Biosensing properties of titanate-nanotube films: Selective detection of dopamine in the presence of ascorbate and uric acid

A novel strategy based on titanate nanotubes (TNTs) for developing an electrochemical biosensor is proposed. Stable TNT films are fabricated on glassy carbon (GC) electrodes by a casting technique. Cyclic voltammetry, electrochemical impedance spectrometry, and linear-sweep voltammetry are used to characterize the TNT membrane-covered GC electrodes (TNT/GCs). The TNT film is shown to demonstrate selectivity by charge exclusion. The TNT film is also shown to be capable of improving the mass transport to the electrode surface and electron transfer between dopamine (DA) and the electrode. Therefore, DA exhibits a quasireversible electrochemical reaction at the TNT/GC electrode. The voltammetric signal of DA is well resolved from those of ascorbate (AA) and uric acid (UA) at the TNT/GC electrode; therefore, DA can be selectively detected in the presence of a large excess of AA and UA at physiological pH. The linear calibration curve for DA is obtained over the concentration range 0.1-30 mu M in a physiological solution that contains 0.1 mM AA and 0.3 mM UA.