In this paper, a novel bimetallic Ce-Ni metal-organic frameworks (Ce-Ni-MOF) are synthesized by hydrothermal reaction, using 1,3,5-benzenetricarboxylic acid as a ligand. In particular, the bimetallic Ce-Ni-MOF with the largest specific surface area and catalytic sites was synthesized when the molar ratio of Ce 3+ to Ni 2+ was 3:7. Bimetallic Ce-Ni-MOF is added to the traditional conductive material of multiwall carbon nanotubes (MWCNTs) to play their synergistic effect, improve the conductivity, specific surface area, and catalytic site of the MWCNTs. A novel bisphenol A (BPA) sensor was successfully prepared by a self-assembled multilayer strategy of Ce-Ni-MOF/MWCNTs modified glassy carbon electrodes (GCE). Field emission scanning electron microscopy, powder X-ray diffraction, and transmission electron microscope were carried out to characterize the Ce-Ni-MOF/MWCNTs. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used as a sensitive analytical method for the determination of BPA, and a wider linear dynamic range of BPA determination in 0.1 μmol·L −1 to 100 μmol·L −1 with a detection limit of 7.8 nmol·L −1 (S/ N = 3). The proposed method was applied to measure the content of BPA in different brands of drinking water with satisfying recovery from 97.4 to 102.4%.
Graphical abstract
A sensitive ratiometric electrochemical strategy for MMC detection is developed. • Polythionine serves as an internal reference for improved response stability. • Ce-Ni-MOF/MWCNTs enhance interfacial electron transfer. • Molecular imprinting enables selective MMC recognition. • MMC detection is validated by UPLC-QTOF-MS in water samples. Mitomycin C (MMC) is a widely used antitumor antibiotic, and its rapid and selective detection is crucial for monitoring its occurrence in environmental water samples. In this work, a ratiometric electrochemical sensor was constructed by sequential modification of a bimetallic Ce-Ni-metal-organic framework (Ce-Ni-MOF)/multi-walled carbon nanotube (MWCNTs) composite, polythionine (pThi) and a molecularly imprinted polymer (MIP) on a glassy carbon electrode. The Ce-Ni-MOF/MWCNTs composite facilitated electron transfer, contributing to the enhanced sensitivity of the sensing platform. The pThi was electropolymerized onto the modified electrode surface to provide an internal reference signal, while the ratiometric response was achieved through two electrochemical channels, with the [Fe(CN)₆] 3−/4 − redox probe serving as the response signal and the pThi signal as the reference, enabling effective correction of measurement variations. Under optimized conditions, the sensor exhibited a linear response to MMC over the concentration range of 0.1–100 nM, with a low detection limit of 0.046 nM and a limit of quantification of 0.075 nM. Owing to the specific molecular recognition of the MIP layer and the internal reference function of pThi, the proposed sensor demonstrated satisfactory selectivity, repeatability, reproducibility and stability. Furthermore, the sensor was successfully applied to the determination of MMC in water samples, achieving recoveries of 87–112%. The analytical performance of the proposed sensor was further validated by comparison with the results obtained using ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS). This work presents a reliable and sensitive ratiometric electrochemical sensing strategy and demonstrates its feasibility through a proof-of-concept study for MMC detection in environmental water samples. Download: Download high-res image (304KB) Download: Download full-size image
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