Green nanotechnology: Adenanthera pavonina-derived silver nanoparticles with antibacterial and photocatalytic properties

The biogenic synthesis of silver nanoparticles has gained significant attention in recent years owing to its eco-friendly nature and promising potential in a wide range of biological and environmental applications. Herein, we report a successful biogenic synthesis of silver nanoparticles (AP-AgNPs) using Adenanthera pavonina as a bio-reducer and a capping agent. Different characterizations techniques were employed to investigate the physicochemical attributes of AP-AgNPs. The XRD analysis revealed the face-centered cubic (FCC) structure of AP-AgNPs along with (111) orientation. The crystallite size of AP-AgNPs was measured to be 21.23 nm. FESEM analysis revealed spherical morphology with an average particles size of 36.77 nm. The UV–vis spectra of AP-AgNPs exhibited characteristic surface plasmon resonance peaks at 420 nm and 448 nm, while the optical band gap estimated from the Tauc plot was 2.70 eV. TG/DT analysis suggested outstanding thermal stability of AP-AgNPs, exhibiting only 12% weight loss up to 800° C. The biogenic AP-AgNPs exhibited moderate colloidal stability (-15.1 mV). AP-AgNPs demonstrated effective dose-dependent antibacterial activity, notably inhibiting Serratia marcescens with a zone of inhibition of 14.67 mm. The photocatalytic performance of AP-AgNPs was evaluated using cationic Methylene Blue and anionic Congo Red dyes, achieving degradation efficiencies of 62.88% and 29.55%, respectively, after 120 min. Therefore, the present study suggests that biogenically synthesized AgNPs from A. pavonina offer a sustainable and effective alternative for biomedical and environmental applications.