Development of the silver nanoparticle loaded gelatin and silk fibroin hydrogel pads for antimicrobial wound dressing applications

Abstract

Gelatin hydrogels and silk fibroin (SF) films were prepared from gelatin and SF solutions containing different amounts of AgNO3 by a solvent-casting technique The AgNO3-containing gelatin and SF solutions were aged under a mechanical stirring for various times to allow for the formation of silver nanoparticles (nAgs).The formation and the size of nAgs in these solutions were characterized by a UV-vis spectrophotometer and transimission electron microscopy (TEM), respectively. To improve the water resistance of the gelatin hydrogels, various contents of glutaraldehyde (GTA) were added to the AgNO3-containing gelation solution to crosslink the nAg-loaded gelatin hudrogels. These hydrogels were tested for their water retention and weight loss behavior, release characteristic of the as-loaded silver by using an atomic absorption spectroscope (AAS), the antibacterial activity against Gram-positive and Gram-negative bacteria and the indirect cytotoxicity. Moreover, we further studied the effect of the initial concentration of AgNO3 that would be loaded in the gelatin solution to finally obatin the nAg-loaded gelatin hydrogel pads. The indirect cytotoxicity, the cell attachment and the cell proliferation were investigated. Furthermore, SF films were treated with 90vol.-% methanol aqueous solution to improve the water resistance. The nAg-loaded SF films were tested for their in vitro degradation behavior, release characteristic of the as-loaded silver and the antimicrobial activity.