Hybrid carbon nanotubes modified glassy carbon electrode for selective, sensitive and simultaneous detection of dopamine and uric acid

Based on a hybrid carbon nanotube composite, a novel electrochemical sensor with high sensitivity and selectivity was designed for the simultaneous determination of dopamine (DA) and uric acid (UA). The hybrid carbon nanotube composite was prepared by ultrasonic assembly of carboxylated multi-walled carbon nanotube (MWCNT-COOH) and hydroxylated single-walled carbon nanotube (SWCNT-OH). And the hybrid (MWCNT-COOH/SWCNT-OH) composite was characterized by field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared (FT-IR) spectroscopy. The electrochemical performances of MWCNT-COOH/SWCNT-OH composite modified glassy carbon electrode (MWCNT-COOH/SWCNT-OH/GCE) were analyzed by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). Under the optimum experimental conditions, the as-prepared sensor showed high sensitivity and selectivity for DA and UA. The calibration curves obtained were linear for the currents versus DA and UA concentrations in the range 2-150 mu M, and limits of detection (LODs) were calculated to be 0.37 mu M and 0.61 mu M (signal-to-noise ratio of 3, S/N = 3), respectively. The recoveries of DA and UA in bovine serum samples at MWCNT-COOH/SWCNT-OH/GCE were in the range 96.18-105.02%, and relative standard deviations (RSDs) were 3.34-7.27%. The proposed electrochemical sensor showed good anti-interference ability, excellent reproducibility and stability, as well as high selectivity, which might provide a promising platform for determination of DA and UA.