Eco-Friendly Synthesis of Silver Nanoparticles Using Plant Extracts and Their Antimicrobial Applications

Abstract

Background: Silver nanoparticles are widely recognized for their broad-spectrum antimicrobial properties and increasing relevance in biomedical applications. However, conventional synthesis methods often involve toxic chemicals and environmentally hazardous processes. Green synthesis using plant extracts has emerged as a sustainable alternative because plant-derived phytochemicals can act as natural reducing and stabilizing agents during nanoparticle formation. Developing eco-friendly nanoparticle synthesis strategies with effective antimicrobial activity is particularly important in healthcare settings where hospital-associated infections and antimicrobial resistance remain major clinical challenges. Objective: To synthesize silver nanoparticles using plant extracts through an environmentally friendly green synthesis approach and to evaluate their antibacterial activity against clinically important bacterial pathogens isolated from a tertiary care hospital in Central Punjab, Pakistan. Methods: This experimental laboratory-based study was conducted between January and June 2025. Plant leaf extracts were used as natural reducing agents to synthesize silver nanoparticles from a 1 mM silver nitrate solution. Nanoparticle formation was confirmed by visual color change and UV–Visible spectrophotometry. Particle size distribution and morphology were analyzed using dynamic light scattering and scanning electron microscopy. Antibacterial activity was evaluated against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae using the agar well diffusion method at nanoparticle concentrations of 25–100 µg/ml. Results: The synthesis process produced stable nanoparticles with a characteristic surface plasmon resonance peak at approximately 430 nm and particle sizes ranging from 20–60 nm (mean ≈35 nm). Antibacterial testing demonstrated inhibition zones ranging from 14.4 ± 1.1 mm to 18.3 ± 1.2 mm across bacterial species. A clear concentration-dependent response was observed, with inhibition zones increasing from 10.4 ± 0.8 mm at 25 µg/ml to 19.2 ± 1.1 mm at 100 µg/ml (p < 0.001). Conclusion: Plant-mediated green synthesis successfully produced stable silver nanoparticles with significant antibacterial activity against clinically important pathogens. These findings highlight the potential of eco-friendly nanoparticle synthesis as a sustainable approach for developing antimicrobial materials for infection control and biomedical applications