Synthesis of Silver Nanoparticles from AgNO₃ via Chemical Reduction and Their Antibacterial Activity

Department of Mathematics and Natural Sciences of State University of Medan, Medan, Indonesia

Abstract

This study focuses on the synthesis of silver (Ag) nanoparticles via chemical reduction of the inorganic compound silver nitrate (AgNO₃), and the evaluation of their antibacterial activity against Staphylococcus aureus and Escherichia coli. The synthesis was performed using AgNO₃ as the precursor in an isopropyl alcohol (IPA) solvent, with sodium borohydride (NaBH₄) as the reducing agent and polyethylene glycol (PEG6000) as the stabilizing agent. The nanoparticles were characterized using a Particle Size Analyzer (PSA), zeta potential measurements, and inductively coupled plasma–optical emission spectrometry (ICP-OES). The results showed that the Ag nanoparticles had an average particle size of 59 nm and a zeta potential of -17.4 mV, indicating good colloidal stability. Antibacterial activity was evaluated using the disk diffusion method, where the Ag nanoparticles produced inhibition zones of 11.07 mm against S. aureus and 8.00 mm against E. coli at a concentration of 15%. These findings suggest that higher concentrations of silver nanoparticles enhance antibacterial effectiveness.