Enzyme-coated liposomes as dual-direction self-propulsive motors

Directional migration in response to specific chemical signals is critical for the survival of biological organisms. This enables living cells to move towards food, escape away from toxins, transport cargo and coordinate collective behavior. Controlling the motion of a motor either towards or away from chemical species is the first step in designing adaptive life-like synthetic motors. Model protocells derived from phospholipids and other amphiphiles have been studied and their movement through catalysis has been observed. However, control of directionality based on chemical cues (chemotaxis) has been difficult to achieve. In this talk, I will discuss both positive and negative chemotaxis of autonomous liposomal protocells based on the interplay between positive enzymatic catalysis-induced chemotaxis and solute-phospholipid interaction-based negative chemotaxis. In doing so, I will systematically rule out currently available mechanisms of colloidal transport and propose a potentially new and previously unrecognized mechanism of transport due to the Hofmeister effect. This opens up the possibility of other mechanisms for the transport of biological colloids.