Rice husk is one of the most abundant biomass resources in the world, yet it is not effectively used. This study focuses on the sustainably rice-husk-extracted lignin, nano-lignin (n-Lignin), lignin-capped silver nanoparticles (LCSN), n-Lignin-capped silver nanoparticles (n-LCSN), and lignin-capped silica-silver nanoparticles (LCSSN), and using them for antibacterial activities. The final n-Lignin-based products had a sphere-like structure, of which the size varied between 50 and 80 nm. We found that while n-Lignin and lignin were less effective against Escherichia coli than against Staphylococcus aureus, n-Lignin/lignin-based hybrid materials, i.e., n-LCSN, LCSN, and LCSSN, were better against E. coli than against S. aureus. Interestingly, the antimicrobial behaviors of n-LCSNs could be further improved by decreasing the size of n-Lignin. Considering the facile, sustainable, and eco-friendly method that we have developed here, it is promising to use n-Lignin/lignin-based materials as highly efficient antimicrobials without environmental concerns.

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