Synthesis, Optimization and Characterization of Cyanobacteria‐Derived Silver Nanoparticles for Enhancing Rice Seed Germination

The rapid advancement of nanotechnology has paved the way for innovative strategies in sustainable agriculture, particularly through the development and use of metallic nanoparticles. Among these, silver nanoparticles (Ag NPs) have garnered significant attention due to their distinct physicochemical characteristics. The current research illustrates the environmentally friendly production of Ag NPs by aqueous extracts of two cyanobacterial strains Westiellopsis ramosa and Nostoc commune. The optimization was performed by systematically changing the parameters of the reaction, such as the pH, temperature, concentration of silver nitrate, volume of the extract and reaction time. Visual evidence of the formation of Ag NPs was observed by a colour change and was further confirmed by an in-depth characterization method which included UV-Vis spectroscopy, FTIR, DLS, TEM, EDAX and FESEM. LC-HRMS was also done to ascertain the bioactive compounds present in the extract. Compared to conventional chemical methods, this green synthesis approach offers a safer, low-toxicity and environmentally benign alternative, utilizing bioactive compounds in cyanobacterial extracts as natural reducing and capping agents. The synthesized Ag NPs significantly enhanced rice seed germination and seedling vigour at optimal concentrations (70 µg/mL for W. Ag NPs, 60 µg/mL for N. Ag NPs), although cytotoxicity was observed above 50 µg/mL. These results reveal the prospects of cyanobacteria-based Ag NPs as a sustainable remedy to enhance seed germination and crop yields in controlled environments, pointing to the possibility of green nanotechnology in overcoming the global agricultural issues.