Multifunctional Fe₃O₄/Alumina Core/Shell MNPs as Photothermal Agents for Targeted Hyperthermia of Nosocomial and Antibiotic-Resistant Bacteria

Abstract

Aims: 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. Materials & Methods: In this work, we propose a targeted hyperthermia therapeutic approach using alumina-coated iron oxide magnetic nanoparticles (Fe₃O₄/alumina core/shell MNPs) as photothermal agents to selectively kill bacteria. Results: Fe₃O₄ 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 Fe₃O₄/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 Fe₃O₄/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 Fe₃O₄/alumina MNPs. Conclusion: This approach provides a potential therapeutic approach for treating patients suffering from nosocomial and antibiotic-resistant bacterial infections.

Keywords::

• Fe₃O₄
• hyperthermia
• magnetic nanoparticle
• near-infrared light
• pathogenic bacteria
• photothermal

Financial & competing interests disclosure

The authors would like to thank the National Science Council of Taiwan for the financial support of this work. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Ethical conduct of research

The authors state that they have obtained appropriate institutional review board approval or have followed the principles outlined in the Declaration of Helsinki for all human or animal experimental investigations. In addition, for investigations involving human subjects, informed consent has been obtained from the participants involved.

Additional information

Funding

The authors would like to thank the National Science Council of Taiwan for the financial support of this work. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.