Statistical optimization of photo-induced biofabrication of silver nanoparticles using the cell extract of Oscillatoria limnetica: insight on characterization and antioxidant potentiality

Abstract

Silver nanoparticles were successfully fabricated through a very simple, rapid, one-step photo-induced green approach. The formation of silver nanoparticles was accomplished using the bioactive compounds in the aqueous extract of fresh Oscillatoria limnetica biomass, which acted as a reducing and capping agent at the same time. The biosynthesis of Oscillatoria-silver nanoparticles (O-AgNPs) was investigated under the influence of different light intensities 57.75, 75.90 and 1276.51 μmol m⁻² s⁻¹ (bright sunlight). UV-Vis (UV) and Fourier transform infrared (FT-IR) spectroscopy were applied to approve the synthesis of AgNPs. Further, the synthesis process under the exposure to sunlight was adjusted via utilizing one factor at a time, and 0.5 mM AgNO₃ concentration, 5 mL O. limnetica solution, pH 6.7 and 30 min sunlight (1276.51 μmol m⁻² s⁻¹) were applied. Furthermore, the central composite design (CCD) was applied to boost the biosynthesis process of O-AgNPs (manufactured at light intensity 75.90 μmol m⁻² s⁻¹). The maximum production of O-AgNPs was attained with 4 detected variables: initial pH level (6.7), AgNO₃ concentration (0.3 mM), O. limnetica extract concentration (3.50 mL) and incubation time (48 h). Moreover, TEM, in addition to SEM, images exposed that the biosynthesized AgNPs were quasi-spherical in shape with a small monodisperse nature, and the size range was between 6.98–23.48 nm in the case of light-induced synthesis (75.90 μmol m⁻² s⁻¹) and 11.58–22.31 nm with sunlight (1276.51 μmol m⁻² s⁻¹).