Non-reciprocal Chemotactic Movement in Enzyme Cascade Under Flow-Free Conditions

The chemotactic guiding of particles using chemical gradients is an important area of research because of possible applications in drug and cargo delivery to specific locations. In addition, the experimental demonstration of non-reciprocal interactions in active systems is of fundamental importance. We have developed a new microchannel architecture that allows reactive particles to be exposed to imposed chemical gradients for a long time under flow-free conditions. Using this setup, we show that particles functionalized with the enzymes, urease, acid phosphatase, and glucose oxidase show positive chemotactic mobility in response to their respective substrate gradients in a concentration dependent manner. Most significantly, when combined, both acid phosphatase, and glucose oxidase-functionalized particles exhibit chemotaxis in response to a gradient of glucose-6-phosphate which acid phosphatase converts to glucose, the substrate for glucose oxidase. These findings underscore the significance of chemical gradient in directing particle movement, offering insights crucial for understanding complex biological processes such metabolon formation and chemotactic signaling. Additionally, our work constitutes the first step in designing intelligent functional assemblies where populations of particles with different functions coordinate their behavior.