ON-OFF nanopores for optical control of transmembrane ionic communication.

Nanoscale photoswitchable proteins could facilitate precise spatiotemporal control of transmembrane communication and support studies in synthetic biology, neuroscience and bioelectronics. Here, through covalent modification of the α-haemolysin protein pore with arylazopyrazole photoswitches, we produced 'photopores' that transition between iontronic resistor and diode modes in response to irradiation at orthogonal wavelengths. In the diode mode, a low-leak OFF-state nanopore exhibits a reversible increase in unitary conductance of more than 20-fold upon irradiation at 365 nm. A rectification ratio of >5 was achieved with photopores in the diode state by either direct or alternating voltage input. Unlike conventional electronic phototransistors with intensity-dependent photoelectric responses, the photopores regulated current output solely based on the wavelength(s) of monochromatic or dual-wavelength irradiation. Dual-wavelength irradiation at various relative intensities allowed graded adjustment of the photopore conductance. By using these properties, photonic signals encoding text or graphic messages were converted into ionic signals, highlighting the potential applications of photopores as components of smart devices in synthetic biology.