Magnetic Particles Show Promise Against Antimicrobial-Resistant Biofilms

Researchers are exploring innovative strategies to combat growing antibiotic resistance. One promising approach involves the use of engineered magnetic particles to physically disrupt and eradicate persistent bacterial biofilms. These complex microbial communities, held together by a matrix of sugars, DNA, and proteins, can shield bacteria from the effects of antimicrobials, allowing them to thrive even in the presence of treatment.

To overcome this obstacle, a research team led by James Chapman, PhD, a senior lecturer in the Department of Environment and Science at Griffith University in Australia, developed magnetic particles with a unique core-shell structure (1). At the center was an iron-based magnetic core, surrounded by a gallium-based eutectic alloy.

"Gallium has some really cool chemistry in that if it's at room temperature, it's a solid, and if it's at body temperature, it's a liquid," Chapman noted during his presentation at Pittcon 2025, which took place March 1-5, in Boston, MA. When these particles were exposed to a magnetic field, something interesting happened. "We picked up some steroids with some rod-shaped particles, and then the high distribution of these star shapes. These star shapes are really interesting in that when the magnetic field was applied, the particles spiked up."

The 2025 Pittcon conference took place at the Boston Convention Center in Boston, MA. Image Credit: Marcio - stock.adobe.com

These spiky particles proved to be highly effective at rupturing bacterial cell membranes, leading to cell death. "To bacteria, that is pretty nasty... and what we found is that that can rupture the cell membrane so we can kill the bacteria using physical means," Chapman said. The team put this concept to the test, growing biofilms of Staphylococcus aureus, MRSA, and Pseudomonas aeruginosa—all notorious for antimicrobial resistance. When the magnetic particles were introduced and the magnetic field activated, the results demonstrated widespread and effective cell death, which increased over time and with size of the magnet.

Further analysis using confocal scanning laser microscopy revealed that the magnetic particles were not only killing the bacteria but also physically removing the biofilm matrix. "The green indicates some really healthy biofilm,” Chapman said, pointing to a figure showing the biofilm surface. “When we turn on the magnetic field for up to 30 minutes, what you see are some red colors... that red indicates that the cells are actually dying, dead, so non-viable." The researchers reported a 99% inactivation rate of the bacterial cells, with only 20% of the biofilm biomass remaining after treatment. "The important point is that it's inactivated. It's all dead. So that gives us a fine chance to be able to cure things," Chapman said.

Further, one of Chapman’s student researchers developed a high-throughput experiment using a standard plate reader to assess the effects of different antibiotic concentrations on bacterial growth. Rather than relying solely on the basic turbidity or optical density measurements provided by the plate reader, they applied chemometric techniques like baseline correction and smoothing to extract more meaningful information from the complex spectral profiles. The chemometric analysis revealed distinct spectral signatures that corresponded to the action of different antibiotics. For example, the spectral changes observed with amoxicillin treatment were indicative of its impact on bacterial cell walls and the release of cellular contents. In contrast, the spectral shifts seen with tetracycline treatment were more reflective of its protein synthesis inhibition mechanism.

Beyond identifying the antibiotics' mechanisms of action, the researchers developed predictive models using spectral data. "You can use a little bit of deep learning and train the models to look at the concentration in chemicals, the time points, whether they are alive or dead, and also the bacterial species as well," Chapman said. These models were able to estimate the antibiotic concentration and bacterial viability based on the spectral fingerprints, demonstrating the potential of this approach to rapidly assess antimicrobial susceptibility and resistance patterns.

As the world grapples with the growing threat of antimicrobial resistance, innovative approaches like this magnetic particle technology and predictive models offer new hope in the fight against persistent and deadly infections. With further development and validation, this physical disruption method could become a crucial tool in the arsenal against one of the most pressing public health challenges.

Reference

1. Chapman J. Development of New Disease Diagnostic Methods Using AI and Spectroscopy. Presented at: Pittcon 2025. March 1-5, 2025; Boston, MA.