Tripolyphosphate-Driven Synthesis of Ag3PO4-Decorated Chitosan Nanoparticles for Enhanced Antimicrobial Activity

Overuse of conventional antibiotics has fueled the rise of drug-resistant pathogens, creating an urgent need for novel antimicrobial platforms. In this study, we developed a novel, green, one-pot tripolyphosphate-driven method to fabricate chitosan (CS) nanoparticles from black soldier fly (Hermetia illucens) puparia and simultaneously deposit crystalline Ag3PO4 (AgP) domains to yield a CS@AgP bionanocomposite. Comprehensive FTIR, XRD, and UV–Vis DRS analyses confirmed successful Ag3PO4 incorporation and a narrowed direct band gap of 1.46 eV. Agar-diffusion assays against Gram-positive (L. monocytogenes ATCC 7646, S. aureus ATCC 6538), Gram-negative (E. coli ATCC 25922, Salmonella sp. ATCC 14028), and fungal (C. albicans ATCC 10231) strains demonstrated dose-dependent inhibition zones up to 30 mm at 25 mg/mL. This dual-function nanocomposite combines sustainable, single-step production with broad visible-light absorption and potent antimicrobial efficacy, offering a versatile platform for antimicrobial coatings and photocatalysis.