Fabrication of silver nanoparticles employing the cyanobacterium Spirulina platensis and its bactericidal effect against opportunistic nosocomial pathogens of the respiratory tract

There are several biomimetic approaches to synthesize silver nanoparticles (AgNPs). The present investigation describes a solitary method for the synthesis of AgNPs in one-pot by means of Spirulina platensis extract. The as-formed AgNPs were characterized by the following methods. Initially, UV-Vis spectrophotometer indicated a distinctive surface plasmon resonance peak for AgNPs at 417 nm. Four-ier Transform Infrared Spectroscopy (FTIR) indicated the particle capping by organics of the extract. Transmission electron microscopy (TEM) con firmed the formation of spherical AgNPs with an average size of 13 nm. X-ray diffraction (XRD) analysis elucidated the crystalline nature of AgNPs. The average particle size and polydispersity index (PDI) of AgNPs were 74.8 nm and 0.285 as recorded by dynamic light scattering (DLS). Thermal gravimetric analysis (TGA) indicated the thermal stability of AgNPs at elevated temperatures. Among all other active components of the algal extract, the proteins could play a major role in reduction, stabilization and encapsulation of AgNPs. Further, the antibacterial activity was assessed against seven different species of bacterial pathogens present in respiratory tract. The AgNPs were found promising against the test pathogens. (C) 2020 Elsevier B.V. All rights reserved.