Tracking CO Release in Cells via the Luminescence of Donor Molecules and/or their By‐Products

Abstract

Carbon monoxide (CO) is a bioactive signalling molecule that is produced endogenously via the breakdown of heme. Beneficial health effects associated with the delivery of CO gas have spurred the development of CO‐releasing molecules (CORMs) that can be used to provide specific amounts of the gas. In addition to their potential use as therapeutics, CORMs are needed to provide insight into the biological targets of CO. In this regard, light‐activated CO‐releasing molecules (photoCORMs), are valuable for examining the effects of localized CO release. Herein we examine luminescent CORMs and photoCORMs that have been reported for tracking CO delivery in cells. A variety of motifs are available that exhibit differing luminescence properties and cover a wide range of wavelengths. Trackable CO donors have been successfully applied to targeting CO delivery to mitochondria, thus demonstrating the feasibility of using such molecules in detailed investigations of the biological roles of CO.

Metal-free carbon monoxide-releasing micelles undergo tandem photochemical reactions for cutaneous wound healing

“…The unmasking of the phenolic groups of 3-HF derivatives led to a large Stokes shi, which was previously used for the design of ratiometric uorescent probes. 51 Recently, Berreau and coworkers [32][33][34][35][36] ingeniously found that extended 3-HF derivatives could release CO under visible light irradiation. In this case, the uorescent extended 3-HF moieties were transformed into nonemissive 3-(benzoyloxy)-2-naphthalenecarboxylic acid (3-BNA) species, enabling self-reporting CO release.…”

“…S6 †), which is in good agreement with the previous results that 3-HF-based CO donors were relatively stable under dark conditions without premature CO leakage even in an aqueous medium. [32][33][34][35][36] From uorescence spectroscopy, we can observe a remarkable uorescence increase for compound B at 606 nm at the initial 40 s irradiation, corresponding to the deprotection of the 2-nitrobenzyl residue (Fig. S7a †).…”

“…Thus, the current design by integrating two photoresponsive moieties into one molecule enabled tandem photochemical reactions and rendered the CO release process visible by uorescence changes by taking advantage of the unique property of 3-HF derivatives. [32][33][34][35][36] To elucidate the underlying photoreaction mechanism of compound B under light irradiation, HPLC and HRMS were used to examine the degraded products. Upon irradiation, compound B was completely consumed within 10 min, while the formation of the intermediate compounds A and the nal photolyzed product, compound C, was observed by HPLC ( Fig.…”

“…Although metal carbonyls hold great promise in both laboratory and clinical investigations, 9,[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] the development of metal-free CORMs has recently been receiveing increasing attention. 27 In this context, boranocarbonates, 28 CO-releasing prodrugs operated in a "click and release" manner, [29][30][31] and photoresponsive organic CORMs such as 3-hydroxyavone (3-HF) derivatives, [32][33][34][35][36][37] xanthene-9-carboxylic acid, 38 BODIPY derivatives, 39 and aromatic a-diketone derivatives 40 have been developed.…”

“…This process features a consecutive uorescence transition from blue-to-red-to-colorless, allowing for the monitoring of the CO release by uorescence readout (Scheme 1b). 33…”