Green nanotechnology has attracted attention worldwide, especially in treating cancer and drug-resistant section 6 microbes. This work aims to investigate the anticancer activity of green silver nanoparticles synthesized by Spirulina platensis phycocyanin (SPAgNPs) on two cancer cell lines: Lung cancer cell line (A-549) and breast cancer cell line (MCF-7), compared to the normal human lung cell line (A138). We also aimed to investigate the bactericidal activity against Staphylococcus aureus ATCC29737, Bacillus cereus ATCC11778, Escherichia coli ATCC8379, and Klebsiella pneumonia, as well as the fungicidal activity against Candida albicans (ATCC6019) and Aspergillus niger. The obtained SPAgNPs were spherical and crystalline with a size of 30 nm and a net charge of −26.32 mV. Furthermore, they were surrounded by active groups responsible for stability. The SPAgNPs scavenged 85% of the DPPH radical with a relative increase of approximately 30% over the extract. The proliferation of cancer cells using the MTT assay clarified that both cancer cells (A-549 and MCF-7) are regularly inhibited as they grow on different concentrations of SPAgNPs. The maximum inhibitory effect of SPAgNPs (50 ppm) reached 90.99 and 89.51% against A-549 and MCF7, respectively. Regarding antimicrobial activity, no inhibition zones occurred in bacterial or fungal strains at low concentrations of SPAgNPs and the aqueous Spirulina platensis extract. However, at high concentrations, inhibition zones, especially SPAgNPs, were more potent for all tested microorganisms than their positive controls, with particular reference to Staphylococcus aureus, since the inhibition zones were 3.2, 3.8, and 4.3 mm, and Bacillus cereus was 2.37 mm when compared to tetracycline (2.33 mm). SPAgNPs have more potent antifungal activity, especially against Aspergillus niger, compared to their positive controls. We concluded that SPAgNPs are powerful agents against oxidative stress and microbial infection.

The metabolic effects of silver nanoparticles AgNPs prepared by phycocyanin extracted from Spirulina platensis on metabolic activities of economic plant Phaseolus vulgaris including seed germination, pigments(chl. a, chl. b and carotenoids) , carbohydrates, total lipids, amino acid contents, proline, protein banding, malondialdehyde as well as the antioxidant enzymes activities, superoxide dismutase [SOD], peroxidase [APX], and non-enzymatic antioxidants such as glutathione reductase (GR), catalase [CAT] have been investigated. The results demonstrated that all studied parameters seed germination, pigments, carbohydrates, and total lipids were stimulated by low concentrations of AgNPs [5-30 ppm]. On the other hand, the high concentrations of AgNPs [40–50 ppm] exhibited an inhibitory effect .The three antioxidant enzymes SOD, CAT, and GR were increased in a dose-dependent manner as a result of the increase in AgNPs concentrations. The total amino acids progressively increased under the same treatment. Electrophoretic polypeptide banding patterns consists of 159 bands with a molecular weight range of 27 to 145 kDa. Ten bands—represented polymorphic loci with the value of 6.21 %, whereas 6 bands—represented monomorphic loci with value of 3.77%. The most polypeptide bands [14 bands] were discovered in phycocyanin treatments at lane 5 with molecular weights ranging from 27 to 129 KDa as well as AgNPs treatments at lanes 9, 11 and 13 with a value reaching 8.80% and molecular weights ranging from 27 to 145 kDa.