A Nano-sized Magnet
Author: Isabel Zhang
From: Chicago, IL, US
You’ve probably heard of (or even used) a compass: an instrument with a magnetized pointer that detects Earth’s natural magnetic poles, allowing it to show the direction north. However, have you ever heard of nano-sized, bacterial compasses?
These biological “compasses” were first discovered in 1975 by a microbiologist named Richard Blakemore. While studying bacteria that live in muddy swamps, he realized that some tended to swim toward the same geographical direction; even when he rotated the microscope, they still wiggled toward one direction!
Today, we know that this behavior is due to a certain organelle (or structure) within the bacteria that responds to Earth’s magnetic fields and serves as a compass for the bacteria. Recently, researchers have come to realize that this seemingly-superpower organelle has promising biomedical applications. But before we dive into these biomedical applications, let’s learn a bit more about what these bacteria exactly are.
What are Magnetosomes?
The bacteria species we’ve been talking about is the magnetotactic bacterium (Magnetospirillum gryphiswaldense). It produces magnetic nanoparticles called magnetosomes, which are membrane-enclosed organelles that have a perfect crystal structure and exhibit magnetic properties.
Inside a magnetotactic bacterium cell, these magnetosomes are arranged in a chain-like manner that’s similar to a string of pearls. This forms a kind of magnetic compass needle that allows the bacteria to navigate along the Earth's magnetic field towards the North or South pole: locations with extreme temperatures and deep, dark water (the perfect living conditions for the bacteria).
Now we’ve seen just how amazing and important the magnetic properties of magnetosomes are in guiding magnetotactic bacteria. However, this magnetic superpower isn’t just helpful for the bacteria— it has the potential to help us humans out too!
Researchers from the University of Bayreuth have recently developed a method to isolate the magnetosome nanoparticles from bacterial cells. When they took these magnetosomes and incubated them with human cells, they found high vitality values of the magnetosome-treated human cells, even at high concentrations of the nanoparticles. In other words, the researchers’ tests showed that there is good biocompatibility between magnetosomes and human cells.
Knowing that magnetosomes are safe for human cells is a promising step towards the biomedical use of magnetosomes and their magnetic processes.
One potential use is for magnetic resonance imaging, or MRI scans: a diagnostic imaging technique that uses strong magnetic fields to generate images of organs in a body. Because MRI works without radiation and allows for detailed, high-resolution pictures, MRI is an optimal diagnostic imaging technique. If we inject magnetosomes into patients’ bloodstreams for MRI tools to detect, they could increase the accuracy of MRI scans, and thus the accuracy of diagnoses!
Another potential use of magnetosomes is as a carrier in magnetic drug delivery. If we load the nanoparticles with chemical agents and magnetically control them throughout a patient’s body, we could effectively guide the drugs to disease sites such as tumors, target the harmful cells, and eliminate the disease.
In addition, magnetosomes could be very useful in the field of theranostics, which combines precise diagnoses with subsequent targeted therapy.
Magnetosomes make incredible compasses for magnetotactic bacteria. If we can use this as inspiration and apply magnetosomes to biomedical techniques, they might just point the way to more effective medical practices and patient lives that are saved.
Despite being nano-sized, magnetosomes are very powerful magnets indeed.
About the Author: Isabel Zhang
Isabel is a senior in high school, and is interested in biology and engineering. In her free time, she loves to bake, sketch, and hang out with her family.
U. (2021, February 19). Bacterial magnetic nanoparticles for biomedical applications. Retrieved from https://phys.org/news/2021-02-bacterial-magnetic-nanoparticles-biomedical-applications.html
Rosenfeldt, S., Mickoleit, F., Jörke, C., Clement, J. H., Markert, S., Jérôme, V., . . . Schenk, A. S. (2021, January 15). Towards standardized purification of bacterial magnetic nanoparticles for future in vivo applications. Retrieved from https://www.sciencedirect.com/science/article/pii/S1742706120304281?via=ihub