Green-synthesized silver nanoparticles from <i>Leptolyngbya valderiana</i> selectively induce apoptotic death in lung adenocarcinoma

Silver nanoparticles (AgNPs) have attracted considerable attention for their potent antiproliferative properties. The search for efficient anti-lung cancer therapeutics led to the biosynthesis of AgNPs from a cyanobacterium, Leptolyngbya valderiana (Gomont) Anagnostidis & Komárek. Within 72 h of exposure of algal biomass to 0.01 M AgNO3, a notable color change of extracellular medium from transparent to dark brown was demonstrated, indicating successful synthesis of Leptolyngbya valderiana-AgNPs (LV-AgNPs). Furthermore, LV-AgNPs were characterized revealing their crystalline nature, oval shape, with sizes averaging 50 ± 21.4 × 39 ± 14 nm and a specific Ag absorption peak at 3 keV. Biosynthesized nanosilver showed remarkable antiproliferative efficacy against lung cancer cells A549 with an IC50 value of 19.78 ± 1.296 μg/mL and had a negligible effect on BEAS-2B and HEK-293 normal cells. Prominent alterations in cellular and nuclear morphology revealed an increased number of disintegrated A549 cells with condensed and fragmented nuclei. Microscopic evaluation of cell death was followed by flow cytometric cell cycle analysis, where the expansion of the sub-G0 population reflected that LV-AgNPs targets G0/G1 phase. Cell death was also associated with the formation of endogenous ROS and disruption of mitochondrial membrane permeability. The above findings suggest that silver nanomaterials produced by L. valderiana can serve as an alternative nano-drug development for lung adenocarcinoma.