Spirulina Robot

Scientists have made hybrid cellular robots from algae

Sergey Vasiliev, Naked Science

Tiny robots moving freely through the bloodstream and "repairing" our body in time is a fantasy that has not yet become a reality. In fact, it is not yet possible to make a biocompatible and inert cage of cellular dimensions, equip it with an energy system and a motor mechanism, control means, and so on. It is necessary to achieve the ability to monitor such devices and manage their movements – all this remains too difficult a task.

In an article published by the journal Science Robotics, Hong Kong scientists led by Li Zhang describe a new conceptual approach to solving such problems. They are considering the possibility of using as a carrier of medical systems of living organisms, namely blue-green algae Spirulina platensis. These are completely safe, edible photosynthetic cyanobacteria with spiral-shaped cells, convenient for movement in a liquid environment.

Spirulina cells were coated with iron oxide nanoparticles, briefly immersing them in a solution. This forced them to react to an external magnetic field, which allowed scientists to control the movement of bacteria: the spiral shape, covered with magnetic particles, is easily directed forward or backward. At the same time, the authors used GM algae lines producing fluorescent protein. Therefore, movements at the surface of the skin were easily visualized, and scientists demonstrated this in experiments on laboratory rats.

Above is a diagram of the coating of algae with nanoparticles. Below are micrographs of cells with an increasingly dense layer, after 6, 24 and 72 hours of immersion / ©Xiaohui Yan et al., 2017

In deeper layers, you can see "biohybrid robots" using MRI. The authors even observed the movements of bacterial cells in the stomach of experimental rats, showing that an external magnetic field really allows you to control this movement well.

Scientists call an extremely important point "biocompatibility at an affordable cost" – the very fact that controlled devices are completely safe for the body. Their complete degradation occurs within hours or days, depending on the thickness of the magnetic coating. Now the authors plan to improve the "biohybrid" system so that it can be used for targeted drug delivery.

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