Bioengineered Ag/AgCl nanoparticles from Kocuria kristinae: sustainable synthesis with potent antibacterial, hepatotoxic, and enzyme-modulating activities

In response to the growing threat of multidrug-resistant microorganisms, there is an urgent necessity for developing eco-friendly synthesis methods for the generation of nanoparticles that can serve efficiently as alternatives to commercial antibacterial agents. In spite of the achievement in this area, their toxicity remains insufficiently explored, underscoring the necessity for detailed toxicological evaluation. Herein, Ag/AgCl nanoparticles were generated via a green biosynthetic approach, where metabolites excreted by the soil-isolated bacterium Kocuria kristinae served as both reducing and stabilizing agents during nanoparticle formation. The resulting nanoparticles were stable, spherical, and had an average size of 40 ± 10 nm, as confirmed by TEM analysis. Their stability was further indicated by a high negative zeta potential of -45.8 mV. Ag/AgCl-NPs showed excellent antibacterial effectiveness against pathogenic S. aureus, P. aeruginosa, A. baumannii, and E. coli ATCC 25922, with an MIC of 7 µg mL^-1, 7 µg mL^-1, 10 µg mL^-1, and 8 µg mL^-1, respectively. Furthermore, the hepatotoxic effects of the biofabricated Ag/AgCl-NPs were evaluated histopathologically and enzymatically in mature male albino rats following intraperitoneal injection of a low dose (10 mg kg^-1) and a high dose (20 mg kg^-1) of Ag/AgCl-NPs. The findings indicated minor to moderate liver toxicity, characterized by steatosis, tissue degradation including necrosis, and hyperplasia of Kupffer cells, according to the dose administered. Nonetheless, liver metabolism and function may be slightly affected, as levels of liver enzymes AST and ALT were considerably reduced (p < 0.05), whereas only ALP showed a significant increase (p < 0.05) in the low-dose nanoparticle-treated group. Thus, the biofabricated Ag/AgCl-NPs can serve as effective bactericidal agents with low to moderate hepatic effects and minimal alteration in liver functioning.