Green synthesis of silver nanoparticles by bloom forming marine microalgae Trichodesmium erythraeum and its applications in antioxidant, drug-resistant bacteria, and cytotoxicity activity

In the present study, we developed an eco-friendly method of stable silver nanoparticles (AgNPs) production using the aqueous extract of Trichodesmium erythraeum. The biosynthesized AgNPs were characterized using UV-Vis spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Energy-Dispersive X-ray (EDX), and X-ray diffraction (XRD). The results affirmed that synthesized AgNPs were crystalline in nature, cubical in shape, and the average size of T. erythraeum silver nanoparticles (TENPs) was 26.5 nm. The antioxidant potential of synthesized AgNPs (500 µg/ml) was 77.01 ± 0.17% in DPPH, 67.5 ± 0.22% in Deoxy-ribose, 52.77 ± 0.42% in ABTS and 88.12 ± 0.26% in nitric oxide radical scavenging assays. The antibacterial results showed excellent inhibition against the clinical strains (Staphylococcus aureus and Proteus mirabilis) and drug-resistant bacterial strains such as E. coli (AmikacinR), S. aureus (TetracyclineR) and S. pneumoniae (PenicillinR). The maximum anti-proliferative effect of TENPs was seen using 50 µg concentration against He La and MCF-7 cell lines, and IC50 values were 25.0 ± 0.50 µg/ml and 30.0 ± 0.50 µg/ml, respectively, at 24 h.