LAUSR

Artificial cells are compartmentalized structures that can mimic essential functions of their biological counterpart. They have been useful to understand and recreate minimalistic metabolic pathways and the structure of protocells. Now, Chen and co-workers report artificial cells that can convert light into biochemical energy in the form of adenosine triphosphate (ATP). The system is composed of two artificial cells, one that converts light into a proton gradient and one that converts this gradient into ATP. To convert light into a proton gradient, the researchers self-assemble an artificial cell made of packed Au–Ag nanorods with an embedded bacteriorhodopsin. The nanorods induce a preferential orientation of the bacteriorhodopsin. As a result, on irradiation, the bacteriorhodopsin pumps protons from inside the artificial cell to the bulk solution. At the steady state, the system can achieve a pH difference of 0.52. The effect is due to coupling between the plasmon resonance of the Au–Ag nanorods and that of rhodopsin. A second artificial cell containing an ATP synthase within a lipidic membrane uses the difference in proton concentration now existing between the outside and inside compartments to drive the synthesis of ATP molecules. AM