Reversible Photocontrol of Biological Systems by the Incorporation of Molecular Photoswitches

Controlling the conformation and activity of biomolecules in a reversible manner is a fascinating challenge that has an outstanding potential for the study of and interference with complex processes in living cells. Spatial and temporal control of cellular processes could provide unparalleled opportunities for studying organism development or disease progression. A variety of synthetic photoswitches, that can undergo a reversible change in their structure upon irradiation with light, have been designed. They are commonly characterized by the absorption maxima of their isomeric firms, as well as by the photostationary state (PSS), defined as the equilibrium composition during irradiation. Azobenzenes remain the most widely used photoswitches in biological applications. The reasons behind this include their easy synthesis, relatively high photostationary states and quantum yields, fast photoisomerization, and low rate of photobleaching.