Electrolyzed Silver Nanoparticles from Aegle marmelos Leaf Extract: A Comparative Study of Antibacterial Potential

Abstract

Aims: To synthesise and characterise silver nanoparticles (AgNPs) using Aegle marmelos leaf extract and evaluate their antibacterial efficacy against selected pathogenic bacteria. Study Design: Experimental laboratory-based comparative study. Place and Duration of Study: Department of Biotechnology, Dr D.Y. Patil College of Arts, Commerce and Science, Pimpri, Pune, India, conducted between January 2024 and June 2025. Methodology: AgNPs were synthesised via green synthesis using Aegle marmelos leaf extract, followed by electrolysis to enhance nanoparticle stability and antibacterial activity. Characterisation was performed using UV-Visible spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and zeta potential analysis. Antibacterial efficacy was assessed using the disc diffusion method against Escherichia coli. The zone of inhibition was measured and compared across treatments, including AgNPs, electrolyzed AgNPs (E-AgNPs), silver nitrate (AgNO₃), and a standard antibiotic, such as Penicillin and Ampicillin. Results: Electrolyzed AgNPs (E-AgNPs) showed enhanced antibacterial activity compared to non-electrolyzed AgNPs and AgNO₃. The highest zone of inhibition was observed for the combination of ampicillin with E-AgNPs (29 mm), followed by standalone E-AgNPs (12 mm) and conventionally synthesized AgNPs (11 mm). Notably, electrolyzed AgNO₃ also exhibited comparable activity (11 mm), while non-electrolyzed AgNO₃ showed minimal inhibition (2 mm). UV-Visible spectra confirmed nanoparticle formation with a peak at 430 nm. FTIR analysis indicated the presence of functional groups responsible for reduction and stabilization. Zeta potential measurements revealed improved stability of E-AgNPs (−26 to −28 mV) compared to non-electrolyzed AgNPs (−20 to −25 mV), indicating enhanced electrostatic repulsion and reduced aggregation. In contrast, AgNO₃ exhibited a nearly neutral zeta potential (−7.4 mV), confirming its instability. Conclusion: Electrolysis enhanced the stability and antibacterial efficacy of green-synthesized AgNPs. Even electrolyzed AgNO₃ showed comparable activity. The strongest effect was seen with E-AgNPs combined with antibiotics, indicating synergy. This eco-friendly dual approach shows promise for future antimicrobial applications.