Antibacterial/Magnetic Iron Oxide Nanoparticles: A Comprehensive Review of Synthesis Methods, Doping Effects, Antibacterial Properties, and Applications in Medical and Food Industries

The alarming rise of multidrug-resistant (MDR) bacteria has necessitated the development of innovative antimicrobial strategies beyond traditional antibiotics. Magnetic nanoparticles (MNPs) have emerged as promising candidates due to their unique physicochemical properties, including high surface area, superparamagnetism, and facile surface modification. This review explores the multi-faceted antibacterial mechanisms of MNPs, including membrane disruption, reactive oxygen species (ROS) generation, metal ion release, biofilm penetration, intracellular uptake, and hyperthermia-induced bacterial eradication. These mechanisms operate synergistically, allowing MNPs to combat a broad spectrum of bacterial pathogens, including biofilm-associated and drug-resistant strains. The incorporation of antibacterial dopants such as silver (Ag⁺), zinc (Zn²⁺), copper (Cu²⁺), cobalt (Co²⁺), and manganese (Mn²⁺) into MNPs further enhances their antimicrobial activity by promoting ROS generation, enzymatic inhibition, and DNA damage, while also improving magnetic and catalytic performance. Surface functionalization further enables targeted delivery, biocompatibility, and multi-functionality for therapeutic and diagnostic applications. MNPs hold significant promise in clinical, food safety, and environmental contexts, particularly for applications such as drug delivery, implant coatings, wound healing, and antimicrobial packaging. Their ability to combine physical, chemical, and biological antibacterial mechanisms positions MNPs as a versatile platform for next-generation antimicrobial technologies aimed at overcoming the global antibiotic resistance crisis.