Synthesis and attachment of silver and copper nanoparticles on cellulose nanofibers and comparative antibacterial study

Metal nanoparticles are considered intriguing to academic society, due to a wide spectrum of applications in electronics, biomedical engineering, optics, and medicine. In this study, effective methods of decorating cellulose nanofibers (CNFs), deacetylated from cellulose acetate nanofibers, with silver nanoparticles (AgNPs) via ultraviolet radiation and copper nanoparticles (CuNPs) via chemical reduction were reported. The formation of metal nanoparticles was confirmed by scanning electron microscopy and transmission electron microscopy. The sizes and the metal contents of AgNPs incorporated CNFs (Ag/CNFs) were demonstrated to correlate well with the concentrations of immersion solutions; whereas sizes of CuNPs decorated CNFs, denoted as Cu/CNFs, did not change significantly upon the increased concentrations of wetting solutions. Bacterial inhibition zones and the bactericidal efficacy were investigated against both gram-negative and gram-positive bacteria; interestingly, the results revealed superior bactericidal activity against E. coli for Ag/CNFs and better antibacterial properties against B. subtilis for Cu/CNFs. Graphic abstract