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 degrees C, 37 degrees C, and 60 degrees 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,F-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.