Green synthesis of silver nanoparticles by cyanobacterial extracts: an approach guarantees potential bioactivity and proper cereal seed germination

Abstract

Background The last few decades witnessed the adoption of green nanotechnology as an environmentally friendly and cost-effective strategy with several biomedical, industrial and agricultural applications. Here, cyanobacteria have been suggested as model microorganisms for bio-nanoparticles production. Objective In the present study, the extracts of a number of cyanobacterial isolates representing different genera and isolated from various aquatic environments of Egypt were explored as a novel source of bioactive silver-based nano-materials. Materials and methods The synthesized nanoparticles were characterized by UV-visible spectroscopy (UV-Vis), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). Results revealed the presence of secondary metabolites in the aqueous extracts necessary for the nano-material biosynthesis. The biological potentials of the produced crude extract-based silver nanoparticles (AgNPs) assessed as antimicrobials indicated high activities against several bacterial and fungal pathogens. These bioactive nanoproducts exhibited antioxidant effects as well. Results and conclusion When extract-based AgNPs were tested for seed germination and seedling development of barley (cvs. Giza-123, Giza-2000) and wheat (cvs. Benisweif-7, Misr-3), relative increases in the germination percentages, germination rate index (GRI%), germination velocity coefficient (GVC%) were scored together with somewhat reductions in the mean germination times (MGT). All in all, the findings of this work emphasis that such silver nanoparticles possess antimicrobial and antioxidant activities besides supporting seed germination and seedling development, hence they are highly recommended as an alternative to high-risk chemically synthetic agrochemicals with no expected phytotoxicity.