Photocatalytic nitric oxide delivery system for surface disinfection

Overview

This research proposes a photocatalytic disinfection platform based on metal salen complexes (M = Cr, Mn, Fe) encapsulated within mesoporous silica microparticles. When exposed to visible or near-UV light, the encapsulated catalysts convert nitrite ions (NO2–) into nitric oxide (NO), which undergoes autoxidation to generate reactive nitrogen species that kill bacteria through nitrosative and oxidative stress. The microparticles can be applied to surfaces and activated on demand by light, enabling controlled, triggerable disinfection without continuous chemical release. Potential applications include antimicrobial surface coatings for healthcare settings, food processing facilities, and any environment where biofilm contamination is a concern.

Technical specifications

• Catalyst design: Metal salen complexes (M = Cr, Mn, Fe; salen = N,N'-bis(salicylidene)-ethylenediamine dianion) inspired by the previously demonstrated ruthenium analog Ru(salen)(X)(NO)
• Photocatalytic mechanism: Visible/near-UV light cleaves the metal–nitrosyl bond, releasing NO from coordinated nitrite; the catalyst is regenerated upon reaction with additional nitrite
• Particle architecture: Mesoporous silica micro- or nanoparticles encapsulating the catalyst, coated with amphiphilic polymers to tune hydrophilicity or hydrophobicity for different surface applications
• Bactericidal action: NO diffuses from the particles and autoxidizes to reactive nitrogen species (NO2, N2O3, peroxynitrite) that produce nitrosative and oxidative stress in bacterial cells
• Analytical capability: Highly sensitive instrumentation available for NO quantification to validate photocatalytic performance
• Collaboration track: Prior experience delivering nanomaterials into bacterial and human cancer cell cultures in collaboration with the Reich group

Technology readiness level

This technology is at an early-to-mid stage of development. The underlying photocatalytic NO release chemistry has been demonstrated with ruthenium salen analogs in sol-gel matrices under near-UV irradiation, establishing proof of concept. The proposed iron and manganese analogs are novel but supported by established precedents in metal-nitrosyl photochemistry. Future validation steps include: (a) synthesizing and screening the new M(salen) complexes for nitrite-to-NO photocatalytic activity, (b) testing the most efficient catalysts against bacterial cultures to measure phototoxicity and benchmark against known antibacterial treatments, (c) encapsulating optimal systems in polymer-coated mesoporous silica particles, and (d) evaluating performance against bacterial biofilms on surfaces.