Autonomous biocompatible systems have emerged to be of immense interest to the research community in recent times, owing to their wide gamut of applications ranging from biomimetics and nanomachinery on one hand to targeted drug delivery on the other. While the electric field generated out of enzyme catalysis has been successfully demonstrated to self-propel these active particles, the role of the intervening bio-fluid media towards altering their motion remains unresolved. We have reported unique interactions between enzyme-catalysis powered micromotors with complex bio-fluids towards achieving highly efficient electro-catalytic propulsion, surpassing the established limits to a large extent. These results may turn out to be of profound importance in realizing unprecedented control on electro-chemically induced locomotion of microscale or nanoscale objects in physiologically relevant fluidic pathways of in-vivo or in-vitro systems.
Bacteria such as Escherichia coli (E. coli) exhibit biased motion if kept in a spatially non-uniform chemical environment. We have brought out unique time-dependent characteristics of bacterial chemotaxis, in response to a diffusing spatial step ligand profile. Experimentally obtained temporal characteristics of the drift velocity are compared with the theoretical and Monte-Carlo simulation-based estimates, and excellent agreements can be obtained. These results bring in new insights on the time-responsive facets of bacterial drift, bearing far reaching implications in understanding their migratory dynamics in the quest of finding foods by swimming towards the highest concentration of food molecules, or for fleeing from poisons, as well as towards the better understanding of therapeutic response characteristics for certain infectious diseases.
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