Fe₃O₄@mPEG-Ag nanoparticles offer non-antibiotic strategy to combat drug-resistant bacteria

A collaborative study by Guangzhou Medical University and South China University of Technology, published in BME Frontiers, introduces Fe₃O₄@mPEG-Ag nanoparticles (NPs) as a groundbreaking non-antibiotic strategy to combat drug-resistant bacteria. This novel nanomaterial integrates the potent antibacterial properties of silver (Ag) with the stability and biocompatibility of magnetite (Fe₃O₄) modified by methoxy poly(ethylene glycol) (mPEG).

Using a serial coprecipitation method, the research team achieved uniform nanoparticle distribution and high colloidal stability. Comprehensive spectroscopic and microscopic characterization confirmed the structural integrity and functional efficacy of the synthesized nanoparticles.

In vitro assays demonstrated strong antibacterial activity against clinically relevant multidrug-resistant strains, including Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, and Enterococcus faecalis. The nanoparticles exhibited a minimum inhibitory concentration (MIC) of 50 µg·ml⁻¹, a level comparable to that of the conventional antibiotic ciprofloxacin. This potent efficacy is driven by a three-pronged mechanism: electrostatic destabilization of bacterial membranes, generation of reactive oxygen species (ROS) under visible light, and controlled release of silver ions that inflict intracellular damage.

Complementing these experimental findings, molecular docking analyses revealed the nanoparticles' ability to inhibit key bacterial enzymes. Effective targeting of DNA gyrase in S. aureus and β-lactamase in E. coli provides a mechanistic explanation for the observed broad-spectrum antibacterial activity. Crucially, cytotoxicity assays confirmed high mammalian cell viability, underscoring the material's potential for safe therapeutic applications.

This research positions Fe₃O₄@mPEG-Ag NPs as a promising nanotherapeutic platform for bacterial control. Their multifaceted antibacterial mechanisms, combined with excellent biocompatibility, make them a compelling candidate for future clinical applications, offering renewed hope in the global fight against antimicrobial resistance. The study highlights the transformative potential of nanotechnology in redefining infection management and paving the way for innovative, antibiotic-free treatments.