Surface-Derivatized Nanoceria with Human Carbonic Anhydrase II Inhibitors and Fluorophores:  A Potential Drug Delivery Device

Human carbonic anhydrase (hCAII) is a metalloenzyme that catalyzes the reversible hydration of carbon dioxide to bicarbonate and is associated with glaucoma (a major cause of blindness). The present study focuses on the use of cerium oxide nanoparticles (nanoceria) as a potential delivery device for hCAII inhibitors. Carboxybenzenesulfonamide, an inhibitor of the hCAII enzyme, was attached to nanoceria particles using epichlorohydrin as an intermediate linkage. Along with the CA inhibitor, a fluorophore (carboxyfluorescein) was also attached on the nanoparticles to enable the tracking of the nanoparticles in vitro as well as in vivo. X-ray photoelectron spectroscopic studies carried out at each reaction step confirmed the successful derivatization of the nanoceria particles. The attachment of carboxyfluorescein was also confirmed by confocal fluorescence microscopy. Preliminary studies suggest that carboxybenzenesulfonamide-functionalized nanoceria retains its inhibitory potency for hCAII.