Insights into the antibacterial mode of action of cress polysaccharide-mediated NiO nanoparticles

The increasing prevalence of antimicrobial resistance necessitates the development of alternative antibacterial strategies. In this study, nickel oxide nanoparticles (NiO NPs) were synthesized using cress (Lepidium sativum) seed mucilage polysaccharides (CSP) as a green reducing and stabilizing agent. The formation of CSP-mediated NiO nanoparticles (CSP-NiO) was confirmed through extensive characterization using UV-Visible, FTIR, XRD, SEM, and EDX techniques. The CSP-NiO NPs exhibited minimal erythrocyte toxicity (< 5% hemolysis at 200 µg/mL) and dose-dependent antibacterial activity against Gram-positive (Staphylococcus aureus and Clostridium tetani) and Gram-negative (Escherichia coli and Klebsiella pneumoniae) bacteria, with MIC values ranging from 25 to 50 µg/mL. The mechanistic investigations revealed increased intracellular reactive oxygen species (ROS) production, membrane disruption (evidenced by protein leakage), and genomic DNA damage in treated bacterial cells. These findings suggest that CSP-NiO NPs exert antibacterial effects through oxidative stress, leading to membrane disruption and genomic DNA damage, thereby establishing them as a sustainable nanomaterial platform for future antimicrobial applications.