Synthesis and Antibacterial Evaluation of Silver-Coated Magnetic Iron Oxide/Activated Carbon Nanoparticles Derived from Hibiscus esculentus

The rise of antimicrobial resistance due to the indiscriminate use of antibiotics has become a global health crisis, contributing to millions of deaths each year. Given the limitations and side effects associated with current antibiotics, there is an urgent need to develop alternative antimicrobial agents that are both safe and effective. In this study, magnetic iron oxide nanoparticles (MIONPs) were synthesized via a chemical co-precipitation technique involving the simultaneous precipitation of Fe²⁺ and Fe³⁺ ions in an alkaline medium and supported on activated carbon (AC) derived from Hibiscus esculentus (HE) fruits, resulting in the formation of MIONPs/HEAC nanocomposites. To enhance their antimicrobial activity, these nanocomposites were further modified with a silver coating via the chemical reduction of silver ions using sodium borohydride, producing MIONPs/HEAC@Ag. The structure and properties of the nanoparticles were analyzed using various techniques. SEM and EDX were used to observe morphology and elemental makeup. DLS and zeta potential measured the size and surface charge. FTIR identified functional groups, and XRD determined crystallinity. The antibacterial activity of MIONPs/HEAC and MIONPs/HEAC@Ag was evaluated against bacterial strains of Escherichia coli and Staphylococcus aureus. The uncoated MIONPs/HEAC showed no antibacterial effect, whereas the MIONPs/HEAC@Ag exhibited significant antibacterial activity, with inhibition zones measuring 11.50 mm for E. coli and 13.00 mm for S. aureus. These results highlight the potential of MIONPs/HEAC@Ag nanocomposites as promising candidates for biomedical applications, particularly in addressing infections caused by antibiotic-resistant bacteria.