Photochemical delivery of nitric oxide

Abstract

There remains considerable interest in developing methods for the targeted delivery of nitric oxide and other small molecule bioregulators such as carbon monoxide to physiological targets. One such strategy is to use a "caged" NO that is "uncaged" by excitation with light. Such photochemical methods convey certain key advantages such as the ability to control the timing, location and dosage of delivery, but also have some important disadvantages, such as the relatively poor penetration of the ultraviolet and visible wavelengths often necessary for the uncaging process. Presented here is an overview of ongoing studies in the author's laboratory exploring new photochemical NO precursors including those with nanomaterial antennas designed to enhance the effectiveness of these precursors with longer excitation wavelengths.

Photo-Controlled Release of NO and CO with Inorganic and Organometallic Complexes

“…As a result, various strategies have been designed to make such species more susceptible to longer wavelength excitation [45,48,51,52,54,76,80,85,90,[116][117][118][119]. With certain platforms, it has proved possible to achieve the NO release at longer wavelength by extending the conjugation of the ligand frame and by adding key substituent groups at strategic positions [65,85,90].…”

Second-order nonlinear optics in coordination chemistry: An open door towards multi-functional materials and molecular switches

“…Along this line, the investigation of new ruthenium-nitrosyl complexes has recently started in the laboratory with the aim of photo-releasing NO• in the 350-500 nm wavelength domain [83]. The nitric oxide radical, NO•, awarded "molecule of the year" by the journal Science in 1992, is a fascinating species associated to many biological processes (e.g., blood pressure regulation, neurotransmission, and moreover actions in cancer biology [84,85]). Ruthenium-nitrosyl complexes seem to be the NO• donor of choice, because they release NO• exclusively under irradiation.…”

The versatile ruthenium(II/III) tetraazamacrocycle complexes and their nitrosyl derivatives

“…The fact that in general UV light (<400 nm) is required for photoactivation is a disadvantage, but for topical applications this is not a limitation [40], and to overcome it, Ford [39,180] devised several strategies. One involves ligands with chromophores as antenna [94,183] to harvest visible light for the photochemical release of NO, which was also used by Mascharak for ruthenium complexes [184]; the other uses quantum dots to allow irradiation with long wavelength light [183,[185][186][187]; and the third is with multi photon excitation [183].…”