect of reactants confined in nanospaces.
Joint wound healing is a complex but critical dynamic process that leads to the restoration of wounded tissue and normal anatomy. Therefore, it is necessary to develop efficient wound dressing with desirable biocompatibility, antibacterial activity, and wound healing ability. In this study, the Ti-doped hydroxyapatite (Ti-HAP) nanorods have been synthesized and incorporated into the chitosan (CS) matrix for joint wound healing. The CS/Ti-HAP nanocomposite hydrogel dressing presents high antibacterial activity and cell viability. Significantly, the in vivo evaluation of joint wound healing efficiency revealed that CS/Ti-HAP dressing demonstrated a faster therapeutic effect than chitosan and CS/HAP groups. The Ti-doping method achieves a high wound healing rate up to 94.2% after two weeks’ treatment. Hence, these results strongly indicate that such CS/Ti-HAP nanocomposites may be promising materials for joint wound healing applications.
Infections are the main reason most people die from burns and diabetic wounds. The clinical challenge for treating wound infections through traditional antibiotics has been growing steadily and has now reached a critical status requiring a paradigm shift for improved chronic wound care. The USA Centers for Disease Control have predicted more deaths from antimicrobial-resistant bacteria than all types of cancers combined by 2050. Thus, the development of new wound dressing materials that do not rely on antibiotics is of paramount importance. Currently, incorporating nanoparticles into scaffolds represents a new concept of ‘nanoparticle dressing' which has gained considerable attraction for wound healing. Silver nanoparticles (Ag-NPs) have been categorized as metal-based nanoparticles and are intriguing materials for wound healing because of their excellent antimicrobial properties. Ag-NPs embedded in wound dressing polymers promote wound healing and control microorganism growth. However, there have been several recent disadvantages of using Ag-NP used to fight infections, like bacteria resistance. This review highlights the therapeutic approaches of using wound dressings functionalized with Ag-NPs and their potential role to revolutionize wound healing. Moreover, the physiology of skin and wounds are discussed to place the use of Ag-NPs in wound care into perspective.
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Nanostructured materials and their multifunctional biomedical application
Chitin is a linear polysaccharide of N-acetylglucosamine, which is highly abundant in nature and mainly produced by marine crustaceans. Chitosan is obtained by hydrolytic deacetylation. Both polysaccharides are renewable resources, simply and cost-effectively extracted from waste material of fish industry, mainly crab and shrimp shells. Research over the past five decades has revealed that chitosan, in particular, possesses unique and useful characteristics such as chemical versatility, polyelectrolyte properties, gel- and film-forming ability, high adsorption capacity, antimicrobial and antioxidative properties, low toxicity, and biocompatibility and biodegradability features. A plethora of chemical chitosan derivatives have been synthesized yielding improved materials with suggested or effective applications in water treatment, biosensor engineering, agriculture, food processing and storage, textile additives, cosmetics fabrication, and in veterinary and human medicine. The number of studies in this research field has exploded particularly during the last two decades. Here, we review recent advances in utilizing chitosan and chitosan derivatives in different technical, agricultural, and biomedical fields.
Silver nanoparticles (Ag NPs) have promising plasmonic properties, however, they are rarely used in biomedical applications because of their potent toxicity. Herein, an electron compensation effect from Au to Ag was applied to design safe [email protected] core-shell NPs. The Ag shell thickness was precisely regulated to enable the most efficient electron enrichment in Ag shell of [email protected] NPs, preventing Ag oxidation and subsequent Ag+ ion release. X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge structure (XANES) analysis revealed the electron transfer process from Au core to Ag shell, and inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis confirmed the low Ag+ ion release from [email protected] NPs. Bare [email protected] NPs showed much lower toxicological responses than Ag NPs in BEAS-2B and Raw 264.7 cells and acute lung inflammation mouse models, and PEGylation of [email protected] NPs could further improve their safety to L02 and HEK293T cells as well as mice through intravenous injection. Further, DTTC attached [email protected] NPs exhibited intense surface-enhanced Raman scattering signals, and were used for Raman imaging of MCF7 cells and Raman biosensing in MCF7 tumor-bearing mice. This electron compensation effect opens up new opportunity for broadening biomedical application of Ag-based NPs.
In Egypt, the improvement in water quality of drainage water has become an important source of irrigation due to the depletion of freshwater resources, increase in population density, industrial activities, land reclamation projects and water stress linked to changes in climate conditions. This work aimed to improve the drainage water quality by using low-cost techniques such as chitosan–silver nanoparticles or immobilized microbial isolates, to use in various activities like irrigation and fish farming. Over a year period starting form January, 2016, synthesized chitosan–silver nanoparticle was characterized by transmission electron microscopy and Fourier-transform infrared and UV–visible spectrum. The bactericidal effect of chitosan–silver nanoparticles was achieved at a concentration of 2 g/l from 40 min to 3 h to remove total coliform, fecal coliform, Staphylococcus aureus, fecal streptococci and Pseudomonas aeruginosa from 198 × 10⁵, 84 × 10⁵, 16 × 10³, 4 × 10³ and 5 × 10³ to zero CFU/ml⁻¹, respectively, while uptake decreased with using immobilized microbial isolates to 38%, 76.1%, 64.6%, 64.4% and 54.7%, respectively. The removal efficiency of BOD, COD, TSS, turbidity and ammonia on chitosan–silver nanoparticles showed a sharp decrease of 89%, 80%, 81%, 90% and 93%, respectively; in contrary, the removal efficiency for immobilized microbial isolates was 38%, 76.1%, 64.6%, 64.4% and 54.7%, respectively. Finally, improvement in El-Gharbia drain water quality by chitosan–silver nanoparticles is higher than immobilized microbial isolates.
The impact of nanomaterials on drug delivery is significant and the emergence of polymeric nanoparticles provides a unique platform for the delivery of drug molecules of a diverse nature. The conventional drug delivery system is widely changing with the development of nanoparticulate drug delivery systems. Because of their unique physicochemical properties, nanomaterials can be used for the strategic development of new drug delivery systems and reformulating existing drugs and therapeutics to escalate the effectiveness, patent protection, patient compliance, and safety of drugs. Nanoscale drug delivery systems such as nanoparticles, nanoliposome, nanoemulsions, nanosuspensions, dendrimers, nanopores, nanotubes, nanocrystals, quantum dots, and nanosponge are believed to have the potential to revolutionize the drug delivery strategy. Nanocarriers can be conjugated with a ligand such as an antibody to favor a targeted therapeutic approach. In the present chapter, we will mainly highlight the current status of the nanoscale drug delivery systems along with the progress of research in the field. Furthermore, we will throw some light on the development of polymeric nanoparticles and how multifunctionality can be engineered into polymeric nanoparticles for tumor-specific treatment. In short, we will provide an update on how nanotherapeutics may revolutionize the entire drug therapy strategy and bring it to a new look in the near future.
Wound dressings that can be formed in situ offer several advantages over the use of preformed dressings such as conformability without wrinkling or fluting in the wound bed, ease of application and improved patient compliance and comfort. Here we describe such an in situ forming hydrogel wound dressing from gelatin, oxidized alginate and borax. Periodate oxidized alginate rapidly cross-links proteins such as gelatin in the presence of borax to give in situ forming hydrogels that are both non-toxic and biodegradable. The composite matrix has the haemostatic effect of gelatin, the wound healing-promoting feature of alginate and the antiseptic property of borax to make it a potential wound dressing material. The hydrogel was found to have a fluid uptake of 90% of its weight which would prevent the wound bed from accumulation of exudates. The water vapour transmission rate (WVTR) of the hydrogel was found to be 2686+/-124 g/m2/day indicating that the hydrogel can maintain a moist environment over wound bed in moderate to heavily exuding wound which would enhance epithelial cell migration during the healing process. The wound healing efficacy of hydrogel was evaluated in experimental full thickness wounds using a rat model which demonstrated that within 2 weeks, the wound covered with gel was completely filled with new epithelium without any significant adverse reactions. These in situ forming hydrogels fulfil many critical elements desirable in a wound dressing material.
Silver has been used for centuries to prevent and treat a variety of diseases, most notably infections. It has been well documented that silver was used in ancient Greece and Rome as a disinfectant for the storage of water and other liquids. For example, silver coins were placed in the jars of liquid to maintain sterility. The American settlers in the 1800s routinely placed silver dollars in barrels of liquids to avoid spoilage, and more recently, NASA used silver to maintain water purity on the space shuttle.
This study addresses current social and ethical concerns as well as the public's perception of research and development in nanotechnology. Significant efforts have to be made to increase public awareness of this new field in order to avoid unexpected and/or unwarranted backlash. Results from a survey on nanotechnology awareness are presented, showing that only 17% of the respondents were able to identify what nanotechnology is, with 76% of the respondents being men.
A polyaniline–titanium dioxide (PANI/TiO2) nanocomposite was prepared by an in-situ chemical oxidation polymerization approach in the presence of colloidal TiO2 at room temperature, and the PANI/TiO2 nanocomposite thin film was formed on a silicon substrate covered with interdigital electrodes to fabricate a gas sensor via the self-assembly method. The gas-responses of the PANI/TiO2 thin film to NH3 and CO toxic gases were examined. The results showed that the response, reproducibility and stability of the PANI/TiO2 thin film to NH3 were superior to CO gas. Compared with NH3 and CO gases, humidity had less effect on the resistance of the PANI/TiO2 thin film. It was also found that the difference between pure PANI and PANI/TiO2 thin films was not only in gas-sensing property but also in surface morphology.
In this paper, a novel Nafion/SiO2 nanocomposite membrane based on the self-assembled Nafion–SiO2 nanoparticles was developed. The average particle size of Nafion–SiO2 nanoparticles prepared by self-assembly process was 2.8 ± 0.5 nm. The self-assembled Nafion–SiO2 nanoparticles significantly enhance the durability of the Nafion/silica nanocomposite membrane as compared to that of conventional Nafion/silica composite and Nafion 212 membranes under wet/dry cyclic tests at 90 °C. With an addition of 5 wt% self-assembled Nafion–SiO2 nanoparticles, the Nafion/SiO2 nanocomposite membrane shows a significantly improved performance stability at cell/humidifying temperatures of 100 °C/60 °C under a current density of 600 mA/cm2, and the degradation rate is 0.12 mV/min, almost 20 times lower than 2.33 mV/min measured on the pristine Nafion 212 membrane under the same conditions. The present results demonstrate the promises of the self-assembled Nafion/SiO2 nanocomposite membrane for elevated-high temperature PEM fuel cells applications.
A bilayer artificial skin composed of a silicone membrane and a collagen sponge layer containing glycosaminoglycans (GAGs) was first developed by Yannas and Burke. They reported that GAGs contained in the collagen sponge layer contributed to the function of the artificial skin. In an attempt to assess the effect of GAGs in the collagen sponge layer, the electron microscopic structure, mechanical strength of collagen sponges, and cell proliferation were examined in vitro, using four kinds of collagen sponges containing: no GAG, chondroitin 6-sulphate (C6S), dermatan sulphate (DER), and hyaluronic acid (HYA). The results indicated that: (1) addition of GAGs scarcely affected the mechanical structure of collagen sponges, (2) addition of C6S and DER reinforced mechanical strength, while addition of HYA did not, (3) addition of C6S and DER significantly decreased cell proliferation.
A bilayer artificial skin composed of an outer layer of silicone polymer and an inner sponge layer of collagen containing chondroitin 6-sulphate was developed by modifying the technique proposed by Yannas et al. The artificial skin was placed on to skin defects on the backs of rats. Histological observation indicated that fibroblasts and capillaries infiltrated into the pores and filled in lattice spaces, resulting in synthesis of the connective tissue matrix and absorption of the original network of collagen and chondroitin 6-sulphate. Epidermal cells migrated from the edge of the wound between the two layers. Post-operative contracture in the wound with the artificial skin was significantly less than in the control.
By exploiting the extremely large effective cross sections ( 10-17-10-16 cm2/molecule) available from surface-enhanced Raman scattering (SERS), we achieved the first observation of single molecule Raman scattering. Measured spectra of a single crystal violet molecule in aqueous colloidal silver solution using one second collection time and about 2×105 W/cm2 nonresonant near-infrared excitation show a clear ``fingerprint'' of its Raman features between 700 and 1700 cm-1. Spectra observed in a time sequence for an average of 0.6 dye molecule in the probed volume exhibited the expected Poisson distribution for actually measuring 0, 1, 2, or 3 molecules.
This paper is based on presentations given during a symposium and related sessions at the 2003 European Burns Association meeting by: Professor Robert E Burrell, Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta, Canada Professor Robert Demling, Professor of Surgery, Harvard Medical School, Boston, MA, USA Dr Simone Pancani, Paediatric Burn Unit, Department of Paediatric Surgery, Anna Meyer Children's Hospital, Florence, Italy Dr Anthony Papp, Burn Unit, Kuopio University Hospital, Finland Dr Ole Strand, Paediatric Surgery, Astrid Lindgren Children's Hospital, Karolinska Hospital, Stockholm, Sweden Dr Veronique Voinchet, Paediatric Burns Unit, Marseille, France The symposium was chaired by Dr Thomas Sjoberg of the University Hospital, Tromso, Norway Silver is an effective antimicrobial agent, but older silver-containing formulations are rapidly inactivated by the wound environment, requiring frequent replenishment. These older formulations may also be pro-inflammatory and may delay healing. Acticoat™ (Smith & Nephew, Hull, UK) is a relatively new form of silver antimicrobial barrier dressing which helps avoid the problems of earlier agents. It has rapid and sustained bactericidal activity, and because of this may reduce inflammation and promote healing. Despite extensive testing and clinical experience, no evidence has emerged of resistance or cytotoxicity to nanocrystalline silver. This article collects together a number of presentations that were given at the 2003 European Burns Association Meeting on the use of Acticoat™ in the management of burns.
A polyetherurethane (PEU) wound covering with non-interconnected micropores up to approximately 5 microns has been prepared by means of a phase inversion process. This highly elastic, very thin (15-20 microns), pliable wound covering showed good, immediate adherence to wet wound surfaces and high water vapor permeability, but was impermeable to bacteria. In guinea pigs epidermal wound healing of partial-thickness wounds under PEU wound coverings was accelerated compared with uncovered controls and an occlusive wound covering, OpSite. Water in liquid form or wound exudate could not leak through the PEU covering, but its high water vapor permeability induced concentration of the wound exudate into a jellylike clot layer, which apparently accelerated reepithelialization. The main conclusion from a clinical study on 20 donor sites was that the use of the PEU covering reduced pain, besides prevention of fluid retention. No differences in epithelialization were seen in comparison to tulle gras-treated wounds.
Silver ions inhibited the oxidation of glucose, glycerol, fumarate, succinate, D- and L-lactate, and endogenous substrates by intact cell suspensions of Escherichia coli. Silver ions reacted with the respiratory chain at two levels. The site most sensitive to inhibition was located between the b-cytochromes and cytochrome a2. The second level of inhibition was in the NADH and succinate dehydrogenase regions of the respiratory chain, and was situated on the substrate side of the flavin components.
The mechanism of action of silver sulfadiazine (AgSD) against Pseudomonas aeruginosa was investigated by use of the isotopes, 110Ag and 35S. AgSD was found to dissociate and only the silver moiety was bound to the cells; no cellular binding of sulfadiazine was detected. Silver was bound in considerable amounts, mainly in the fraction containing the cell proteins and carbohydrates. The DNA of log phase cells showed a degree of binding of silver which varied with time of incubation. The DNA-bound silver increased to a peak value during inhibition of growth and then declined to a low level. Growth did not occur until the Ag/DNA ratio had fallen below a certain level. The data suggest that inhibition of bacterial growth results from interference of DNA function by binding of silver ions along the helical chain.
Although cyclic AMP has been considered to regulate cell proliferation, the mechanism of this function is largely unknown. Recent studies suggest that cyclic AMP promotes the proliferation of skin cells in a dose-dependent manner. An ointment containing dibutyryl cyclic AMP has been used in the treatment of skin ulcers and found to be effective in promoting tissue repair. To search more efficacious wound management, the authors developed a new wound dressing composed of a spongy atelo-collagen sheet containing dibutyryl cyclic AMP. This wound dressing was evaluated in two types of animal tests. One is the application of the wound dressing to a full-thickness skin defect in order to evaluate the granulation tissue formation and the wound size reduction. The wound dressing was found to promote the granulation tissue formation and naturally reduce the wound size. The other test was the application of the wound dressing to the full-thickness skin defect, leaving behind a skin island in a central portion, in order to evaluate the epithelialization. This skin island left in a full-thickness skin defect was extremely enlarged. The enlargement of the skin island seems to be related to the epithelialization from the margin of the skin island as well as by the expansion of a skin island induced by contraction of the developed granulation tissue in the surrounding wound area. These results suggest that an atelo-collagen spongy sheet containing dibutyryl cyclic AMP is effective in promoting the granulation tissue formation and epithelialization.
The biosafety of a new hydrogel wound dressing material consisting of dextran dialdehyde cross-linked gelatin was evaluated (i) in vitro in cultures of dermal fibroblasts, epidermal keratinocytes, and endothelial cells, three cell types which play a major role in the process of cutaneous wound healing, and (ii) in vivo by subcutaneous implantation studies in mice. The cytotoxicities of this hydrogel, two semi-occlusive polyurethane dressings (Tegaderm and OpSite), and a hydrocolloid dressing (DuoDERM) were compared by measuring cell survival with the tetrazolium salt reduction (MTT) assay after incubations of the wound dressing samples for up to 6 d, in the presence of--but not in direct contact with--the cells. In vitro, the degree of cytotoxicity of the new hydrogel was greater in keratinocyte cultures than in fibroblast and endothelial cell cultures, and increased upon longer incubation time. In keratinocyte cultures, the semi-occlusive polyurethane dressings, the hydrocolloid, and the hydrogel dressings induced low, high and acceptable degrees of cytotoxicity, respectively. The toxicity of the isolated hydrogel components was assessed in Balb MK keratinocyte cultures. In these cells, epidermal growth-factor-stimulated thymidine incorporation into DNA was higher in the presence of gelatin. By contrast, concentrations of dextran dialdehyde as low as 0.002% were found to significantly decrease thymidine incorporation (P < 0.01). Subcutaneous implantation studies in mice showed that in vivo the hydrogel was biocompatible since the foreign body reaction seen around the implanted hydrogel samples was moderate and became minimal upon increasing implantation time. These results indicate that dextran dialdehyde cross-linked gelatin hydrogels have an appropriate biocompatibility.
This study evaluated the antimicrobial activity of ACTICOAT Antimicrobial Barrier Dressing (Westaim Biomedical Corp, Fort Saskatchewan, Alberta, Canada), a silver-coated wound dressing, and compared it with silver nitrate, silver sulfadiazine, and mafenide acetate. The minimum inhibitory concentrations (MIC), minimum bactericidal concentrations (MBC), zone of inhibition, and killing curves were determined with 5 clinically relevant bacteria. The data indicate that ACTICOAT silver had the lowest MIC and MBC and generated similar zones of inhibition to silver nitrate and silver sulfadiazine. Viable bacteria were undetectable 30 minutes after inoculation with the dressing, whereas it took 2 to 4 hours for silver nitrate and silver sulfadazine to achieve the same result. Mafenide acetate generated the biggest zones of inhibition, but it had the highest MICs and MBCs, and a significant number of bacteria still survived after 6 hours of treatment. The results suggest that ACTICOAT Antimicrobial Barrier Dressing has better antimicrobial performance than either of the existing silver-based products. ACTICOAT dressing killed the bacteria that were tested much faster, which is a very important characteristic for a wound dressing acting as a barrier to invasive infection to have. The study also suggests that a single susceptibility test such as a MIC or zone of inhibition test does not provide a comprehensive profile of antimicrobial activity of a topical antimicrobial agent or dressing. A combination of tests is desirable.
Fungal infections of burn wounds have become an important cause of burn-associated morbidity and mortality. The nature of fungal infections dictates aggressive treatment to minimize the morbidity associated with these infections. Persons with large total body surface area burns are particularly susceptible to fungal infections and are treated in such a manner as to minimize their risk of infection.
This study examined the in vitro fungicidal efficacy of a variety of different topical agents. By placing fungal inocula in contact with mafenide acetate, silver nitrate, silver sulfadiazine, and a nanocrystalline silver-coated dressing, we determined the kill kinetics of these topical agents against a spectrum of common burn wound fungal pathogens.
The topical antimicrobials that were tested demonstrated varying degrees of efficacy against these pathogens.
The nanocrystalline silver-based dressing provided the fastest and broadest-spectrum fungicidal activity and may make it a good candidate for use to minimize the potential of fungal infection, thereby reducing complications that delay wound healing.
In case of bulk loss of tissue or non-healing wounds such as burns, trauma, diabetic, decubitus and venous stasis ulcers, a proper wound dressing is needed to cover the wound area, protect the damaged tissue, and if possible to activate the cell proliferation and stimulate the healing process. In this study, synthesis of a novel polymeric bilayer wound dressing containing epidermal growth-factor (EGF) -loaded microspheres was aimed. For this purpose, a natural, nontoxic and biocompatible material, gelatin, was chosen as the underlying layer and various porous matrices in sponge form were prepared from gelatin by freeze-drying technique. As the external layer, elastomeric polyurethane membranes were used. Two different doses of EGF was added into the prepared gelatin sponges (1 and 15 microg/cm2) to activate cell proliferation. EGF addition was carried out either in free form or within microspheres to achieve prolonged release of EGF for higher efficiency. The prepared systems were tested in in vivo experiments on full-thickness skin defects created on rabbits. At certain intervals, wound areas were measured and tissues from wound areas were biopsied and processed for histological examinations. The wound areas decreased upon low-dose EGF application but the difference between the affects of free EGF and microsphere loaded EGF was not so distinct. Upon increasing the dose of EGF by a factor of 15, it was observed that controlled release of EGF from microspheres provided a higher degree of reduction in the wound areas. Histological investigations showed that the prepared dressings were biocompatible and did not cause any mononuclear cell infiltration or foreign body reaction. The structure of the newly formed dermis was almost the same as that of the normal skin.
The effects of chitin [(1 --> 4)-2-acetamido-2-deoxy-beta-D-glucan] and its partially deacetylated derivatives, chitosans, on the proliferation of human dermal fibroblasts and keratinocytes were examined in vitro. Chitosans with relatively high degrees of deacetylation strongly stimulated fibroblast proliferation while samples with lower levels of deacetylation showed less activity. Fraction, CL313A, a shorter chain length, 89% deacetylated chitosan chloride was further evaluated using cultures of fibroblasts derived from a range of human donors. Some fibroblast cultures produced a positive mitogenic response to CL313A treatment with proliferation rates being increased by approximately 50% over the control level at an initial concentration of 50 microg/ml, whilst others showed no stimulation of proliferation or even a slight inhibition (< 10%). The stimulatory effect on fibroblast proliferation required the presence of serum in the culture medium suggesting that the chitosan may be interacting with growth factors present in the serum and potentiating their effect. In contrast to the stimulatory effects on fibroblasts, fraction CL313A inhibited human keratinocyte mitogenesis with up to 40% inhibition of proliferation being observed at 50 microg/ml. In general highly deacetylated chitosans were more active than those with a lower degree of deacetylation. These data demonstrate that highly deacetylated chitosans can modulate human skin cell mitogenesis in vitro. Analysis of their effects on cells in culture may be useful as a screen for their potential activity in vivo as wound healing agents, although in the case of fibroblasts it is important to select appropriate strains of cells for use in the screen.
The objective in this study was to determine whether exposure to pure silver increases the rate of re-epithelialization across a partial thickness wound. A meshed skin graft, placed on an excised burn wound was used as a healing model.
The rate of meshed skin graft epithelial closure on an exposed burn using a moist healing environment was shown. A moistened silver delivery system (Acticoat) was compared with a standard xeroform and eight ply gauze dressing continually moistened with a 0.01% neomycin and polymyxin solution (NP). Twenty burn patients with deep burns of over 15% of TBS were excised and grafted with 2:1 meshed grafts. One graft area was treated with the antibiotic solution and another with the silver delivery. The meshed graft was performed within 3 days of injury.
No infections were noted and quantitative swab cultures gave less than 10(2) bacteria in all cases at wound closure. At day 7, re-epithelialization was complete with silver and 55% closed with NP solution. Wound closure was complete in the NP solution group at day 10. Silver increased re-epithelialization rate by over 40%, a significant increase. Graft take was over 95% in both groups.
Silver released in a moist wound surface environment significantly increases the rate of re-epithelialization compared to a standard antibiotic solution.
Silver is an effective antimicrobial agent, but older silver-containing formulations are rapidly inactivated by the wound environment, requiring frequent replenishment. These older formulations may also be pro-inflammatory and may delay healing. Acticoat (Smith & Nephew, Hull, UK) is a relatively new form of silver antimicrobial barrier dressing which helps avoid the problems of earlier agents. It has rapid and sustained bactericidal activity, and because of this may reduce inflammation and promote healing. Despite extensive testing and clinical experience, no evidence has emerged of resistance or cytotoxicity to nanocrystalline silver. This article collects together a number of presentations that were given at the 2003 European Burns Association Meeting on the use of Acticoat in the management of burns.
Dibutyryl chitin (DBC) is a modified chitin carrying butyryl groups at 3 and 6 positions; its peculiarity is that it dissolves promptly in common solvents, while being insoluble in aqueous systems. The high biocompatibility of dibutyryl chitin in the form of films and non-wovens has been demonstrated for human, chick and mouse fibroblasts by the Viability/Cytotoxicity assay, In situ Cell Proliferation assay, Neutral Red Retention assay, Lactate Dehydrogenase Release assay, MTS cytotoxicity assay, and scanning electron microscopy. DBC was hardly degradable by lysozyme, amylase, collagenase, pectinase and cellulase over the observation period of 48 days at room temperature, during which no more than 1.33% by weight of the DBC filaments (0.3 mm diameter) was released to the aqueous medium. DBC non-wovens were incorporated into 5-methylpyrrolidinone chitosan solution and submitted to freeze-drying to produce a reinforced wound dressing material. The latter was tested in vivo in full thickness wounds in rats. The insertion of 4x4 mm pieces did not promote any adverse effect on the healing process, as shown histologically. DBC is therefore suitable for contacting intact and wounded human tissues.
Acticoat, chlorhexidine acetate 0.5%, and fusidic acid 2% were compared to assess the antibacterial effect of an application on experimental 15% BSA, full-thickness burn wounds in rats swabbed 24 h earlier with a 10(8) standard strain of methicillin-resistant Staphylococci. The swabbed organism was recovered from the eschar of all groups except the fusidic acid group. While there were significant differences between treatment groups and control group, the mean eschar concentrations did not differ significantly between the Acticoat and chlorhexidine acetate groups, but there were significant differences between the fusidic acid group and the other treatment groups. There were no statistically significant differences between treatment groups, and between control group and the chlorhexidine acetate group regarding recovery of the seeded organism from muscle, but there were significant differences between the control group and Acticoat group, and between control the group and the fusidic acid group. While no systemic spread was seen in the treatment groups, it was seen in six animals in the control group. The animal data suggest that fusidic acid is the most effective agent in the treatment of methicillin-resistant Staphylococcus aureus-contaminated burn wounds, and Acticoat is a choice of treatment with the particular advantage of limiting the frequency of replacement of the dressing.
To evaluate the safety and efficacy of Acticoat use in primary burn injuries and other skin injuries in premature neonates.
An audit of eight premature neonates who sustained burn injuries and other cutaneous injuries from various agents were treated with Acticoat. Serum silver levels were measured in three neonates. Wounds were assessed for infection and blood cultures were taken where sepsis was suspected.
Neonates ranged from 23 to 28 weeks gestation (weight: 578-1078 g). Causative injury mechanisms included: alcoholic chlorhexidine, alcoholic wipes, electrode jelly, extravasated intravenous fluids, artery illuminator, temperature probe and adhesive tape removal. Total burned body surface area ranged from 1 to 30%. All neonates were treated with Acticoat dressing changed every 3-7 days. All wounds re-epithelialised by day 28 and scar management was not required. There were four mortalities secondary to problems associated with extreme prematurity. Serum silver levels ranged from 0 to 1 micromol/L. There were no wound infections or positive blood cultures during the treatment period.
Acticoat is a suitable dressing for premature neonates who have sustained burn injury, with the advantage of minimal handling as the dressing need only be changed every 3-7 days.
Electrospinning of type I collagen in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) to fabricate a biomimetic nanofibrous extracellular matrix for tissue engineering was investigated. The average diameter of collagen nanofibers electrospun from 8% collagen solution in HFIP was 460 nm (range of 100-1200 nm). The as-spun collagen nanofibrous matrix was chemically cross-linked by glutaraldehyde vapor with a saturated aqueous solution and then treated with aqueous 0.1m glycine to block unreacted aldehyde groups. With vapor phase cross-linking for 12h, porosity of the collagen matrix decreased from 89% to 71%. The collagen nanofibrous matrix showed good tensile strength, even in aqueous solution. Effects on cytocompatibility, cell behavior, cell and collagen nanofiber interactions, and open wound healing in rats were examined. Relatively low cell adhesion was observed on uncoated collagen nanofibers, whereas collagen nanofibrous matrices treated with type I collagen or laminin were functionally active in responses in normal human keratinocytes. Collagen nanofibrous matrices were very effective as wound-healing accelerators in early-stage wound healing. Our results indicate that cross-linked collagen nanofibers coated with ECM proteins, particularly type I collagen, may be a good candidate for biomedical applications, such as wound dressing and scaffolds for tissue engineering.
To assess the toxicity of copper nanoparticles (23.5 nm) in vivo, LD(50), morphological changes, pathological examinations and blood biochemical indexes of experimental mice are studied comparatively with micro-copper particles (17 microm) and cupric ions (CuCl(2).2H(2)O). The LD(50) for the nano-, micro-copper particles and cupric ions exposed to mice via oral gavage are 413, >5000 and 110 mg/kg body weight, respectively. The toxicity classes of nano and ionic copper particles both are class 3 (moderately toxic), and micro-copper is class 5 (practically non-toxic) of Hodge and Sterner Scale. Kidney, liver and spleen are found to be target organs of nano-copper particles. Nanoparticles induce gravely toxicological effects and heavy injuries on kidney, liver and spleen of experimental mice, but micro-copper particles do not, on mass basis. Results indicate a gender dependent feature of nanotoxicity. Several factors such as huge specific surface area, ultrahigh reactivity, exceeding consumption of H(+), etc. that likely cause the grave nanotoxicity observed in vivo are discussed.
Electrospinning of chitin/silk fibroin (SF) blend solutions in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) was investigated to fabricate a biomimetic nanostructured scaffolds for tissue engineering. The morphology of the electrospun chitin/SF blend nanofibers was investigated with a field emission scanning electron microscope (FE-SEM). The average diameters of chitin/SF blend fibers decreased from 920 to 340nm, with the increase of chitin content in blend compositions. The miscibility of chitin/SF blend fibers was examined by solution viscosity measurement. The chitin and SF were immiscible in the as-spun nanofibrous structure. The dimensional stability of chitin/SF blend nanofibers, with or without water vapor after-treatment, was conducted by immersing in water. As-spun SF-rich blend nanofibrous matrices were lost their fibrous structure after the water immersion for 24h, and then changed into membrane-like structure. On the contrary, nanofibrous structures of water vapor-treated SF-rich blends were almost maintained. To assay the cytocompatibility and cell behavior on the chitin/SF blend nanofibrous scaffolds, cell attachment and spreading of normal human epidermal keratinocyte and fibroblasts seeded on the scaffolds were studied. Our results indicate that chitin/SF blend nanofibrous matrix, particularly the one that contained 75% chitin and 25% SF, could be a potential candidate for tissue engineering scaffolds because it has both biomimetic three-dimensional structure and an excellent cell attachment and spreading for NHEK and NHEF.
Novel N,O-acyl chitosan (NOAC) derivatives were synthesized to examine their fungicidal activity against the gray mould fungus Botrytis cinerea (Leotiales: Sclerotiniaceae) and the rice leaf blast fungus Pyricularia oryzae (Teleomorph: Magnaporth grisea). The fungicidal activity was evaluated by the radial growth bioassay. NOAC derivatives were more active against the two plant pathogens than chitosan itself, and the effect was concentration dependent. Against B. cinerea, 4-chlorobutyryl chitosan (EC50=0.043%), decanoyl chitosan (EC50=0.044%), cinnamoyl chitosan (EC50=0.045%), and p-methoxybenzoyl chitosan (EC50=0.050%) were the most active (12-13-fold more active than chitosan). (Un)-substituted benzoyl chitosan derivatives were more active against B. cinerea than most of these with N,O-alkyl derivatives. Against P. oryzae chitosan derivatives with lauroyl, methoxy acetyl, methacryloyl and decanoyl were the most active.
The survival and functioning of a bone biomaterial requires a rapid and stable vascularization after implantation. However, the mechanisms involved in the context of the complex healing microenvironment are poorly understood. To evaluate the vascularization potential of bone biomaterials, angiogenic stimuli were added to human dermal microvascular endothelial cells (HDMEC) growing on three-dimensional (3-D) bone biomaterials consisting of porous hydroxyapatite, porous calcium phosphate, porous nickel-titanium, successfully being used in humans, and also silk fibroin nets. HDMEC did not migrate to form microcapillary-like structures as they did on cell culture plastic. In cocultures of HDMEC and primary human osteoblast cells (HOS) or the human osteoblast-like cell line MG-63 on these biomaterials, a tissue-like self-assembly of cells occurred with time, with endothelial cells forming microcapillary-like structures containing a lumen and giving a strong PECAM-1 expression at cell interfaces. These microcapillary-like structures were intertwined between cell layers of osteoblasts and did not form when exogenous angiogenic stimuli were added to these cocultures. The life span of HDMEC was also significantly enhanced by coculture; with HDMEC being present for up to at least 42 days, compared to the monoculture where cells began to die rapidly after 1 week without passage. This coculture system may be applicable to a prevascularization strategy for biomaterials prior to implantation. Irrespective of this, the coculture model holds promise for studies to deepen our understanding of bone regeneration on 3-D substrates. Most importantly, these data raise important questions concerning the exact nature of pro-angiogenic drug- or gene-delivery systems to be incorporated into scaffolds. Our results underline the necessity to take into account the in situ production of growth factors by invading mesenchymal cells in the regenerative niche.
Bioartificial liver and hepatocyte transplantation is anticipated to supply a temporary metabolic support for candidates of liver transplantation or for patients with fulminant liver failure. An essential restriction of this form is the inability to acquire an enough amount of hepatocytes. Enhancement of the proliferation and differentiated function of hepatocytes is becoming a pursued target. Here, porcine hepatocytes were successfully immobilized on nano-sized gold colloid particles to construct a "hepatocyte/gold colloid" interface at which hepatocytes can be quickly proliferated. The properties of this resulting interface were characterized and confirmed by scanning electron microscopy and atomic force microscopy. The proliferative mechanism of hepatocytes was also discussed. The proliferated hepatocytes could be applied to the clinic based on their excellent functions for the synthesis of protein, glucose and urea as well as lower lactate dehydrogenase release.
Acute toxicological effects of copper nano-particles in vivo
- Chen Z Ha Meng
- Chen Cy Gm
- Zhao Yl
- Jia
- Ga
Chen Z, Meng HA, Xing GM, Chen CY, Zhao YL, Jia GA, et al. Acute toxicological effects of copper nano-particles in vivo. Toxicol Lett 2005;163:109–20.
Influence of glycosaminoglycans on the collagen sponges component of a bilayer artificial skin
- K Matsuda
- S Suzuki
- N Isshiki
- K Yoshioka
- R Wada
- T Okada
Matsuda K, Suzuki S, Isshiki N, Yoshioka K, Wada R, Okada
T, et al. Influence of glycosaminoglycans on the collagen
sponges component of a bilayer artificial skin. Biomaterials
1990;11:351-5.
Development of new wound dressing composed of spongy collagen sheet containing dibutyryl cyclic AMP
- H Shibata
- N Shioya
- Y Kuroyangi
Shibata H, Shioya N, Kuroyangi Y. Development of new
wound dressing composed of spongy collagen sheet
containing dibutyryl cyclic AMP. J Biomater Sci Polym Ed
1997;8:601-21.