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Bisphenol A (BPA) and its substitute bisphenol S (BPS) are desirable materials widely used in manufacturing plastic products but can pose carcinogenic risks to humans. A new conductive iron-based metal-organic framework (Fe-HHTP)-modified pencil graphite electrode (PGE) for electrochemically sensing BPA and BPS was prepared and fully characterized by SEM, TEM, FT-IR, XRD, and XPS. Results showed that the optimal conditions for preparing Fe-HHTP/PGE were a pH of 6.5, a Fe-HHTP concentration of 2 mg·mL -1 , a deposition potential of 0 V, and a deposition time of 100 s. The Fe-HHTP/PGE prepared under such conditions harbored a significant electrocatalytic activity with a detection limit of 0.8 nM for BPA and 1.7 nM for BPS (S/N = 3). Correspondingly, the electrochemical response current was linearly correlated to BPA and BPS, ranging from 0.01 to 100 μM. Fe-HHTP/PGE also obtained satisfactory recoveries by 93.8-102.1% and 96.0-101.3% for detecting BPA and BPS in plastic food packaging samples. Our work has provided a novel electrochemical tool to simultaneously detect BPA and BPS in food packaging samples and environmental matrixes., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

The electronic conductive metal-organic frameworks (EC-MOFs) based on a single ligand are not suitable for the accurate detection of bisphenol A (BPA) due to the limitations of their electron-transfer-based sensing mechanism. To overcome this drawback, we developed EC-MOFs with novel dual-ligands, 2,3,6,7,10,11-hexahydroxy-sanya-phenyl (HHTP) and tetrahydroxy 1,4-quinone (THQ), and metal ions. A new class of 2D π-conjugation-based EC-MOFs (M-(HHTP)(THQ)) was synthesized by a self-assemble technique. Its best member (Cu-(HHTP)(THQ)) was selected and combined with reduced graphene (rGO) to form a Cu-(HHTP)(THQ)@rGO composite, which was thoroughly characterized by X-ray diffraction, field scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Cu-(HHTP)(THQ)@rGO was drop-cast onto a glassy carbon electrode (GCE) to obtain a sensor for BPA detection. Cyclic voltammetry and electrochemical impedance tests were used to evaluate the electrode performance. The oxidation current of BPA on the Cu-(HHTP)(THQ)@rGO/GCE was substantially higher than on unmodified GCE, which could be explained by a synergy between Cu-(HHTP)(THQ) (which provided sensing and adsorption) and rGO (which provided fast electron conductivity and high surface area). Cu-(HHTP)(THQ)@rGO/GCE exhibited a linear detection range for 0.05-100 μmol·L -1 of BPA with 3.6 nmol·L -1 (S/N = 3) detection limit. We believe that our novel electrode and BPA sensing method extends the application perspectives of EC-MOFs in the electrocatalysis and sensing fields.

Nanozymes have received much attention due to their advantages of lower cost, higher stability, and simple preparation when compared to conventional enzymes. Herein, we prepared a peroxidase-mimicking nanozyme by the growth of silver nanoparticles (AgNPs) on the surface of a metal-organic framework (MOF) called MIL-101 (Fe), obtaining the AgNPs@MOF. The AgNPs@MOF was applied as surface-enhanced Raman spectroscopy (SERS) substrate and simultaneously served as peroxidase mimics to oxidize the without Raman-active leucomalachite green into the Raman-active malachite green. Based on the excellent peroxidase-mimicking activity and high SERS enhancement of AgNPs@MOF, a highly sensitive and specific SERS sensing platform was proposed to monitor cholesterol. Under the optimized conditions, the established biosensor achieved a broad dynamic detection range of 1.0–100 μM and a relatively low limit of detection down to 0.36 μM. More importantly, this reported sensing platform was employed to detect cholesterol in human serum with excellent accuracy and precision, providing great potential in health management and clinical diagnosis. • A SERS biosensor for cholesterol detection was developed based on silver nanoparticles@metal-organic frameworks with peroxidase-mimicking activities • A broad dynamic response range for cholesterol in a range from 1.0 to100 μM with a limit of detection of 0.36 μM. • The proposed strategy can be applied to monitor cholesterol in human serum samples. [ABSTRACT FROM AUTHOR]