Crystallized silver nanoparticles (SNPs) have been biosynthesized by Spirulina platensis in an aqueous system. An aqueous solution of silver ions was treated with a live biomass of Spirulina platensis for the formation of SNPs. These nanoparticles showed an absorption peak at 430 nm in the UV-visible spectrum, corresponding to the plasmon resonance of SNPs. The transmission electron micrographs of nanoparticles in an aqueous solution showed the production of SNPs (average size of most particles: ∼12 nm) by Spirulina platensis. The X-Ray Diffraction (XRD) spectrum of the nanoparticles confirmed the formation of metallic silver, and the average size of the crystallite was estimated from the peak profile by the Scherrer method. The synthesized SNPs had an average size of 11.6 nm.
