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Ciprofloxacin (CIP), a quinolone antibiotic, was rapidly and sensitively detected by integrating the molecularly imprinted polymer (MIP) with an ultra-sensitive electrochemiluminescence (ECL) method. g-C3N4, a typical polymer semiconductor, exhibited outstanding ECL efficiency and excellent ECL stability after combining with an iron-based metal–organic framework (MIL-101). Subsequently, the molecularly imprinted polypyrrole was electropolymerized on the composites of MIL-101-g-C3N4 modified glassy carbon electrode (GCE). The specific sites that could target rebinding the CIP molecules were formed on the surface of MIP after extracting the CIP templates. The determination of specific concentrations of CIP could be realized according to the difference in ECL intensity (△ECL) between the eluting and rebinding of the CIP. Under optimal conditions, a good linear response of △ECL and the logarithm of CIP concentrations was obtained in the range 1.0 × 10–9 ~ 1.0 × 10–5 mol/L, with a detection limit of 4.5 × 10–10 mol/L (S/N = 3) (the working potential was -1.8 ~ 0 V). The RSD of all points in the calibration plot was less than 5.0% and the real samples recovery was between 98.0 and 104%. This paper displays satisfactory selectivity and sensitivity, providing a rapid, convenient, and cheap method for the determination of CIP in real samples. [ABSTRACT FROM AUTHOR]

Herein, a novel molecular imprinting polypyrrole electrochemical sensor was fabricated based on a zirconia and carbon core–shell structure (ZrO2@C) and a nitrogen-doped graphene (NPG) modified glassy carbon electrode (GCE) for ultrasensitive recognition of dopamine (DA). The NPG was prepared by a sacrificial-template-assisted pyrolysis method and ZrO2@C was synthesized via annealing treatment of a zirconium-based metal–organic framework (UiO-66). A convenient electropolymerization method was used to prepare the pyrrole (Py) conductive molecularly imprinted polymer (MIP) in the presence of DA. The elution process of DA was performed by a simple overoxidation process under alkaline conditions. Differential pulse voltammetry (DPV) was used to assess the electrochemical performance of the sensors. The MIP-based electrochemical sensor with specific binding sites could be used for selective recognition of DA. Under the optimal conditions, the linear range of such a sensor was 5.0 × 10−9–1.0 × 10−4 mol L−1 and the detection limit was 3.3 × 10−10 mol L−1 (S/N = 3). This sensor exhibited suitable selectivity, stability, and reproducibility, which suggested that it could be a promising candidate for rapid diagnostic methods in dopamine investigations. [ABSTRACT FROM AUTHOR]

[Display omitted] • The MIP/Uio-66@CDs modified GCE was constructed for detection of chloramphenicol. • The composites of Uio-66@CDs effectively improved the MIP loading amount and the charge transfer. • The CAP determination was based on the charge transfer difference (△Rct) before and after the MIP/Uio-66@CDs/GCE rebinding the chloramphenicol. • The detection limit is low as 0.061 pmol/L. In this study, a supersensitive electrochemical impedance spectroscopy (EIS) analysis method combined the molecularly imprinted polypyrrole (MIP) which electropolymerized on the composites of zirconium-based metal organic framework (Uio-66) and carbon dots (CDs) modified glassy carbon electrode (GCE) was developed for chloramphenicol (CAP) determination. The integration of Uio-66 and CDs effectively promoted the sensitivity of the proposed MIP senor by improving the surface area and the charge transfer of electrode. By extraction of CAP template, the specific sites were formed on the MIP surface which can rewrap the CAP target molecules. The CAP determination was based on the charge transfer difference (△Rct) before and after the MIP/Uio-66@CDs/GCE rebinding the CAP. The results showed that △Rct responded good linearity to the logarithm of CAP concetration in the range of 0.1 – 100 pmol/L, with a low detection limit of 0.061 pmol/L (S/N = 3), exhibiting high sensitivity and specificity for the determination of CAP. [ABSTRACT FROM AUTHOR]