Silicium dioxide nanoparticles as carriers for photoactivatable CO-releasing molecules (PhotoCORMs).

Silicium dioxide nanoparticles of about 20 nm diameter containing azido groups at the surface were prepared by emulsion copolymerization of trimethoxymethylsilane and (3-azidopropyl)triethoxysilane and studied by transmission electron microscopy (TEM). A photoactivatable CO-releasing molecule (PhotoCORM) based on [Mn(CO)(3)(tpm)](+) (tpm = tris(pyrazolyl)methane) containing an alkyne-functionalized tpm ligand was covalently linked to the silicium dioxide nanoparticles via the copper-catalyzed azide-alkyne 1,3-dipolar cycloaddition (CuAAC "click" reaction). The surface functionalization of the particles with azido groups and manganese CORMs was analyzed by UV-vis, IR, (1)H and (13)C CP-MAS NMR spectroscopies as well as energy-dispersive X-ray spectroscopy (EDX). The myoglobin assay was used to demonstrate that the CORM-functionalized nanoparticles have photoinducible CO-release properties very similar to the free complex. In the future, such functionalized silicium dioxide nanoparticles might be utilized as delivery agents for CORMs in solid tumors.