Green synthesized silver nanoparticles (AgNPs) using aqueous extract of Calotropis procera and its antimicrobial activity on clinical bacteria isolates

Abstract

The green synthesis of nanoparticles, utilizing aqueous plant extract as a capping and stabilizing agent, has attracted significant attention in various domains, particularly in pharmaceuticals and drug delivery. In this investigation, silver nitrate (AgNO3) salts were employed as precursors to fabricate silver nanoparticles using Calotropis procera (leaves/flower) extract, and the resulting nanoparticles were characterized. Fourier Transform Infrared (FTIR) spectroscopy revealed three primary functional groups at peaks of 2851.4 cm-1, 1543.1 cm-1, and 1323.2 cm-1, responsible for capping and stabilizing the synthesized C.p-AgNPs. Scanning Electron Microscopy (SEM) demonstrated that the synthesized C.p-AgNPs exhibited spherical shapes with an average particle size ranging from 20 nm to 30 nm. Energy-dispersive X-ray (EDX) analysis of the synthesized C.p-AgNPs indicated the presence of pure silver (Ag) at 54.32% in the region of 2.7 to 3.1 keV. Furthermore, the antimicrobial activity of C.p-AgNPs was examined, with the best inhibition observed at 0.5 mg/mL on Gram-negative bacteria S. aureus (12.0 mm) and Streptococcus spp (13.0 mm), and on Gram-positive bacteria E. coli (16.0 mm) and Salmonella spp (14.0 mm). The antimicrobial efficacy was dose-dependent, suggesting the potential for eradicating resistant human pathogenic bacteria. The antibacterial potential of C.p-AgNPs could be enhanced by increasing their concentration, depending on the specific application. Based on the study's findings, C.p-AgNPs derived from Calotropis procera can be employed for various biomedical purposes, such as textile coating by incorporating C.p-AgNPs in fibers and food storage by nanocapsulation of food items to extend their shelf life.