Microbes instead of micro robots
Scientists have proposed to treat cancer with the help of magnetic bacteria
Swiss scientists have proposed using magnetosensitive bacteria for targeted delivery of drugs to a cancerous tumor, the movement of which in blood vessels can be controlled using a magnetic field. The results of the study are published in the journal Advanced Functional Materials (Mirkhani et al., Living, Self‐Replicating Ferrofluids for Fluidic Transport).
Cancer drugs have side effects, so for many years scientists have been trying to find a way to deliver active substances to the tumor – the only place in the body where they should act. One approach is to control blood flow using tiny vehicles – micro robots placed in blood vessels.
Researchers from the Swiss Higher Technical School of Zurich decided to use real bacteria sensitive to the magnetic field instead of micro robots.
"One of the main advantages of bacteria over micro–robots is that they are easy to produce. We can simply grow them in bioreactors," the school's press release (Magnetic bacteria as micropumps – VM) quotes the head of the study, Simone Schürle, professor of the Department of Medical Sciences and Technology.
Such bacteria were discovered in nature 45 years ago and were called Magnetospirillum. These microorganisms absorb iron dissolved in water. Inside them, iron oxide crystals are formed, which line up in a row. Like a compass needle, these bacteria align along the lines of the Earth's magnetic field, and if a magnet is brought to the container where they are located, then they will all gather near the poles of the magnet.
A bacterium of the genus Magnetospirillum. Thanks to a number of iron oxide crystals (yellow), these bacteria are oriented like a compass needle. Photo: Science Photo Library.
Swiss biologists have studied in the laboratory how to control the flow of liquids containing Magnetospirillum using a magnetic field.
It turned out that with the help of weak rotating magnetic fields, it is possible to deploy bacteria in thin tubes that mimic blood vessels. With a large number of microorganisms, scientists managed to move the surrounding liquid in the right direction. The bacteria acted as micro-pumps.
Using superimposed magnetic fields that locally amplify or neutralize each other, scientists were able to limit the activity of bacteria to a small area, and control the flow of liquid with very high accuracy. The authors supported the laboratory experiments with computer simulation of the process.
The authors note that their work focuses on the study and description of how bacteria can control the flow inside a living organism, but the same principle can be used outside the body, for example, to locally mix different liquids in very small vessels without the need to manufacture and control mechanical micro-pumps.
Scientists understand that before using magnetosensitive bacteria in the human body, it is necessary to study their safety – for example, to find out if they cause an allergic reaction.
As such, "live therapeutic agents" have long been used in medicine – for medical reasons, certain patients are injected with intestinal bacteria.
It is even easier to use synthesized bacteria grown in the laboratory. In this case, it is possible to obtain absolutely safe microorganisms with controlled functional properties, the researchers note.
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