Green Synthesis of Silver Nanoparticles Using Nigella sativa Seeds and Apple Peel Extracts and Their Antimicrobial Activity Against Escherichia coli

In nanotechnology, synthesizing silver nanoparticles (AgNPs) with plant-based extracts has emerged as an eco-friendly and sustainable method. Objectives: To focus on the green synthesis and characterization of AgNPs using extracts from Nigella sativa seeds (black seed) and Malus domestica (apple) peels, both rich in bioactive phytochemicals that serve as natural reducing and stabilizing agents. Methods: The synthesis process was verified by UV-Vis spectroscopy using typical surface plasmon resonance (SPR) peaks (~410 nm), which means that the AgNPs were formed successfully. Dynamic light scattering (DLS) analysis was used to determine the hydrodynamic size (117 nm) and uniformity of the AgNPs, and the zeta potential analysis showed the low negative surface charges because of capping using plant biomolecules. The antimicrobial activity of the synthesized AgNPs was tested against Escherichia coli, a common pathogenic bacterium. Results: Results showed significant antibacterial effects, with a zone of inhibition of 27 mm. The previously stated mechanisms, such as ROS generation and apoptosis-like responses, were removed, as they were not experimentally verified. The use of N. sativa and apple peel extracts provided a cost-effective and environmentally benign synthesis route, enhancing nanoparticle stability and bioactivity. Conclusions: These findings highlight the potential of green-synthesized silver nanoparticles as effective antimicrobial agents specifically against E. coli, without extending claims to untested biomedical or environmental applications.