A green method for fabrication of a biocompatible gold-decorated-bacterial cellulose nanocomposite in spent coffee grounds kombucha: A sustainable approach for augmented wound healing

Leveraging waste materials, notably spent coffee grounds (SCG), as nitrogen sources facilitate the synthesis of metallic nanoparticles (NPs) and the concurrent production of bacterial cellulose (BC) as a by-product within the kombucha consortium. The synthesis of gold nanoparticles (Au-NPs) through the involvement of a symbiotic culture of bacteria and yeast (SCOBY) offers an environmentally friendly alternative pathway, contrasting with non-environmental chemical synthesis methods. Herein, we proposed an eco-benign synthesis of Au-NPs and the functionalization of chitosan-bacterial cellulose (CBC) nanocomposites by incorporating Au NPs via in-situ biosynthesis in SCG kombucha consortium, mainly containing lactic acid bacteria (LAB) and Saccharomyces strain. The Au-NPs produced were in polymorphism shapes, which largely dominate with spherical shapes with an average size of 20 nm. Furthermore, The CBC nanocomposite incorporating Au-NPs (Au-CBC) was successfully synthesized and presented with uniformly metallic NPs distributed on the surface and inner layer of nanocomposites, which was characterized by a scanning electron microscope (SEM) and 3-D Raman mapping. The efficacy of Au-CBC as a wound dressing material was substantiated through its sustained release of Au3+ ions, exceptional biocompatibility, cell attachment, hemocompatibility, in-vitro antibacterial activity, and successful in-vivo wound healing. These findings advocate for the green synthesis of Au NPs and highlight the potential of this promising gold nanocomposite, which is comparatively underutilized in wound dressing materials when contrasted with silver nanoparticles (Ag NPs).