Development of gelatin hydrogel pads as antibacterial wound dressings

Study and evaluation of a gelatin- silver oxide nanoparticles releasing nitric oxide production of wound healing dressing for diabetic ulcer

This study aimed to develop a novel Gelatin silver oxide material for releasing nitric oxide bionanocomposite wound dressing with enhanced mechanical, chemical, and antibacterial properties for the treatment of diabetic wounds. The gelatin- silver oxide nanoparticles (Ag2O-NP) bio nanocomposite was prepared using chitosan and gelatin polymers incorporated with silver oxide nanoparticles through the freeze-drying method. The samples were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. Results showed that the Ag2O-NP nanoparticles increased porosity, decreased pore size, and improved elastic modulus. The Ag2O-NP wound dressing exhibited the most effective antibacterial properties against Staphylococcus aureus and Escherichia coli. Among the samples, the wound dressing containing silver oxide nanoparticles demonstrated superior physical and mechanical properties, with 48% porosity, a tensile strength of 3.2 MPa, and an elastic modulus of 51.7 MPa. The fabricated wound dressings had a volume ratio of empty space to total volume ranging from 40% to 60%. In parallel, considering the complications of diabetes and its impact on the vascular system, another aspect of the research focused on developing a per2mediated wound dressing capable of releasing nitric oxide gas to regenerate damaged vessels and accelerate diabetic wound healing. Chitosan, a biocompatible and biodegradable polymer, was selected as the substrate for the wound dressing, and beta-glycerophosphate (GPβ), tripolyphosphate (TPP), and per2mediated alginate (AL) were used as crosslinkers. The chitosan-alginate (CS-AL) wound dressing exhibited optimal characteristics in terms of hole count and uniformity in the scanning electron microscope test. It also demonstrated superior water absorption (3854%) and minimal air permeability. Furthermore, the CS-AL sample exhibited an 80% degradation rate after 14 days, indicating its suitability as a wound dressing. The wound dressing was loaded with S-nitrosoglutathione (GSNO) powder, and the successful release of nitric oxide gas was confirmed through the grease test, showing a peak at a wavelength of 540 nm. Subsequent investigations revealed that the treatment of human umbilical vein endothelial cells (HUVECs) with high glucose led to a decrease in the expression of PER2 and SIRT1, while the expression of PER2 increased, which may subsequently enhance the expression of SIRT1 and promote cell proliferation activity. However, upon treatment of the cells with the modified materials, an increase in the expression of PER2 and SIRT1 was observed, resulting in a partial restoration of cell proliferative activity. This comprehensive study successfully developed per2-mediated bio-nanocomposite wound dressings with improved physical, mechanical, chemical, and antibacterial properties. The incorporation of silver oxide nanoparticles enhanced the antimicrobial activity, while the released nitric oxide gas from the dressing demonstrated the ability to mitigate vascular endothelial cell damage induced by high glucose levels. These advancements show promising potential for facilitating the healing process of diabetic wounds by addressing complications associated with diabetes and enhancing overall wound healing.

Adhesivity-tuned bioactive gelatin/gellan hybrid gels drive efficient wound healing

Gelatin-based hydrogels have been widely used for wound healing applications. However, increase in ligand density and reduction in pore size with increasing gelatin concentration may delay wound healing by limiting cell infiltration. In this study, we address this shortcoming by combining gelatin with gellan-which is super hydrophilic and non-adhesive to cells. We show that UV crosslinked hybrid gels composed of methacrylated gelatin (GelMA) and methacrylated gellan gum (mGG), possess considerably larger pores and improved mechanical properties compared to GelMA gels. Reduced spreading and reduced formation of focal adhesions on hybrid gels combined with lower contractility and faster detachment upon trypsin-induced de-adhesion suggests that hybrid gels are less adhesive than GelMA gels. Gradual release of fibroblast growth factor (FGF) and silver nanoparticles (AgNPs) incorporated in hybrid gels not only boosts cell migration, but also confers anti-bacterial activity against gram-positive and gram-negative bacteria at concentrations nontoxic to cells. Full thickness wound healing in Wistar rats revealed increased granulation tissue formation in hybrid gels, fastest epithelialization and highest collagen deposition in rats treated with FGF entrapped hybrid gels. Together, our results demonstrate how adhesive tuning and incorporation of bioactive factors can be synergistically combined for achieving complete wound healing.

Biosynthesis of Peptide Hydrogel-Titania Nanoparticle Composites with Antibacterial Properties

The photoantibacterial properties of titania nanoparticles (TiO2NPs) are attracting much interest, but the separation of their suspension limits their application. In this study, the encapsulation of commercial TiO2NPs within self-assembling tripeptide hydrogels to form hgel-TiO2NP composites with significant photoantibacterial properties is reported. The Fmoc-Phe3 hydrogelator was synthesized via an enzymatic method. The resulting composite was characterized with DLS, ζ-potential, SAXS, FESEM-EDS and rheological measurements. Two different concentrations of TiO2NPs were used. The results showed that, by increasing the TiO2NP quantity from 5 to 10 mg, the value of the elastic modulus doubled, while the swelling ratio decreased from 63.6 to 45.5%. The antimicrobial efficacy of hgel-TiO2NPs was tested against a laboratory Staphylococcus aureus (S. aureus) strain and two methicillin-resistant S. aureus (MRSA) clinical isolates. Results highlighted a concentration-dependent superior antibacterial activity of hgel-TiO2NPs over TiO2NPs in the dark and after UV photoactivation. Notably, UV light exposure substantially increased the biocidal action of hgel-TiO2NPs compared to TiO2NPs. Surprisingly, in the absence of UV light, both composites significantly increased S. aureus growth relative to control groups. These findings support the role of hgel-TiO2NPs as promising biocidal agents in clinical and sanitation contexts. However, they also signal concerns about TiO2NP exposure influencing S. aureus virulence.

Hydrogels as Scaffolds in Bone-Related Tissue Engineering and Regeneration

Several years have passed since the medical and scientific communities leaned toward tissue engineering as the most promising field to aid bone diseases and defects resulting from degenerative conditions or trauma. Owing to their histocompatibility and non-immunogenicity, bone grafts, precisely autografts, have long been the gold standard in bone tissue therapies. However, due to issues associated with grafting, especially the surgical risks and soaring prices of the procedures, alternatives are being extensively sought and researched. Fibrous and non-fibrous materials, synthetic substitutes, or cell-based products are just a few examples of research directions explored as potential solutions. A very promising subgroup of these replacements involves hydrogels. Biomaterials resembling the bone extracellular matrix and therefore acting as 3D scaffolds, providing the appropriate mechanical support and basis for cell growth and tissue regeneration. Additional possibility of using various stimuli in the form of growth factors, cells, etc., within the hydrogel structure, extends their use as bioactive agent delivery platforms and acts in favor of their further directed development. The aim of this review is to bring the reader closer to the fascinating subject of hydrogel scaffolds and present the potential of these materials, applied in bone and cartilage tissue engineering and regeneration.

Development and Evaluation of Hydrogel Wound Dressings Loaded with Herbal Extracts

The current study aimed to develop carbomer based hydrogel dressings, incorporating ethanolic extracts of Rosmarinus officinalis aerial parts, Achillea millefolium and Calendula officinalis flowers. The pharmaceutical properties of the obtained hydrogels, as well as their texture and antimicrobial activity, were further evaluated. Five wound dressing formulations based on carbopol were prepared. The addition of the ethanolic extracts to the formulation slightly lowered the pH of the hydrogels, as expected. The Rosmarinus officinalis aerial parts extract loaded hydrogel proved to be the firmest one. In terms of consistency and viscosity, the behavior of the five hydrogels was relatively similar. Based on the texture analysis, the texture of the hydrogels has been affected to some extent by the addition of the ethanolic extracts, decreasing their consistency, firmness, and adhesiveness. The hydrogel loaded with Rosmarinus officinalis aerial parts extract and the one incorporating the blend of extracts (mixture of the three above-mentioned extracts) proved to have a good antimicrobial activity. The studied hydrogel formulations could serve as a basis for the development of novel wound dressing materials, although more extended in vivo studies would be needed in order to support current results.

Recent advances in polymeric transdermal drug delivery systems

Transdermal delivery has proven to be one of the most favorable methods among novel drug delivery systems. Since drugs administered by transdermal delivery systems avoid the gastrointestinal tract, and thus avoid conversion by the liver, the likelihood of liver dysfunction and gastrointestinal tract irritation as side effects is low. Drug delivery through the skin has other advantages, such as maintaining an effective rate of drug delivery over time, a steady rate of circulation, and the benefits of a passive delivery system and diffusion. Transdermal drug delivery is achieved using patches which consist of different and specific layers. In the last few decades, many types of patches have been approved worldwide, such as medical plasters, which have been generally applied to the skin for localized diseases. Such patches can be traced back to ancient China (around 2000 BCE) and are the early precursors of today's transdermal patches. With the help of effective design, materials, manufacturing, and evaluation, a large number of drugs can now be administered using this valuable advanced technology. This study reviews different types of polymer patches, their advantages and disadvantages, and different studies related to transdermal drug delivery methods, and the advantages and disadvantages of each method. Different mechanisms of transdermal drug delivery system with patches are also discussed.

The Influence of Enzymatic Hydrolysis of Whey Proteins on the Properties of Gelatin-Whey Composite Hydrogels

Amino-acids, peptides, and protein hydrolysates, together with their coordinating compounds, have various applications as fertilizers, nutritional supplements, additives, fillers, or active principles to produce hydrogels with therapeutic properties. Hydrogel-based patches can be adapted for drug, protein, or peptide delivery, and tissue healing and regeneration. These materials have the advantage of copying the contour of the wound surface, ensuring oxygenation, hydration, and at the same time protecting the surface from bacterial invasion. The aim of this paper is to describe the production of a new type of hydrogel based on whey protein isolates (WPI), whey protein hydrolysates (WPH), and gelatin. The hydrogels were obtained by utilizing a microwave-assisted method using gelatin, glycerol, WPI or WPH, copper sulfate, and water. WPH was obtained by enzymatic hydrolysis of whey protein isolates in the presence of bromelain. The hydrogel films obtained have been characterized by FT-IR and UV-VIS spectroscopy. The swelling degree and swelling kinetics have also been determined.

Xylan-based hydrogels for potential skin care application

Skin care biomaterials from natural compounds are increasingly needed in recent. We demonstrate a simple strategy to fabricate the dialdehyde xylan (DAX) crosslinked hydrogel with skin care potential. The hydrogel mainly consists of dialdehyde xylan, which is used as crosslinker for gelatin (G). Glycerol (Gly) and nicotinamide (NCA) are introduced here for improving the texture, antibacterial property as well as skin care functionality. The in vitro release results demonstrate that NCA can be released smoothly from the xylan-based gel, whereby the xylan-based fabricated gel can be utilized as an ideal matrix gel in skin care with loading and release function. The antibacterial ability is in the following order: Yeast > Bacillus subtilis > Staphylococcus aureus. The cytocompatibility experiments confirm the excellent viability of the gel. These merits demonstrate the fabricated hydrogel as a potential material in skin care.

Gelatin-stabilized composites of silver nanoparticles and curcumin: characterization, antibacterial and antioxidant study

This is a preliminary study of a material comprising gelatin (Gel), silver nanoparticles (AgNPs) and curcumin (Cur) aimed for wound-healing treatment. Gelatin was used to stabilize AgNPs and encapsulate curcumin to form a therapeutic composite (GelCurAg) for their strong bactericidal and antioxidant properties. GelCurAg formulations with different gelatin concentrations were characterized to attain information about their physiochemical properties and the loading efficiency of therapeutic agents. In vitro assessment of GelCurAg focused on antibacterial, antioxidant and cytotoxic aspects. The results suggested that Gel1CurAg (synthesized from 1% gelatin solution) could be utilized as potential therapeutic agents in treating infectious wound owing to its bactericidal and antioxidant effects and low toxicity for clinical uses.

Preparation and properties of gelatin hydrolysate modified with polysiloxane quaternary ammonium salts

PSiQAEp-GH polymers were synthesized by the reaction of gelatin hydrolysate (GH) and polysiloxane quaternary ammonium salts containing epoxy group (PSiQAEp) with different molecular weight from 3147 to 12996. The results of FTIR, ¹H NMR and ¹³C NMR showed that the reaction occurred between primary amino group of arginine in GH and epoxy of PSiQAEp. The XRD and DSC studies showed that the degree of short-range order of PSiQAEp-GH reduced and its glass transition temperature (Tg) lowered more than 10 °C compared with GH. The determinations of moisture absorption and contact angle (CA) indicated that the hydrophobility of PSiQAEp-GH was better than GH. The tests of inhibitory zone and minimum bactericidal concentration (MBC) illustrated that the PSiQAEp-GHs exhibited excellent antibacterial activity, and the antibacterial activity depended on both the chemical structure of PSiQAEp-GHs and the biological structure of the bacteria.

Photo-Crosslinked Polymeric Matrix with Antimicrobial Functions for Excisional Wound Healing in Mice

Wound infection extends the duration of wound healing and also causes systemic infections such as sepsis, and, in severe cases, may lead to death. Early prevention of wound infection and its appropriate treatment are important. A photoreactive modified gelatin (GE-BTHE) was synthesized by gelatin and a conjugate formed from the 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA) and the 2-hydroxyethyl methacrylate (HEMA). Herein, we investigated the photocurable polymer solution (GE-BTHE mixture) containing GE-BTHE, poly(ethylene glycol) diacrylate (PEGDA), chitosan, and methylene blue (MB), with antimicrobial functions and photodynamic antimicrobial chemotherapy for wound dressing. This photocurable polymer solution was found to have fast film-forming property attributed to the photochemical reaction between GE-BTHE and PEGDA, as well as the antibacterial activity in vitro attributed to the ingredients of chitosan and MB. Our in vivo results also demonstrated that untreated wounds after 3 days had the same scab level as the GE-BTHE mixture-treated wounds after 20 s of irradiation, which indicates that the irradiated GE-BTHE mixture can be quickly transferred into artificial scabs to protect wounds from an infection that can serve as a convenient excisional wound dressing with antibacterial efficacy. Therefore, it has the potential to treat nonhealing wounds, deep burns, diabetic ulcers and a variety of mucosal wounds.

Recent Progress in Polymer Research to Tackle Infections and Antimicrobial Resistance

Global health is increasingly being threatened by the rapid emergence of drug-resistant microbes. The ability of these microbes to form biofilms has further exacerbated the scenario leading to notorious infections that are almost impossible to treat. For addressing this clinical threat, various antimicrobial polymers, polymer-based antimicrobial hydrogels and polymer-coated antimicrobial surfaces have been developed in the recent past. This review aims to discuss such polymer-based antimicrobial strategies with a focus on their current advancement in the field. Antimicrobial polymers, whose designs are inspired from antimicrobial peptides (AMPs), are described with an emphasis on structure-activity analysis. Additionally, antibiofilm activity and in vivo efficacy are delineated to elucidate the real potential of these antimicrobial polymers as possible therapeutics. Antimicrobial hydrogels, prepared from either inherently antimicrobial polymers or biocide-loaded into polymer-derived hydrogel matrix, are elaborated followed by various strategies to engineer polymer-coated antimicrobial surfaces. In the end, the current challenges are accentuated along with future directions for further expansion of the field toward tackling infections and antimicrobial resistance.

Nano cellulose dispersed chitosan film with Ag NPs/Curcumin: An in vivo study on Albino Rats for wound dressing

With an aim to develop chitosan film with controllable swelling behavior and maximum antimicrobial efficacy, we hereby report cellulose nano crystals loaded chitosan films with Curcumin/Ag nano particles embedded as strong antimicrobial agents. The CNC had average size of 40-90nm with poly dispersity index of 3.641. The TEM analysis of Ag NPs, produced via DMF reduction, revealed a particle size range of 15-25nm. The Surface Plasmon resonance (SPR) of these Ag NPs shifted from 380 to 440nm, with the increase in concentration of Ag (I). The TGA of the film samples Ch/CNC, and Ch/CNC (Ag₄₆₃/Cur₄₅₀) exhibited% weight loss of around 95 and 80 respectively, thus indicating higher stability due to presence of Ag NPs. In XRD analysis 2θ reflections at 38.12, 44.28 and 66.46°^, confirmed the presence planes (1 1), (2 0) and (2 0) respectively. In skin irritation test, the mean Erythema scores observed after 72h was zero for both the Curcumin and Ag NPs/Curcumin loaded films. The percent wound reduction, observed for the film samples Ch/CNC (Cur₄₅₀) and Ch/CNC (Ag NP₄₆₃/Cur₄₅₀) was 57.8 and 97.2 respectively, indicating better suitability of Ag NPs/Curcumin loaded film.

Advances in the Fabrication of Antimicrobial Hydrogels for Biomedical Applications

This review describes, in an organized manner, the recent developments in the elaboration of hydrogels that possess antimicrobial activity. The fabrication of antibacterial hydrogels for biomedical applications that permits cell adhesion and proliferation still remains as an interesting challenge, in particular for tissue engineering applications. In this context, a large number of studies has been carried out in the design of hydrogels that serve as support for antimicrobial agents (nanoparticles, antibiotics, etc.). Another interesting approach is to use polymers with inherent antimicrobial activity provided by functional groups contained in their structures, such as quaternary ammonium salt or hydrogels fabricated from antimicrobial peptides (AMPs) or natural polymers, such as chitosan. A summary of the different alternatives employed for this purpose is described in this review, considering their advantages and disadvantages. Finally, more recent methodologies that lead to more sophisticated hydrogels that are able to react to external stimuli are equally depicted in this review.

Poly(ethylene glycol)-Based Hyperbranched Polymer from RAFT and Its Application as a Silver-Sulfadiazine-Loaded Antibacterial Hydrogel in Wound Care

A multifunctional branched copolymer was synthesized by Reversible Addition-Fragmentation Chain Transfer polymerization (RAFT) of poly(ethylene glycol) diacrylate (PEGDA M_n = 575) and poly(ethylene glycol) methyl methacrylate (PEGMEMA M_n = 500) at a feed molar ratio of 50:50. Proton nuclear magnetic resonance spectroscopy (¹H NMR) confirmed a hyperbranched molecular structure and a high degree of vinyl functionality. An in situ cross-linkable hydrogel system was generated via a "click" thiol-ene-type Michael addition reaction of vinyl functional groups from this PEGDA/PEGMEMA copolymer system in combination with thiol-modified hyaluronic acid. Furthermore, encapsulation of antimicrobial silver sulfadiazine (SSD) into the copolymer system was conducted to create an advanced antimicrobial wound care dressing. This hydrogel demonstrated a sustained antibacterial activity against the bacterial strains Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli in comparison to the direct topical application of SSD. In addition, in vitro toxicology evaluations demonstrated that this hydrogel-with low concentrations of encapsulated SSD-supported the survival of embedded human adipose derived stem cells (hADSCs) and inhibited growth of the aforementioned pathogens. Here we demonstrate that this hydrogel encapsulated with a low concentration (1.0% w/v) of SSD can be utilized as a carrier system for stem cells with the ability to inhibit growth of pathogens and without adverse effects on hADSCs.

Gelatin-Graphene Nanocomposites with Ultralow Electrical Percolation Threshold

Gelatin-graphene conductive biopolymer nanocomposites (CPCs) with ultralow percolation threshold are designed by reducing in situ graphene oxide nanosheets with ascorbic acid and suppressing the aggregation of the graphene nanosheets. The resulting conductive nanocomposites show a record-low electrical percolation threshold of 3.3 × 10(-2) vol%, which arises from the homogeneous dispersion of the graphene nanosheets within the gelatin matrix.

Silk protein-based hydrogels: Promising advanced materials for biomedical applications

Hydrogels are a class of advanced material forms that closely mimic properties of the soft biological tissues. Several polymers have been explored for preparing hydrogels with structural and functional features resembling that of the extracellular matrix. Favourable material properties, biocompatibility and easy processing of silk protein fibers into several forms make it a suitable material for biomedical applications. Hydrogels made from silk proteins have shown a potential in overcoming limitations of hydrogels prepared from conventional polymers. A great deal of effort has been made to control the properties and to integrate novel topographical and functional characteristics in the hydrogel composed from silk proteins. This review provides overview of the advances in silk protein-based hydrogels with a primary emphasis on hydrogels of fibroin. It describes the approaches used to fabricate fibroin hydrogels. Attempts to improve the existing properties or to incorporate new features in the hydrogels by making composites and by improving fibroin properties by genetic engineering approaches are also described. Applications of the fibroin hydrogels in the realms of tissue engineering and controlled release are reviewed and their future potentials are discussed.

STATEMENT OF SIGNIFICANCE

This review describes the potentiality of silk fibroin hydrogel. Silk Fibroin has been widely recognized as an interesting biomaterial. Due to its properties including high mechanical strength and excellent biocompatibility, it has gained wide attention. Several groups are exploring silk-based materials including films, hydrogels, nanofibers and nanoparticles for different biomedical applications. Although there is a good amount of literature available on general properties and applications of silk based biomaterials, there is an inadequacy of extensive review articles that specifically focus on silk based hydrogels. Silk-based hydrogels have a strong potential to be utilized in biomedical applications. Our work is an effort to highlight the research that has been done in the area of silk-based hydrogels. It aims to provide an overview of the advances that have been made and the future course available. It will provide an overview of the silk-based hydrogels as well as may direct the readers to the specific areas of application.

Evaluation of in vitro wound adhesion characteristics of composite film and wafer based dressings using texture analysis and FTIR spectroscopy: a chemometrics factor analysis approach

Comparing adhesion of film and wafer based dressings using texture analysis and FTIR spectroscopy combined with chemometrics target factor analysis.

Development and characterization of a novel, antimicrobial, sterile hydrogel dressing for burn wounds: single-step production with gamma irradiation creates silver nanoparticles and radical polymerization

Patients with burn wounds are susceptible to wound infection and sepsis. This research introduces a novel burn wound dressing that contains silver nanoparticles (SNPs) to treat infection in a 2-acrylamido-2-methylpropane sulfonic acid sodium salt (AMPS-Na(+) ) hydrogel. Silver nitrate was dissolved in AMPS-Na(+) solution and then exposed to gamma irradiation to form SNP-infused hydrogels. The gamma irradiation results in a cross-linked polymeric network of sterile hydrogel dressing and a reduction of silver ions to form SNPs infused in the hydrogel in a one-step process. About 80% of the total silver was released from the hydrogels after 72 h immersion in simulated body fluid solution; therefore, they could be used on wounds for up to 3 days. All the hydrogels were found to be nontoxic to normal human dermal fibroblast cells. The silver-loaded hydrogels had good inhibitory action against Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus. Results from a pilot study on a porcine burn model showed that the 5-mM silver hydrogel was efficient at preventing bacterial colonization of wounds, and the results were comparable to the commercially available silver dressings (Acticoat(TM) , PolyMem Silver(®) ). These results support its use as a potential burn wound dressing.

Gelatin-based biomaterial engineering with anhydride-containing oligomeric cross-linkers

Chemically cross-linked gelatin hydrogels are versatile cell-adhesive hydrogel materials that have been established for a variety of biomedical applications. The most prominent cross-linker is glutaraldehyde, which, however, has been described to cause compatibility problems and loss of microscopic but relevant structural features. A recently developed oligomeric cross-linker that contains anhydride functionalities was evaluated as cross-linker for the fabrication of gelatin-based hydrogels and microparticles. In a fast curing reaction, hydrogels composed of gelatin and oligomeric cross-linker were fabricated with good conversion over a wide concentration range of constituents and with cross-linkers of different anhydride contents. Hydrogel properties, such as dry weight and mechanics, could be controlled by hydrogel composition and rheological properties correlated to elastic moduli from 1 to 10 kPa. The gels were shown to be cytocompatible and promoted cell adhesion. In soft formulations, cells migrated into the hydrogel bulk. Gelatin microparticles prepared by a standard water-in-oil emulsion technique were also treated with the novel oligomers, and cross-linking degrees matching those obtained with glutaraldehyde were obtained. At the same time, fewer interparticular cross-links were observed. Fluorescein-derivatized cross-linkers yielded labeled microparticles in a concentration-dependent manner. The oligomeric cross-linkers are presented as an efficient and possibly more functional and compatible alternative to glutaraldehyde. The engineered hydrogel materials hold potential for various biomedical applications.

Investigation of Regenerated Cellulose/Poly(acrylic acid) Composite Films for Potential Wound Healing Applications: A Preliminary Study

Regenerated cellulose/poly(acrylic acid) composite films have been synthesized for wound dressing applications. The water absorbency of these films was studied as a function of amount of cross-linker N,N′-methylenebisacrylamide and cellulose contents in the feed mixture. The samples, having different compositions, showed tensile strength and percent elongation in the range of 9.98×105 to 13.40×105 N/m2 and 110 to 265, respectively. The water vapor transmission rate (WVTR) for various films was found to be in the range of 2.03 to 7.18 mg/cm2/h. These films were loaded with antibacterial drug miconazole nitrate and their release was studied in the physiological pH at 37°C. The release data was found to fit well the diffusion controlled Higuchi model. Finally the films demonstrated fair antibacterial and antifungal action, thus establishing their strong candidature as wound dressing materials.

Antimicrobial hydrogels for the treatment of infection

The increasing prevalence of microbial infections, especially those associated with impaired wound healing and biomedical implant failure has spurred the development of new materials having antimicrobial activity. Hydrogels are a class of highly hydrated material finding use in diverse medical applications such as drug delivery, tissue engineering, as wound fillers, and as implant coatings, to name a few. The biocompatible nature of many gels make them a convenient starting platform to develop selectively active antimicrobial materials. Hydrogels with antimicrobial properties can be obtained through the encapsulation or covalent immobilization of known antimicrobial agents, or the material itself can be designed to possess inherent antimicrobial activity. In this review we present an overview of antimicrobial hydrogels that have recently been developed and when possible provide a discussion relevant to their mechanism of action.

Silver-doped self-assembling di-phenylalanine hydrogels as wound dressing biomaterials

Chronic and acute wounds can be quickly contaminated and infected by microorganisms such as bacteria, multi-resistant organisms or fungi. The introduction of silver as anti-microbial agent into wound management has widely been demonstrated to be effective and contribute to wound healing. As a consequence, many approaches and different materials have been employed to synthesize antibacterial silver-hydrogels. In this work the introduction of silver particles into the fibrillar structure of self-assembling aromatic di-phenylalanine derivatives modified with aromatic groups such as 9-fluorenylmethoxycarbonyl is proposed to produce antibacterial wound dressings. Hydrogels doped with increasing amounts of silver were tested and adopted to modify flax textiles. The influence of silver on the structure of hydrogels was studied using light and confocal microscopy, while SEM-EDX allowed the characterization of the hydrogel coating on the surface of the textile substrates as well as the identification and distribution of silver nanoparticles. The antibacterial potential of the treated flax was demonstrated through microbiological tests on Staphylococcus aureus. The combination of the physico-chemical and anti-bacterial properties, together with the ease of preparation of these biomaterials, fulfils the requirement of clinically-effective wound dressings.