Green Synthesis of Silver Nanoparticles with Silkworm Excretions and their Potential Antibiofilm Activity on Oral Bacteria

ABSTRACTDental caries is a chronic infectious disease that causes tooth loss and root breakdown in children and young adults, with a prevalence ranging from 60-80% in children and almost 100% in adults. Green synthesis of metallic nanoparticles is a highly economical and practical way to reduce antimicrobial resistance. Green synthesis of silver nanoparticles (AgNPs) was performed using silkworm pellets and validated by characterization studies (UV-visible spectroscopy, XRD, FTIR, and SEM). Antibacterial activity was evaluated against three oral bacterial strains (S. mutans, S. oralis, and S. gingivalis) by MIC, time-kill, and antibiofilm assays. qRT-PCR was performed to evaluate the expression of biofilm-formation genes (gftB, gftC, gftD, srtA, and comD). Scanning electron microscopy (SEM) showed that the synthesized AgNPs were between 40 and 55 nm (in). The synthesized AgNPs were found to reduce biofilms and exopolysaccharides in accordance with the MIC and agar well diffusion. Antibacterial activity was found to be highly significant with NPs, as evidenced by the downregulation of the qRT-PCR genes. The green-synthesized AgNPs from silkworm excreta exhibited antibacterial activity against oral bacteria, with a high percentage of biofilm inhibition and downregulation of biofilm-forming genes.