Abstract

Progress in the research and development of green synthesis of silver nanoparticles and their applications has reached new heights in the last decade. In this study, one-step rapid facile biosynthesis of silver nanoparticles is reported, and in vitro cytotoxicity of these nanoparticles has been investigated in an HCT116 cell line. Biogenic silver nanoparticles were synthesized from the culture supernatant of Gram-positive (B. thuringiensis and S. aureus) and Gram-negative bacteria (E. coli and S. typhimurium) using UV light, termed as BTAgNP, SAAgNP, ECAgNP, and STAgNP, respectively. The synthesized silver nanoparticles were characterised by standard characterisation methods such as field emission scanning electron microscopy (FESEM), dynamic light scattering (DLS), UV-visible spectroscopy, and Fourier transform infrared spectroscopy (FTIR). An in silico investigation was performed to elucidate the mechanism of their synthesis. Uniformly distributed ECAgNP, SAAgNP, STAgNP, and BTAgNP with stable zeta potentials were synthesized with the sizes 22.6 +/- 5.2 nm, 21.2 +/- 4.8 nm, 23.3 +/- 6.8 nm, and 29.3 +/- 5.2 nm, respectively. The synthesized silver nanoparticles were found to exhibit significant antibacterial activity against their source bacteria. An in vitro assessment revealed their biogenicity and concentration-dependent cytotoxicity and genotoxicity in colon cell lines with the occurrence of morphological deformities, oxidative stress, apoptosis, and cell cycle arrest. The study provided an insight into the biogenic differences in the biological effects of silver nanoparticles.