Precision intervention based on infection site: strategies and advances of magnetic nanomaterials in bacterial therapy.

Bacterial infections, especially those involving drug-resistant pathogens and biofilms, pose a severe global health threat. Conventional antibiotic therapies are limited by poor penetration, low specificity, and bacterial resistance mechanisms. Magnetic nanoparticles (MNPs) offer a promising alternative by combining magnetically guided targeting, magnetothermal/photothermal effects, multifunctional drug delivery, and imaging capabilities. Their antibacterial efficacy depends critically on the anatomical and pathological features of the infection site. For skin and superficial infections, near-infrared (NIR) light, particularly in the second biological window (NIR-II), enables synergistic photothermal/photodynamic/chemodynamic therapies. For deep soft tissue and bone infections, alternating magnetic fields (AMF) provide deep-penetrating magnetothermal activation or targeted enrichment, often combined with image-guided intervention. For cavity organ and implant-related infections, surface functionalization, local drug delivery, and endoscopic energy application allow precise interfacial intervention. This review systematically discusses MNP-based strategies tailored to different infection sites, integrating advances in material design, synergistic mechanisms, and preclinical progress. It also addresses challenges in multifunctional integration, biosafety, and clinical translation, and outlines future directions toward intelligent, theranostic, and synergistic antibacterial platforms.