Neutrobots
Chinese scientists have introduced "neutrobots" to deliver drugs directly to the brain
Sergey Vasiliev, Naked Science
Brain diseases are difficult to treat, not only because it is the most complex organ of our body. It is also the most protected: even blood vessels are not connected to the tissues of the central nervous system, being separated from them by cells of the blood-brain barrier. The permeability of the BBB is selective: it passes oxygen and nutrients, but does not pass toxins, viruses and other potentially dangerous agents. However, it also does not allow you to get to the brain and a lot of useful substances.
It is not surprising that scientists from different countries are trying to create means to overcome BBB: for example, hollow nanoparticles that could penetrate to brain cells, delivering medicine inside and releasing it already in place. And the team of Zhiguang Wu from Harbin University of Technology has assembled a whole micro robot for this. They talked about their development in an article published in the journal Science Robotics (Zhang et al., Dual-responsive biohybrid neutrobots for active target delivery).
In the diagram, the authors showed the device as a whole, as well as its movement under the influence of a magnetic field through the circulatory system and BBB to a tumor in the brain / ©Zhang et al.
Scientists have called the system a "neutrobot" because fragments of neutrophils, immune blood cells, are used for assembly. This happens as follows. First, the authors prepared microscopic and elastic particles of "magnetic nanogel": their polymer frame, which has magnetic properties, can collect quite a lot of water together with the necessary medicine. Further, the cells of E. coli bacteria were killed and "gutted", removing everything superfluous and leaving only fragments of cell membranes. They were coated with gel particles.
The bacterial membrane acts "like a red rag" on immunity. Therefore, when the prepared particles mixed with neutrophils, they quickly attacked them and carried out phagocytosis, absorbing a potentially dangerous object. Due to the magnetic properties of the nanogel, their movement can be controlled by acting on an external magnetic field to direct cells to the brain. Neutrophils are able to pass through the BBB easily and independently, being attracted by inflammatory signals from the diseased brain. They also carry a useful medicinal cargo with them.
Scientists have demonstrated the efficiency of their "neutrobots" not only "in vitro", but also on live laboratory mice – a model line that is used for studies of glioma, a brain tumor. Nanogel particles were loaded with the anticancer drug paclitaxel, placed in bacterial membranes and neutrophils, and then ready-made "neutrobots" were injected into the tail vein. Soon it was recorded that they really overcame the BBB and delivered the medicine to the tissues of the central nervous system.
Now the authors plan to finalize and improve their system. First of all, scientists are interested in the process of controlling the movements of "neutrobots" and controlling their movement. So far, the magnetic field acts quite widely, directing a whole mass of such microscopic systems in the right direction and losing a lot of particles along the way.
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