Multi-wavelength photo-activation of transmembrane chloride transport in distinct vesicle populations using photocaged indolocarbazole anionophores.

Synthetic ionophores enable the study of transmembrane ion transport and show promise as therapeutics or for engineering responsive synthetic cells. Incorporation of photolabile protecting groups (photocages) allows for OFF-ON control over transport to spatiotemporally regulate activity; however, systems incorporating two different photocages such that two wavelengths of irradiation are required for activation are unknown. Here, we report a family of photocaged indolocarbazole-based anionophores that enable multi-wavelength photo-activation of chloride transport in lipid bilayer vesicles. Mono- and di-ortho-nitrobenzyl photocaged derivatives fully inhibit anion binding and transport until irradiation cleaves the protecting group to restore activity. Introduction of a BODIPY photocage afforded a unique dual-photocaged transporter, in which sequential irradiation at 530 nm and 365 nm triggers stepwise photocage cleavage to regenerate the active anionophore. This strategy also allows for selective activation of anion transport in different vesicles in a mixed population containing different mono-photocaged transporters. These results establish photocaged indolocarbazoles as a versatile platform for photo-responsive ionophores and enable unprecedented multi-wavelength sequential control of transmembrane transport in separate vesicle populations. Beyond fundamental insights into the design of stimuli-responsive transporters, this approach provides new opportunities for spatiotemporal regulation of ion transport in artificial and living cellular systems.