Lignin and copper nanocomposite coating for antibacterial mask

Lignin is a natural phenolic polymer characterized with renewable, sustainable and biocompatible, but yet remain underutilized. In the post-pandemic era, people are conventionally reusing mask but without any disinfections to prevent infection of virus in public places, which could lead to accumulation of bacteria and secondary infections. The development of antibacterial mask from lignin would simultaneously address the hygiene issues of used mask due to microbe accumulation and provide novel approach for lignin valorization. Herein, lignin/copper nanoparticle with excellent water dispersibility, antibacterial activity, and non-cytotoxicity was synthesized by in situ reduction of copper ions in lignin nanoparticles. The structure of lignin/copper nanoparticle, and antibacterial performance of the mask were thoroughly explored to understand the key factors to tune the process. Antibacterial mask was then prepared by simple dip coating of the lignin/copper nanocomposite onto the middle layer of a mask, which could effectively prevent the penetration of bacteria from the outer layer into the inner layer. The results of this study provide a feasible approach to prepare antibacterial mask using plant-derived, sustainable, and cheap raw material, namely lignin, which facilitate the high value valorization of lignin.