What are Xenobots? Our definition

What are Xenobots? Our definition

They are smaller than a millimetre and basically just a bunch of cells: Xenobots. Scientists at the University of Vermont and Tufts University succeeded in producing small robots made of organic material in the early 2020s using stem cells from the smooth clawed frog (Latin: Xenopus laevis). Based on the combination of active and passive cells and a computer-calculated shape, they can be constructed for different purposes. Now, a new groundbreaking discovery has been made by the research group around Sam Kriegman and Douglas Blackiston: Xenobots are also capable of reproducing themselves.

The creation of an artificial organism

Xenobots consist of a combination of skin and heart muscle cells. While the skin cells serve to form the body shape, the heart muscles are responsible for locomotion: With their property of continuous contraction, the xenobots can thus be set in motion and move independently. How the organic robots function, how they are virtually programmed, is determined by their shape and the distribution of the two types of cells: depending on the type of use, a computer uses artificial intelligence to calculate the required shape and the cells positioned within it. To create a Xenobot, the cells are first combined in the incubator and, by their nature, stick together over the course of a few days. The mould is then made by hand, using tiny tweezers and electrodes.

In addition to the contractile cells of the heart muscle, xenobots can also be equipped with cilia: These are fine, hair-like protrusions on the cell envelope. On the one hand, they are used for locomotion – so a xenobot can also swim – on the other hand, they can be used to perceive signals from the environment. It has already been possible to make the organisms change colour when they are exposed to blue light.

Incidentally, the xenobots draw the energy they need for their movements from the fat and proteins of their own cells. When this is used up, they stop their activity and die. These dead cells are then biodegradable and could be absorbed by the human organism for medical use. Their energy currently lasts for about a week, with cilia-controlled xenobots being active for longer than the muscle-controlled versions.

Self-healing and replication

One characteristic of xenobots is their ability to heal themselves: if you cut their shape, the interfaces stick together on their own. The latest research results now also attest to their ability to reproduce themselves. In one experiment, embryonic stem cells of the frog were placed in a salt solution, whereupon they initially formed small spherical clusters. With the formation of cilia after three days, these were now able to move around in the solution. Loose stem cells were now added to the xenobots thus created, which were then swept into small cell clusters by them. These cell clusters gave rise to new, floating robots that were also capable of reproduction.

This kind of reproduction was observed by the scientists by chance and was not created deliberately. However, they then used the computer to investigate which conditions best support this process. Two areas were examined: on the one hand, external factors such as temperature and composition of the salt solution, and on the other hand, the specific shape of the xenobot. The computer examined a total of 6000 possible shapes and came to the conclusion: The shape best suited for reproduction resembles a torus with an open mouth, similar to a Pac-Man. Under the best possible conditions, they succeeded in maintaining reproduction for five generations.

Potential for the future

At present, the small organic robots can’t really do much and don’t offer any practical benefits, but they do give an idea of what could be possible in the future. They could be used in a number of areas, especially in medicine: For example, medicines could be transported to their destination or arteriosclerosis could be scraped from the walls of the blood vessels. It would also be conceivable to locate cancer cells, radioactive contamination or other pathogens. In order not to be rejected by the human immune system, however, these organisms would have to be constructed from human stem cells. But there could also be applications outside medicine: The University of Vermont, for example, sees a way to fish microplastics out of the oceans.

Source: Fast Company

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