Eri Silk Fibroin-Mediated Biosynthesis of Silver Nanoparticles with In Vitro Antibacterial Activity Against Vibrio parahaemolyticus

The emergence of antibiotic-resistant Vibrio parahaemolyticus poses a challenge to sustainable shrimp aquaculture and highlights the need for effective antibacterial alternatives. In this study, silver nanoparticles were biosynthesized using Eri silk fibroin (ESF) as both a reducing and stabilizing biopolymer. Eri silkworms can be reared on cassava leaves, an abundant agricultural by-product in Thailand, thereby supporting waste valorization and the circular bioeconomy. Optimal synthesis was achieved at an AgNO3-to-ESF weight ratio of 1:4, 60 °C, and 4 h, yielding 82.8% ESF-AgNPs with a particle size of 10.8 ± 2.3 nm and a polydispersity index of 0.19 ± 0.01. TEM, XRD, and XPS confirmed the formation of well-dispersed metallic Ag0. The particles remained colloidally stable for at least four weeks. ESF-AgNPs exhibited minimum inhibitory and bactericidal concentrations of 12.5 and 25 µg/mL, respectively; inhibited biofilm formation by 52.45–99.98%; and increased intracellular reactive oxygen species generation. After 72 h, silver release reached 5.70% in deionized water and 9.30% in TSB containing 3% NaCl. Artemia franciscana survival remained 96.2% after 24 h at the MBC. These findings support ESF as a sustainable platform for producing antibacterial and antibiofilm AgNPs with a preliminary safety margin, although further in vivo efficacy and chronic-toxicity studies are required before practical application.