Beta galactosidase mediated bio-enzymatically synthesized nano-gold with aggrandized cytotoxic potential against pathogenic bacteria and cancer cells

The current investigation reports bactericidal and cytotoxicity evaluation of bio-enzymatically formulated nano‑gold (AuNPs) using physiologically significant enzyme β galactosidase. The AuNPs were characterized using spectroscopic and microscopic techniques. The anti-pathogenic efficacy of AuNPs as a potential drug was observed against five contagious bacterial strains of Escherichia coli, Staphylococcus aureus, group B Streptococcus, Acinetobacter baumannii and Klebsiella pneumonia. The estimation of minimum bactericidal concentration, minimum inhibitory concentration, scanning electron microscopy and fluorescence microscopy conclude enhanced bactericidal effects of green AuNPs. The cytotoxicity of AuNPs against human cervical (HeLa), breast (MCF-7) and liver (Hep 3B) cancer cells was evaluated. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was adopted to analyze antitumor potential of AuNPs. Cell nuclear morphology associated with apoptosis after treatment with NPs was assessed against MCF-7 cells through 4,6-diamidino-2-phenylindole staining. Apoptotic activity of AuNPs was determined against HeLa cells using annexin V/ propidium iodide double staining by flow cytometric analysis. The AuNPs exhibited excellent efficacy against these cell lines and future prospects of usage as potential nano-drugs and drug delivery vehicles. [Display omitted] •Bio-enzymatic synthesis of nano‑gold by β galactosidase•Microscopic and biophysical characterization of AuNPs•Excellent inhibitory activity of AuNPs against five pathogenic bacterial cells•Enhanced cytotoxic effects of AuNPs against three different cancer cells