Visible\nLight Triggerable CO Releasing Micelles

Carbon monoxide (CO), along with\nnitric oxide and hydrogen sulfide,\nis one of a trinity of known gasotransmitters, or endogenously produced\ngaseous molecules that signal and regulate a panoply of physiological\nfunctions. CO releasing molecules (CORMs) are chemical tools that\nenable the study and application of this ephemeral gas, that, ideally,\nrelease CO on-demand when externally stimulated. Surveying the available\ntriggers, photolysis is potentially advantageous: It is contactless\nand grants practitioners unparalleled spatial and temporal control.\nHowever, current phototriggered CORMs are capricious and do not meet\ncurrent needs. Presented here is a highly efficient platform for the\nvisible light triggered release of CO gas. This platform is built\non a unique CO containing functionality, the cyclopropenone, which\nundergoes facile decarbonylation through visible light (470 nm) mediated\nphotoredox catalysis. Due to the exothermic strain-release that occurs\nupon formation of CO, this photoreaction is rapid, quantitative, and\nhas tunable release rates. To render this photo-CORM water-soluble,\ndeliverable, and to keep reactants in proximity, necessary components\nwere polymerized into block copolymers that self-assemble into CO\nreleasing micelles (CORMIs). This platform was compared directly to\nother state-of-the-art CORMs, showing significantly improved CO production\nefficiency, lower toxicity, tunable release rates, and consistent\nefficacy in <i>ex vivo</i> and <i>in vitro</i> settings.