Bactericidal potential of different size sericin-capped silver nanoparticles synthesized by heat, light, and sonication.

Present study was aimed to assess the bactericidal potential of sericin-capped silver nanoparticles (Se-AgNPs) synthesized by heat, light, and sonication. Se-AgNPs were characterized by size analyzer, UV spectrophotometry, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. Average size of Se-AgNPs synthesized by heat, light and sonication was 53.60, 78.12, and 7.49 nm, respectively. All (10) bacterial strains were exposed to Se-AgNPs prepared from different methods to compare their antibacterial potentials. Largest zone of inhibition (13 ± 1.15 mm) was observed for sonication-based nanoparticles (NPs) against Klebseilla pneumoniae while the smallest zone of light assisted NPs against Serratia rubidaea (5 ± 1 mm). Bacterial strains were also exposed to different concentrations (0.2%, 0.3%, and 0.6%) of Se-AgNPs which showed largest zone (12 ± 1 mm) of inhibition for 0.4% of Se-AgNPs against Protius mirabilis and smallest zone (5 ± 1.154 mm) for 0.3% of Se-AgNPs against Escherichia coli. Furthermore, effect of different temperatures (5°C, 37°C, and 60°C) and pH (3, 7, and 12) on the efficacy and stability of Se-AgNPs was also evaluated against different bacterial strains. Sonication mediated NPs showed highest bactericidal results against K. pneumoniae (F 3,8  = 6.154; p = 0.018) with smallest size NPs (7.49 nm) while lowest bactericidal results against S. rubidaea (5 ± 1 mm) were shown with largest size (78.12 nm) NPs prepared by natural light. These variations of bactericidal activities of NPs with difference size endorse that the Se-AgNPs with smallest size have highest antibacterial activity than larger size NPs. Moreover, Se-AgNPs maintain their bactericidal potency at wide range of temperature and pH, hence seemed stable.