Gold nanoparticles on a thiol-functionalized silica network for ascorbic acid electrochemical detection in presence of dopamine and uric acid

A simple preparation methodology able to stabilize gold nanoparticles and to obtain an electrode which detects ascorbic acid, uric acid, and dopamine by different techniques is presented. A 3-mercaptopropyl-functionalized silica network was synthesized using the sol-gel method. Gold nanoparticles (nAu) were immobilized on the material at synthesis by adding a sol of these previously prepared particles to the reaction mixture. The electrochemical behavior of the SiO2/MPTS/Au carbon paste electrode was studied using cyclic voltammetry in the presence of a hexacyanoferrate probe molecule. The presence of nAu in the functionalized silica network changes the electrochemical characteristics of the material, favoring the electron transfer process of this complex ion. The SiO2/MPTS/Au electrode was proven to be an efficient tool in the simultaneous determination of ascorbic acid (H(2)AA), dopamine (DA), and uric acid (UA) using square wave voltammetry techniques. With the nAu on the electrode, an increase in the peak current related to the redox process of the H(2)AA, DA, and UA was observed. The separations of the anodic peak potentials between DA/H(2)AA and UA/H(2)AA were 310 and 442 mV, respectively. The results obtained show that the SiO2/MPTS/Au electrode can be used in the simultaneous determination of H(2)AA, DA, and UA.