Nitric Oxide Uncaging from a Hydrophobic Chromium(III) PhotoNORM: Visible and Near-Infrared Photochemistry in Biocompatible Polymer Disks

Abstract

Devices consisting of polymer disks (PDs) of optically clear or translucent, medical-grade silicone loaded with a new hydrophobic, oxygen-stable, photoactivated nitric oxide-releasing moiety (photoNORM) are described. The photoNORM is the new O -nitrito chromium(III) complex trans- [Cr(PetA)(ONO) 2 ](BF 4 ) (PetA = 5,14-dimethyl-7,12-diphenyl-1,4,8,11-tetraaza-cyclotetradecane), of which the synthesis, X-ray crystal structure, and solution-phase photochemistry are described. Several different commercially available silicone polymers were tested with this photoNORM, and nitric oxide photouncaging with 451 nm light from these systems is compared. In addition, PDs were loaded with the photoNORM and neodymium-sensitized upconverting nanoparticles (Nd-UCNPs). The Nd-UCNPs absorb NIR light at ∼800 nm and activate NO release from the trans- [Cr(PetA)(ONO) 2 ] + cation. The use of such ensembles as implants provides a potential strategy for the in vivo uncaging of NO at physiological targets triggered by tissue-transmitting NIR excitation. Also reported are the X-ray crystal structures of cis - and trans -{Cr(PetA)Cl 2 ]Cl.

Visible-to-NIR-Light Activated Release: From Small Molecules to Nanomaterials

“…Ford and co-workers recently developed a Cr III nitrito complex 324 ( Figure 51 ), which photoreleased NO upon irradiation at 451 nm 1257 and also upon irradiation at 800 nm when loaded onto polymer disks containing Nd-sensitized upconverting nanoparticles (see also section 6.4.2 ).…”

“…1255,1256 Complex 321 was combined with anthracene or pyrene "antenna" ligands (323a and 323b, Figure 50) that harvest light and act as fluorescent reporters. 1255, 1256 Ford and co-workers recently developed a Cr III nitrito complex 324 (Figure 51), which photoreleased NO upon irradiation at 451 nm 1257 and also upon irradiation at 800 nm when loaded onto polymer disks containing Nd-sensitized upconverting nanoparticles (see also section 6.4.2).…”

“…NO donors are often coupled with a visible-light absorbing sensitizer or a NIR-absorbing upconverting species to improve photorelease . The carriers are often biocompatible polymers, and the NO donors may either be present in a mixture or covalently attached . Polymeric gels are another common tool for delivering NO into organisms. ,,,− For example, a Mn II nitrosyl complex-based sol-gel was demonstrated to release NO upon irradiation at 780 nm .…”

Nitric Oxide-Releasing Polymeric Materials for Antimicrobial Applications: A Review

“…Furthermore, UV can be harmful to normal cells of human, so NO releasing materials triggered by physiological friendly visible lights or near-infrared lights (NIR) would have more advantages in antibacterial therapy. Researchers have developed small molecule photoresponsive NO donors triggered by visible lights with wavelengths of 390 nm [127] (also reported with 380 nm [128]), 405 nm [73], 500 nm [129], 530–550 nm [130], and even NIR with wavelengths of 800 nm [131] and 980 nm [132] (partly presented in Figure 7).…”

Photodissociation of the Product from a Transition-Metal Center Allows the Catalytic Cycle to Proceed: The Rhodium(I)-Catalyzed [2+2+1] Carbonylative Cycloaddition of Diynes

“…Photochemically induced reductive elimination is photochemically induced to form the coordinatively unsaturated metal species, to which inert bonds, such as a C–H bond, add oxidatively . In addition, photoirradiation is also utilized in the dissociation of a strongly coordinating π-acidic ligand due to the dπ–pπ* back-bonding. − This corresponds to a simple ligand exchange via the formation of the coordinatively unsaturated species in the catalytic cycle. However, to the best of our knowledge, there is no example of a catalytic process in which photoirradiation is used to promote the release of the formed product, thus providing a vacant coordination site .…”