Preparation and characterization by radiation of poly(vinyl alcohol) and poly(N‐vinylpyrrolidone) hydrogels containing aloe vera

In these studies, hydrogels for wound dressings were made from a mixture of aloe vera and poly(vinyl alcohol) (PVA)/poly(N‐vinylpyrrolidone) (PVP) by freezing and thawing, γ‐Ray irradiation, or a two‐step process of freezing and thawing and γ‐ray irradiation. We examined the physical properties, including gelation, water absorptivity, gel strength, and degree of water evaporation, to evaluate the applicability of these hydrogels for wound dressings. The PVA:PVP ratio was 6:4, the dry weight of aloe vera was in the range 0.4–1.2 wt %, and the solid concentration of the PVA/PVP/aloe vera solution was 15 wt %. We used γ radiation doses of 25, 35, and 50 kGy to expose mixtures of PVA/PVP/aloe vera to evaluate the effect of radiation dose on the physical properties of the hydrogels. Gel content and gel strength increased as the concentration of aloe vera in the PVA/PVP/aloe vera gels decreased and as radiation dose increased and the number of freeze–thaw cycles was increased. The swelling degree was inversely proportional to the gel content and gel strength. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1477–1485, 2003     

Preparation and characterization by radiation of hydrogels of PVA and PVP containing Aloe vera

In these studies, hydrogels for wound dressing were made from a mixture of Aloe vera, poly(vinyl alcohol) (PVA) and poly(N‐vinylpyrrolidone) (PVP) by freeze‐thaw, gamma‐ray irradiation, or a two‐step process of freeze‐thaw and gamma‐ray irradiation. Physical properties, such as gelation, water absorptivity, gel strength and degree of water evaporation were examined to evaluate the applicability of these hydrogels to wound dressing. The PVA:PVP ratio was 6:4, and the dry weight of Aloe vera was in the range of 0.4‐1.2 wt %. The solid concentration of PVA/PVP/Aloe vera solution was 15 wt %. Mixtures of PVA/PVP/Aloe vera were exposed to gamma irradiation doses of 25, 35 and 50 kGy to evaluate the effect of irradiation dose on the physical properties of the hydrogels. Gel content and gel strength increased as the concentration of Aloe vera in PVA/PVP/Aloe vera decreased and as irradiation dose increased and freeze‐thaw was repeated. Swelling degree was inversely proportional to gel content and gel strength. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1612–1618, 2004     

Investigation on the formation mechanisms of hydrogels made by combination of γ‐ray irradiation and freeze‐thawing

Hydrogels based on poly(vinyl alcohol) (PVA)/water‐soluble chitosan (ws‐chitosan)/glycerol were prepared by γ‐ray irradiation, freeze‐thawing, and combination of γ‐ray irradiation and freeze‐thawing, respectively. The influence of freeze‐thawing cycles, the irradiation doses, and the sequence of freeze‐thawing and irradiation processes on the rheological, swelling, and thermal properties of these hydrogels was investigated to evaluate the formation mechanisms of hydrogels made by combination of irradiation and freeze‐thawing. For hydrogels made by freeze‐thawing followed by irradiation, the physical crosslinking is destroyed partially while chemical crosslinking is formed by irradiation. However, the chemical crosslinking density reduces with the increase of freeze‐thawing cycles. Hydrogels made by irradiation followed by freeze‐thawing bear less degree of physical crosslinking with the increase of irradiation dose for the increased chemical crosslinking density. It is found that these hydrogels own larger swelling capacity and better transparent appearance than those made by freeze‐thawing followed by irradiation. Moreover, the former hydrogels have larger mechanical strength than the latter at low freeze‐thawing cycles. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Thermal and rheological properties of poly(vinyl alcohol) and water‐soluble chitosan hydrogels prepared by a combination of γ‐ray irradiation and freeze thawing

Poly(vinyl alcohol) (PVA)/water‐soluble chitosan (ws‐chitosan) hydrogels were prepared by a combination of γ‐irradiation and freeze thawing. The thermal and rheological properties of these hydrogels were compared with those of hydrogels prepared by pure irradiation and pure freeze thawing. Irradiation reduced the crystallinity of PVA, whereas freeze thawing increased it. Hydrogels made by freeze thawing followed by irradiation had higher degrees of crystallinity and higher melting temperatures than those made by irradiation followed by freeze thawing. ws‐Chitosan disrupted the ordered association of PVA molecules and decreased the thermal stability of both physical blends and hydrogels. All the hydrogels showed shear‐thinning behavior in the frequency range of 0.2–100 rad/s. Hydrogels made by freeze thawing dissolved into sol solutions at about 80°C, whereas those made by irradiation showed no temperature dependence up to 100°C. The chemical crosslinking density of the hydrogels made by irradiation followed by freeze thawing was much greater than that of hydrogels made by freeze thawing followed by irradiation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Medicated wound dressings based on poly(vinyl alcohol)/poly(N‐vinyl pyrrolidone)/chitosan hydrogels

Poly(vinyl alcohol)/poly(N‐vinyl pyrrolidone) (PVP)/chitosan hydrogels were prepared by a low‐temperature treatment and subsequent ⁶⁰Co γ‐ray irradiation and then were medicated with ciprofloxacin lactate (an antibiotic) and chitosan oligomer (molecular weight = 3000 g/mol). The gel content, swelling ratio, tensile strength, and crystallinity of the hydrogels were determined. The effects of the chitosan molecular weight, the low‐temperature treatment procedure, and the radiation dosage on the hydrogel properties were examined. The molecular weight of chitosan was lowered by the irradiation, but its basic polysaccharide structure was not destroyed. Repeating the low‐temperature treatment and γ‐ray irradiation caused effective physical crosslinking and chemical crosslinking, respectively, and contributed to the mechanical strength of the final hydrogels. The incorporation of PVP and chitosan resulted in a significant improvement in the equilibrium swelling ratio and elongation ratio of the prepared hydrogels. The ciprofloxacin lactate and chitosan oligomer were soaked into the hydrogels. Their in vitro release behaviors were examined, and they were found to follow diffusion‐controlled kinetics. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2453–2463, 2006     

Performance and characterization of irradiated poly(vinyl alcohol)/polyvinylpyrrolidone composite hydrogels used as cartilages replacement

In this article, hydrogels were prepared by compounding polyvinylpyrrolidone (PVP) with poly(vinyl alcohol) (PVA), which is used as artificial cartilages, by means of repeating freezing and thawing and irradiation, for improving their mechanical and surface lubricative properties. The structures and properties, including gel content, crystallized degree, elastic modulus, and frictional coefficients of the compound hydrogels with different PVP contents and irradiative conditions, were examined and compared. The existence of PVP macromolecules interfered with the crystallization of PVA hydrogels resulted in the decrease of gel contents and elastic modulus, as well as the unstable external frictional coefficient in water. After irradiation treatment, these performances increased with irradiation intensity in lower dose ranges. The solubility and exudation of PVP in water were prevented and reduced because of the chemical crosslink of PVA and PVP, and the lubricative properties of PVA/PVP hydrogels in water were improved. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and antibacterial effects of PVA‐PVP hydrogels containing silver nanoparticles

The poly(vinyl alcohol)/poly(N‐vinyl pyrrolidone) (PVA–PVP) hydrogels containing silver nanoparticles were prepared by repeated freezing–thawing treatment. The silver content in the solid composition was in the range of 0.1–1.0 wt %, the silver particle size was from 20 to 100 nm, and the weight ratio of PVA to PVP was 70 : 30. The influence of silver nanoparticles on the properties of PVA–PVP matrix was investigated by differential scanning calorimeter, infrared spectroscopy and UV–vis spectroscopy, using PVA–PVP films containing silver particles as a model. The morphology of freeze‐dried PVA–PVP hydrogel matrix and dispersion of the silver nanoparticles in the matrix was examined by scanning electron microscopy. It was found that a three‐dimensional structure was formed during the process of freezing–thawing treatment and no serious aggregation of the silver nanoparticles occurred. Water absorption properties, release of silver ions from the hydrogels and the antibacterial effects of the hydrogels against Escherichia coli and Staphylococcus aureus were examined too. It was proved that the nanosilver‐containing hydrogels had an excellent antibacterial ability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 125–133, 2007     

Preparation of novel bilayer hydrogels by combination of irradiation and freeze–thawing and their physical and biological properties

BACKGROUND: Hydrogels made by irradiation or freeze–thawing often exhibit poor mechanical strength; therefore we investigated a novel synthetic method to circumvent this detrimental effect. We report a series of novel bilayer poly(vinyl alcohol) (PVA)/water‐soluble chitosan (ws‐chitosan)/glycerol hydrogels prepared by a combination of irradiation and freeze–thawing. Scanning electron microscopy morphology, swelling behavior, mechanical strength, elongation at break, PVA dissolution behavior and bovine serum albumin (BSA) release profile of the bilayer hydrogels were compared with those of hydrogels made by irradiation and freeze–thawing followed by irradiation. The cytotoxicity of the bilayer hydrogels was studied using a tetrazolium salt (MTT) assay. RESULTS: The novel bilayer hydrogels contain one layer made by freeze–thawing followed by irradiation and the other layer made by irradiation. The preparation method provides the two layers with good combination force in the wet state. However, the two layers are not combined very well in the freeze‐dried state due to the difference in microstructure. The bilayer hydrogels have large swelling capacity and good mechanical strength, and these properties can be varied by changing freeze–thawing cycles, irradiation doses and the relative thickness of the two layers. The PVA and BSA release behaviors show that the bilayer hydrogels have a small amount of dissolved PVA and can prolong the BSA release time. The MTT assay shows that extracts of the bilayer hydrogels are non‐toxic towards L929 mouse fibroblasts. CONCLUSION: The novel bilayer hydrogels prepared in this study show good physical properties with no cytotoxicity, indicating that they are suitable for biomedical applications, such as in wound dressings and drug delivery devices. Copyright © 2009 Society of Chemical Industry     

Effect of ionizing irradiation and blending of natural rubber latex on polyvinylalcohol gelation by using chemical and freezing–thawing processes for use in the field of construction engineering

The aim of this work is to study the gelation behavior of polyvinylalcohol (PVA) and natural rubber latex (NRL) using two methods: The first was chemical gelation by adding sodium borate as a crosslinking to obtain a modeling clay gel able to draw easily under tension (using drum mill) or by using hand pressing. Irradiation was then applied at 2.5 Mrad to possess more crosslinking effect, where stable and rubbery‐gel shape in the dimension was obtained. The second method, where samples of liquid PVA were frozen and thawed for three consecutive cycles. The obtained gel was quite rubbery but completely soluble in hot water at 70°C. Irradiation was performed at 2.5 Mrad to produce a highly rubbery gel and resistant to boiled water. Also, blending of NRL with PVA induced a significant increase in gel‐elasticity and resistivity to boiled water. Factors affecting the properties of the prepared gel such as gel draw ability and gel strength were studied. The study was supported with thermal and scanning electron microscopy (SEM) to investigate the modification of PVA‐gel behavior through irradiation and blending with NRL processes. The results indicated that the PVA‐gel obtained by chemical method or blended with NRL through freezing–thawing gelation gave a superior ability for cement loading. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Rheological investigation of poly(vinyl alcohol)/poly(N-vinyl pyrrolidone) mixtures in aqueous solution and hydrogel state

Rheological behavior of poly(vinyl alcohol) (PVA) and poly(N-vinyl pyrrolidone) (PVP) mixtures in aqueous solutions and hydrogel state was investigated. The complex dependence of the viscosity on PVA/PVP mixture composition could be attributed to cumulative effects of electrostatic interactions, hydrogen bonding or association phenomena. Physical hydrogels were prepared by freezing/thawing method and their viscoelastic properties were followed as a function of number of cryogenic cycles and aging time at 37 °C. From swelling experiments, it was observed that the diffusion of water molecules into the hydrogel pores is Fickian (for low number of cryogenic cycles) and it becomes pseudo-Fickian as the sample is submitted to more than 10 freezing/thawing cycles. PVA/PVP hydrogels obtained by physical interactions present a high degree of tailorability and they are suitable candidates for biomedical applications.     

A novel pH‐sensitive and freeze‐thawed carboxymethyl chitosan/poly(vinyl alcohol) blended hydrogel for protein delivery

BACKGROUND: Blended hydrogels are widely applied in medical fields. They can provide many advantages, such as biocompatibility and biodegradability. Many materials and methods are used to obtain blended hydrogels. In this work, carboxymethyl chitosan (CMCS) and poly(vinyl alcohol) (PVA) blended hydrogels were prepared using the freezing and thawing technique. The properties of the hydrogels prepared, i.e. gel fraction, swelling and pH‐responsive behaviors, were investigated. RESULTS: The gel fraction increased with increasing time of freezing and thawing as determined through gravimetric analysis. It was also found that the equilibrium degree of swelling improved obviously due to the addition of CMCS compared to pure PVA hydrogel. The blended hydrogel with composition CMCS/PVA 80/20 (by weight) possessed the highest swelling ratio. The results of the influence of pH values on the swelling behavior showed that minimum swelling ratios of the hydrogels occurred near the isoelectric point of CMCS. Protein release studies were performed under various pH conditions: the release was much slower under acid than under basic conditions. The release showed a burst in the first 15 h and then steadily increased. CONCLUSION: The addition of CMCS can improve the physical properties of pure PVA hydrogels and provide pH sensitivity. It is concluded that PVA hydrogels containing CMCS could be potentially applied as oral delivery systems for protein drugs. Copyright © 2009 Society of Chemical Industry     

Novel physical hydrogels composed of opened‐ring poly(vinyl pyrrolidone) and chitosan derivatives: Preparation and characterization

A novel, physically stabilized hydrogel system composed of chitosan (Chi) or its derivatives [e.g., carboxymethyl chitosan (CMC), sodium carboxymethyl chitosan, or trimethyl carboxymethyl chitosan (TMCMC)] with poly(vinyl pyrrolidone) (PVP) or opened‐ring poly(vinyl pyrrolidone) (OR–PVP) were prepared and characterized. TMCMC was synthesized by a novel method with dimethylsulfate as the methylation agent. The synthesized materials were characterized by Fourier transform infrared spectroscopy, ¹H‐NMR, ¹³C‐NMR, and size exclusion chromatography. The mechanical properties, gel fraction, swelling behavior, and water state of the prepared hydrogels were investigated. Gelation occurred when the OR–PVP and Chi solutions were blended within a few seconds. However, the gelation of the OR–PVP and CMC solutions needed pH adjustment. No gelation occurred when the solutions of TMCMC and PVP or OR–PVP were blended. The quaternization or protonization of  NH₂ groups may have prevented the gelation of the solutions. The amino groups of Chi derivatives should have been free to take part in hydrophilic bonds between the two polymers. The physical entanglement of polymeric chains and strong hydrogen bonds between the polymers were considered as mechanisms for the formation of the physical hydrogels. The physical hydrogels showed ionic and pH‐sensitive swelling properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

辐射交联PVA/PVP/胶原复合水凝胶的制备及性能研究

采用辐射交联与冻融循环相结合的方法,将胶原引入聚乙烯醇(PVA)/聚乙烯基吡咯烷酮(PVP)水凝胶体系,制备具有较高生物活性的PVA/PVP/胶原复合水凝胶。通过含水率、溶胀性能、力学性能及微观结构研究胶原对复合水凝胶结构与性能的影响,并优选最佳体系进行体外细胞毒性实验(MTT法)。研究结果表明,复合水凝胶具有均匀分布的三维多孔结构,胶原的添加增大水凝胶网络空间结构,其初始含水率达92%,并在10 h内达到溶胀平衡,但力学性能降低。辐射交联与冻融循环相结合的方法有利于提高胶原水凝胶制备效率,胶原结构不改变,其体外细胞存活率从PVA/PVP水凝胶的77.3%提高到93.8%,细胞相容性提高。     

Biodegradability, antimicrobial activity and properties of PVA/PVP hydrogels prepared by γ-irradiation

Polyvinyl alcohol/polyvinyl pyrrolidone (PVA/PVP) hydrogel has been prepared by using γ-irradiation technique. In the present study the conclusion on miscibility of PVA/PVP blends, confirmed qualitatively and quantitatively by using Fourier transform infrared spectroscopy and differential scanning calorimetry, respectively. PVA and PVP are found to form a thermodynamically miscible pair. The physical properties such as gel fraction and water absorption performance of the prepared hydrogels were measured, it was found that the gel fraction increases with increasing irradiation dose while the swelling of PVA/PVP blended hydrogels nearly tends to increase with increasing PVP content and reduced with enhanced irradiation doses. The hydrogel pore structure of various PVA/PVP compositions were tested with SEM. Ability of PVA/PVP hydrogels to absorb and release antimicrobial compounds was tested using amoxicillin as an antibacterial and ketoconazole as an antifungal. Antimicrobial activity of PVA/PVP hydrogels was examined using four bacteria, and four fungi. No antibacterial or antifungal activities of non-loaded PVA/PVP of various compositions were detected while the loading ones found to have antimicrobial activity. Results showed resistance of Pseudomonas aeruginosa and Candida albicans to PVA/PVP, while Bacillus subtilis was very sensitive. Biodegradation of PVA/PVP hydrogels was investigated by burial method in two types of local soils (clay and sandy soils). The highest degradation rate was found to be achieved using clay soil. Also, effect of irradiation dose on its biodegradability was tested. The results showed that the radiation prepared PVA/PVP hydrogels can be use as biomaterials.     

Characterization of hydrogels based on chitosan and copolymer of poly(dimethylsiloxane) and poly(vinyl alcohol)

Copolymers composed of poly(vinyl alcohol) (PVA) and poly(dimethylsiloxane) (PDMS) were crosslinked with chitosan to prepare semi‐interpenetrating polymer network (IPN) hydrogels by an ultraviolet (UV) irradiation method for application as potential biomedical materials. PVA/PDMS copolymer and chitosan was cast to prepare hydrogel films, followed by a subsequent crosslinking with 2,2‐dimethoxy‐2‐phenylacetophenone as a nontoxic photoinitiator by UV irradiation. Various semi‐interpenetrating polymer networks (semi‐IPNs) were prepared from different weight ratios of chitosan and the copolymer of PVA/PDMS. Photocrosslinked hydrogels exhibited an equilibrium water content (EWC) in the range of 65–95%. Swelling behaviors of these hydrogels were studied by immersion of the gels in various buffer solutions. Particularly, the PCN13 as the highest chitosan weight ratio in semi‐IPN hydrogels showed the highest EWC in time‐dependent and pH‐dependent swelling. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2591–2596, 2002     

Development of potentially biocompatible hydrogels with cylindrical pores prepared from polyvinyl alcohol and low‐molecular weight polyacrylic acid

In the present work, blend hydrogels from PVA and two different low PAA molecular weights, Mw 1800 g/mol and 5000 g/mol were prepared through the freezing thawing (F‐T) physical crosslinking method. The obtained materials were fully characterized by means of scanning electron microscopy (SEM) in order to analyze their morphology, gel fraction (GF) to determine the crosslinking degree and Fourier transformed infrared spectroscopy (FTIR) to analyze the PVA‐PAA interactions. Thermal characterizations [thermogravimetric analysis (TGA) and dynamic scanning calorimetry (DSC)] were conducted to study the relevant thermal characteristics. Sorption tests at different pH values (4 and 7) obtained from different aqueous systems were also inquired. The effects of PAA contents (between 1 and 5 wt%) and Mw of the used PAA on the hydrogel final properties were analyzed and related to the most probably PVA‐PAA interactions. POLYM. ENG. SCI., 59:1479–1488 2019. © 2019 Society of Plastics Engineers     

Comparison the properties of PVA/Na+‐MMT nanocomposite hydrogels prepared by physical and physicochemical crosslinking

A novel physicochemical crosslinked nanocomposite hydrogel based on polyvinyl alcohol (PVA) and natural Na‐montmorillonite (Na⁺‐MMT) was synthesized by chemical crosslinking of nanocomposite hydrogel followed by a freezing‐thawing process. The effects of physical crosslinking, as well as physicochemical crosslinking, on the structure, morphology, and properties (thermal, mechanical, swelling, and deswelling) of nanocomposite hydrogels were investigated and compared with each other. The structure and morphology of nanocomposites were studied by Fourier transform infrared, X‐ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy techniques. The thermal and mechanical properties of nanocomposites that were affected by physical and physicochemical crosslinking were evaluated by thermogravimetric analysis, differential scanning calorimeter, dynamic mechanical analysis, hardness test, and Water vapor transmission rate (WVTR) experiments. The results showed that the physicochemical crosslinking of a PVA nanocomposite leads to a reduction in crystallinity and melting temperature, as well as an increase in the Hardness and WVTR compared to a physically crosslinked PVA nanocomposite hydrogel. The swelling and deswelling experiments were performed using a gravimetric method, and it was shown that controlled crosslinking of PVA nanocomposite hydrogel with glutaraldehyde causes the swelling ratio to increase and the cumulative amount of water loss to decrease. The swelling (sorption) and deswelling (desorption) kinetics data for physically and physicochemical crosslinking of nanocomposite hydrogels were fitted with a fickian model. It is concluded that through control crosslinking of PVA nanocomposite can lead to a hydrogel with higher swelling capacity than that is in conventional PVA nanocomposite hydrogel. POLYM. COMPOS., 37:897–906, 2016. © 2014 Society of Plastics Engineers     

Comparative study of gamma and ion beam irradiation of polymeric nanocomposite on electrical conductivity

Poly(vinyl alcohol) (PVA) was used to prepare nanocomposites of multi‐wall carbon nanotubes (MWCNT) and functionalized carbon nanotubes (MWCNT‐NH₂) in existence of 2‐carboxyethyl acrylate oligomers (CEA). Radiation‐induced crosslinking of the prepared matrix was carried out via gamma and ion beam irradiation. A comparative study of gamma and ion beam irradiation effect on the electrical conductivity of nanocomposite was conducted. The gelation of the gamma irradiated matrix outperforms the ion beam irradiated matrix. The order of gelation is PVA > (PVA/CEA) > (PVA/CEA)‐MWCNT > (PVA/CEA)‐MWCNT‐NH₂. There is a significant reduction in the swelling of the nanocomposite. The formation of nanocomposites was confirmed by scanning electron microscopy, energy‐dispersive X‐ray (EDX) and FTIR examinations. The direct current electrical properties of PVA/nanocomposites are examined at room temperature by applying electric voltage from 1 to 20 V. The results revealed that the electrical conductivity is increased by adding the carbon nanotubes and irradiation by gamma and ion beam. At an applied electric voltage 20 V, in the electrical conductivity of the unirradiated PVA was from 9.20 × 10^?8 S cm^?1. After adding MWCNT an increase up to 4.70 × 10^?5 S cm^?1 was observed. While after ion beam irradiation, a further increase up to 9.30 × 10^?5 S cm^?1 was noticed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46146.     

Preparation and characterization of PVA/PVP/glycerin/antibacterial agent hydrogels using <Emphasis Type="Italic">γ</Emphasis>-irradiation followed by freeze-thawing

Hydrogels for wound dressings from a mixture of poly(vinyl alcohol) (PVA), poly(N-vinylpyrrolidone) (PVP), glycerin and an antibacterial agent were obtained by a γ-irradiation combined with freeze-thawing. The physical properties such as the gelation and swelling degree of the hydrogels were examined. When the PVP/PVA ratio was 6: 4 (wt%) and prepared by combined irradiation and freeze-thawing, it showed an excellent swelling capacity (>1,200%). The antibacterial effect of the hydrogels containing the antibacterial agents was observed to be effective as the concentration of antibacterial agents increased. The results demonstrated that hydrogel in a proper blending ratio could be used as a wound dressing that can accelerate wound healing with an antibacterial effect.     

Investigation of polyvinyl alcohol nanocomposite hydrogels containing chitosan nanoparticles as wound dressing

Polymeric hydrogels, water-swollen 3?D networks of the polymers, have found wide ranges of applications in the medical fields, such as wound care and wound dressing, in order to prevent infections. Prevention from microorganisms transfer in to the wounds is one of the ideal wound dressing duties of polyvinyl alcohol (PVA) hydrogels. In this study, at the start, under optimal conditions, nanoparticles of chitosan using ionotropic gelation method were synthesized and in the next step in order to achieve particles with a minimum size, they were evaluated by scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). Then after to obtain a wound dressing with preferable properties, nanocomposite hydrogels using a combination of PVA and 5, 10 and 15?wt% chitosan nanoparticles were prepared through freezing-thawing cycles. The necessary features of PVA nanocomposite hydrogels for wound dressing were investigated. The dispersion state of nanoparticles and structure of samples were evaluated by SEM microscopy. The nanoparticle size and the nanoparticle size distribution of chitosan was determined using the dynamic light scattering test at the nanometer scale. The physical behavior of hydrogels such as swelling and gel fraction was studied and their mechanical properties were investigated by compressive test. Finally the antimicrobial test and biocompatibility as cell viability were carried out. The results proved that the PVA nanocomposite hydrogels fulfill the requirements of a good wound dressing with desirable characteristics such as favorable swelling and acceptable strength, excellent barrier against microbial penetration.