Robots….Made of Frog Cells?

Addressing some of humanity’s greatest challenges, including disease and pollution, requires innovation that pushes the boundaries of what’s possible. Many potential solutions use synthetic materials that tax the environment heavily, solving a problem by creating another. Science fiction often promises us futuristic robots with unfounded technical abilities, but science has recently reinvented the standards of robotics with Xenobots. Xenobots are living, programmable machines. Unlike traditional robots, which are made from synthetic materials such as metal and plastic, these microscopic entities are created from the embryonic cells of the African clawed frog (Xenopus Laevis). The embryo cells are structured into different shapes using computers. Artificial intelligence optimizes the shapes of Xenobots by determining which shape is best for each task. Since Xenobots are made from biological cells, they are biodegradable and can repair themselves. These features suggest Xenobots have groundbreaking potential in fields such as medicine, where they have potential for targeted drug delivery usage. The environmental science field especially shows potential for Xenobots to combat pollution. These machines will not only reduce environmental strain, but also show immense promise in tackling pressing ecological problems like microplastic pollution.

The process of creating a Xenobot begins with harvesting embryonic stem cells from the early stage embryos of an African clawed frog. An embryo forms after fertilization, when a sperm cell and an egg cell combine to create a single-celled zygote. The zygote then rapidly divides to create an embryo. At this stage, the cells are pluripotent. This means that they have the potential to differentiate into various specialized cell types. In the cell's natural environment, these cells receive signals from the frog to differentiate. However, in a laboratory setting, these cells can be manipulated to develop into the two predetermined cell types needed to make a Xenobot: epithelial cells and cardiac cells.

Epithelial cells, which form the outer layer of the skin, are cohesive to one another, meaning they bind to each other to create a sturdy structure for Xenobots that allows it to stay intact. Since these skin cells are supposed to be part of a living system, they naturally repair themselves when damaged, which allows Xenobots to be even more resilient. The second type of cell are cardiac muscle cells, also known as heart muscle cells. Cardiac muscle cells contain specialized proteins and ion channels that allow them to generate their own electrical impulses, so they do not need signals from the brain. This means that these cells can contract rhythmically and are what allow the Xenobots to move or push objects without needing external energy sources. After differentiation, the skin and cardiac cells are manually assembled into specific configurations guided by artificial intelligence. For instance, a Xenobot designed to move efficiently through water might require a shape that minimizes drag and concentrates cardiac cells in regions where rhythmic contractions can generate forward propulsion. After the shape is determined, researchers manually use microsurgical tools to assemble the cells into a Xenobot. The cells then bind, using proteins on their surfaces called cell adhesion molecules, and stabilize. After this, the Xenobot essentially becomes a functional living machine that is controlled by the design and the intrinsic properties of the cells. 

Recently, groundbreaking research discovered the Xenobot’s ability to perform kinematic self-replication. In 2021, a study led by the University of Vermont found that Xenobots could gather free-floating cells in their environment— a controlled liquid medium in laboratories—and assemble them into entirely new Xenobots. This method of self-replication is unprecedented in biology, and works only due to unique properties of Xenobots. 

Xenobots have already demonstrated immense promise in revolutionizing medicine. One of these applications in medicine is targeted drug delivery. A paper published in Bentham Science states that Xenobots can be utilized to deliver drugs to specific targets, potentially reducing cytotoxicity in cancer treatments and addressing neurodegenerative disorders like Alzheimer’s and Parkinson’s disease. Cytotoxicity describes the damage which drugs, especially chemotherapy, do to cells. Unlike conventional medication that flows throughout the entire bloodstream, possibly damaging healthy tissues, Xenobots can be programmed to navigate to specific locations. Addressing neurodegenerative disorders is extremely challenging due to the blood brain barrier, which is a protective layer of tightly packed cells lining the blood vessels in the brain. This layer of cells prevents any harmful substances from entering the brain, but also prevents therapeutic drugs. However, due to the small size of Xenobots and their programmable nature, they might one day be engineered to cross the brain blood barrier. Furthermore, in an article in Science Robotics, researchers demonstrated that Xenobots have an ability to self-repair and close up wounds. When Xenobots encounter a damaged area, their cohesive structure allows them to reorganize and adapt to seal gaps or close wounds effectively. The fact that they’re made out of cells gives them an unique advantage in integrating with other biological tissues. 

Not only do Xenobots show great potential in medicine, they may have more transformative effects on the environment. One of the greatest pollutants in our oceans and waterways are microplastics, tiny plastic particles that pose a threat to marine ecosystems and, through the food chain, to human health. A study published in ScienceAdvances demonstrated that specialized nanorobots, such as Xenobots, had microplastic removal efficiency of over 90 percent over 100 trials. Moreover, Xenobots can play a role in restoring the balance of aquatic microbiomes. A study published by Nature Communications showed that specialized microrobots like Xenobots were able to remove 92 percent of nanoplastics and 70 percent of microplastics while incorporating algae to restore the microbiome. Algae have the ability to absorb and degrade pollutants, including certain plastic components, through natural biochemical processes. By using Xenobots to incorporate algae, it could aid itself in the removal of microplastics. 

Although Xenobots show great potential in these fields, their development and deployment raise important ethical and regulatory questions. As with any emerging technology, especially one that contains living entities, it is essential to ensure that the use of Xenobots does not have unintended consequences. The regulatory protocols of Xenobots are still developing. The specific rules addressing their self-replication ability and potential ecological impacts have yet to be fully established. However, protocols must ensure that Xenobots cannot persist or reproduce uncontrollably outside of laboratory settings, as this could disrupt natural ecosystems. If Xenobots were unchecked in the wild, it may interrupt natural ecosystems. Another significant consideration is the potential impact of Xenobot mass-production on frog populations. As stated before, Xenobots are created from embryos of the African clawed frog. Large-scale production of Xenobots would require a consistent and substantial supply of frog embryos. This could lead to overharvesting of frogs, disrupting their natural populations and the ecosystems they inhabit. An additional issue may be the overall energy consumption of Xenobot production. The optimization of a Xenobot’s design relies on artificial intelligence or machine learning. While this gives extremely precise and functional Xenobots, machine learning algorithms require substantial computational resources. This raises concerns about the overall environmental footprint of Xenobot usage. It is imperative that scientists address these issues by developing more energy-efficient artificial intelligence models or exploring alternative computational methods to minimize the carbon footprint of Xenobot.

Overall, despite these small challenges, the future of Xenobots is bright. Xenobots blend robotics and biology to solve some of humanity’s most vital issues. The application of Xenobots is extremely relevant to us, given our proximity to the Hudson River. The Hudson River constantly faces pollution, but with the deployment of Xenobots, New York City can revolutionize its approach to restoring this crucial waterway.