Titanium dioxide (TiO2) nanotubes were fabricated by anodisation of titanium foil in 0.15 M ammonium fluoride in an aqueous solution of glycerol (90 % v/v). Electropolymerisation of pyrrole and deposition of gold nanoparticles on to the TiO2 nanotube array electrode were carried out by cyclic voltammetry (CV). Electrochemical characterization of the sensor was performed by CV and electrochemical impedance spectroscopy. The morphology of the electrode was studied after every step of modification using field emission scanning electron microscope and atomic force microscope. The sensor was tested for AA and other biomolecules in phosphate buffered saline solution of pH 7 using CV, differential pulse voltammetry and amperometry. The sensor exhibited very high sensitivity of 63.912 μA mM−1 cm−2 and excellent selectivity to ascorbic acid (AA) in the presence of other biomolecules such as uric acid, dopamine, glucose and para-acetaminophen. It also showed very good linearity (<em class="a-plus-plus">R</em> = 0.9995) over a wide range (1 μM–5 mM) of detection. The sensor was tested for AA in lemon and found its concentration to be 339 mg ml−1.
Dr. Satheesh Babu T. G., Dhanya Varadarajan, Gayathri Murugan, T. Ramachandran, and Dr. Bipin G. Nair, “Gold Nanoparticle–Polypyrrole Composite Modified TiO2 Nanotube Array Electrode for the Amperometric Sensing of Ascorbic Acid”, Journal of Applied Electrochemistry, vol. 42, pp. 427-434, 2012.