A light-weight and high-efficacy antibacterial nanocellulose-based sponge via covalent immobilization of gentamicin

Covalent grafting of gentamicin to nanocellulose-based sponge was realized for the first time. The named sponge was prepared by initially multi-crosslinking among cellulose nanofibers (CNF), cellulose acetoacetate (CAA) and 3-aminopropyl(triethoxy)silane (APTES) followed by surface modification with gentamicin via the formation of enamine bond. The structure and mechanical performances of the obtained gentamicin-functionalized CNF sponge were characterized with FT-IR, XPS, EDX, SEM, Nitrogen adsorption-desorption measurement, and compressive test. Its antibacterial activity against E. coli and S. aureus was evaluated using disc diffusion and colony forming units (CFU) count methods. The results showed that gentamicin was successfully grafted on the surface of CNF sponges without significant change in morphology and slight improvement in mechanical performance. The superior lightness of the sponge (0.0174 g cm^-3) was demonstrated by showing the sponge could be supported by a flower branch without crushing it. Gentamicin-functionalized CNF sponges showed excellent antibacterial performance against E. coli and S. aureus, with bactericidal rates of over 99.9%.