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.