Eco-benign synthesis of nano-gold chitosan-bacterial cellulose in spent ground coffee kombucha consortium: Characterization, microbiome community, and biological performance

Biomaterials that are mediocre for cell adhesion have been a concern for medical purposes. In this study, we fabricated nano-gold chitosan-bacterial cellulose (CBC-Au) via a facile in-situ method using spent ground coffee (SGC) in a kombucha consortium. The eco-benign synthesis of monodispersed gold nanoparticles (Au NPs) in modified bacterial cellulose (BC) was successfully achieved in the presence of chitosan (CHI) and a symbiotic culture of bacteria and yeast (SCOBY). The dominant microbiome community in SGC kombucha were Lactobacillaceae and Saccharomycetes. Chitosan-bacterial cellulose (CBC) and CBC-Au affected the microfibril networks in the nano cellulose structures and decreased the porosity. The modified BC maintained its crystallinity up to 80 % after incorporating CHI and Au NPs. Depth profiling using X-ray photoelectron spectroscopy (XPS) indicated that the Au NPs were distributed in the deeper layers of the scaffolds and a limited amount on the surface of the scaffold. Aspergillus niger fungal strains validated the biodegradability of each scaffold as a decomposer. Bacteriostatically CBC-Au showed better antimicrobial activity than BC, in line with the adhesion of NIH-3T3 fibroblast cells and red blood cells (RBCs), which displayed good biocompatibility performance, indicating its potential use as a medical scaffold.