Investigation of PVA/ws-chitosan hydrogels prepared by combined γ-irradiation and freeze-thawing

γ-Irradiation combined with freeze-thawing, i.e. irradiation followed by freeze-thawing and freeze-thawing followed by irradiation, was applied to prepare poly(vinyl alcohol) (PVA)/water soluble chitosan (ws-chitosan) hydrogels for wound dressing. The properties of these hydrogels were investigated and compared to those prepared by freeze-thawing and by irradiation, respectively. Hydrogels made by irradiation followed by freeze-thawing show larger swelling capacity and mechanical strength, higher thermal stability, lower water evaporation rate, and are less turbid than those made by pure freeze-thawing and freeze-thawing followed by irradiation. Hydrogels made by irradiation alone cannot be used as wound dressing due to their poor mechanical strength. SEM results show that the final structure of hydrogels made by combined irradiation and freeze-thawing is mainly determined by the first processing step. It is found that the appropriate amount of ws-chitosan can endow hydrogels with large swelling capacity and mechanical strength. The presence of ws-chitosan provides the hydrogels with good antibacterial activity against Escherichia coli (E. coli).     

High-efficient and synergetic antibacterial nanocomposite hydrogel with quaternized chitosan/Ag nanoparticles prepared by one-pot UV photochemical synthesis

Hydrogel dressings have significant advantages such as absorption of tissue exudate, maintenance of proper moist environment, and promotion of cell proliferation. However, facile preparation method and high-efficient antibacterial hydrogel dressings are still a great challenge. In this study, a facile approach to prepare antibacterial nanocomposite hydrogel dressing to accelerate healing was explored. The hydrogels consisted of quaternized chitosan and chemically cross-linked polyacrylamide, as well as silver nanoparticles (AgNPs) stabilized by chitosan. The synthesis of the hydrogels including the formation of AgNPs and polymerization of acrylamide was accomplished simultaneously under UV irradiation in 1 hour without adding initiator. The hydrogels showed favorable tensile strength of ∼100 kPa with elongation at break over 1000% and shear modulus of ∼10⁴ Pa as well as suitable swelling ratio, which were appropriate for wound dressing. The combination of quaternized chitosan and AgNPs exhibited high-efficient and synergetic antibacterial performance with low cytotoxicity. In vivo animal experiments showed that the hydrogel can effectively prevent wound infection and promote wound healing. This study provides a facile method to produce antibacterial hydrogel wound dressing materials.     

The Novelty in Fabrication of Poly Vinyl Alcohol/κ-Carrageenan Hydrogel with <Emphasis Type="Italic">Lactobacillus bulgaricus</Emphasis> Extract as Anti-inflammatory Wound Dressing Agent

Material barrier properties to microbes are an important issue in many pharmaceutical applications like wound dressings. A wide range of biomaterials has been used to manage the chronic inflamed wounds. Eight hydrogel membranes of poly vinyl alcohol (PVA) with κ-carrageenan (KC) and Lactobacillus bulgaricus extract (LAB) have been prepared by using freeze–thawing technique. To evaluate the membranes efficiency as wound dressing agents, various tests have been done like gel fraction, swelling behavior, mechanical properties, etc. The antibacterial activities of the prepared membranes were tested against the antibiotic-resistant bacterial isolates. In addition, the safety usage of the prepared hydrogel was checked on human dermal fibroblast cells. The anti-inflammatory properties of the prepared hydrogel on LPS-PBMC cell inflammatory model were quantified using enzyme-linked immunosorbent assay (ELISA) and real-time polymerase chain reaction (RT-qPCR). The analysis data of TGA, SEM, gel fraction, and swelling behavior showed changes in properties of prepared PVA\KC\LAB hydrogel membrane than pure PVA hydrogel membrane. The antibacterial activities of the prepared membranes augmented in LAB extract-prepared membranes. Out of the eight used hydrogel membranes, the PVAKC4 hydrogel membrane is the safest one on fibroblast cellular proliferation with a maximum proliferation percentage 97.3%. Also, all the used hydrogel membrane showed abilities to reduce the concentration of IL-2 and IL-8 compared with both negative and positive control. In addition, almost all the prepared hydrogel membrane showed variable abilities to downregulate the expression of TNF-α gene with superior effect of hydrogel membrane KC1. PVA/KC/LAB extract hydrogel membrane may be a promising material for wound dressing application and could accelerate the healing process of the chronic wound because of its antimicrobial and anti-inflammatory properties.     

An Investigation and Characterization on Alginate Hydogel Dressing Loaded with Metronidazole Prepared by Combined Inotropic Gelation and Freeze-Thawing Cycles for Controlled Release

The purpose of this study was to investigate the effect of combined Ca²⁺ cross-linking and freeze-thawing cycle method on metronidazole (model drug) drug release and prepare a wound film dressing with improved swelling property. The hydrogel films were prepared with sodium alginate (SA) using the freeze-thawing method alone or in combination with ionotropic gelation with CaCl₂. The gel properties such as morphology, swelling, film thickness, and content uniformity and in vitro dissolution profiles using Franz diffusion cell were investigated. The cross-linking process was confirmed by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. In vitro protein adsorption test, in vivo wound-healing test, and histopathology were also performed. The hydrogel (F2) composed of 6% sodium alginate and 1% metronidazole prepared by combined Ca²⁺ cross-linking and freeze-thawing cycles showed good swelling. This will help to provide moist environment at the wound site. With the in vivo wound-healing and histological studies, F2 was found to improve the wound-healing effect compared with the hydrogel without the drug, and the conventional product.KEY WORDS: alginate, Ca²⁺ cross-linking, freeze-thawing, swelling, wound dressing     

Oxidized chondroitin sulfate-cross-linked gelatin matrixes: a new class of hydrogels

A naturally occurring glycosaminoglycan such as chondroitin-6-sulfate was first converted in to its aldehyde derivative by periodate oxidation and used as a cross-linking agent for gelatin giving rise to a new class of hydrogels. Cross-linking was predominantly due to Schiff's base formation between the epsilon-amino groups of lysine or hydroxylysine side groups of gelatin and the aldehyde groups in oxidized chondroitin sulfate. The hydrogels were prepared from chondroitin sulfate with different degrees of oxidation and gelatin. They were characterized for degree of cross-linking, cross-linking density, equilibrium swelling, water vapor transmission rate, internal structure, and blood-compatibility. Degree of cross-linking of the gels determined by trinitrobenzene sulfonic acid assay showed that, the higher the degree of oxidation of the polysaccharide, the higher the degree of cross-linking. Examination of the internal structure by scanning electron microscopy showed that the hydrogels were highly porous in nature with interconnecting pores ranging from 50 to 200 mum. Equilibrium swelling showed that the gels retained about 90% water and did not undergo dehydration rapidly. The hydrogels were nontoxic and blood-compatible. Since an important phase of early wound healing has been shown to involve secretion of glycosaminoglycans such as chondroitin sulfate by fibroblasts which form a hydrophilic matrix suitable for remodeling during healing, this new class of hydrogels prepared from chondroitin sulfate and gelatin without employing any extraneous cross-linking agents are expected to have potential as wound dressing materials.     

Synthesis of antibacterial PVA/CM-chitosan blend hydrogels with electron beam irradiation

A series of excellent hydrogels were prepared from poly(vinyl alcohol) (PVA) and carboxymethylated chitosan (CM-chitosan) with electron beam irradiation (EB) at room temperature. Electron spectroscopy analysis of the blend hydrogels revealed that good miscibility was sustained between CM-chitosan and PVA. The properties of the prepared hydrogels, such as the mechanical properties, gel fraction and swelling behavior were investigated. The mechanical properties and equilibrium degree of swelling improved obviously after adding CM-chitosan into PVA hydrogels. The gel fraction determined gravimetrically showed that a part of CM-chitosan was immobilized onto PVA hydrogel. The further analyses of FTIR and DSC spectra of the prepared gels after extracting sol manifested that there was a grafting interaction between PVA and CM-chitosan molecules under irradiation. The antibacterial activity of the hydrogels against Escherichia coli was also measured via optical density method. The blend hydrogels exhibited satisfying antibacterial activity against E. coli, even when the CM-chitosan concentration was only 3 wt%.     

壳聚糖/ 魔芋葡甘露聚糖复合膜体内外促创面愈合研究

目的:制备壳聚糖/魔芋葡甘露聚糖复合膜,研究其促创面愈合作用。方法:壳聚糖溶液和魔芋葡甘露聚糖溶液混合后冷冻干燥制成复合膜。扫描电镜观察膜的形态和孔径,并研究比较膜的吸水率,水蒸气透过率,拉伸强度,断裂伸长率和体外降解率。建立大鼠皮肤损伤模型,敷以复合膜治疗,比较创面愈合率,观察创面组织染色结果,评价复合膜的促创面愈合作用。结果:壳聚糖/魔芋葡甘露聚糖复合膜具有三维网状结构,壳聚糖复合魔芋葡甘露聚糖后,膜的吸水率、拉伸强度和断裂伸长率提高,体外降解加速,水蒸气透过率改善。愈合实验表明壳聚糖/魔芋葡甘露聚糖膜具有促进创面愈合作用。结论:壳聚糖/魔芋葡甘露聚糖复合膜制备工艺简单,能有效促进创面愈合,具有成为创伤敷料的潜力。     

Preparation of silver nanoparticles and riboflavin embedded electrospun polymer nanofibrous scaffolds for in vivo wound dressing application

Biocompatible silver-based nanofibrous frameworks have attracted intensive attention in wound dressing materials ascribed to their greater stability, minimal toxicity, excellent antibacterial activity, and extended therapeutic efficiency. The present investigation delineates a simple approach to synthesize silver nanoparticles (Ag NPs), and riboflavin (RF) decorated polyvinyl alcohol/β-Cyclodextrin (PVA/β-CD) electrospun nanofibrous scaffolds envisioning their application in wound dressings. PVA/β-CD polymer matrix regulates the stabilization of Ag NPs and RF. Also, it promotes the wound healing process and skin regeneration. The morphology, thermal properties, and their structure were also evaluated. Likewise, mechanical properties, biodegradation and drug release profile of the nanofibrous scaffolds were evaluated. In addition Antibacterial studies of the resultant nanofibrous scaffolds showed a strong inhibitory effect against Staphylococcus aureus and Escherichia coli at a considerable level. Moreover, Ag NPs-RF/PVA/β-CD nanofibrous scaffold were studied for its in vitro cytotoxicity using human embryonic kidney cells (HEK-293), and the results suggested that Ag NPs and RF present in the nanofibrous scaffolds exhibited its cytotoxicity. Besides, wound healing efficiency of the Ag NPs-RF decorated nanofibrous scaffolds was assessed using full thickness excision wounds in rat models displayed as an excellent biomaterial for wound dressings.     

PVA based nanofiber containing cellulose modified with graphitic carbon nitride/nettles/trachyspermum accelerates wound healing

Today, bacterial cellulose has received a great deal of attention for its medical applications due to its unique structural properties such as high porosity, good fluid uptake, good strength, and biocompatibility. This study aimed to fabricate and study bacterial cellulose/graphitic carbon nitride/nettles/trachyspermum nanocomposite by immersion and PVA/BC/g-C₃N₄/nettles/trachyspermum nanofiber by electrospinning method as a wound dressing. The g-C₃N₄ and g-C₃N₄ solution were synthesized and then were characterized using Fourier transform infrared, X-ray diffraction, Zeta Potential, and scanning electronic microscope analyzes. Also, the antibacterial properties of the synthesized materials were proved by gram-positive and gram-negative bacteria using the minimum inhibitory concentration method. Besides, the toxicity, migration, and cell proliferation results of the synthesized materials on NIH 3T3 fibroblasts were evaluated using MTT and scratch assays and showed that the BC/PVA/g-C₃N₄/nettles/trachyspermum composite not only had no toxic effect on cells but also contributed to cell survival, cell migration, and proliferation has done. To evaluate the mechanical properties, a tensile strength test was performed on PVA/BC/g-C₃N₄/nettles/trachyspermum nanofibers, and the results showed good strength of the nanocomposite. In addition, in vivo assay, the produced nanofibers were used to evaluate wound healing, and the results showed that these nanofibers were able to accelerate the wound healing process so that after 14 days, the wound healing percentage showed 95%. Therefore, this study shows that PVA/BC/g-C₃N₄/nettles/trachyspermum nanofibers effectively inhibit bacterial growth and accelerate wound healing.     

Topical Niosome Gel Containing an Anthocyanin Complex: a Potential Oral Wound Healing in Rats

Anthocyanins from dietary sources showing potential benefits as anti-inflammatory in oral lesions were developed as an anthocyanin complex (AC), comprised of extracts of Zea mays (CC) and Clitoria ternatea (CT), and formulated into a niosome gel to prove its topical oral wound healing in vitro and in vivo investigations. The AC formed nano-sized clusters of crystalline-like aggregates, occurring through both intra- and inter-molecular interactions, resulting in delivery depots of anthocyanins, following encapsulation in niosomes and incorporation into a mucoadhesive gel. In vitro permeation of anthocyanins was improved by complexation and further enhanced by encapsulation in niosomes. Collagen production in human gingival fibroblasts was promoted by AC and AC niosomes, but not CC or CT. The in vivo wound healing properties of AC gel (1 and 10%), AC niosome gel (1 and 10%), fluocinolone acetonide gel, and placebo gel were investigated for incisional wounds in the buccal cavities of Wistar rats. AC gel and AC niosome gel both reduced wound sizes after 3 days. AC niosome gel (10%) gave the highest reduction in wound sizes after day 3 (compared to fluocinolone acetonide gel, p?<?0.05), and resulted in 100% wound healing by day 5. Histological observations of cross-sectioned wound tissues revealed the adverse effects of fluocinolone gel and wound healing potential of AC niosome gel. Topical application of AC niosome gel exhibited an anti-inflammatory effect and promoted oral wound closure in rats, possibly due to the improved mucosal permeability and presence of delivery depots of AC in the niosome gel.     

Rheological characterisation of a novel thermosensitive chitosan/poly(vinyl alcohol) blend hydrogel

Thermosensitive hydrogels that are triggered by changes in environmental temperature thus resulting in in situ hydrogel formation have recently attracted the attention of many investigators for biomedical applications. In the current work, the thermosensitive hydrogel was prepared through the mixture of chitosan (CS), poly(vinyl alcohol) (PVA) and sodium bicarbonate. The mixture was liquid aqueous solutions at low temperature (about 4 °C), but a gel under physiological conditions. The hydrogel was characterized by FTIR, swelling and rheological analysis. The effect of hydrogel composition and temperature on both the gel process and the gel strength was investigated from which possible hydrogel formation mechanisms were inferred. In addition, the hydrogel interior morphology as well as porosity of structure was evaluated by scanning electron microscopy (SEM). The potential of the hydrogels as vehicles for delivering bovine serum albumin (BSA) were also examined. In this study, the physically crosslinked chitosan/PVA gel was prepared under mild conditions without organic solvent, high temperature or harsh pH. The viscoelastic properties, as investigated rheologically, indicate that the gel had good mechanical strength. The gel formed implants in situ in response to temperature change, from low temperature (about 4 °C) to body temperature, which was very suitable for local and sustained delivery of proteins, cell encapsulation and tissue engineering.     

Nanocomposite regeneration systems for wound healing

The regeneration system “Biokol” based on the principles of combining synthetic and natural biopolymers has been investigated. The wound dressing consists of “large” (200–250 nm) particles of a synthetic biopolymer and a gel component, which consists of “small” polysaccharide elements 10–20 nm in size. The system can be used both separately and in combination with the gel complex and cell cultures. In properties (vapor and gas permeability, mechanical properties, conductivity, resistance to microbes, etc.), it corresponds to the upper layer of the skin. When applied to the wound, the dressing changes its adhesiveness: first, owing to its hydrophilicity and low hydrophobicity, it closely adheres to the wound surface, and after some time, which corresponds to the time the polysaccharide complex is released from the dressing, it becomes hydrophobic and easily separates from the wound. Owing to these properties, the system can be used at all stages of wound healing.     

角蛋白/海藻酸钠/聚丙烯酰胺水凝胶皮肤敷料的制备及创口修复研究

为了获得更为理想的皮肤创口修复敷料,在海藻酸钠(SA)和聚丙烯酰胺(PAM)水凝胶的基础上复合人发角蛋白(KTN),制得KTN/SA/PAM水凝胶皮肤敷料。用电子万能测试机、扫描电子显微镜等对其进行表征,结果显示,KTN/SA/PAM水凝胶皮肤敷料拉伸强度为42.41 kPa,弹性模量11.19 kPa,接近人体皮肤组织;与带血猪皮的黏附性可高达为5.1 kPa,2 h吸水率为144.3%,较好地满足了皮肤创口修复敷料的基本要求。进一步的大鼠皮肤创面修复实验显示,KTN/SA/PAM水凝胶皮肤敷料相对于市售创口贴和SA/PAM水凝胶具有更好的修复能力,创口皮肤组织切片组织学分析表明,经KTN/SA/PAM皮肤敷料处理后的创口处未成熟组织区域最小,胶原纤维排列最为整齐,14 d后,伤口愈合程度与正常皮肤几乎接近。预示KTN/SA/PAM皮肤敷料可能是一种较有前景的皮肤伤口修复敷料。     

Hydrocellular Foam Dressing Promotes Wound Healing along with Increases in Hyaluronan Synthase 3 and PPARα Gene Expression in Epidermis

Background

Hydrocellular foam dressing, modern wound dressing, induces moist wound environment and promotes wound healing: however, the regulatory mechanisms responsible for these effects are poorly understood. This study was aimed to reveal the effect of hydrocellular foam dressing on hyaluronan, which has been shown to have positive effects on wound healing, and examined its regulatory mechanisms in rat skin.

Methodology/Principal Findings

We created two full-thickness wounds on the dorsolateral skin of rats. Each wound was covered with either a hydrocellular foam dressing or a film dressing and hyaluronan levels in the periwound skin was measured. We also investigated the mechanism by which the hydrocellular foam dressing regulates hyaluronan production by measuring the gene expression of hyaluronan synthase 3 (Has3), peroxisome proliferator-activated receptor α (PPARα), and CD44. Hydrocellular foam dressing promoted wound healing and upregulated hyaluronan synthesis, along with an increase in the mRNA levels of Has3, which plays a primary role in hyaluronan synthesis in epidermis. In addition, hydrocellular foam dressing enhanced the mRNA levels of PPARα, which upregulates Has3 gene expression, and the major hyaluronan receptor CD44.

Conclusions/Significance

These findings suggests that hydrocellular foam dressing may be beneficial for wound healing along with increases in hyaluronan synthase 3 and PPARα gene expression in epidermis. We believe that the present study would contribute to the elucidation of the mechanisms underlying the effects of hydrocellular foam dressing-induced moist environment on wound healing and practice evidence-based wound care.     

In situ forming and rutin-releasing chitosan hydrogels as injectable dressings for dermal wound healing

An in situ gel-forming system composed of rutin- and tyramine-conjugated chitosan derivatives, horseradish peroxidase (HRP), and hydrogen peroxide (H(2)O(2)) was prepared and applied to dermal wound repair. Rutin was employed to enhance production and accumulation of extracellular matrix in the healing process. In vitro study demonstrates that released rutin significantly enhanced cell proliferation as compared with media without rutin. In vivo wound healing study was performed by injecting hydrogels on rat dorsal wounds with a diameter of 8 mm for 14 days. Histological results demonstrated that rutin-conjugated hydrogel exhibited enhancement of wound healing as compared with treatments with PBS, hydrogel without rutin, and a commercialized wound dressing (Duoderm). More specifically, rutin-conjugated hydrogels induced better defined formation of neo-epithelium and thicker granulation, which is closer to the original epithelial tissue. As a result, this study suggests that the in situ gel-forming system can be a promising injectable gel-type wound dressing.     

Raman spectroscopy and WAXS method as a tool for analysing ion-exchange properties of alginate hydrogels

Hydrogels are cross-linked three-dimensional macromolecular networks that contain a large fraction of water within their structure. One of the most important properties of alginate hydrogels, leading to their broad versatility, is their ability for controlled uptake, release and retention of molecules. This ability, in turn, is due to specific interactions of the macromolecular network with the diffusing or retained molecule. Raman spectroscopy has been employed to characterize the diffusion properties of solutes in hydrogels. Besides their application in the food sector, they are used in many biomedical, pharmaceutical and technical areas; for example, as a natural tissue or drug carriers. In the latter case, controlled release of drugs from a wound dressing is of particular interest-or ion exchange between the drug and the structure of the dressing. Raman active vibrations were used to show the areas responsible for the penetration of the model azo-dyes (based on non-genotoxic benzidine analogs) within Ca-alginate/carboxymethylcellulose Medisorb A wound dressing. In this case, the intensity of the stretching bands was used to obtain the concentration profiles of the model dye in alginate/carboxymethylcellulose gel (Medisorb A). The characteristic band at 1511 cm(-1) indicates that new band positions were observed following dye adsorption on wound dressing. The Raman spectra of alginate immersed for different times in Ringer's solution reveal peak shifts. Differences in peak shapes and the appearance of new bands are observed as the sodium content increased. Raman spectra give direct information on the exchange process. There are also new peaks appearing at 1034-1016 and 850 cm(-1) regions in the spectra after the release studies. This could, therefore, correspond to a partial bonding between sodium and oxygen atoms (the guluronic units originate a band at approximately 1025 cm(-1)). The aim of the examination in this paper also was to investigate the crystallinity index of Medisorb A wound dressing dyed (or undyed) and Medisorb A wound dressing after the release process in Ringer's solution (the crystallinity index is about 65%). In WAXS curves we can observed additional peaks (2theta at 32 degrees and 45 degrees ).     

Flexible approach to amperometric oxygen determination

In vitro and in vivo results obtained from a novel flexible amperometric oxygen sensor are reported. The sensor is fabricated using thin film deposition techniques and is operated by the application of a pulsed waveform. Development of the sensor was undertaken in order to produce a device that is capable of being sited at the interface of a wound and an overlying wound dressing. Oxygen determinations in such an environment would aid in gaining an undertanding of the role of oxygen in wound healing and the type of wound dressing that would provide an environment conducive towards wound healing. In vitro data indicate that linearity of response is good although other performance characteristics are irreproducible. In vivo response to oxygen has been observed 50 h after insertion into a porcine sham wound. Expected trends were followed when changes to the oxygen regime of the wound space were effected, but absolute values of oxygen tension are difficult to state with certainty. This may be due to poor calibration stability and inadequate sealing of the sensor from the surrounding environment.     

Wound dressing based on PVA nanofiber containing silk fibroin modified with GO/ZnO nanoparticles for superficial wound healing: In vitro and in vivo evaluations

Silk fibroin (SF), extracted from Bombyx mori, has unique physicochemical properties to achieve an efficient wound dressing. In this study, reduced graphene oxide (RGO)/ZnO NPs/silk fibroin nanocomposite was made, and an innovative nanofiber of SF/polyvinyl alcohol (PVA)/RGO/ZnO NPs was ready with the electrospinning technique and successfully characterized. The results of MIC and OD analyses were used to investigate the synthesized materials' antibacterial effects and displayed that the synthesized materials could inhibit growth against Staphylococcus aureus and Escherichia coli bacteria. However, both in vitro cytotoxicity (MTT) and scratch wound studies have shown that RGO/ZnO NPs and SF/PVA/RGO/ZnO NPs are not only non-toxic to NIH 3T3 fibroblasts, but also can cause cell viability, cell proliferation, and cell migration. Furthermore, improving the synthesized nanofiber's structural properties in the presence of RGO and ZnO NPs has been confirmed by performing tensile strength, contact angle, and biodegradation analyses. Also, in a cell attachment analysis, fibroblast cells had migrated and expanded well in the nanofibrous structures. Moreover, in vivo assay, SF/PVA/RGO/ZnO NPs nanofiber treated rats and has been shown significant healing activity and tissue regeneration compared with other treated groups. Therefore, this study suggests that SF/PVA/RGO/ZnO NPs nanofiber is a hopeful wound dressing for preventing bacteria growth and improving superficial wound repair.     

Molecular dynamics study of the influence of solvents on the structure and mechanical properties of poly(vinyl alcohol) gels

Molecular dynamics (MD) simulations were employed to study the influence of solvents on the structure and mechanical properties of physically crosslinked poly(vinyl alcohol) (PVA) gels. Firstly, three kinds of PVA precursor gels were made by adding water, dimethyl sulfoxide (DMSO) and a mixture of DMSO and water (4:1 by weight), respectively. The solvents in the precursor gels were then exchanged with water to obtain three kinds of PVA hydrogels. Solvent in the precursor gel with a mixture of DMSO and water was also exchanged with ethanol and DMSO, respectively. It was found that the tensile strength and failure strain of the PVA hydrogel prepared from precursor gel with a mixture of DMSO and water was the highest, and the polymer network was more homogeneous than the other two PVA hydrogels. The polymer network of PVA gel with ethanol or with DMSO was more heterogenous than with water, and the tensile strength and failure strain were much lower. The torsional activity of polymer chains of PVA gel with ethanol was much stronger than PVA gel with water and DMSO.     

Design and characterization of multifaceted lyophilized liposomal wafers with promising wound healing potential

Various dressings are available to heal chronic wounds which many times fail to achieve the expected results. To overcome some of their drawbacks, formulation of a novel dressing; lyophilized liposomal wafers having better wound healing potential has been proposed in the present study. The drug incorporated in the formulation is gatifloxacin (GTX) which is a fourth-generation fluoroquinolone antibiotic having in vitro activity against both Gram-negative and Gram-positive bacteria. The formulation was designed in three stages where at first liposomes were prepared, the liposomes were converted to gel using chitosan and lastly this gel was lyophilized to form liposomal wafers. Liposomes were prepared by varying the concentration of lipid and cholesterol and evaluated for particle size, entrapment efficiency, in vitro cumulative release, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Liposomes were converted to liposomal gel using chitosan and evaluated for texture, clarity, viscosity, spreadibility and in vitro drug release. Finally, this liposomal batch was subjected to lyophilization to convert it to liposomal wafers and subjected to SEM, differential scanning calorimetric, X-ray diffraction and drug release studies. The in vivo studies were carried out on Wistar rats where wound healing potential of the wafers was confirmed by histopathological evaluation.