Construction and application of an electrochemiluminescence sensor based on oxygen evolution reaction and self-supporting electrode

Abstract

The application discloses construction and application of an electrochemiluminescence sensor based on an oxygen evolution reaction and a self-supporting electrode, and belongs to the field of photoelectrochemistry, sensing analysis and material science technology.In the application, a Mn-NiFe-MOF / foam nickel-iron self-supporting electrode is synthesized by a one-step solvothermal method, which can not only enhance an electrochemiluminescence signal by catalyzing an oxygen evolution reaction, but also serve as a carrier of luminol, so that an electron transfer path between active oxygen and luminol is shortened, and the ECL efficiency of a luminol-H2O system is significantly improved.In addition, an amphoteric ion polymer is integrated onto the self-supporting electrode to resist non-specific adsorption of other functional components or bacteria in cosmetic raw materials.In the presence of a target 9-cis astaxanthin, dissolved oxygen is consumed, leading to a decrease in the ECL signal of luminol, so that the concentration of 9-cis astaxanthin can be accurately quantified.Based on this, the electrochemiluminescence sensor exhibits a wide detection range and a low detection limit, and exhibits excellent performance in the analysis of cosmetic raw materials.

Description

Technical Field

[0001] This invention discloses the construction and application of an electrochemiluminescence sensor based on the oxygen evolution reaction and a self-supporting electrode, belonging to the fields of photoelectrochemistry, sensing analysis, and materials science and technology. Background Technology

[0002] In cosmetic ingredients, L-astaxanthin exhibits higher antioxidant and anti-aging activity than D-astaxanthin and meso-astaxanthin, making the identification of astaxanthin chirality particularly important. Among them, cis-astaxanthin, especially 9-cis-astaxanthin, shows higher antioxidant activity in vitro compared to its all-trans isomer. Commercially available astaxanthins possess varying chiral structures due to different sources, making analysis challenging. Therefore, accurate and efficient analysis of 9-cis-astaxanthin is crucial for improving the efficacy of cosmetics. Electrochemiluminescence (ECL) analysis offers high sensitivity and low background signal, effectively monitoring 9-cis-astaxanthin in cosmetic raw materials. However, the sensor's detection accuracy and lifespan can be affected by interfering substances in the sample. Therefore, developing effective antifouling interfaces to resist such interferences is essential. Zwitterionic polymers, with their overall electroneutrality and uniform charge distribution, are considered promising antifouling materials and have been widely applied in sensor analysis.

[0003] In ECL systems, luminol primarily relies on H₂O₂ and dissolved O₂ as co-reactants to achieve ECL emission by generating reactive oxygen species. It is well known that the inherent instability of H₂O₂ and the low solubility of O₂ significantly limit luminol ECL emission. To enhance the ECL signal of luminol, numerous co-reaction promoters have been developed to catalyze the decomposition of H₂O₂, dissolved O₂, and dissolved oxygen. However, the biotoxicity of H₂O₂ and the low content of dissolved O₂ limit the catalytic efficacy of co-reaction promoters and the sensing applications of luminol systems. Therefore, developing a novel co-reactant to improve the analytical applications of luminol systems is imperative.

[0004] The oxygen evolution reaction (OER) is a key half-reaction in water splitting, continuously generating reactive oxygen species (ROS) to achieve luminol ECL emission. During OER, H₂O can serve as an effective co-reactant in the luminol system. OER involves a complex four-electron transfer process; therefore, designing efficient OER catalysts to promote luminol-water ECL emission is crucial. Metal-organic frameworks (MOFs) are considered ideal catalysts for OER due to their large specific surface area and diverse structures. To improve the stability and lifespan of the OER catalyst, Mn-NiFe-MOF is grown in situ on the surface of nickel-iron foam as a self-supporting electrode. Furthermore, luminol is integrated onto the self-supporting electrode, effectively shortening the distance between luminol and the generated ROS, thus achieving strong and stable ECL emission of the luminol-water system.

[0005] In this invention, luminol is used as the luminescent agent, H2O as the co-reactant, and Mn-NiFe-MOF / nickel-iron foam as the co-reaction promoter to construct a highly efficient ECL antifouling sensor for the detection of 9-cis-astaxanthin in cosmetic raw materials. Due to its larger electrochemically active surface area and faster OER kinetics, the prepared Mn-NiFe-MOF / nickel-iron foam self-supporting electrode can continuously generate reactive oxygen species, effectively improving the ECL emission of luminol in H2O. Furthermore, a zwitterionic polymer of sulfonate betaine methacrylate is prepared and integrated into the Mn-NiFe-MOF / nickel-iron foam self-supporting electrode as an antifouling component to avoid the non-specific adsorption of interfering substances in cosmetic raw materials. With the introduction of 9-cis-astaxanthin, it consumes the generated reactive oxygen species, thereby reducing the ECL signal of luminol. Based on this, the ECL sensor constructed using the Mn-NiFe-MOF / nickel-iron foam self-supporting electrode can achieve the tracking and monitoring of 9-cis-astaxanthin in cosmetic raw materials. Summary of the Invention

[0006] One of the technical objectives of this invention is to overcome the shortcomings of the prior art by combining OER catalysis and ECL analysis to prepare a Mn-NiFe-MOF / foamed nickel-iron self-supporting electrode.

[0007] The second technical objective of this invention is to develop a high-efficiency ECL sensor that does not require external co-reactants, based on the catalytic effect of the prepared Mn-NiFe-MOF / foamed nickel-iron self-supporting electrode. The raw materials used are low-cost, the preparation process is simple, and the operation is safe.

[0008] The third technical objective of this invention is to provide an application for an ECL sensor based on OER and self-supporting electrodes constructed by the aforementioned method, namely, for trace monitoring of 9-cis-astaxanthin in cosmetic raw materials, which has certain industrialization prospects.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] 1. Construction of an ECL sensor based on OER and self-supporting electrodes

[0011] A Mn-NiFe-MOF / foamed nickel-iron self-supporting electrode was immersed in a luminol solution with a concentration of 0.6–0.8 mg / mL and stirred at room temperature for 1 h to obtain a luminol-loaded Mn-NiFe-MOF / foamed nickel-iron self-supporting electrode. A zwitterionic polymer of sulfobetaine methacrylate was introduced into the luminol-loaded Mn-NiFe-MOF / foamed nickel-iron self-supporting electrode as an antifouling component, and an ECL sensor based on OER and a self-supporting electrode was constructed.

[0012] The Mn-NiFe-MOF / foamed nickel-iron self-supporting electrode is prepared by sequentially activating the foamed nickel-iron with ultrasonication using 2M HCl, ultrapure water, and ethanol; dissolving 5.0 mg of MnCl2·4H2O in 15 mL of N,N-dimethylformamide and 2.0 mL of ethanol to form solution A; dissolving 6.0 mg of 2,5-dihydroxyterephthalic acid in 15 mL of N,N-dimethylformamide to form solution B; immersing the activated foamed nickel-iron in the mixture of solutions A and B, ultrasonicating for 5 min, and reacting at 120℃ for 24 h; collecting the immersed foamed nickel-iron, washing it sequentially with N,N-dimethylformamide and ethanol, and drying it at 60℃ to obtain the Mn-NiFe-MOF / foamed nickel-iron self-supporting electrode.

[0013] The zwitterionic polymer of betaine sulfonate methacrylate was prepared by dispersing a mixture of 265 μL of glycidyl methacrylate and 2.23 g of betaine sulfonate methacrylate in 10 mL of a mixed solution of methanol and water (V1:V2 = 1:1), stirring for 10 min, and then purging with nitrogen for 15 min; adding 16.2 mg of initiator azobisisobutyronitrile, and continuing to purge with nitrogen for 15 min; heating the mixture at 60 °C for 6 h, and then cooling it at room temperature for 5 h; dispersing the resulting product in water and purifying it three times with methanol; and freeze-drying the purified product to obtain the zwitterionic polymer of betaine sulfonate methacrylate.

[0014] 2. The application of the ECL sensor based on OER and self-supporting electrodes constructed by the described method is for the detection of 9-cis-astaxanthin in cosmetic raw materials.

[0015] The prepared ECL sensor based on OER and self-supporting electrode was immersed in different concentrations of 9-cis-astaxanthin. A three-electrode system was constructed using an Ag / AgCl electrode as the reference electrode, a platinum wire as the auxiliary electrode, and a prepared Mn-NiFe-MOF / foamed nickel-iron self-supporting electrode as the working electrode for ECL signal testing. A phosphate buffer solution with a pH of 8–10 was used as the detection solution. The applied scanning voltage range was 0–1V, and the photomultiplier tube voltage was 700V. Based on the measured ECL signals, the working curve was plotted, showing that the detection range of the constructed ECL sensor was 10 pM–100 μM, with a detection limit as low as 3.29 pM. It exhibits high stability, specificity, and reproducibility, making it suitable for trace monitoring of 9-cis-astaxanthin in cosmetic raw materials.

[0016] The beneficial technical effects of the present invention are as follows:

[0017] 1. This invention prepares a Mn-NiFe-MOF / foamed nickel-iron self-supporting electrode, which can not only enhance the ECL signal by catalyzing the OER process, but also serve as a carrier for luminol, thereby shortening the distance between reactive oxygen species and luminol and achieving effective signal amplification;

[0018] 2. This invention constructs an ECL sensor based on OER and a self-supporting electrode. By utilizing the prepared Mn-NiFe-MOF / foamed nickel-iron self-supporting electrode to integrate the highly efficient catalytic and antifouling components of the OER process, such as betaine sulfonate methacrylate zwitterionic polymer, the detection sensitivity and accuracy of the ECL sensor are improved, and its service life is extended.

[0019] 3. The ECL sensor based on OER and self-supporting electrode constructed in this invention exhibits a wide linear range and low detection limit for the detection of 9-cis-astaxanthin in cosmetic raw materials, as well as high stability, specificity and reproducibility. It is suitable for chiral identification and content monitoring of astaxanthin and has certain industrialization prospects. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the scope of protection of the present invention is not limited thereto. Any changes made to the technical solutions of the present invention by those skilled in the art should fall within the scope of protection of the present invention.

[0021] Example 1: Construction of an ECL sensor based on OER and self-supporting electrodes

[0022] A Mn-NiFe-MOF / nickel-iron foam self-supporting electrode was immersed in a 0.6 mg / mL luminol solution and stirred at room temperature for 1 h to obtain a luminol-loaded Mn-NiFe-MOF / nickel-iron foam self-supporting electrode. A zwitterionic polymer of sulfonate betaine methacrylate was introduced into the luminol-loaded Mn-NiFe-MOF / nickel-iron foam self-supporting electrode as an antifouling component, constructing an ECL sensor based on OER and a self-supporting electrode. The Mn-NiFe-MOF / nickel-iron foam self-supporting electrode was prepared by sequentially reacting 2M HCl, ultrapure water, and ethanol with the luminol-loaded nickel foam. Iron was ultrasonically activated; 5.0 mg of MnCl2·4H2O was dissolved in 15 mL of N,N-dimethylformamide and 2.0 mL of ethanol to form solution A; 6.0 mg of 2,5-dihydroxyterephthalic acid was dissolved in 15 mL of N,N-dimethylformamide to form solution B; the activated nickel-iron foam was immersed in the mixture of solution A and solution B, ultrasonically treated for 5 min, and reacted at 120 °C for 24 h; the immersed nickel-iron foam was collected, washed sequentially with N,N-dimethylformamide and ethanol, and dried at 60 °C to obtain a Mn-NiFe-MOF / nickel-iron foam self-supporting electrode;

[0023] The zwitterionic polymer of betaine sulfonate methacrylate was prepared by dispersing a mixture of 265 μL of glycidyl methacrylate and 2.23 g of betaine sulfonate methacrylate in 10 mL of a mixed solution of methanol and water (V1:V2 = 1:1), stirring for 10 min, and then purging with nitrogen for 15 min; adding 16.2 mg of initiator azobisisobutyronitrile, and continuing to purge with nitrogen for 15 min; heating the mixture at 60 °C for 6 h, and then cooling it at room temperature for 5 h; dispersing the resulting product in water and purifying it three times with methanol; and freeze-drying the purified product to obtain the zwitterionic polymer of betaine sulfonate methacrylate.

[0024] Example 2: Construction of an ECL sensor based on OER and self-supporting electrodes

[0025] A luminol-loaded Mn-NiFe-MOF / nickel-iron foam self-supporting electrode was immersed in a luminol solution with a concentration of 0.7 mg / mL and stirred at room temperature for 1 h to obtain a luminol-loaded Mn-NiFe-MOF / nickel-iron foam self-supporting electrode. A zwitterionic polymer of sulfobetaine methacrylate was introduced into the luminol-loaded Mn-NiFe-MOF / nickel-iron foam self-supporting electrode as an antifouling component, constructing an ECL sensor based on OER and a self-supporting electrode. The Mn-NiFe-MOF / nickel-iron foam self-supporting electrode was prepared by sequentially reacting 2M HCl, ultrapure water, and ethanol with the luminol-loaded nickel foam. Iron was ultrasonically activated; 5.0 mg of MnCl2·4H2O was dissolved in 15 mL of N,N-dimethylformamide and 2.0 mL of ethanol to form solution A; 6.0 mg of 2,5-dihydroxyterephthalic acid was dissolved in 15 mL of N,N-dimethylformamide to form solution B; the activated nickel-iron foam was immersed in the mixture of solution A and solution B, ultrasonically treated for 5 min, and reacted at 120 °C for 24 h; the immersed nickel-iron foam was collected, washed sequentially with N,N-dimethylformamide and ethanol, and dried at 60 °C to obtain a Mn-NiFe-MOF / nickel-iron foam self-supporting electrode;

[0026] The zwitterionic polymer of betaine sulfonate methacrylate was prepared by dispersing a mixture of 265 μL of glycidyl methacrylate and 2.23 g of betaine sulfonate methacrylate in 10 mL of a mixed solution of methanol and water (V1:V2 = 1:1), stirring for 10 min, and then purging with nitrogen for 15 min; adding 16.2 mg of initiator azobisisobutyronitrile, and continuing to purge with nitrogen for 15 min; heating the mixture at 60 °C for 6 h, and then cooling it at room temperature for 5 h; dispersing the resulting product in water and purifying it three times with methanol; and freeze-drying the purified product to obtain the zwitterionic polymer of betaine sulfonate methacrylate.

[0027] Example 3: Construction of an ECL sensor based on OER and self-supporting electrodes

[0028] A luminol-loaded Mn-NiFe-MOF / nickel-iron foam self-supporting electrode was immersed in a luminol solution with a concentration of 0.8 mg / mL and stirred at room temperature for 1 h to obtain a luminol-loaded Mn-NiFe-MOF / nickel-iron foam self-supporting electrode. A zwitterionic polymer of sulfonate betaine methacrylate was introduced into the luminol-loaded Mn-NiFe-MOF / nickel-iron foam self-supporting electrode as an antifouling component, constructing an ECL sensor based on OER and a self-supporting electrode. The Mn-NiFe-MOF / nickel-iron foam self-supporting electrode was prepared by sequentially reacting 2M HCl, ultrapure water, and ethanol with the luminol-loaded nickel foam. Iron was ultrasonically activated; 5.0 mg of MnCl2·4H2O was dissolved in 15 mL of N,N-dimethylformamide and 2.0 mL of ethanol to form solution A; 6.0 mg of 2,5-dihydroxyterephthalic acid was dissolved in 15 mL of N,N-dimethylformamide to form solution B; the activated nickel-iron foam was immersed in the mixture of solution A and solution B, ultrasonically treated for 5 min, and reacted at 120 °C for 24 h; the immersed nickel-iron foam was collected, washed sequentially with N,N-dimethylformamide and ethanol, and dried at 60 °C to obtain a Mn-NiFe-MOF / nickel-iron foam self-supporting electrode;

[0029] The zwitterionic polymer of betaine sulfonate methacrylate was prepared by dispersing a mixture of 265 μL of glycidyl methacrylate and 2.23 g of betaine sulfonate methacrylate in 10 mL of a mixed solution of methanol and water (V1:V2 = 1:1), stirring for 10 min, and then purging with nitrogen for 15 min; adding 16.2 mg of initiator azobisisobutyronitrile, and continuing to purge with nitrogen for 15 min; heating the mixture at 60 °C for 6 h, and then cooling it at room temperature for 5 h; dispersing the resulting product in water and purifying it three times with methanol; and freeze-drying the purified product to obtain the zwitterionic polymer of betaine sulfonate methacrylate.

[0030] Example 4 describes the application of an ECL sensor based on OER and a self-supporting electrode constructed using the methods described in Examples 1, 2, and 3, for the detection of 9-cis-astaxanthin in cosmetic raw materials. The prepared ECL sensor based on OER and a self-supporting electrode was immersed in different concentrations of 9-cis-astaxanthin. A three-electrode system was constructed using an Ag / AgCl electrode as the reference electrode, a platinum wire as the auxiliary electrode, and a prepared Mn-NiFe-MOF / foamed nickel-iron self-supporting electrode as the working electrode for ECL signal testing. A phosphate buffer solution with a pH of 8 was used as the detection solution. The applied scanning voltage range was 0–1V, and the photomultiplier tube voltage was 700V. Based on the measured ECL signals, a working curve was plotted, showing that the constructed ECL sensor has a detection range of 10 pM–100 μM and a detection limit as low as 3.29 pM, exhibiting high stability, specificity, and reproducibility, making it suitable for trace monitoring of 9-cis-astaxanthin in cosmetic raw materials.

[0031] Example 5 describes the application of an ECL sensor based on OER and a self-supporting electrode constructed using the methods described in Examples 1, 2, and 3, for the detection of 9-cis-astaxanthin in cosmetic raw materials. The prepared ECL sensor based on OER and a self-supporting electrode was immersed in different concentrations of 9-cis-astaxanthin. A three-electrode system was constructed using an Ag / AgCl electrode as the reference electrode, a platinum wire as the auxiliary electrode, and a prepared Mn-NiFe-MOF / foamed nickel-iron self-supporting electrode as the working electrode for ECL signal testing. A phosphate buffer solution with pH 9 was used as the detection solution. The applied scanning voltage range was 0–1V, and the photomultiplier tube voltage was 700V. Based on the measured ECL signals, a working curve was plotted, showing that the constructed ECL sensor has a detection range of 10 pM–100 μM and a detection limit as low as 3.29 pM, exhibiting high stability, specificity, and reproducibility, making it suitable for trace monitoring of 9-cis-astaxanthin in cosmetic raw materials.

[0032] Example 6 describes the application of an ECL sensor based on OER and a self-supporting electrode constructed using the methods described in Examples 1, 2, and 3, for the detection of 9-cis-astaxanthin in cosmetic raw materials. The prepared ECL sensor based on OER and a self-supporting electrode was immersed in different concentrations of 9-cis-astaxanthin. A three-electrode system was constructed using an Ag / AgCl electrode as the reference electrode, a platinum wire as the auxiliary electrode, and a prepared Mn-NiFe-MOF / foamed nickel-iron self-supporting electrode as the working electrode for ECL signal testing. A phosphate buffer solution with a pH of 10 was used as the detection solution. The applied scanning voltage range was 0–1V, and the photomultiplier tube voltage was 700V. Based on the measured ECL signals, a working curve was plotted, showing that the constructed ECL sensor has a detection range of 10 pM–100 μM and a detection limit as low as 3.29 pM, exhibiting high stability, specificity, and reproducibility, making it suitable for trace monitoring of 9-cis-astaxanthin in cosmetic raw materials. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the construction process of an ECL sensor based on OER and self-supporting electrodes (Foamed Nickel Iron: NFF; Glycidyl Methacrylate: GMA; Sulfonate Betaine Methacrylate: SBMA; Azobisisobutyronitrile: AIBN; Sulfonate Betaine Methacrylate Zwitterionic Polymer: GCS; 9-cis-Astaxanthin: 9-cis-Ast).

[0034] Figure 2 Scanning electron microscope (SEM) images of (A) Mn-NiFe-MOF, (B) Mn-NiFe-MOF@luminol, and (C) Mn-NiFe-MOF@luminol / GCS.

[0035] Figure 3 Infrared spectra of H4DOBDC and Mn-NiFe-MOF (2,5-dihydroxyterephthalic acid: H4DOBDC).

[0036] Figure 4 Infrared spectra of SBMA and GCS.

[0037] Figure 5 The X-ray photoelectron spectra of Mn-NiFe-MOF are shown below. (A) X-ray photoelectron spectrum of the whole region; (B) High-resolution X-ray photoelectron spectrum of Ni 2p region; (C) High-resolution X-ray photoelectron spectrum of Fe 2p region; (D) High-resolution X-ray photoelectron spectrum of Mn 2p region.

[0038] Figure 6 The image shows the scanning electron microscope (SEM) image and corresponding elemental mapping of Mn-NiFe-MOF / NFF.

[0039] Figure 7 (A) Linear sweep current-voltage curves, (B) Tafel plots, and (C) double-layer capacitance values ​​are shown for NFF, NiFe-MOF / NFF, and Mn-NiFe-MOF / NFF.

[0040] Figure 8 ECL intensity-potential curves for NFF@luminol, NiFe-MOF / NFF@luminol, and Mn-NiFe-MOF / NFF@luminol.

[0041] Figure 9 ECL intensity-potential curves of Mn-NiFe-MOF / NFF@luminol in the voltage ranges of 0–0.7V (inset) and 0–1V.

[0042] Figure 10 ECL intensity-potential curves of Mn-NiFe-MOF / NFF@luminol in saturated solutions of air, N2, and O2, respectively.

[0043] Figure 11 This is the electron paramagnetic resonance spectrum of the luminol-H2O system.

[0044] Figure 12 Contact angle diagrams for GCE and GCS-modified GCE (glassy carbon electrode: GCE).

[0045] Figure 13 Fluorescence imaging of ITO modified with ITO and GCS after incubation in fluorescein-labeled bovine serum albumin.

[0046] Figure 14 Fluorescent imaging of bacterial adhesion on a glass slide and a GCS-coated glass slide.

[0047] Figure 15 The diagram shows the optimization results of the ECL sensor based on OER and self-supporting electrode, where (A) is the optimized scan potential, (B) is the optimized pH, and (C) is the optimized scan rate.

[0048] Figure 16 (A) ECL response curves (10 pM, 100 pM, 1 nM, 10 nM, 100 nM, 1 μM, 10 μM and 100 μM) and (B) corresponding calibration curves are shown for the ECL sensor based on OER and self-supporting electrode after incubation with different concentrations of 9-cis-astaxanthin.

[0049] Figure 17 The following are the (A) signal stability, (B) storage stability, (C) selectivity, and (D) reproducibility of an ECL sensor based on OER and self-supporting electrodes.

Claims

1. A method for constructing an electrochemiluminescence sensor based on the oxygen evolution reaction and a self-supporting electrode, characterized in that, A luminol-loaded Mn-NiFe-MOF / foamed nickel-iron self-supporting electrode was immersed in a luminol solution with a concentration of 0.6 ~ 0.8 mg / mL and stirred at room temperature for 1 h to obtain a luminol-loaded Mn-NiFe-MOF / foamed nickel-iron self-supporting electrode. A zwitterionic polymer of sulfobetaine methacrylate was introduced into the luminol-loaded Mn-NiFe-MOF / foamed nickel-iron self-supporting electrode as an antifouling component, thus constructing an electrochemiluminescence sensor based on the oxygen evolution reaction and the self-supporting electrode.

2. The method for constructing an electrochemiluminescence sensor based on the oxygen evolution reaction and a self-supporting electrode as described in claim 1, characterized in that, The Mn-NiFe-MOF / foamed nickel-iron self-supporting electrode was prepared by sequentially activating the foamed nickel-iron with ultrasonication using 2 M HCl, ultrapure water, and ethanol. Solution A was prepared by dissolving 5.0 mg of MnCl2·4H2O in 15 mL of N,N-dimethylformamide and 2.0 mL of ethanol. Solution B was prepared by dissolving 6.0 mg of 2,5-dihydroxyterephthalic acid in 15 mL of N,N-dimethylformamide. The activated foamed nickel-iron was immersed in the mixture of solutions A and B, ultrasonically treated for 5 min, and reacted at 120 °C for 24 h. The immersed foamed nickel-iron was collected, washed sequentially with N,N-dimethylformamide and ethanol, and dried at 60 °C to obtain the Mn-NiFe-MOF / foamed nickel-iron self-supporting electrode.

3. The method for constructing an electrochemiluminescence sensor based on the oxygen evolution reaction and a self-supporting electrode as described in claim 1, characterized in that, The zwitterionic polymer of betaine methacrylate is prepared by dispersing a mixture of 265 μL of glycidyl methacrylate and 2.23 g of betaine methacrylate in 10 mL of a mixed solution of methanol and water. V 1: Water V 2 = 1:1, stirred for 10 min, then purged with nitrogen for 15 min; added 16.2 mg of initiator azobisisobutyronitrile, and continued purging with nitrogen for 15 min; heated the mixture at 60 °C for 6 h, and cooled at room temperature for 5 h; dispersed the obtained product in water and purified it three times with methanol; freeze-dried the purified product to obtain zwitterionic polymer of sulfobetaine methacrylate.

4. The use of an electrochemiluminescence sensor based on the oxygen evolution reaction and a self-supporting electrode constructed by the method described in claim 1, characterized in that, Application in the detection of 9-cis-astaxanthin in cosmetic raw materials.

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