Metal complex strategies for photo-uncaging the small molecule bioregulators nitric oxide and carbon monoxide

Abstract

Photochemical release (uncaging) of small molecule bioregulators (SMBs) such as nitric oxide (NO) or carbon monoxide (CO) at physiological sites offers exquisite control of timing, location and dosage. However, photo-uncaging faces two major problems that challenge its therapeutic applications: the relatively poor transmision of visible light through tissue and the need to deliver the appropriate precursors to the desired targets. In this brief review are discussed research activitites that address these issues of spatial-temporal control. Contents:1. Introduction 2. Key issues in photo-uncaging 3. Nitric oxide and carbon monoxide precursors.3.1 PhotoNORMs 3.2 PhotoCORMs 4. Two-photon excitation 5. Quantum dots platforms. 6. Polymer, metallic and other nanomaterial platforms. 7. Upconverting nanoparticles as antennas 8. Biological targeting 9. Summary and perspective 10. Abbreviations 11. Acknowledgements 12. Appendix: Discussion of "first order rate laws" in photochemical reactions. 13. References

Near-Infrared and Visible Photoactivation to Uncage Carbon Monoxide from an Aqueous-Soluble PhotoCORM

“…Since a 2008 report by Schatzschneider et al, 39 various studies have used the LMn I (CO)3 motif in designing pho-toCORMs active under excitation by visible or ultraviolet light. 2,11,[40][41][42] The results of the single photon, visible light excitation of 1 and 2, described in detail here, are qualitatively consistent; namely, CO is labilized with moderate quantum yields upon exciting the dominant MLCT absorption bands. Such systems provide the opportunity to deliver CO precisely to physiological targets but are limited by the low penetration depths of these shorter wavelengths.…”

Nanoscale lipid vesicles functionalized with a nitro-aniline derivative for photoinduced nitric oxide (NO) delivery

“…In this regard many efforts have been made to deliver NO in a controlled manner with the help of light. [2][3][4] Due to the very short lifetime (seconds) of NO in blood, for effective therapeutic applications, appropriate storage and delivery methods must be carefully considered.…”

One‐Pot Intercalation Strategy for the Encapsulation of a CO‐Releasing Organometallic Molecule in a Layered Double Hydroxide

“…[7][8][9] CO release from CORMs may be triggered hydrolytically, by ligand substitution, photoactivation (socalled photoCORMs), changes in pH, exposure to reactive oxygen species (ROS), and enzymatic hydrolysis. [8,[12][13][14] However, in many instances the direct delivery of molecular CORMs is likely to be inefficient and may suffer from problems such as enzymatic degradation, poor bioavailability, poor circulation stabil-and controlled release of CO, with two key benefits being the prevention of the premature interaction of the CORM with the biological environment, and the retention of potentially toxic decarbonylation fragments. [15][16][17][18][19] CO-releasing materials (COR-MAs) have been prepared by immobilizing CORMs in a micellar system, [20] functionalized nanodiamond, [21] silica, iron oxide and mesoporous Al-MCM-41 nanoparticles, [22][23][24][25] graphene oxide nanosheets, [26] non-wovens, [27] and metal-organic frameworks.…”

“…13 C{ 1 H} CP MAS NMR spectra of (a) ALF795 and (b) Zn,Al-ALF795. Asterisks denote spinning sidebands.…”