Poly(β-cyclodextrin)/carbon quantum dots modified glassy carbon electrode: Preparation, characterization and simultaneous electrochemical determination of dopamine, uric acid and tryptophan

A novel poly(β-cyclodextrin) (β-CD)/carbon quantum dots (CQDs) composite based sensor was successfully fabricated on glassy carbon electrode through electrochemical polymerization. As-prepared β-CD/CQDs modified electrode was used for the simultaneous determination of dopamine (DA), uric acid (UA) and tryptophan (Trp). Electrochemical responses of as-prepared electrode were investigated by cyclic voltammetry, electrochemical impedance spectroscopy and differential pulse voltammetry. In co-existence system containing DA, UA and Trp, three oxidation peaks well separated from each other and the potential separations of oxidation peaks of DA-UA and UA-Trp were respectively large up to 150 and 420 mV, owing to the synergistic effect of β-CD and CQDs. The linear amperometric responses for DA, UA and Trp were obtained in the concentration range of 4-220, 0.3-200 and 5-270 μM, respectively, with the limits of detection of 0.14, 0.01, 0.16 μM (S/N = 3) and the limits of quantification of 0.45, 0.04, 0.50 μM (S/N = 10). Moreover, as-prepared β-CD/CQDs modified electrode exhibited prominent selectivity, stability and reproducibility, which had promising application for the simultaneous determination of DA, UA and Trp.