Our bodies are composed of trillions of cells, each with unique functions that work together to keep us alive. A fundamental question in biology is how cells move within complex systems, how they know where to go, and how they become so complex. Chemotaxis, the process by which cells move in response to chemical signals in their environment, is a crucial aspect of this movement. Researchers at the Okinawa Institute of Science and Technology (OIST) created synthetic droplets to mimic chemotaxis in a controlled laboratory setting. By isolating and studying the movement of these droplets, they gained insights into the principles of movement in simple biological systems.
The synthetic droplets used in the study contained a high concentration of the bovine protein BSA and the enzyme urease, which catalyzes the breakdown of urea into ammonia. As ammonia is produced, it diffuses into the solution, creating a higher pH around the droplets. This pH gradient enables the droplets to detect each other and move in response to the chemical signals. The researchers found that the movement of the droplets is facilitated by the Marangoni effect, where molecules flow from areas of high surface tension to low tension. This effect is influenced by changes in pH, which affects surface tension, making it easier for molecules to move.
When two synthetic droplets are close enough that their halos interact, the pH in the environment between them rises, causing them to move together. As the droplets merge, larger droplets produce more ammonia and have a larger surface area, attracting smaller droplets to them. This cooperative movement of droplets mimics the chemotaxis observed in biological systems, providing new insights into how cells or organisms move in response to chemical signals in their environment. The controlled laboratory setting allowed researchers to understand the complex mechanisms involved in this process.
The research not only sheds light on basic questions about biological movement but also provides insights into the early forms of life and the possibility of creating new biologically inspired materials. Chemotaxis through the Marangoni effect could have played a role in the development of life in the oceans billions of years ago, as organic molecules migrated and interacted in a primordial soup. The research also has implications for future technologies, such as creating responsive materials that sense and react to chemical gradients, for applications in micro-robotics or drug delivery.
The collaboration between researchers from different units at OIST highlights the importance of interdisciplinary research and the human factors that drive scientific work. The project began during the coronavirus pandemic when members from different units began talking and sharing ideas, leading to the development of the synthetic droplets. The unique research environment at OIST, where units are physically close to each other and encourage collaboration, facilitated the project. The ongoing partnership between the three units has led to fruitful outcomes, with more insights into the minute movements of life at different scales. This collaborative effort has pushed the boundaries of understanding in basic research and has opened up new possibilities for future discoveries in biology and technology.
