Multifunctional Fe 3 O 4 /Alumina Core/Shell MNPs as Photothermal Agents for Targeted Hyperthermia of Nosocomial and Antibiotic-Resistant Bacteria

Abstract

The appearance of antibiotic-resistant bacterial strains is a serious problem in medical treatment. Thus, it is imperative to explore new therapeutic approaches and antibiotics with which to treat patients suffering from bacterial infections. In this work, we propose a targeted hyperthermia therapeutic approach using alumina-coated iron oxide magnetic nanoparticles (Fe(3)O(4)/alumina core/shell MNPs) as photothermal agents to selectively kill bacteria. Fe(3)O(4) MNPs possess photothermal capabilities under near-infrared (NIR) light illumination. The temperature of the MNP suspension (1.33 µg/µl, 60 µl) under illumination with NIR light increased 20°C over 5 min. Functionalization of the surface of the MNPs with an alumina coating allows them to have targeting capability toward bacteria. The prepared Fe(3)O(4)/alumina core/shell MNPs possess several desirable features, including magnetic properties, absorption capability in the NIR region and the ability to target bacteria. The magnetic properties of the Fe(3)O(4)/alumina MNPs allow conjugated target species to aggregate at a specific location under a magnetic field. A NIR laser can then be used to specifically irradiate the aggregated spot to photokill target bacteria. The cell growth of nosocomial bacteria, including Gram-positive, Gram-negative and antibiotic-resistant bacterial strains, can be effectively inhibited by over 95% within 10 min of light irradiation when targeted by Fe(3)O(4)/alumina MNPs. This approach provides a potential therapeutic approach for treating patients suffering from nosocomial and antibiotic-resistant bacterial infections.