Microcystis aeruginosa mediated biofabrication of silver nanoparticles exhibiting antibacterial, antioxidant, anticancer, and azo dye degrading catalytic activities

Abstract

In this study, a green, facile, and cost-effective method to synthesize silver nanoparticles (AgNPs) from silver nitrate using cell extract of unicellular cyanobacterium, Microcystis aeruginosa, has been reported. These biosynthesized AgNPs were characterized by UV-visible spectroscopy showing absorption peak at 470 nm. TEM and EDX analyses confirmed spherical shape of AgNPs with diameter range of 5–45 nm. The results of Fourier transform infrared (FTIR) spectroscopy analyses revealed proteins as reducing/capping agent. These AgNPs clearly demonstrated considerable antibacterial action against Gram positive and Gram negative bacterial pathogens. AgNPs also revealed notable antioxidative potential (71.08±0.78%) at minimum concentration of 100 μg/mL and significant cytotoxic activity against SiHa cancer cell line with IC50 value of 0.89 μg/mL after 72-h treatment. The AgNP treatment also promoted arrest of cancer cells in the sub-G1 phase of cell cycle. Western blot analysis of SiHa cells treated with increasing doses of AgNPs clearly demonstrated decreasing expression of apoptotic proteins, pro-caspase-3 and intact PARP suggesting activation of apoptosis. These AgNPs significantly degrade toxic azo dye and Congo red through catalytic reduction. The degradation observed was 77.21% in 60 min under visible light irradiation. Graphical Abstract: (Figure presented.) © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2023.