Green therapeutics’ bio-AgNPs: a sustainable solution for multidrug-resistant pathogens

Abstract The escalating crisis of lethal multidrug resistance (MDR) pathogens and the alarming rise of resistance to last-resort antibiotics necessitate urgent exploration of innovative green therapeutic solutions. This study investigates the biogenic synthesis of silver nanoparticles (AgNPs) utilizing aqueous leaf extract from Moringa oleifera (MO) and evaluates their antibacterial efficacy against Gram-negative nosocomial pathogens. Among 150 nosocomial isolates, 3% demonstrated susceptibility to all tested antibiotics, underscoring the severity of the resistance dilemma. The antibacterial potential of the synthesized MO-AgNPs was assessed alongside their cytotoxic effects on a normal mouse liver cell line (BNL). The biosynthesis process involved the reduction of silver nitrate to silver using the MO leaf extract. Comprehensive characterization techniques—including UV-Vis spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, Zeta potential analysis, Dynamic Light Scattering (DLS), X-ray Diffraction (XRD), Scanning Electron Microscopy with Energy Dispersive X-ray (SEM-EDX), and Transmission Electron Microscopy (TEM) confirmed the formation of spherical MO-AgNPs with an average crystalline size of 12.89 nm. Antibacterial activity was evaluated via the broth microdilution method, revealing that MO-AgNPs exhibited bactericidal effects at a minimum inhibitory concentration (MIC) of ≤ 8 µg/mL for 80% of the pathogens, including 62% of difficult-to-treat (DTR) pathogens and over 90% among antibiotic class resistant groups, including colistin (Col R), extended-spectrum cephalosporins (ECR), fluoroquinolones (FQR), and carbapenems (CR). Importantly, these MICs remained below the cytotoxic threshold (IC 50 = 13.47 µg/mL). These findings highlight the potential of biosynthesized MO-AgNPs as a novel broad-spectrum antibacterial agent, presenting a promising green therapeutic strategy to combat resistant bacterial infections.