Fig. 1

Simultaneous complementary photoswitching of HTI tweezers. Two simultaneous processes are encountered at each wavelength of irradiation: at 435 nm tweezers 1 transform into their high affinity form (E-1) while tweezers 2 isomerize into their low affinity form (E-2). At 530 nm the processes are reversed and Z-1 and Z-2 are restored