Gold modified bacterial cellulose from coconut water waste and its antibacterial activity

This study was aimed to synthesize gold-modified bacterial cellulose nanoparticle (Au-BCNP) from the local Indonesian waste of coconut water. Gold-modified bacterial cellulose (Au-BC) was synthesized by immersing the bacterial cellulose in gold chloride solution (HAuCl4). Sodium borohydride (NaBH4) was used to reduce the absorbed gold ion (Au+) to the metallic gold particles (Au) inside of bacterial cellulose. Three concentration ratios of HAuCl4 and NaBH4 was performed (10:1; 50:1; and 100:1). Gold nanoparticles (AuNPs) were chemically bonded to the bacterial cellulose surface. Au-BC nanoparticle composites were characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FTIR) spectroscopy and X-ray power diffraction (XRD). Antibacterial activity of Au-BC composites were performed against the Escherichia coli, Pseudomonas aeruginosa and Salmonella typhi (Gram-negative) as well as Staphylococcus aureus (Gram-positive). The neat fibril network of Au-BC composites could be observed using SEM analysis. Au-BC nanoparticle composites showed slightly rough fibril compared to authentic BC. The presence of metallic gold was confirmed using EDX as well as XRD. The Au-BC composite also showed good antibacterial activity against four types of bacteria used with the highest antibacterial activity was found in the Au-BC nanocomposite using HAuCl4 and NaBH4 ratio of 1:100.