Receptor

Enzyme

Membrane

Chemotaxis

Biology

Biophysics

Protocell

Catalysis

Artificial cell

Liposome

Chemistry

Phospholipid

Biochemistry

Enzyme catalysis

Nature Nanotechnology

The ability of cells or cell components to move in response to chemical signals is critical for the survival of living systems. This motion arises from harnessing free energy from enzymatic catalysis. Artificial model protocells derived from phospholipids and other amphiphiles have been made and their enzymatic-driven motion has been observed. However, control of directionality based on chemical cues (chemotaxis) has been difficult to achieve. Here we show both positive or negative chemotaxis of liposomal protocells. The protocells move autonomously by interacting with concentration gradients of either substrates or products in enzyme catalysis, or Hofmeister salts. We hypothesize that the propulsion mechanism is based on the interplay between enzyme-catalysis-induced positive chemotaxis and solute–phospholipid-based negative chemotaxis. Controlling the extent and direction of chemotaxis holds considerable potential for designing cell mimics and delivery vehicles that can reconfigure their motion in response to environmental conditions. Enzyme-coated liposomal motors show either positive or negative chemotaxis depending on the interplay between enzyme catalysis and solute–phospholipid interactions.

Positive and negative chemotaxis of enzyme-coated liposome motors