Search

Advanced wound dressings that can deliver potent antibacterial action are still much in need, especially for treating wound infections caused by drug-resistant bacteria. In this research, we utilized electron beam (EB) irradiation to develop antibacterial hydrogel sheet dressings from poly(vinyl alcohol) (PVA) and silver nanoparticles (AgNPs) in a two-step processing and evaluated their bactericidal efficacy, as well as the AgNP release. The effect of the irradiation dose on the swelling, gel fraction, network parameters, and mechanical properties of the hydrogels was first determined to establish the optimal doses for the two-step processing. The prototypic hydrogel sheets were then formed in the first EB irradiation and served as a matrix for the AgNP synthesis by the reduction of the silver nitrate precursors during the second EB irradiation. The diffusion assay showed that the minimal inhibition concentration (MIC) of the AgNP-load hydrogels was 0.25 and 0.5 mg/cm2 against Escherichia coli and Staphylococcus aureus, respectively. At these MIC levels, the released AgNPs increased sharply before reaching the maximum, ~950 and 1800 ppb, at 24 h as analyzed by atomic absorption. Therefore, we successfully demonstrated that this two-step processing by EB irradiation provides a convenient platform to fabricate AgNP-loaded hydrogel dressings that can be further developed for wound healing. [ABSTRACT FROM AUTHOR]

Hydrogels are soft materials that contain high water content within their 3-dimensional structure. Such extremely hydrated environment allows hydrogels to recapitulate the structure of many native tissues inside the body. In biomedical application, hydrogels have been extensively used as biocompatible materials, drug delivery systems, and tissue-engineered scaffolds that can be designed to possess either permanent or slow-degradation properties. In this research, we applied gamma irradiation to develop transparent and conformal hydrogel sheets with sufficient mechanical strength from poly(vinyl alcohol) (PVA) and further modified the based PVA matrix with naturally-derived silk fibroin (SF) protein and silver nitrate (AgNO3) for wound healing purpose. The physical and mechanical properties of based PVA hydrogels formed at varied irradiation doses from 10 - 80 kGy were first characterized. The dose of 60 kGy was found to be optimal to process flexible and elastic PVA sheets with equilibrium degree of swelling of 1000%, gel fraction of 90%, and tensile strength of 19 kPa. To further enhance water absorption capacity, 10 - 40% (w/w) silk fibroin was added to the based PVA matrix. Based on water absorption and gel fraction data, hydrogel sheets with 8PVA:2SF formulation was selected for antibacterial test. Disc diffusion assay showed that the incorporation of 0.4 mM AgNO3 in 8PVA:2SF hydrogel sheets could inhibit the growth of Staphyllococcus aureus and Pseudomonas aeruginosa. These results demonstrated that a prototypic, antibacterial hydrogel sheet dressing composed of both synthetic and natural polymers could be developed within a single-step by gamma irradiation technique. [ABSTRACT FROM AUTHOR]