Array of recessed gold nanoelectrodes formed with polymethylmethacrylate for individual detection of ascorbic acid, dopamine and uric acid

A series of recessed gold nanoelectrode arrays with different array densities are patterned on polymethylmethacrylate (PMMA) coated gold substrate by precisely controlled patterning through electron beam lithography. The influence of the nanoelectrode density of the arrays and scan rate on the diffusion regimes and hence electrochemical behaviors are systematically investigated. It is demonstrated that the electrostatic interaction exists between the oxygen-containing groups of the PMMA nanocylinder and the charged analytes in solution. The difference in the electrostatic interaction of dopamine (DA), ascorbic acid (AA), and uric acid (UA) with PMMA nanocylinders leads to differentiation of the oxidation of the three species. Thus, an electrochemical sensing platform for the detection of individual components in a mixture of DA, AA, and UA is developed. The linear ranges and detection limits of individual components in the mixture are 3.5-125 μM and 0.66 μM for DA, 30-190 μM and 7.5 μM for AA, 20-170 μM and 6.38 μM for UA, respectively, on the array electrode.