Scutellaria\nbaicalensis Polysaccharide-Mediated Green Synthesis\nof Smaller Silver Nanoparticles\nwith Enhanced Antimicrobial and Antibiofilm Activity

Abstract

Silver\nnanoparticles (AgNPs) have attracted widespread\nattention\nin multidrug-resistant bacterial infections. However, the application\nof AgNPs synthesized by conventional methods is restricted by its\nhigh costs, toxicity, and poor stability. Herein, a water-soluble\npolysaccharide (Scutellaria baicalensis polysaccharide, SBP) rich in reducing sugars was used as both the\nreductant and stabilizer to greenly synthesize spherical AgNPs@SBP\nwith smaller particle sizes (11.18 ± 2.50 nm) and higher negative\nzeta potential (−23.05 ± 2.76 mV), which was favorable\nto enhance its antimicrobial activity and improve pH and thermal stability.\nBesides, SBP facilitated the adhesion and penetration of AgNPs@SBP\nto methicillin-resistant Staphylococcus aureus (MRSA) and carbapenem-resistant Escherichia coli (CREC), thus significantly enhancing its antibacterial activity\n(increased by 32-fold and 64-fold, respectively). Likewise, AgNPs@SBP\nat a low concentration (7.8 μg/mL) could effectively penetrate\nand inhibit nearly 90% of MRSA and CREC biofilm formation. Antimicrobial\nmechanism studies showed that AgNPs@SBP could lead to more severe\ncell membrane damage and genetic material leakage by upregulating\nreactive oxygen species and depolarizing mitochondrial membrane potential,\nultimately resulting in the apoptosis of bacteria. Overall, the wrapping\nof SBP significantly enhanced the antibacterial and antibiofilm activity\nof AgNPs, which possessed great potential in the prevention and treatment\nof multidrug-resistant bacterial infections.