Facile synthesis, structure, biocompatibility and antimicrobial property of gold nanoparticle composites from cellulose and keratin.

A novel, one-pot method was developed to synthesize gold nanoparticle composite from cellulose (CEL), wool keratin (KER) and chloroauric acid. Two ionic liquids, butylmethylimmidazolium chloride and ethylmethylimmidazolium bis(trifluoromethylsulfonyl)imide were used to dissolve CEL, KER and HAuCl4. X-ray diffraction and X-ray photoelectron results show that Au3+ was completely reduced to Au0NPs with size of (5.5±1) nm directly in the composite with NaBH4. Spectroscopy and imaging results indicate that CEL and KER remained chemically intact and were homogeneously distributed in the composites with Au0NPs. Encapsulating Au0NPs into [CEL+KER] composite made the composite fully biocompatible and their bactericidal capabilities were increased by the antibacterial activity of Au0NPs. Specifically, the [CEL+KER+Au0NPs] composite exhibited up to 97% and 98% reduction in growth of antibiotic resistant bacteria such as vancomycin resistant Enterococcus faecalis and methicillin resistant Staphylococcus aureus, and was not cytotoxic to human fibroblasts. While [CEL+KER] composite is known to possess some antibacterial activity, the enhanced antibacterial observed here was due solely to added Au0NPs. These results together with our previous finding that [CEL+KER] composites can be used for controlled delivery of drugs clearly indicate that the [CEL+KER+Au0NPs] composites possess all required properties for successful use as dressing to treat chronic ulcerous infected wounds.