Highly electrochemical performance of Ni-ZIF-8/ N S-CNTs/CS composite for simultaneous determination of dopamine, uric acid and L-tryptophan.

• The Ni-ZIF-8/N S-CNTs/CS/GCE sensor exhibited superior properties for the simultaneous determination of DA, UA and L-Trp. • The synergistic effect between the Ni-ZIF-8 and N S-CNTs significantly enhanced the peak current response of DA, UA and L-Trp. • Ni-ZIF-8/N S-CNTs/CS/GCE electrochemical sensing platform showed excellent reproducibility and stability. • The fabricated sensor held great potential for the DA, UA and L-Trp detection in human urine, amino acid injection and human serum sample. The accurate simultaneous determination and quantification of biological small molecules including dopamine (DA), uric acid (UA) and L-tryptophan (L-Trp) are necessary to diagnose or monitor possible disease, which further provide important information about the interaction between these analytes during the physiological processes. In this present work, a novel and rapid electrochemical sensor toward the simultaneous determination of dopamine (DA), uric acid (UA) and L-tryptophan (L-Trp) was prepared based on modification of Ni-ZIF-8/N S-CNTs/CS composite upon the bare glassy carbon electrode. The electrochemical response of DA, UA and L-Trp on the Ni-ZIF-8/N S-CNTs/CS/GCE was explored via cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), chronocoulometry (CC) and differential pulse voltammetry (DPV) techniques. The results illustrated that these three analytes displayed the well-resolved and intense electrochemical signals on the designed electrode, owing to the synergic effect originating from Ni-ZIF-8 with highly porous framework structure and N S-CNTs with excellent conductivity. The voltammetric response of Ni-ZIF-8/N S-CNTs/CS/GCE indicated its outstanding electrocatalytic performance for the electrochemical reaction of DA, UA and L-Trp with a wide linear ranges of 8∼500 μM, 1∼600 μM and 5∼850 μM and low detection limits of 0.93, 0.41 and 0.69 μM, respectively. More importantly, the proposed sensor was successfully applied to measure DA, UA and L-Trp in the real samples, meaning that the present method delivered great potential in the field of routine sensing applications. [ABSTRACT FROM AUTHOR]