Antialgal and antiproliferative activities of the algal silver nanoparticles against the toxic cyanobacterium Microcystis aeruginosa and human tumor colon cell line

Abstract This work aims at comparing the efficiency of different algal groups for the biosynthesis of Ag-NPs and studying the efficacy of the biosynthesized Ag-NPs against the bloom-forming cyanobacterium M. aeruginosa as well as in vitro cytotoxic activity on human tumor colon cell line and normal retina cell line. The macroalgae Sargassum cinereum, Turbinaria decurrens, Jania rubens, Caulerpa racemsoa and the cyanobacterium Nostoc careneum were used during this study for the biosynthesis of Ag-NPs. Characterization of Ag-NPs was carried out by UV-Vis spectroscopy, TEM, DLS, and FT-IR. The cultures of cancer promoter cyanobacterium Microcystis aeruginosa were subjected to increased concentrations (0, 2, 4, 6, 8, and 10%) of Ag-NPs for 7 days. The effect of Ag-NPs on growth and photosynthetic activity of M. aeruginosa was measured. In vitro cytotoxic activity of Ag-NPs on human tumor colon (HCT116) cell line and normal retina (RPE1) cell line were investigated during this study using MTT assay. The investigated algae showed an excellent ability for the biosynthesis of Ag-NPs, especially the brown seaweeds. Pronounced decreases in growth rates and photosynthetic pigments of the studied cyanobacterium were recorded after the treatment with different concentrations of the biosynthesized Ag-NPs. Inhibition of the growth of M. aeruginosa increased by increasing the Ag-NPs concentration and incubation period. Generally, the inhibition effects of Ag-NPs on carotenoid pigment contents of the investigated cyanobacterium were relatively lower than those of chlorophyll a. The cytotoxicity results showed that Ag-NPs caused a remarkable decrease in the development of tumor colon (HCT116) cell line and have no side effect on human epithelial cell RPE1 (normal retina cell line) during the incubation period. Biosynthesized silver nanoparticles could be an effective antialgal and antiproliferative agent against cancer cells without any harmful effect on the human epithelial cells.