A facile sensitive l-tyrosine electrochemical sensor based on a coupled CuO/Cu2O nanoparticles and multi-walled carbon nanotubes nanocomposite film

Abstract

L-tyrosine in human urine is an essential biomarker for the early detection of various cancers. A facile electrochemical method for preparing a coupled copper oxide/cuprous oxide nanoparticles and multi-walled carbon nanotubes nanocomposite film modified glass carbon electrode (CuO/Cu₂O/MWCNTs/GCE) via in situ growth is proposed for electrochemical sensing of L-tyrosine. The electrocatalytic activity of CuO/Cu₂O/MWCNTs/GCE was investigated for L-tyrosine by cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA), and the morphology and shape of the nanocomposite film were characterized by scanning electron microscope (SEM), energy-dispersive spectroscopy (EDS), transmission electron microscope (TEM) and X-ray powder diffraction (XRD). An irreversible oxidation peak for L-tyrosine at a potential of 0.645 V (vs. SCE) was observed in pH 8.0 of phosphate buffer solution at the CuO/Cu₂O/MWCNTs/GCE electrode. The as-fabricated L-tyrosine sensor shows a fast response time (less than 2 s), a wide linear range 2 × 10⁻⁷–2 × 10⁻⁴ M, a high sensitivity of 1001 μA mM⁻¹ cm⁻² and a low detection limit of 9.6 × 10⁻⁹ M (at signal/noise = 3) in pH 8.0 phosphate buffer solution at 0.645 V. The nanocomposite film electrode has been successfully applied to determine L-tyrosine in human urine. It exhibits high electrocatalytic activity, satisfactory repeatability, stability, fast response and good selectivity against potentially interfering species, which suggests its potential for the development of a sensitive, selective, easy-operation and low-cost L-tyrosine sensor for practical routine analyses. The proposed new facile electrochemical growth method has the potential to expand the range of nanocomposite materials applied for the detection of various electroactive substances.