MIP / CoNiFe-PBA / RGO / GCE working electrode and preparation method and application thereof

Abstract

The invention discloses an MIP / CoNiFe-PBA / RGO / GCE working electrode as well as a preparation method and application thereof, and belongs to the technical field of food safety detection.The prepared CoNiFe-PBA-based self-reporting type molecularly imprinted electrochemical sensor has the following outstanding performances when detecting BPA: the detection limit is as low as 0.18 nM (S / N = 3), the linear range is 1.0-500.0 nM, and in a milk sample labeling recovery experiment, the detection limit is as low as 0.18 nM (S / N = 3), and the detection limit is as low as 0.18 nM (S / N = 3). The recovery rate is 97.18 to 102.96 percent, and the relative standard deviation is 1t; the current retention rate is 93.81% (n is equal to 3) for 100 nM BPA detection in a continuous 15-day water immersion test (0.1 M PBS, pH 7.4) under the room temperature, and the signal attenuation is 8.6% after 10 times of continuous use, and the current retention rate is 93.81% (n is equal to 3) for 100 nM BPA detection.

Description

Technical Field

[0001] This invention belongs to the field of food safety testing technology, and in particular relates to a MIP / CoNiFe-PBA / RGO / GCE working electrode, its preparation method, and its application. Background Technology

[0002] Bisphenol A (BPA) is an important industrial chemical with an annual production exceeding ten million tons. It is widely used in the production of polycarbonate plastics and epoxy resins, and is commonly found in food packaging, medical devices, and dental materials. However, BPA readily migrates from products, with leaching rates reaching 4.7-23 ng / cm³. 2 BPA can enter the human body through the food chain, interfering with the endocrine system and inducing oxidative stress, metabolic disorders, and even epigenetic abnormalities. Although countries have set strict limits on the migration of BPA, existing detection technologies (such as high-performance liquid chromatography-mass spectrometry and enzyme-linked immunosorbent assay) rely on large instruments and specialized operations, making it difficult to meet the needs of rapid on-site detection.

[0003] Although molecularly imprinted electrochemical sensors (MIECS) have advantages such as low cost and simple operation, their practical application still faces three challenges: (1) Signal dependence problem: Traditional sensors need to introduce exogenous redox probes, which makes the signal stability significantly affected by environmental factors; (2) Sensitivity limitation: Conventional molecularly imprinted polymers (MIPs) have low mass transfer efficiency and insufficient detection capability for trace BPA (<1nM); (3) Interference resistance defects: Sugars, phenols and other substances in food matrices can easily cause electrode contamination, resulting in false positive signals.

[0004] Existing research indicates that nanomaterial modification can effectively improve sensor performance. Reduced graphene oxide (RGO), with its high specific surface area and excellent conductivity, significantly enhances electron transport efficiency. MOF (metal-organic framework) derivatives (such as Fe-MOF) provide abundant adsorption sites by constructing porous structures. PBAs (Prussian blue analogues) exhibit unique advantages in electrochemical sensing due to their tunable redox activity and open framework structure. However, PBA-modified electrodes prepared by traditional drop-coating methods suffer from poor material adhesion and uneven film layers, severely affecting sensor reproducibility and lifespan. In-situ electropolymerization technology, with its significant controllability, excellent reproducibility, robust interfacial bonding, and efficient mass transfer and recognition capabilities, is easily implemented on electrode surfaces and has become one of the standard methods for preparing high-performance electrochemical sensors. Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes a MIP / CoNiFe-PBA / RGO / GCE working electrode, its preparation method, and its application. An RGO conductive substrate is prepared by electrochemical reduction of GO (graphene oxide), and CoNi-MOF is grown in situ on the RGO conductive substrate. CoNi-MOF possesses a high specific surface area and a porous structure rich in oxygen-containing functional groups, significantly improving mass transfer efficiency and the accessibility of electrochemical active sites. Cyclic voltammetry is used to convert CoNi-MOF to CoNiFe-PBA, whose inherent Co... 2+ / Co 3+ and Fe 2+ / Fe 3+ Reversible electron transfer of redox couple, combined with Ni 2+ The synergistic catalytic regulation of the catalyst generates an intrinsic signal at 0.47V (vs. Ag / AgCl). A working electrode for the electrochemical sensor was fabricated using a CoNiFe-PBA / RGO composite material, and a bisphenol A electrochemical sensing platform was successfully constructed. This sensing platform enables rapid on-site detection of bisphenol A in food, providing an effective means for real-time quality monitoring of food processing and laying the technological foundation for the development of portable food safety testing equipment.

[0006] One of the technical solutions provided by this invention:

[0007] A method for preparing a MIP / CoNiFe-PBA / RGO / GCE working electrode includes the following steps: modifying a conductive substrate with RGO (reduced graphene oxide) and CoNiFe-PBA (cobalt-nickel-iron Prussian blue analogue) to enhance electrode sensitivity; then, using BPA (bisphenol A) as a template molecule and o-PD (o-phenylenediamine) as a functional monomer, preparing a molecularly imprinted thin film on the surface of the RGO and CoNiFe-PBA modified conductive substrate using electrochemical in-situ electropolymerization technology to improve electrode specificity; and finally, eluting the template molecule to obtain the MIP / CoNiFe-PBA / RGO / GCE working electrode. The functional monomer can be replaced with mercaptoaniline.

[0008] Furthermore, the preparation method of the MIP / CoNiFe-PBA / RGO / GCE working electrode includes the following steps:

[0009] (1) Electrochemically reduce GO on the surface of a conductive substrate to form an RGO conductive substrate;

[0010] (2) Electrodeposition of CoNi-MO (cobalt-nickel metal-organic framework) precursor on RGO surface;

[0011] (3) CoNi-MOF was converted to CoNiFe-PBA in potassium ferricyanide solution by cyclic voltammetry, and its inherent Co2+ / Co 3+ and Fe 2+ / Fe 3+ Reversible electron transfer of redox couple, combined with Ni 2+ The synergistic catalytic regulation effect generates an endogenous signal at 0.47V (vs. Ag / AgCl);

[0012] (4) Using o-PD as the functional monomer and BPA as the template molecule, a molecularly imprinted membrane was prepared by electropolymerization. The template molecule was then eluted to obtain the MIP / CoNiFe-PBA / RGO / GCE working electrode.

[0013] The specific operation includes the following steps: Immersing a pretreated conductive substrate in a graphite oxide suspension, and depositing reduced graphite oxide using cyclic voltammetry to obtain RGO / GCE; immersing the RGO / GCE in an organic solution containing Et3NHCl, H2BDC, Co(NO3)2·6H2O, and Ni(NO3)2·6H2O, and preparing CoNi-MOF / RGO / GCE using a potentiostatic deposition method; placing the CoNi-MOF / RGO / GCE in a solution containing K3[Fe( CoNiFe-PBA / RGO / GCE was prepared by cyclic voltammetry in a KCl solution containing bisphenol A and o-phenylenediamine. The CoNiFe-PBA / RGO / GCE was placed in a buffer system containing bisphenol A and o-phenylenediamine, and a molecularly imprinted polymer layer was formed on the surface of the CoNiFe-PBA / RGO / GCE by electrochemical in-situ electropolymerization. Bisphenol A was eluted, and the surface was thoroughly rinsed with deionized water to obtain the MIP / CoNiFe-PBA / RGO / GCE working electrode.

[0014] Furthermore, the conductive substrate is selected from a metal substrate, a carbon material substrate, or a conductive glass substrate.

[0015] Furthermore, the concentration of bisphenol A is 1.5 mM; the molar ratio of bisphenol A to the functional monomer is 1:(5-20);

[0016] Furthermore, when preparing the RGO / GCE, the cyclic voltammetry cycle number is 20; the scan rate is 50 mV / s; and / or, when preparing the CoNi-MOF / RGO / GCE, the deposition time is 300 s; and / or, when preparing the CoNiFe-PBA / RGO / GCE, the cyclic voltammetry cycle number is 5; the scan rate is 50 mV / s; and / or, when preparing the molecularly imprinted polymer layer, the cyclic voltammetry cycle number is 15; the scan rate is 50 mV / s.

[0017] Furthermore, the specific procedure for eluting bisphenol A is as follows: methanol, acetic acid and water are mixed in a volume ratio of 7:3:2 to obtain an eluent, and eluted for 30 minutes.

[0018] The second technical solution provided by this invention:

[0019] A working electrode of MIP / CoNiFe-PBA / RGO / GCE prepared by the above preparation method.

[0020] The third technical solution provided by this invention:

[0021] Application of the above-mentioned MIP / CoNiFe-PBA / RGO / GCE working electrode in the fabrication of a self-reporting molecularly imprinted electrochemical sensor based on a cobalt-nickel-iron Prussian blue analogue.

[0022] The fourth technical solution provided by this invention:

[0023] A self-reporting molecularly imprinted electrochemical sensor based on a cobalt-nickel-iron Prussian blue analogue was constructed using the aforementioned MIP / CoNiFe-PBA / RGO / GCE as the working electrode, Ag / AgCl as the reference electrode, and Pt foil as the counter electrode.

[0024] The self-reporting molecularly imprinted electrochemical sensor provided by this invention uses RGO (reduced graphene oxide) and CoNiFe-PBA (cobalt-nickel-iron Prussian blue analogue) to modify the electrode, constructing a sensing interface. Self-reporting detection is achieved using the characteristic redox signal of CoNiFe-PBA at 0.47V (vs. Ag / AgCl), eliminating the need for an external signal probe. The MIP film uses o-PD (o-phenylenediamine) as the functional monomer, forming specific recognition sites on the electrode surface through an electropolymerization reaction.

[0025] The fifth technical solution provided by this invention:

[0026] Application of the above-mentioned self-reporting molecularly imprinted electrochemical sensor based on cobalt-nickel-iron Prussian blue analogue in the detection of bisphenol A.

[0027] The self-reporting molecularly imprinted electrochemical sensor provided by this invention has a linear detection range of 1-500.0 nM for BPA and a detection limit of 0.18 nM. It is suitable for rapid and accurate detection of trace BPA in food and has good reproducibility and stability, providing a new detection tool for food safety monitoring.

[0028] Furthermore, before detecting bisphenol A, MIP / CoNiFe-PBA / RGO / GCE needs to be incubated. The incubation process includes the following steps: immersing the MIP / CoNiFe-PBA / RGO / GCE in a 500 nM bisphenol A solution and incubating for 20 min.

[0029] Compared with the prior art, the present invention has the following advantages and technical effects:

[0030] This invention employs in-situ conversion technology to prepare CoNi-MOF precursor into CoNiFe-PBA through electrochemical conversion, overcoming the material detachment problem caused by traditional drop coating methods and improving film adhesion.

[0031] This invention provides a self-reporting signal mechanism, utilizing the Co inherent in the CoNiFe-PBA lattice. 2+ / Co 3+ and Fe 2 + / Fe 3+ Reversible electron transfer of redox couple, combined with Ni 2+ The synergistic catalytic regulation of the signal enables autonomous optimization of the electron transport path. This endogenous signal amplification mechanism avoids the introduction of exogenous probes, resulting in a significant improvement in signal stability.

[0032] This invention provides a three-dimensional recognition interface, in which RGO and CoNiFe-PBA are used to construct a hierarchical porous structure, which significantly improves the density of effective imprint sites.

[0033] The CoNiFe-PBA-based self-reporting molecularly imprinted electrochemical sensor prepared in this invention exhibits the following outstanding performance in BPA detection: a detection limit as low as 0.18 nM (S / N = 3), a linear range of 1.0-500.0 nM, a recovery rate of 97.18-102.96% in a milk sample spike recovery experiment, a relative standard deviation of <4.31%, a signal attenuation of 8.6% after 10 consecutive uses, and a current retention rate of 93.81% (n = 3) for the detection of 100 nM BPA in a 15-day continuous water immersion test (0.1 M PBS, pH 7.4) at room temperature. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1A is a schematic diagram of the CoNiFe-PBA synthesis process, B is a schematic diagram of the MIP (molecularly imprinted polymer) preparation process, and C is a schematic diagram of the construction process of the MIP / CoNiFe-PBA / RGO / GCE working electrode and its application as an electrochemical sensor platform for detecting bisphenol A.

[0036] Figure 2 The images show the scanning electron microscope (SEM) characterization of the modified components on the working electrode. In the images, A represents RGO / GCE, B represents CoNi-MOF / RGO / GCE, C represents CoNiFe-PBA / RGO / GCE, D represents MIP / CoNiFe-PBA / RGO / GCE, E represents NIP / CoNiFe-PBA / RGO / GCE, and FM represents the EDS elemental distribution analysis of CoNiFe-PBA / RGO / GCE.

[0037] Figure 3 X-ray photoelectron spectroscopy characterization of CoNi-MOF / RGO and CoNiFe-PBA / RGO composites, where (A) is a comparison of the full spectrum of the composites, (B) is C1s, (C) is Co2p, (D) is Ni2p, (E) is N1s, and (F) is Fe2p.

[0038] Figure 4 Electrochemical performance tests were conducted on different electrodes. (A) shows a comparison of cyclic voltammetry curves: a) bare GCE, b) CoNi-MOF / RGO / GCE, c) CoNiFe-PBA / RGO / GCE, d) MIP / CoNiFe-PBA / RGO / GCE before template molecule removal, e) MIP / CoNi-MOF / PANI / RGO / GCE after template molecule removal, f) MIP / CoNi-MOF / PANI / RGO / GCE with 500 nMBPA adsorbed, and (B) shows a comparison of differential pulse voltammetry responses.

[0039] Figure 5 The following are the experimental results of the optimization of sensor preparation parameters in Example 2: (A) shows the optimization results of the number of RGO electrodeposition cycles; (B) shows the optimization of CoNi-MOF deposition time; (C) shows the optimization of MIP scan cycle; (D) shows the optimization of template molecule elution time; (E) shows the optimization of MIP sensor incubation time; and (F) shows the DPV experimental conditions of CoNiFe-PBA / GCE, NiFe-PBA / RGO / GCE, and CoNiFe-PBA / RGO / GCE in 0.1M KCl solution and 0.1M phosphate buffer (pH 7.0).

[0040] Figure 6The results show the quantitative detection performance of BPA by a self-reporting molecularly imprinted electrochemical sensor based on CoNiFe-PBA. (A) shows the differential pulse voltammetric response curves (0-500 nM) of BPA at different concentrations, and (B) shows the linear relationship between the change in current response (ΔI) and the concentration of BPA.

[0041] Figure 7 The linear relationship between peak area in high performance liquid chromatography and bisphenol A concentration;

[0042] Figure 8 The results show the selective detection of various compounds by a self-reporting molecularly imprinted electrochemical sensor (MIP) based on CoNiFe-PBA and an electrochemical sensor (NIP) with NIP / CoNiFe-PBA / RGO / GCE as the working electrode;

[0043] Figure 9 The reproducibility test results for the CoNiFe-PBA-based self-reporting molecularly imprinted electrochemical sensor are shown in (A) and (B). Detailed Implementation

[0044] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0045] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0046] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0047] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0048] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0049] The room temperature in this invention refers to 25±2℃.

[0050] Existing analytical methods lack the sensitivity and reliability required for effective detection of trace bisphenol A (BPA) in food and the environment. This invention develops a molecularly imprinted electrochemical sensing platform based on RGO and CoNiFe-PBA for the detection of trace BPA. MIPs have become one of the most effective molecular recognition elements in electrochemical sensors, providing excellent target selectivity for the detection of target analytes.

[0051] This invention provides a process for constructing a self-reporting molecularly imprinted electrochemical sensor based on CoNiFe-PBA (a cobalt-nickel-iron Prussian blue analogue). Figure 1 A is a schematic diagram of the CoNiFe-PBA synthesis process, B is a schematic diagram of the molecularly imprinted polymer preparation process, and C is a schematic diagram of the construction process of the MIP / CoNiFe-PBA / RGO / GCE working electrode and its application as an electrochemical sensor platform for detecting bisphenol A.

[0052] This invention transforms pre-deposited CoNi-MOF into CoNiFe-PBA through an electrochemical reaction, which allows for precise control of composition and morphology while maintaining strong electrode adhesion. The resulting CoNiFe-PBA nanocomposite material can amplify electrochemical signals and provides an inherent self-reporting function.

[0053] The preparation process of MIP / CoNiFe-PBA / RGO / GCE provided in this embodiment of the invention includes the following three stages: (i) modifying the surface of GCE by electrochemical deposition of RGO to form a stable sensing platform (RGO / GCE), which significantly increases the electroactive surface area and facilitates subsequent functionalization; (ii) electrodepositing a cobalt-nickel metal-organic framework (CoNi-MOF) on RGO / GCE, and then converting it into a ternary Prussian blue analog (CoNiFe-PBA) in potassium ferricyanide solution through five cyclic voltammetric scans to generate the CoNiFe-PBA / RGO / GCE platform; (iii) preparing a MIP film by electropolymerizing o-phenylenediamine (o-PD) with bisphenol A template, generating selective recognition sites on the CoNiFe-PBA / RGO / GCE modified electrode polymer film. This MIP membrane significantly improves sensor selectivity through specific BPA binding, while the CoNiFe-PBA component provides intrinsic redox activity for self-reporting detection. The synergistic design combines the molecular recognition capability of MIPs with the electrochemical redox activity of CoNiFe-PBA and the high conductivity of RGO, thereby significantly improving sensor performance.

[0054] Example 1: Preparation of the MIP / CoNiFe-PBA / RGO / GCE working electrode

[0055] S1. Pretreatment of glassy carbon electrode:

[0056] GCE (3 mm in diameter) was polished on a polishing cloth with alumina slurry (abrasive particles with diameters of 0.3 μm for coarse polishing and 0.03 μm for fine polishing). Then, it was ultrasonicated in deionized water and ethanol for 15 seconds in sequence, and then dried at room temperature to obtain a pretreated glassy carbon electrode.

[0057] Synthesis of S2.GO (graphene oxide):

[0058] In this embodiment, graphene oxide (GO) is synthesized by a modified Hummers method. The specific steps are as follows: natural graphite is reacted with potassium permanganate (6 g / g graphite) in a concentrated sulfuric acid / phosphoric acid (volume ratio 9:1) mixture at 50°C for 12 h, then quenched with hydrogen peroxide, and GO is obtained by dialysis until the pH is neutral.

[0059] Preparation of S3.RGO / GCE (Reduced Graphene Oxide / Glassy Carbon Electrode)

[0060] 0.25 g of GO prepared in S2 was placed in 25 mL of PBS (0.1 M, pH 8) and sonicated for 45 min to obtain a uniform GO suspension. Then, the pretreated glassy carbon electrode prepared in S1 was immersed in the suspension, and RGO (reduced graphene oxide) electrodeposition was achieved by cyclic voltammetry (20 cycles between -1.4 and 0 V (relative to Ag / AgCl), with a scan rate of 50 mV / s) to obtain RGO / GCE (reduced graphene oxide / glassy carbon electrode).

[0061] Preparation of S4.CoNiFe-PBA / RGO / GCE electrode:

[0062] S4-1. The RGO / GCE prepared in S3 was immersed in a DMF solution containing 10 mM Et3NHCl, 15 mM H2BDC, 1 mM Co(NO3)2·6H2O and 9 mM Ni(NO3)2·6H2O, and then electrodeposited at a constant potential of -1.3 V for 300 s to form CoNi-MOF / RGO / GCE;

[0063] S4-2. CoNi-MOF / RGO / GCE was placed in a KCl supporting electrolyte solution (0.1M) containing 5mM K3[Fe(CN)6] and electrochemically deposited (5 cycles of voltammetric conversion at a scan rate of 50mV / s between -0.1 and 1.0V) to synthesize the CoNiFe-PBA / RGO / GCE electrode.

[0064] Fabrication of S5.MIP / CoNiFe-PBA / RGO / GCE electrode:

[0065] The CoNiFe-PBA / RGO / GCE electrode prepared by S4 was further functionalized by electropolymerization in an acetate buffer system (1.0 M, pH 5.2) containing 1.5 mM bisphenol A (BPA, template molecule) and 9 mM o-phenylenediamine (o-PD, functional monomer): a molecularly imprinted polymer (MIP) layer was formed by cyclic voltammetry (15 cycles at a rate of 50 mV / s, relative to the Ag / AgCl electrode, between 0-0.9 V). Then, the template molecule was eluted with a methanol / acetic acid / water (volume ratio 7:3:2) solution for 20 min, and the electrode was thoroughly rinsed under ultrasonic treatment to obtain the molecularly imprinted working electrode, namely MIP / CoNiFe-PBA / RGO / GCE.

[0066] Comparative Example 1: Preparation method of NIP / CoNiFe-PBA / RGO / GCE working electrode

[0067] S1-S4. Same as Example 1;

[0068] S5. The CoNiFe-PBA / RGO / GCE electrode prepared in S4 was further functionalized by electropolymerization in an acetate buffer system (1.0 M, pH 5.2) containing 9 mM o-phenylenediamine (o-PD, functional monomer): a molecularly imprinted polymer (MIP) layer was formed by cyclic voltammetry (15 cycles at a rate of 50 mV / s, relative to the Ag / AgCl electrode, between 0-0.9 V). Then, template molecules were eluted with a methanol / acetic acid / water solution (volume ratio 7:3:2) for 20 min, and thoroughly rinsed under ultrasonic treatment to prepare a non-imprinted control electrode, namely NIP / CoNiFe-PBA / RGO / GCE.

[0069] Performance Test 1

[0070] The RGO / GCE, CoNi-MOF / RGO / GCE, CoNiFe-PBA / RGO / GCE, MIP / CoNiFe-PBA / RGO / GCE prepared in Example 1 and the NIP / CoNiFe-PBA / RGO / GCE prepared in Comparative Example 1 were characterized:

[0071] The electrode structure was characterized using scanning electron microscopy (SEM). Prior to the synthesis of metal-organic frameworks (MOFs), graphene oxide was electrochemically reduced to generate a GCE electrode surface modified with reduced graphene oxide, providing enhanced conductivity and uniform nucleation sites for subsequent MOF growth. Figure 2 As shown in Figure A, RGO / GCE exhibits a typical wrinkled surface morphology, providing abundant nucleation sites for in-situ MOF growth; SEM analysis confirmed the successful growth of CoNi-MOF on the RGO-functionalized glassy carbon electrode surface, as shown in Figure A. Figure 2 As shown in Figure B, the CoNi-MOF / RGO / GCE exhibits uniformly distributed MOF crystal particles with a distinct polyhedral morphology, forming a three-dimensional porous structure, which contrasts sharply with the two-dimensional planar structure of the original RGO / GCE substrate. CoNi-MOF was electrochemically converted to CoNiFe-PBA by five cycles of cyclic voltammetry (CV) in a 0.1 M KCl supporting electrolyte solution containing 5 mM K3[Fe(CN)6]. SEM analysis (…) Figure 2 As shown in Figure C), the obtained CoNiFe-PBA / RGO / GCE exhibits an irregular blocky morphology with improved crystallinity. This structural reorganization enhances stability and electrochemical activity, making it an ideal sensing platform. Surface analysis reveals that the molecularly imprinted polymer (MIP) film is uniformly deposited on the CoNiFe-PBA / RGO / GCE surface, and its surface roughness is increased compared to the bare electrode (e.g., ...). Figure 2As shown in Figure D), the increased surface roughness significantly expands the effective detection area while maintaining excellent film uniformity. Characterization of the NIP / CoNiFe-PBA / RGO / GCE prepared in Comparative Example 1 revealed similar morphological characteristics, but it lacked the voids characteristic of template imprints, thus confirming the molecular recognition capability of the MIP film (e.g., ...). Figure 2 (As shown in E).

[0072] Energy-dispersive X-ray spectroscopy (EDS) elemental imaging confirmed the successful synthesis of CoNiFe-PBA / RGO / GCE, and the uniform distribution of cobalt, nickel, and iron confirmed their integration into the PBA structure (e.g., ...). Figure 2 (as shown in FM) Figure 2 FM reveals the elemental distribution analysis of CoNiFe-PBA / RGO / GCE, showcasing the spatial distribution of all constituent elements. The uniform nitrogen (N) distribution confirms the presence of cyanide bridging groups in the CoNiFe-PBA structure, while prominent carbon (C) and oxygen (O) signals indicate the preservation of the RGO conductivity network. Furthermore, the spatial correlation distribution of cobalt, nickel, and iron confirms that the cobalt-nickel-iron-PBA nanocrystals are uniformly grown on the reduced graphene oxide substrate, rather than physically mixed. The elemental distribution results are consistent with XPS analysis (…). Figure 3 The high degree of consistency demonstrates the successful synthesis of the CoNiFe-PBA / RGO / GCE electrode and the uniformity of its structure.

[0073] The chemical composition and electronic states of CoNi-MOF / RGO and CoNiFe-PBA / RGO composites were systematically investigated using X-ray photoelectron spectroscopy (XPS). High-resolution scans of the Co 2p, Ni 2p, Fe 2p, C 1s, and O 1s core layers were obtained to elucidate the interfacial interactions and valence states in these hybrid materials. Figure 3 Image (A) shows the full spectrum of the composite material, revealing characteristic peaks for Ni 2p, Co 2p, O 1s, and C 1s. The spectrum of CoNiFe-PBA / RGO exhibits clear Fe 2p and N 1s signals, confirming the successful incorporation of these elements and the formation of CoNiFe-PBA. The C1s spectrum of CoNi-MOF / RGO (as shown in image A) is also presented. Figure 3As shown in (B), a significant C=C / CC peak is observed at 284.8 eV, characteristic of RGO, along with distinct peaks at 286.78 eV (CO) and 288.88 eV (OC=O), corresponding to carboxylic acid ligands. The positive binding energy shift of the CO peak indicates a significant electronic interaction between the Co / Ni metal center and the oxygen-containing functional groups, consistent with interfacial charge transfer and redistribution. After conversion to CoNiFe-PBA / RGO, the carboxylic acid characteristic disappears, and a new peak appears at 286.58 eV, attributed to the C≡N group. This shift reflects the π-electron delocalization between RGO and the metal d orbitals (Co / Ni), leading to interfacial charge transfer, reducing the electron density of the C≡N bond, and thus increasing its binding energy. Furthermore, the RGO-derived C=C / CC peak remains unchanged at 284.8 eV, indicating structural stability throughout the conversion. The Co 2p spectrum of CoNi-MOF / RGO (as shown in Figure B) further supports this. Figure 3 In the middle (C)), there are two main peaks located at 781.48 eV (Co 2p). 3 / 2 ) and 796.88eV (Co2p 1 / 2 ), accompanied by satellite peaks at 786.28 eV and 798.38 eV. Similarly, the Ni 2p spectrum (e.g.) Figure 3 As shown in (D), the core peak is located at 856.58 eV (Ni 2p). 3 / 2 ) and 874.88eV (Ni 2p 1 / 2 The corresponding satellite peaks are at 860.78 eV and 879.08 eV. These results indicate the presence of Co in the synthesized bimetallic composite. 2+ and Ni 2+ After conversion to CoNiFe-PBA, the strong-field coordination of the cyanide ligand leads to Co... 2+ (781.98eV) and Ni 2+ The binding energy shifted positively at (856.88 eV), while the satellite peak intensity decreased. These spectral changes confirm the formation of Fe in the composite structure. 3+ -C≡N-Co 2+ / Ni 2+ Bridging configuration. The transition from CoNi-MOF / RGO to CoNiFe-PBA / RGO caused significant changes in the XPS spectrum. N1s energy spectrum evolution (e.g.) Figure 3 As shown in Figure (D), a distinct cyanide-coordinated nitrogen peak appears at 397.98 eV, while the secondary peak at 402.58 eV indicates the presence of surface-oxidized nitrogen species (NO3). - / NO2 - In addition, the Fe2p energy spectrum (such as...) Figure 3The [Fe(CN)6] shown in (E) exhibits characteristic [Fe(CN)6] at 708.78 eV and 721.68 eV. 3- These results provide strong evidence for the successful construction of cyanide-bridged bimetallic Prussian blue analogue structures.

[0074] Comparative Example: Preparation of the working electrode of 2CoNiFe-PBA / RGO / GCE

[0075] Same as Example 1, except that the CoNiFe-PBA / RGO / GCE electrode prepared in S4 was not further functionalized.

[0076] Comparative example: Fabrication of the 3CoNi-MOF / RGO / GCE working electrode

[0077] S1-S3. Same as Example 1;

[0078] Preparation of S4.CoNi-MOF / RGO / GCE electrode:

[0079] The RGO / GCE prepared by S3 was immersed in a DMF solution containing 10 mM Et3NHCl, 15 mM H2BDC, 1 mM Co(NO3)2·6H2O and 9 mM Ni(NO3)2·6H2O, and then electrodeposited at a constant potential of -1.3 V for 300 s to form CoNi-MOF / RGO / GCE.

[0080] Performance Test 2

[0081] Electrochemical measurements were performed on the working electrodes prepared in Example 1 and Comparative Examples 2-4:

[0082] Electrochemical experiments were conducted on a CHI850E electrochemical workstation using a three-electrode system. The MIP / CoNiFe-PBA / RGO / GCE electrode prepared in Example 1 was used as the working electrode, and Ag / AgCl was used as the reference electrode. A 1cm Pt foil was used. 2 The electrode was used as the counter electrode to construct a self-reporting molecularly imprinted electrochemical sensor based on CoNiFe-PBA; then, the electrodes prepared in Comparative Examples 2-4 were used as working electrodes, and Ag / AgCl was used as the reference electrode, and Pt foil (1 cm) was used. 2 It was used as the counter electrode to construct an electrochemical sensor; CV and DPV measurements were performed in the potential range of 0.5–1 V, using a solution containing 2.5 mM [Fe(CN)6]. 3- / 4- 0.1M KCl solution, scan rate 50 mV·s -1 All tests were conducted at room temperature.

[0083] The electrochemical performance of the above-mentioned electrochemical sensor was characterized by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Since differential pulse voltammetry is more sensitive than cyclic voltammetry, it was used to evaluate the detection performance of the electrochemical sensor for bisphenol A. The electrochemical performance of bare GCE (bare glassy carbon electrode) and different modified electrodes was tested by CV and DPV in 0.1M PBS (pH 7.0) solution with 0.1M KCl as the supporting electrolyte.

[0084] like Figure 4 As shown in Figure (A), the CoNiFe-PBA / RGO / GCE working electrode (Comparative Example 2, Curve c) exhibits obvious redox peaks, which are characteristic of Prussian blue analogues. However, bare GCE (curve a) and CoNi-MOF / RGO / GCE (Comparative Example 3, Curve b) do not show characteristic responses under the same conditions. This indicates that the electrode containing CoNiFe-PBA has a significant current response, while this response cannot be detected in bare GCE and electrodes modified with the precursor CoNi-MOF. After the CoNi-MOF precursor is electrochemically converted to CoNiFe-PBA, the resulting CoNiFe-PBA / RGO / GCE shows excellent electrochemical performance, characterized by clear redox peaks and improved charge transfer kinetics. The performance improvement is attributed to the synergistic effect between the redox activity of CoNiFe-PBA and the highly conductive RGO network, which enables the entire nanocomposite material to achieve efficient electron transport. Before template molecule removal, the peak current of the MIP / CoNiFe-PBA / RGO / GCE working electrode (as shown by curve d) was significantly reduced; after template molecule removal, the current response was fully recovered (as shown by curve e) because the molecular voids generated in the MIP matrix restored the electron transfer path, allowing the embedded CoNiFe-PBA centers to contact the electrode surface. This result confirms that BPA has been successfully incorporated into the polymer MIP film. The attenuation of the current signal is caused by the electrically insulating MIP layer, which hinders the electron transfer dynamics at the electrode interface. The current response recovered after template molecule elution confirms that BPA molecules were successfully removed from the MIP film. After incubation in 500 nM BPA for 20 min, the sensor exhibited a significant current attenuation (as shown by curve f) because the BPA re-bonded in the molecular voids hindered electron transfer between the redox probe and the electrode surface. The signal attenuation caused by re-adsorption confirms the selective recognition capability of MIP / CoNiFe-PBA / RGO / GCE, which is due to the hindered electron transfer dynamics.

[0085] DPV response results (such as) Figure 4 (As shown in B) and CV measurement results ( Figure 4The results (shown in Figure A) show a high degree of agreement, confirming the consistency of electrochemical behavior under different technologies. The significant current changes before and after BPA binding indicate the successful integration of molecular recognition and electrochemical signal transduction in the sensing platform. These results demonstrate an effective coupling between molecular recognition sites and electrochemical signal conversion, where analyte binding directly alters the interfacial electron transfer kinetics.

[0086] Example 2

[0087] This embodiment is based on Example 1 and examines the effects of the number of RGO electrodeposition cycles (corresponding to the adjusted number of cycles in S3 of Example 1), CoNi-MOF deposition time (corresponding to the adjusted electrodeposition time in S4-1 of Example 1), MIP scan cycle (corresponding to the adjusted number of cycles in S5 of Example 1), template molecule elution time (corresponding to the adjusted template molecule elution time in Example 1), and MIP sensor incubation time on the detection of bisphenol A by MIP / CoNiFe-PBA / RGO / GCE.

[0088] To optimize sensor performance, key experimental parameters were evaluated, and the analytical signal ΔI was defined as: ΔI = I0 - I, where I0 represents the peak current after removing the template molecule (BPA), and I corresponds to the peak current after exposure to 500 nM BPA solution. The differential peak current reflects the specific binding capacity of the imprinted pores. Figure 5 As shown. This invention systematically studied the effects of the above-mentioned key parameters, including the number of RGO electrodeposition cycles, CoNi-MOF deposition time, MIP scan cycle, template molecule elution time, and MIP sensor incubation time, in order to maximize the current response for BPA detection.

[0089] Figure 5 Figure (A) shows that the response current of the sensor is affected by the scanning cycle of RGO electrodeposition. Initially, as RGO is gradually deposited, the electroactive surface area increases, and ΔI increases with the number of scans within 20 scans. However, after exceeding this value, ΔI begins to gradually decrease. This decrease is attributed to excessive RGO accumulation, which forms an excessively thick layer on the electrode surface, thereby hindering the electron transport efficiency.

[0090] The deposition amount of CoNi-MOF plays a crucial role in the formation of CoNiFe-PBA. For example... Figure 5 As shown in Figure (B), ΔI increases sharply with the extension of the CoNi-MOF electrodeposition time, reaching a maximum value at 300 s. After this time, ΔI stabilizes, indicating that the sensor response no longer shows further improvement. Therefore, 300 s is selected as the optimal electrodeposition time for CoNi-MOF to ensure that the sensor performance reaches its maximum value while avoiding over-deposition.

[0091] The number of o-PD electropolymerization cycles plays a decisive role in the thickness of the MIP film. Too few cycles will result in a film that is too thin and insufficient imprint cavity, thereby reducing detection sensitivity. However, too many cycles will form a film that is too thick, thus hindering template removal and the formation of recognition sites. Figure 5 The results (C) indicate that the best performance is achieved at 15 cycles, where the film thickness is ideal and the ΔI response reaches its peak. This balance ensures effective molecular recognition while maintaining the sensor's sensitivity.

[0092] Effective template removal is crucial for forming functional recognition cavities in molecularly imprinted polymer (MIP) films. Figure 5 As shown in Figure (D), the signal intensity reached saturation after elution with methanol / acetic acid / water (volume ratio 7:3:2) for 30 minutes, indicating that bisphenol A (BPA) had been completely desorbed. Extending the elution time (30-40 minutes) resulted in a decrease in the current response due to polymer expansion and cavity degradation; therefore, 30 minutes was determined to be the optimal elution time.

[0093] The sensitivity of the sensor was optimized through incubation studies. Figure 5 In the incubation test (E), at a 500 nM analyte concentration, the signal response stabilized after 20 min, indicating that the cavity was saturated. This equilibrium indicated that all sites were occupied, and no further signal changes were observed. Therefore, 20 min was chosen as the optimal incubation time to ensure effective analyte binding while maintaining detection performance.

[0094] To further improve the sensitivity of the sensor, this invention systematically optimizes the electrochemical conversion of single-metal and bimetallic metal-organic frameworks (MOFs) to Prussian blue analogues (PBAs), as well as the direct electrode modification on glassy carbon electrode (GCE) and reduced graphene oxide (RGO) substrates.

[0095] The preparation method of NiFe-PBA / RGO / GCE is as follows:

[0096] S1-S3. Same as Example 1;

[0097] Preparation of S4.NiFe-PBA / RGO / GCE electrode

[0098] S4-1 The RGO / GCE prepared in S3 was immersed in a DMF solution containing 10 mM Et3NHCl, 15 mM H2BDC and 9 mM Ni(NO3)2·6H2O, and then electrodeposited at a constant potential of -1.3 V for 300 s to form Ni-MOF / RGO / GCE.

[0099] S4-2. Ni-MOF / RGO / GCE was placed in a K3[Fe(CN)6] (5mM) KCl supporting electrolyte solution (0.1M) and electrochemically deposited (5 cycles of voltammetric conversion at a scan rate of 50mV / s between -0.1 and 1.0V) to synthesize NiFe-PBA / RGO / GCE electrode.

[0100] The preparation method of CoNiFe-PBA / GCE is as follows:

[0101] S1. Same as Example 1;

[0102] S2. The pretreated glassy carbon electrode from S1 was immersed in a DMF solution containing 10 mM Et3NHCl, 15 mM H2BDC, 1 mM Co(NO3)2·6H2O and 9 mM Ni(NO3)2·6H2O, and then electrodeposited at a constant potential of -1.3 V for 300 s to form CoNi-MOF / GCE;

[0103] S3. CoNi-MOF / GCE was placed in a KCl supporting electrolyte solution (0.1M) containing 5mM K3[Fe(CN)6] and electrochemical deposition was performed (5 cycles of voltammetric conversion at a scan rate of 50mV / s between -0.1 and 1.0V) to finally obtain the CoNiFe-PBA / GCE electrode.

[0104] like Figure 5 As shown in Figure (F), CoNiFe-PBA / RGO / GCE exhibits a significantly enhanced current response in PBS compared to NiFe-PBA / RGO / GCE. This improvement can be attributed to the synergistic effect among the Co, Ni, and Fe centers, which enhances redox activity. Specifically, the introduction of Co appears to modulate the electronic structure of the active sites, promoting more efficient electron transfer.

[0105] In contrast, CoNiFe-PBA / GCE exhibits a weak response under the same conditions because the limited surface area of ​​the bare GCE restricts MOF deposition and subsequent PBA formation. The experimental results indicate that RGO functionalization is crucial for optimizing sensor performance, thanks to its enhanced surface area and electron transport properties.

[0106] Performance Test 3

[0107] Application of a self-reporting molecularly imprinted electrochemical sensor based on CoNiFe-PBA in the detection of bisphenol A.

[0108] Under the optimal conditions determined in Example 2 (i.e., based on Example 1, replacing the template molecule elution time in S5 using a methanol / acetic acid / water (volume ratio 7:3:2) solution with 30 min), MIP / CoNiFe-PBA / RGO / GCE was prepared and incubated (MIP / CoNiFe-PBA / RGO / GCE was immersed in a 500 nM bisphenol A solution for 20 min). Using MIP / CoNiFe-PBA / RGO / GCE as the working electrode and Ag / AgCl as the reference electrode, a Pt foil (1 cm²) was used. 2 Using CoNiFe-PBA as the counter electrode, a self-reporting molecularly imprinted electrochemical sensor was constructed. The linear range, detection limit, selectivity, repeatability, reproducibility, stability, and spiked recovery detection performance of the electrochemical sensor for detecting bisphenol A were determined.

[0109] 1. Linear range and detection limit of a self-reporting molecularly imprinted electrochemical sensor based on CoNiFe-PBA for the detection of bisphenol A:

[0110] The MIP / CoNiFe-PBA / RGO / GCE working electrode was immersed in buffer solutions of different concentrations of bisphenol A for 20 min, and then tested using the differential current photovoltaic (DPV) method to obtain the relationship curve between the differential current response (ΔI) and the BPA concentration (C). The electrochemical response of this electrochemical sensor to different concentrations of bisphenol A (0.0-500 nM) was studied using the DPV method. Figure 6 As shown in (A), the oxidation peak current exhibits a proportional current decay phenomenon with increasing BPA concentration (0-500 nM). The observed current decay is linearly correlated with the occupancy of BPA binding sites, which is confirmed by a control experiment with structural analogs. Figure 7 Calibration curve (e.g.) Figure 6 The differential current response (ΔI) shown in Figure (B) exhibits an excellent linear correlation with BPA concentration (C) in the range of 1–500 nM, described by the regression equation as: ΔI(μA) = 0.11789C(nM) + 25.66038(R) 2 Quantitative performance evaluation (=0.9991) shows that it has good quantitative performance in a wide linear dynamic range of 1-500 nM, and the calculated limit of detection (LOD) is 0.18 nM, indicating that it has sufficient sensitivity and can be used for BPA monitoring applications in the environment and food.

[0111] To verify the accuracy of this electrochemical sensor in detecting bisphenol A, this invention uses high-performance liquid chromatography (HPLC) as a reference method for BPA quantification. Figure 7 As shown, the two technologies exhibit excellent consistency (R0). 2=0.9993, slope =0.30405±0.004), confirming the reliability of the electrochemical analysis performed in this invention across the entire concentration range (1-500 nM).

[0112] Table 1 shows the comparison results of BPA detection using different modified electrodes. As can be seen from Table 1, the self-reporting molecularly imprinted electrochemical sensor based on CoNiFe-PBA prepared in this invention exhibits superior performance, with a wider detection range (1-500 nM) and a lower detection limit (0.18 nM), placing it at the forefront among reported BPA detection platforms. Control experiments using electrodes modified with non-imprinted polymers (NIP) revealed significantly different recognition characteristics. The NIP / CoNiFe-PBA / RGO / GCE system showed only a slight response to changes in BPA concentration, following the relationship: ΔI(μA)=0.02568C(nM)+19.10505(R 2 =0.9987), indicating that its sensitivity is lower than that of molecularly imprinted sensors, confirming the crucial role of molecular imprinting in selective recognition. The selectivity stems from the carefully designed three-dimensional cavities within the MIP membrane, whose geometry is complementary to the BPA crystal structure. In contrast, the homogeneous polymer matrix of NIP lacks such specially designed recognition sites, thus only generating weak and non-specific interactions. These results demonstrate that the molecular imprinting technology provided by this invention can create the functional cavities necessary for selective recognition and signal amplification of targets.

[0113] Table 1

[0114]

[0115] The references are:

[0116] Chen,W.-Y.,Mei,L.-P.,Feng,J.-J.,Yuan,T.,Wang,A.-J.,et al.(2015).Electrochemical determination of bisphenol A with a glassy carbon electrodemodified with gold nanodendrites.MicrochimicaActa,182(3),703-709;

[0117] Dai,Y.,Dou,Z.,Zhou,R.,Luo,L.,Bian,L.,et al.(2021).Quality Evaluationof Artemisia capillaris Thunb.Based on Qualitative Analysis of the HPLCFingerprint and UFLC-Q-TOF-MS / MS Combined with Quantitative Analysis of Multicomponents.JournalofAnalytical Methodsin Chemistry,2021(1),5546446;

[0118] Dey,B.,Ahmad,M.W.,Al-Shannaq,R.,Al-Humaidi,J.Y.,Hossain,S.K.S.,etal.(2024).Non-Enzymatic Electrochemical Sensing of Bisphenol A in Drinking Waterand Milk Using Bimetallic Nickel-Copper Metal–OrganicFramework.JournalofAnalysis and Testing,8(4),451-465;

[0119] Li,Y.,Wang,H.,Yan,B.,&Zhang,H.(2017).An electrochemical sensor forthe determination of bisphenol A using glassy carbon electrode modified withreduced graphene oxide-silver / poly-l-lysine nanocomposites.JournalofElectroanalytical Chemistry,805,39-46;

[0120] Yu, H., Feng, X., Chen, Chemistry,45(5),713-720.

[0121] 2. Selectivity, repeatability, reproducibility and stability analysis

[0122] The selectivity, stability, repeatability, and reproducibility of a CoNiFe-PBA-based self-reporting molecularly imprinted electrochemical sensor for BPA detection were evaluated to verify its long-term accuracy in BPA detection. The selectivity evaluation of this sensor is crucial for practical applications.

[0123] To evaluate the selectivity of the sensor, competitive adsorption experiments were conducted using interfering agents dopamine (DA), ascorbic acid (AA), phenanthrene (PTE), and glucose (GS). Figure 8 As shown, the current response attenuation of the CoNiFe-PBA-based self-reporting molecularly imprinted electrochemical sensor for BPA (500 nM) was 2.66–2.99 times that of competing analytes. Notably, interference tests revealed minimal signal changes, confirming its excellent selectivity. This performance stems from the precise geometric matching between the molecularly imprinted holes and BPA recognition, as well as the synergistic integration of optimal functional group arrangement. The results indicate that the sensor possesses excellent specificity, exhibiting almost no cross-reactivity with structurally similar compounds. The MIP holes electropolymerized on CoNiFe-PBA / RGO / GCE exhibit a template-specific memory effect through geometric complementarity, functional group arrangement, and hydrophobic pocket matching. These properties enable MIP / CoNiFe-PBA / RGO / GCE to selectively distinguish structurally different compounds.

[0124] The reliability of the sensor was further verified through system evaluation of three key performance parameters (repeatability, reproducibility, and long-term stability). High signal stability was demonstrated through ten consecutive dynamic DPV analyses. DPV analysis (such as...) Figure 9As shown in (B), the signal gradually decayed by 8.6% over 10 measurement cycles in a 100 nM bisphenol A solution, confirming the robust operating characteristics of the sensor; Figure 9 As shown in (A), the five independently manufactured sensor electrodes exhibit excellent manufacturing reproducibility with minimal differences between the electrodes (relative standard deviation = 1.87%, n = 5), and the low RSD values ​​confirm the stability of the material synthesis and electrode modification schemes.

[0125] The MIP / CoNiFe-PBA / RGO / GCE working electrode prepared in this invention exhibits excellent storage stability, retaining 96.47% of its initial response after 14 days at 4°C. At room temperature, in a 15-day water immersion test (0.1M PBS, pH 7.4), the current retention rate for detecting 100 nM BPA was 93.81% (n=3), with a response variability of less than 8.4% (RSD=5.61%). Throughout the test, the sensor maintained stable performance in detecting 100 nM BPA, confirming its excellent long-term robustness. Stability assessments under storage and use conditions confirm the superior robustness of the MIP / CoNiFe-PBA / RGO / GCE platform. These results demonstrate the reliability of the CoNiFe-PBA-based self-reporting molecularly imprinted electrochemical sensor prepared in this invention for long-term sensing applications.

[0126] 3. Spike recovery detection of actual samples

[0127] To evaluate the practical applicability of this sensor, a recovery study was conducted on pretreated commercial milk samples. The accuracy of the method was evaluated by standard calibration using bisphenol A (BPA)-added standard samples at three concentration levels (25, 100, and 250 nM). Each concentration level was analyzed in triplicate (n = 3) under standardized conditions. As shown in Table 2, the sensor exhibited extremely high accuracy, with recoveries ranging from 97.18% to 102.96% at all test concentrations, while also demonstrating excellent precision (RSD = 2.40–4.31%, n = 3). The electrochemical results were validated by high-performance liquid chromatography (HPLC), demonstrating the consistency of the method (RSD). 2 =0.9993, slope =0.30405±0.004), see Table 3 for details of the HPLC detection results of BPA content in milk. These results confirm the reliability of the sensor in accurately quantifying bisphenol A in complex samples.

[0128] Table 2

[0129]

[0130] Table 3

[0131]

[0132] In summary, this invention innovatively proposes a self-reporting electrochemical sensor for the detection of bisphenol A (BPA). It combines molecularly imprinted polymers (MIPs), reduced graphene oxide (RGO), and CoNiFe-PBA nanocomposite materials to develop a CoNiFe-PBA-based self-reporting molecularly imprinted electrochemical sensor. The RGO substrate serves as a stable conductive platform with enhanced electroactive surface area, while the electrochemical conversion of CoNi-MOF to CoNiFe-PBA on RGO / GCE improves the sensor's sensitivity and provides an intrinsic redox signal for the self-reporting function. Molecular imprinting is achieved through the electrochemical polymerization of o-phenylenediamine monomers in the presence of a BPA template, significantly improving the sensor's specific recognition capability for BPA. Under optimized conditions, the sensor exhibits a detection range of 1-500 nM for BPA and a limit of detection (LOD) of 0.18 nM. The sensing platform exhibits excellent selectivity, reproducibility, and stability, demonstrating satisfactory recovery rates in milk samples with added BPA. The developed self-reporting sensor has the potential to efficiently detect BPA in complex real-world samples.

[0133] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a MIP / CoNiFe-PBA / RGO / GCE working electrode, characterized in that, Includes the following steps: A conductive substrate was modified with reduced graphene oxide and a cobalt-nickel-iron Prussian blue analogue. Bisphenol A was used as a template molecule and o-phenylenediamine as a functional monomer. A molecularly imprinted film was prepared on the surface of the conductive substrate modified with reduced graphene oxide and a cobalt-nickel-iron Prussian blue analogue by electrochemical in-situ electropolymerization. The template molecule was then washed off to obtain the MIP / CoNiFe-PBA / RGO / GCE working electrode.

2. The preparation method according to claim 1, characterized in that, Specifically, the following steps are included: A pretreated conductive substrate is immersed in a graphene oxide suspension, and reduced graphene oxide is deposited by cyclic voltammetry to obtain RGO / GCE. The RGO / GCE is then immersed in an organic solution containing Et3NHCl, H2BDC, Co(NO3)2·6H2O, and Ni(NO3)2·6H2O, and CoNi-MOF / RGO / GCE is obtained by potentiostatic deposition. The CoNi-MOF / RGO / GCE is placed in a KCl solution containing K3[Fe(CN)6], and CoNiFe-PBA / RGO / GCE is obtained by cyclic voltammetry. The CoNiFe-PBA / RGO / GCE is placed in a buffer system containing bisphenol A and o-phenylenediamine, and a molecularly imprinted polymer layer is formed on the surface of the CoNiFe-PBA / RGO / GCE by electrochemical in-situ electropolymerization. After elution of bisphenol A, the MIP / CoNiFe-PBA / RGO / GCE working electrode is obtained.

3. The preparation method according to claim 2, characterized in that, The conductive substrate is selected from metal substrates, carbon material substrates, or conductive glass substrates.

4. The preparation method according to claim 2, characterized in that, When preparing the RGO / GCE, the cyclic voltammetry cycle number is 20; the scan rate is 50 mV / s; and / or, when preparing the CoNi-MOF / RGO / GCE, the deposition time is 300 s; and / or, when preparing the CoNiFe-PBA / RGO / GCE, the cyclic voltammetry cycle number is 5; the scan rate is 50 mV / s; and / or, when preparing the molecularly imprinted polymer layer, the cyclic voltammetry cycle number is 15; the scan rate is 50 mV / s.

5. The preparation method according to claim 2, characterized in that, The specific procedure for eluting bisphenol A is as follows: methanol, acetic acid and water are mixed in a volume ratio of 7:3:2 to obtain an eluent, and eluted for 30 minutes.

6. A MIP / CoNiFe-PBA / RGO / GCE working electrode prepared by the preparation method according to any one of claims 1-5.

7. The application of the MIP / CoNiFe-PBA / RGO / GCE working electrode of claim 6 in the preparation of a self-reporting molecularly imprinted electrochemical sensor based on a cobalt-nickel-iron Prussian blue analogue.

8. A self-reporting molecularly imprinted electrochemical sensor based on a cobalt-nickel-iron Prussian blue analogue, characterized in that, The electrode was constructed using the MIP / CoNiFe-PBA / RGO / GCE electrode as described in claim 6, with Ag / AgCl as the reference electrode and Pt foil as the counter electrode.

9. The application of the self-reporting molecularly imprinted electrochemical sensor based on a cobalt-nickel-iron Prussian blue analogue as described in claim 8 in the detection of bisphenol A.

10. The application according to claim 9, characterized in that, Before detecting bisphenol A, MIP / CoNiFe-PBA / RGO / GCE needs to be incubated. The incubation process includes the following steps: immersing the MIP / CoNiFe-PBA / RGO / GCE in a 500 nM bisphenol A solution and incubating for 20 min.

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