Simultaneous voltammetric detection of six biomolecules using a nanocomposite of titanium dioxide nanorods with multi-walled carbon nanotubes

•Nanocomposite of titanium dioxide nanorods and multi-walled carbon nanotubes was synthesized.•Nanocomposite was immobilized on the surface of a glassy carbon electrode.•Simultaneous electrochemical detection of six biomolecules was achieved.•Real sample applications were performed using human urine and chocolate powder. In this proof-of-concept study, a novel nanocomposite of titanium dioxide nanorods with multi-walled carbon nanotubes (TiO2NRs-MWCNTs) was synthesized using a solvo-thermal method and characterized by transmission electron microscopy (TEM) and Fourier-transform infrared spectroscopy (FTIR). The nanocomposite of TiO2NRs-MWCNTs was utilized to modify the surface of a glassy carbon electrode (GCE) using 1.5% (v/v) Nafion™ solution for a proof-of-concept study to detect uric acid (UA), xanthine (XA), theophylline (TP) and theobromine (TB) in the presence of ascorbic acid (AA) and dopamine (DA). Simultaneous detection of these six biomolecules was performed using differential pulse voltammetry (DPV) in a wide potential window from -0.3 V to -1.6 V (vs. Ag/AgCl) at pH 4.0. The TiO2NRs-MWCNTs/GCE showed strong, stable and six simultaneous well-separated anodic peaks at 0.13, 0.35, 0.50, 0.85, 1.10 and 1.28 V for AA, DA, UA, XA, TP and TB, respectively. The calibration curves showed linearity to 191.0, 147.0, 537.0, 586.0, 893.0, 1653.0 µM with detection limits of 0.51, 0.06, 0.05, 0.09, 0.56 and 0.75 µM for AA, DA, UA, XA, TP and TB, respectively. The electrochemical performance of the TiO2NRs-MWCNTs/GCE displayed good reproducibility for simultaneous determination of six analytes. Finally, our preliminary results suggested that the TiO2NRs-MWCNTs/GCE can provide a promising platform for rapid quantitative detection of AA, DA, UA, XA, TP and TB in quality control studies of real samples such as pharmaceuticals and food products. [Display omitted]