Antimicrobial Efficacy of Silver Nanoparticles (AgNPs) in Combination with Hand Sanitizer against Foodborne and Spoilage Bacteria

Silver nanoparticles (AgNPs) are recognized for their broad-spectrum antimicrobial properties against foodborne bacteria, including E. coli, S. aureus, and B. subtilis. This study investigated whether AgNPs at varying concentrations (0.10%, 0.25%, 0.50%) could enhance the antimicrobial efficacy of a diluted hand sanitizer (1%) against these three strains. Bacterial growth was monitored by optical density (OD600) at 2, 4, and 24 hours post-inoculation. UV-Visible spectroscopy confirmed AgNP synthesis (SPR peak at 430 nm). The optimum AgNP concentration was organism-dependent: 0.25% AgNPs with 1% sanitizer produced greatest inhibition of E. coli and B. subtilis at 4 hours, while 0.50% AgNPs showed superior and sustained inhibition of S. aureus at 4 and 24 hours. These differences are attributed to cell wall architecture. AgNP-enhanced sanitizers show potential for food safety applications, though cytotoxicity concerns require resolution before human use.