Green Synthesis and Immobilization of AgNPs by Lumpy Corn Stalk As Interlayer Filling Material for Durable Antibacterial

Lumpy corn stalk is conventionally used as interlayer filling material in plywood, while high temperature and humidity in tropical and subtropical areas are easy to cause bacteria growth on plywood. Silver nanoparticles (AgNPs) are one of efficient antibacterial metal nanoparticles due to their excellent broad-spectrum antibacterial properties. But most of these AgNPs are normally in solution and easy to aggregate, which limits their utilization. Besides, the synthesis of AgNPs always needs chemical reducing agents, which can cause environmental and cost problems. In this study, lumpy corn stalk with honeycomb-like structure acted as green reducing agent and stabilizer to in situ synthesize AgNPs, the obtained antibacterial lumpy corn stalk (CS@AgNPs) could be used as interlayer filling material to protect plywood from bacteria erosion. Durable antibacterial study showed that the bacteriostatic properties of lumpy CS@AgNPs against E. coli and S. aureus were stronger and more durable than commercial Ag+ spray and hydrogel. The antibacterial mechanism may be that the controlled-released AgNPs destroyed the morphological structure of bacteria by penetrating into the bacterial cell membrane, following by leaking cellular content. Notably, the final release amount of AgNPs from lumpy CS@AgNPs after 12 days in buffer solution was only 0.011 mg/L, which was 9 times lower than the domestic drinking water limit presented by United States Environmental Protection Agency (USEPA). The plywood with lump CS@AgNPs as interlayer filling material could keep efficient and durable bacteria killing activity in 21 days, which could be used safely in food packaging, furniture and flooring fields.