SYNTHESIS, CHARACTERIZATION AND ANTIBACTERIAL ACTIVITY OF SILVER NANOPARTICLES SYNTHESIZED FROM Ocimum gratissimum LEAF AGAINST SOME ANTIBIOTIC-RESISTANT CLINICAL ISOLATES

The rise of antibiotic resistance necessitates exploring alternative antimicrobial agents. Nanomedicine offers promising solutions, by enhancing the antimicrobial potencies of the plant extracts. The present research aimed at synthesizing, characterizing and determining the antibacterial activity of O. gratissimum leaf synthesized Silver Nanoparticles (AgNPs) against some antibiotic-resistant clinical isolates. The test bacteria were collected from Dutse General Hospital and Rasheed Shekoni Teaching Hospital and confirmed using standard phenotypic and genotypic techniques. The AgNPs were prepared using the green synthesis method, and characterized using UV-visible spectral analysis, Scanning Electron Microscopy (SEM), Energy-Dispersion X-Ray Spectroscopy (EDS), and Fourier-Transform Infrared Spectroscopy (FT-IR). The antibacterial activity of the AgNPs was determined using agar well diffusion method. The phytochemicals analysis indicates the presence of alkaloids, flavonoids, phenols, saponins, glycosides, and tannins, with concentrations ranging from 4.964± 0.002 to 1113.064± 14.336 mg/g. The UV-visible spectral analysis shows characteristics of the surface Plasmon peak at 415 nm, where the SEM/ EDS reveals that the particles are spherical, with an average size of 26.58 nm, evenly distributed, and have 65.20% Ag elemental compositions. The FT-IR results show various compound groups participated in the capping and reducing of AgNO3 to AgNPs. The statistical results reveal significant difference (P< 0.05) between various concentrations of the AgNPs treatments, with methanolic extract AgNPs at 100 mg/ml, ciprofloxacin (10 µg), methanolic extract AgNPs at 100 mg/ml, and ethanolic extract AgNPs at 100 mg/ml having highest mean± SD inhibition zones against Escherichia coli, Salmonella enterica, Pseudomonas aeruginosa and Staphylococcus aureus respectively. The findings show that S. aureus, E. coli, and P. aeruginosa are the most susceptible to AgNPs with the smallest Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) values, while S. enterica and had the lowest susceptibility with the largest MIC and MBC values. It was concluded that O. gratissimum leaf synthesized AgNPs have antimicrobial effects on some antibiotic-resistant clinical isolates tested. Further research on plant-based synthesized AgNPs is suggested to explore their potential applications.