Controllable Nitric Oxide Release in the Presence of Gold Nanoparticles

A major problem associated with nitric oxide (NO) donors is the release of the desired amount of NO at a specific site. A number of platforms have been developed for the regulation of NO dosage. We present the use of citrate-stabilized gold nanoparticles as a platform to regulate NO release. Because of the affinity between gold and thiols, the characteristic -S-NO bond of S-nitrosothiols (RSNOs) breaks in the presence of gold nanoparticles, thereby releasing NO and modifying the gold nanoparticle surface with the corresponding thiol. This system allows for surface-controlled NO release, where the amount of NO released is proportional to the number of thiols bound to the gold nanoparticle surface. Moreover, by employing an amperometric technique to detect the maximum NO release, we were able to estimate the stoichiometry of the reaction, that is, the number of adsorbed RSNO molecules per gold nanoparticle. A kinetic model for NO release and its subsequent decomposition is proposed and used to fit the experimental results. The reaction was found to be zeroth- and first-order with respect to RSNO and gold nanoparticles, respectively.