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 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.
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.
In this study, a molecular imprinted polypyrrole electrochemical sensor that electropolymerized on zirconia and core-shell structure ( ZrO 2 @C ) and nitrogen-doped graphene (NPG) modified glassy carbon electrode (GCE) was developed for dopamine (DA) determination. ZrO 2 @C was prepared by the carbonized zirconium-based metal-organic framework (UiO-66) in the inert environment at a high temperature to improve its' conductivity and whereafter modified on the surface of NPG/GCE. The surface of ZrO 2 @C/NPG/GCE was modified by molecular imprinting polymer (MIP) in the presence of pyrrole (Py) and DA to formulate the recognition sites of DA. The electrochemical sensor Ppy-MIP/ZrO 2 @C/NPG/GCE with specific binding sites could be used for selective recognition and sensitive detection of DA. Under the optimal conditions, the linear range of such sensor was 5.0 × 10 -9 ~ 1.0 × 10 -4 mol/L and the detection limit was 3.3 × 10 -10 mol/L (S/N = 3).
A highly efficient electrochemiluminescence resonance energy transfer (ECL-RET) aptasensor was constructed for ultrasensitive detection of diethylstilbestrol (DES). The composite composed of silver orthophosphate and zirconium-based metal-organic frameworks (Ag 3 PO 4 -UiO-66) was prepared as a sensing platform for aptasensor incubation. Ag 3 PO 4 , a novel ECL donor, whose emission could be obviously enhanced through loading on UiO-66. Particularly, the composite of Ag 3 PO 4 -UiO-66 could minimize the aggregation of Ag 3 PO 4 , which provided a novel possibility for the construction of high ECL efficiency sensors. UiO-66 presented ultrahigh surface area to improve the loading capacity of Ag 3 PO 4 and DES-specific aptamer. Notably, Ag 3 PO 4 with superb catalytic property could immobilize DES aptamer via Ag–NH 2 bond and further ensured the distance between the ECL donor and the energy receptor. To design a novel ECL-RET system, GO nanosheets were synthesized as a suitable ECL acceptor which could be fixed through electrostatic adsorption. Owing to the superior spectral overlap, GO could significantly quench the ECL emission of Ag 3 PO 4 . Under the optimal conditions, the constructed ECL-RET aptasensor showed a satisfactory response to DES in a linear range of 1.0 × 10 -14 ~ 1.0 × 10 -8 M and the detection limit was 7.2 × 10 -15 M (S/N = 3). This paper not only developed a novel approach for environmental water quality monitoring but also offered more opportunities for building highly sensitive ECL-RET aptasensors.
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