Magnetic Nanoparticles in Biofilm Disruption: A Promising Approach to Combat Marine Fouling

Marine biofilms, which are formed by the growth of various organisms, can negatively affect underwater surfaces such as boat hulls and bridge foundations. They can lead to increased fuel consumption, corrosion, and damage to the substrate, resulting in extra costs for biofilm removal procedures. Removing bacterial biofilms early on can prevent the attachment of harmful macro-organisms. This project proposes using magnetic nanoparticles (MNPs) to remove marine biofilms under alternating magnetic fields. Spherical iron oxide MNPs of 20 nm diameter were synthesized by the polyol method and their morphology, crystallinity and magnetic properties were evaluated by electron microscopy, X-ray diffraction and static and dynamic magnetometry. The MNPs are magnetite with a size close to the superparamagnetic/ferromagnetic transition at room temperature and present a saturation magnetization close to that of bulk magnetite. The synthesized MNPs were coated with a biocompatible layer of silicon dioxide via a sol-gel method and polyethyleneimine, a positively charged polymer with antimicrobial properties. The integrity of these coatings were verified and quantified using transmission electron microscopy, Z-potential measurements, and thermogravimetric analysis. The MNPs were internalized within <i>C. marina</i> biofilms and placed under alternating magnetic fields. Several high-frequency alternating magnetic fields, in the hundreds of kHz range, were tested. This frequency range is designed to promote MNP heating for our MNP morphology and composition. The morphology of the biofilm and viability of the bacteria before and after alternating magnetic field treatment were evaluated by fluorescence microscopy. The study will investigate the most effective MNP treatment regime and the effects of mechanical or thermal excitation on biofilm and bacterial physiology. The proposed research has the potential to provide a new and effective approach to addressing the problem of marine biofilms and could be used to treat biofilm caused by antibiotic resistant bacteria strains.