Eco-friendly synthesis of silver nanostructures using medicinal plant Vernonia amygdalina Del. leaf extract for multifunctional applications

Abstract

Ethiopian medicinal plant, Vernonia amygdalina Del. mediated green silver nanostructures (V-SNS) were successfully synthesized for the first time. The surface amalgamation of biomolecules of plant leaf extract around Ag nanostructures has also been approved by the most advanced techniques which were employed to characterize the NSs. The presence of absorbance maxima, λmax at 454 nm confirms the formation of V-SNS. UV-DRS studies revealed the band gap of 2.09 eV for NSs. The role of biomolecules as capping agents for V-SNS was authenticated by FT-IR spectra. The presence of four sharp peaks in the XRD pattern of NSs confirmed the highly crystalline nature of NSs. The TGA-DTA studies revealed that Ag NS is thermally stable above 570 °C. The purity of the NSs was corroborated by SEM-EDAX analysis. The average particle size of V-SNS was deduced to be 35.24 nm. In addition, TEM micrographs revealed the presence of V-SNS with varieties of nano-sized shapes. TEM-HRTEM-SAED analysis authenticated the presence of silver NS with interplanar spacing values of 0.248 nm and 0.243 nm which conformed to Ag (111) lattice fringes of silver. The V-SNS showed significant synergistic antibacterial influence versus S. aureus, E. coli, P. aeruginosa, and E. aerogenes. The uppermost zone of inhibition of 18 mm was inscribed against P. aeruginosa bacteria. The better electrochemical properties of V-SNS electrode as revealed by cyclic voltammograms, Nyquist and Bode plots make it suitable for potential electrochemical sensor application. V-SNS exhibited better photocatalytic activities against Acid orange 8 and Acid red 88 dyes.