Tri-Herbal Synergistic Green Synthesis of Silver Nanoparticles: Thorough Characterization and Highly Potent Antibacterial Activity Against Multi-Drug Resistant Pathogens

This antimicrobial resistance (AMR) poses a serious global health challenge, and innovative, sustainable strategies are required for the management of multidrug-resistant (MDR) pathogens. This paper investigates the green synthesis of silver nanoparticles (AgNPs) from aqueous extracts of Allium sativum (garlic), Zingiber officinale (ginger), and Nigella sativa (black cumin), leveraging the synergy of the phytochemically potent botanicals in a tri-extract model. Characterization of the as-synthesized AgNPs was through surface plasmon resonance in the UV–Visible region (420–450 nm). Dynamic light scattering (DLS) confirmed the polydisperse nature with a hydrodynamic mean size of 1044.7 nm, and zeta potential analysis (–17.9 mV) considered the colloidal stability as moderate. FTIR analysis established the presence of hydroxyl, carbonyl, and amine groups in the stabilization of the nanoparticles. SEM imaging showed the prevalent spherical morphology, and EDX proved the elemental presence of silver in addition to bioorganic residues. Antimicrobial activity of the AgNPs was concentration-dependent on Escherichia coli, Staphylococcus epidermidis, and Pseudomonas aeruginosa, with the maximum inhibition reported for E. coli and P. aeruginosa. Surprisingly, resistance in the case of Acinetobacter baumannii was exhibited by it in all concentrations used in the experiment. Evaluation against contemporary literature (2020–2024) for comparison identifies the augmented antimicrobial performance as well as the novelty of the tri-extract model. The combinatorial model not only enhances the phytochemical diversity but also the functional capabilities of the nanoparticles in comparison with the single-extract model. These findings justify the development of the phytogenic AgNPs as a promising bio-based intervention for the management of the MDR infections, with the potential for antimicrobial coatings, wound healing, as well as nanopharmaceuticals.