Molecular insights to alkaline based bio-fabrication of silver nanoparticles for inverse cytotoxicity and enhanced antibacterial activity.

Abstract High demand for silver nanoparticles due to their extensive applications in different field has raised need of eco-friendly green synthesis with determined biomedical effects. This study proposes a novel rapid controlled alkaline based green synthesis of antibacterial silver nanoparticles from Calotropis gigantea for reduced cytotoxic effects. Silver nanoparticles termed as FAg, FAg1N, and FAg5N were synthesized with the help of floral extract of Calotropis gigantea as reducing and capping agent in presence of UV light and NaOH for catalysis and were characterized for their physiochemical properties by FESEM, DLS, UV–Visible spectrophotometry and FTIR. Facile synthesized Silver nanoparticles FAg1N and FAg5N showed enhanced antibacterial effects than FAg with increased NaOH concentration. Cytotoxic effect was found to be reduced at optimized alkaline conditioned FAg1N than FAg and FAg5N. Molecular dynamics study depicted the significant role of configurational change in “Calotropin” at variable alkalinity for controlling the size and physiological properties of synthesized AgNPs. The mechanism of cytotoxicity was revealed as consequences of variability in the interaction of Sod1 and P53 proteins with AgNPs surface for oxidative stress induction and programmed cell death. Highlights • Alkaline based size controlled biosynthesis of AgNP (FAg1N, 2N,5N and 10N) were done using Calotropis gigantea. • Biosynthesized FAg1N was most biocompatible compared to FAg2N, FAg5N and others. • Antibacterial activity of green synthesized AgNP increased with increase in NaOH concentration during synthesis. • Configurational changes in “Calotropin” in alkaline condition controls size of AgNP synthesis. • AgNP exhibit cytotoxicity by molecular interaction with Sod1 and P53 leading to altered oxidative stress and apoptosis. [ABSTRACT FROM AUTHOR]