Working electrode for estradiol detection electrochemical sensor, electrochemical sensor and application thereof
By modifying the electrode substrate with oxides and carbon nanotubes, an electrochemical sensor for estradiol detection was constructed, which solved the problems of insufficient sensitivity and specificity in the prior art and realized efficient and simple estradiol detection.
Patent Information
- Application Number
- CN202511820166.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-04
- Publication Date
- 2026-03-06
Smart Images
Figure CN121612955A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a working electrode for an electrochemical sensor for estradiol detection, an electrochemical sensor, and their applications, belonging to the field of electrochemical biosensor technology. Background Technology
[0002] Estradiol (E2) is a steroidal estrogen and one of the main estrogens secreted by the ovaries. As a core regulator of the human endocrine system, it plays a crucial role in reproductive system development, metabolic homeostasis maintenance, and neuroendocrine regulation. Fluctuations in estrogen concentrations in biological samples such as blood and urine are directly related to the development of diseases such as polycystic ovary syndrome, breast cancer, and menopausal syndrome. Accurate monitoring of estradiol levels not only provides important evidence for the early diagnosis of gynecological diseases but also serves as a key technical support for the development of individualized hormone replacement therapy plans and efficacy evaluation.
[0003] Meanwhile, estradiol was one of the first 12 endocrine disruptors identified as persistent pollutants in the Stockholm Convention on Persistent Organic Pollutants, signed in 2002. Estradiol can bioaccumulate in ecosystems through the food chain and accumulate in adipose tissue, causing damage to human organs and inducing diseases such as breast cancer, prostate cancer, and reproductive disorders. Therefore, estradiol is listed as a priority pollutant by the EU Water Framework Directive. However, for economic reasons, some farms still illegally use estrogens as growth promoters to improve breeding efficiency and the lean meat ratio of livestock, which exacerbates the accumulation of estradiol in humans and other organisms and its destructive effects on the ecological environment. Therefore, sensitive, rapid, and low-cost methods for measuring estradiol pollution in the environment are needed to track and monitor its levels.
[0004] Currently, methods for detecting estradiol mainly include gas chromatography, high-performance liquid chromatography, enzyme-linked immunosorbent assay (ELISA), fluorescence immunoassay, and suspension array technology. While each method has its advantages, they all have limitations. For example, these methods often require multiple sample preparation steps, including extraction and cleaning procedures; some technologies also generate waste liquid containing organic solvents, leading to environmental pollution, and the detection procedures are complex and expensive, hindering continuous in-situ analysis. However, with the development of point-of-care testing technologies, estradiol detection is being upgraded towards convenient operation, rapid response, and non-invasive portability to meet the practical needs of point-of-care diagnosis and health management.
[0005] Electrochemical sensing technology has become a research hotspot in estradiol detection due to its numerous advantages, including low instrument cost, simple operation, automation, and high accuracy. Zheng Zhixiang et al. (Construction and Application Research of Estradiol Electrochemical Sensor Based on Pd / g-C3N4-SWCNTs. Journal of Analytical Testing. October 2019) used melamine with abundant π electrons on its surface and single-walled carbon nanotubes as precursors. Through solid-state grinding-thermal polymerization, they stacked the two materials via π-π electrostatic interactions to obtain a graphitic carbon nitride-SWC-NTs composite material. Then, using Na2PdCl4 as a Pd nanoparticle precursor, g-C3N4-SWCNTs were functionalized through self-assembly to obtain the Pd / g-C3N4-SWCNTs complex. The electrocatalytic oxidation performance of this material for estradiol was studied using electrochemical methods such as cyclic voltammetry. The results showed that the sensor constructed from this material had good stability and selectivity, and there was no significant difference in methodology compared to HPLC. However, the preparation process of Pd / g-C3N4-SWCNTs composite materials is complex, and the sensitivity and selectivity of their detection still need to be improved. Summary of the Invention
[0006] The first objective of this invention is to provide a working electrode for an electrochemical sensor for estradiol detection, providing a working electrode for an electrochemical sensor that combines sensitivity and specificity for estradiol detection.
[0007] The second objective of this invention is to provide an electrochemical sensor for estradiol detection, which offers both sensitivity and specificity for the detection of estradiol.
[0008] The third objective of this invention is to provide a working electrode for an electrochemical sensor for estradiol detection or the application of an electrochemical sensor for estradiol detection in estradiol detection, in order to solve the problem that the sensitivity and specificity of estradiol detection in the prior art still need to be improved.
[0009] To achieve the above objectives, the technical solution adopted by the working electrode of the estradiol detection electrochemical sensor in this invention is as follows: A working electrode for an electrochemical sensor for estradiol detection, wherein the electrode substrate surface is modified with an electrode material layer; the electrode material layer is composed of an oxide and a perfluorosulfonic acid polymer, or is composed of an oxide, carbon nanotubes and a perfluorosulfonic acid polymer; the oxide is one of zinc oxide, tin dioxide, and iron(III) oxide.
[0010] The beneficial effects of the above solution are as follows: the working electrode of the estradiol detection electrochemical sensor of the present invention is a pioneering invention. Extensive experiments in the early stages of this invention revealed that oxides such as zinc oxide, tin dioxide, and iron(III) oxide possess excellent anti-interference properties and molecular recognition capabilities, enabling accurate detection of estradiol at low concentrations or in the presence of other interfering factors. This has broad application prospects in multiple fields such as clinical diagnosis, environmental monitoring, and food safety.
[0011] Furthermore, the oxide modified with the working electrode of the estradiol detection electrochemical sensor of the present invention does not require a complicated preparation process, which greatly simplifies the preparation process of the working electrode and facilitates its widespread use. Moreover, the present invention also provides new application directions for oxides.
[0012] As a further improvement, the mass ratio of the oxide to the carbon nanotube is (4~4.5):1.
[0013] As a further improvement, the modification involves preparing the material to be modified into a dispersion, then coating it onto the surface of an electrode substrate, and drying it to form an electrode material layer.
[0014] As a further improvement, 10 μL of perfluorosulfonic acid polymer solution is used for every (4~4.5) mg of oxide.
[0015] As a further improvement, the mass concentration of the perfluorosulfonic acid polymer in the perfluorosulfonic acid polymer solution is 5.0% to 5.4%.
[0016] As a further improvement, the solvent of the dispersion is a mixed solution of ethanol and water; the volume ratio of ethanol to water is (1~1.2):(3~3.5).
[0017] As a further improvement, the particle size of the oxide is 10~60 nm.
[0018] To achieve the above objectives, the technical solution adopted by the estradiol detection electrochemical sensor in this invention is as follows: An electrochemical sensor for estradiol detection includes a working electrode, a reference electrode, and a counter electrode, wherein the working electrode is a working electrode for an electrochemical sensor for estradiol detection.
[0019] The beneficial effects of the above scheme are as follows: This invention utilizes an oxide-modified electrode substrate to prepare a working electrode, which, together with a reference electrode and a counter electrode, forms a three-electrode system to construct an electrochemical sensor. The estradiol detection electrochemical sensor prepared by this invention exhibits outstanding advantages in estradiol detection reactivity and selectivity.
[0020] Specifically, the reference electrode or counter electrode is selected from, but is not limited to, a platinum electrode, a titanium electrode, a saturated calomel electrode, a silver-silver chloride electrode, a mercury oxide electrode, and a graphite electrode.
[0021] To achieve the above objectives, the technical solution adopted in this invention for the application of a working electrode for an electrochemical sensor for estradiol detection or an electrochemical sensor for estradiol detection in estradiol detection is as follows: An electrochemical sensor for estradiol detection, comprising a working electrode or an application of an electrochemical sensor for estradiol detection in the detection of estradiol, wherein the application is not for disease diagnosis or treatment purposes.
[0022] The beneficial effects of the above scheme are as follows: Experiments have shown that as the concentration of estradiol in the electrolyte increases, the electrochemical signal generated by the working electrode gradually increases, showing a good linear relationship, and the lowest detection limit can reach 0.2 μM, which has high sensitivity and excellent sensing performance.
[0023] Furthermore, when the sample to be tested contains estradiol (E2), testosterone (T), cortisol (HC), and cortisone (COR), the oxidation peak of estradiol does not change significantly, indicating that the electrochemical sensor constructed in this invention only has a good response to estradiol, while it has almost no response to testosterone, cortisol, and cortisone. This fully demonstrates that the estradiol electrochemical sensor provided by this invention has good anti-interference performance.
[0024] As a further improvement, the application includes the following steps: (1) Place the working electrode, reference electrode and counter electrode in the same electrolyte, add estradiol standard solutions of different concentrations to change the concentration of estradiol in the electrolyte, and use differential pulse voltammetry to detect it. Use the estradiol concentration as the abscissa and the corresponding peak current as the ordinate to establish a standard curve of estradiol molecules. (2) Place the working electrode, reference electrode and counter electrode in the electrolyte of the sample to be tested, perform differential pulse voltammetry scanning, record the peak current, and combine with the standard curve obtained in step (1) to obtain the content of estradiol molecules in the sample to be tested. Attached Figure Description
[0025] Figure 1 The image shows the DPV diagram of the electrochemical sensor for estradiol detection in Example 1 of this invention, characterized by electrochemical characterization in different concentrations of estradiol (response of zinc oxide to different concentrations of estradiol, detection range of 2-100 μM estradiol, LOD of 2OD estradiol). Figure 2 The DPV diagrams of the electrochemical sensor for estradiol detection in Example 2 of this invention (response of iron oxide to different concentrations of estradiol, detection range is 5-100 μM estradiol). Figure 3 This is a scanning electron microscope (SEM) image of the modified material of the working electrode for the estradiol detection electrochemical sensor in Example 3 of the present invention. Figure 4 The image shows the DPV diagram of the electrochemical sensor for estradiol detection in Example 3 of the present invention, which is characterized by electrochemical characterization in different concentrations of estradiol (the response of porous tin oxide to different concentrations of estradiol, the detection range is 200 nM-1 μM estradiol, and the detection limit is 200 nM estradiol). Figure 5 The image shows the DPV diagram of the electrochemical sensor for estradiol detection in Example 4 of this invention, which is the response of tin oxide to different concentrations of estradiol. The detection range is 600 nM-10 μM estradiol, and the detection limit is 600 nM estradiol. Figure 6 The graph shows the linear fitting results of the estradiol detection electrochemical sensor in Example 4 of this invention for different concentrations of estradiol in 0.01M PBS (pH 7.2~7.4); Figure 7 The response of the estradiol detection electrochemical sensor in Example 5 of the present invention to 1 μM estradiol (E2), testosterone (T), cortisol (HC) and cortisone (COR); Figure 8 This is a comparison of the sensitivity of electrochemical sensors constructed using zinc oxide and carbon nanotubes as modifying materials in different mass ratios in Example 6 of the present invention to estradiol molecules (wherein, from left to right and from top to bottom, the mass ratios of zinc oxide and carbon nanotubes are 4:1, 4:2, 4:3, and 4:4). Detailed Implementation
[0026] Estrogen, primarily produced by the ovaries, plays a crucial role in the female reproductive cycle, and accurate estrogen detection is essential for a comprehensive assessment of women's reproductive health. Meanwhile, estradiol is also a persistent endocrine disruptor that can accumulate in ecosystems through the food chain, causing organ damage and inducing various serious diseases. Therefore, establishing a sensitive, rapid, and low-cost method for estradiol detection is crucial not only for meeting the needs of point-of-care diagnosis and health management but also for tracking and monitoring the levels of estradiol contamination.
[0027] Current technologies such as liquid chromatography, liquid chromatography-mass spectrometry, and gas chromatography-mass spectrometry often require sample pretreatment, are time-consuming, and involve expensive equipment. Compared to these methods, electrochemical detection methods have attracted significant attention for estradiol detection due to their high sensitivity, simple instrumentation, and fast reaction speed. However, estradiol exhibits a weak redox signal on bare glassy carbon electrodes. To improve the electrocatalytic activity and anti-interference ability of estradiol on the electrode surface, various materials have been used to modify the electrodes and apply them to the electrochemical detection of estradiol. However, the preparation processes of many materials in existing technologies are complex, and the sensitivity and specificity of electrochemical sensors constructed using modified electrodes as working electrodes still need improvement in estradiol detection.
[0028] Based on this, the present invention first provides a working electrode for an electrochemical sensor for estradiol detection. The working electrode is constructed by modifying the electrode substrate (e.g., a glassy carbon electrode) with oxides such as zinc oxide, tin dioxide, or iron oxide. The constructed working electrode for the electrochemical sensor for estradiol detection exhibits high chemical stability and high sensitivity, and has a relatively low detection limit when detecting estradiol.
[0029] Furthermore, the present invention further modifies the electrode substrate with carbon nanotubes (CNTs). The working electrode prepared by modifying the electrode substrate with oxides and carbon nanotubes has a high specific surface area, excellent electronic conductivity and catalytic activity, and can significantly improve the adsorption capacity and oxidation efficiency of estradiol. To improve the sensitivity of estradiol detection, preferably, the mass ratio of the oxide to carbon nanotubes is (4~4.5):1.
[0030] Further, the material to be modified (e.g., oxides and perfluorosulfonic acid polymers, oxides, carbon nanotubes and perfluorosulfonic acid polymers) is uniformly dispersed in a mixed solution of ethanol and water, then coated onto the surface of the electrode substrate and allowed to stand to form a film. To effectively prevent material aggregation and ensure film uniformity, preferably, the mass-to-volume ratio of the oxide to the mixed solution is 4 mg:500 μL, and the volume ratio of the ethanol to water is (1~1.2):(3~3.5).
[0031] Furthermore, 10 μL of perfluorosulfonic acid polymer solution is used for every (4~4.5) mg of oxide.
[0032] Furthermore, the particle size of the oxide is 10~60 nm.
[0033] Secondly, this invention utilizes the working electrode of an estradiol detection electrochemical sensor to construct an electrochemical sensor. The preparation method of this electrochemical sensor is simple and the conditions are easy to control. It combines the characteristics of good conductivity and catalysis, which makes the sensor exhibit outstanding advantages in terms of detection response and selectivity.
[0034] Finally, this invention provides the application of the above-described working electrode or electrochemical sensor in estradiol detection.
[0035] Furthermore, the process in application is as follows: (1) Place the working electrode, reference electrode and counter electrode in the same electrolyte, add estradiol standard solutions of different concentrations to change the concentration of estradiol in the electrolyte, and use differential pulse voltammetry to detect it. Use the estradiol concentration as the abscissa and the corresponding peak current as the ordinate to establish a standard curve of estradiol molecules. (2) Place the working electrode, reference electrode and counter electrode in the electrolyte of the sample to be tested, perform differential pulse voltammetry scanning, record the peak current, and combine with the standard curve obtained in step (1) to obtain the content of estradiol molecules in the sample to be tested.
[0036] The present invention will be further described in detail below with reference to specific embodiments. Unless otherwise specified, the equipment and reagents used in the embodiments, experimental examples and comparative examples are all commercially available.
[0037] I. Specific embodiments of the working electrode and electrochemical sensor for estradiol detection according to the present invention: Example 1 In this embodiment, a working electrode for an electrochemical sensor for estradiol detection is prepared using zinc oxide as a modifying material and a glassy carbon electrode as the electrode substrate. Then, an electrochemical sensor is constructed using this electrode, and electrochemical characterization is performed. The specific implementation method is as follows: 1. Add 4 mg of zinc oxide (50±10 nm) to a mixed solution of 125 μL of anhydrous ethanol and 375 μL of deionized water, and sonicate for 3 minutes to mix the material evenly to obtain the electrode modified material.
[0038] 2. Add 10 μL of Nafion reagent (the mass concentration of perfluorosulfonic acid polymer in Nafion reagent is 5.0%~5.4%) to the electrode modification material mixture obtained in step 1, and sonicate in a room temperature water bath for 30 minutes to ensure that the material is mixed evenly.
[0039] 3. Take 2.5 μL of the material obtained in step 2 and drop it onto the glassy carbon electrode (3 mm in diameter) and let it stand for a period of time to wait for film formation. Repeat this step after film formation (to ensure that the glassy carbon electrode is not exposed and can be completely covered by the material) to obtain the zinc oxide modified electrode (i.e. the working electrode for the estradiol detection electrochemical sensor).
[0040] 4. Using the zinc oxide modified electrode obtained in step 3 as the working electrode, a three-electrode system is formed with the counter electrode (platinum mesh electrode) and the reference electrode (silver chloride electrode), and then coupled with a chemical working device to construct an electrochemical sensor.
[0041] 5. Connect the electrochemical sensor constructed in step 4 to the electrochemical workstation. Add a standard solution of estradiol molecules to an appropriate amount of electrolyte (0.01M PBS buffer solution) to prepare a series of standard solutions of different concentrations. Inject these solutions into the electrolytic cell for differential pulse voltammetry (DPV) detection. The DPV scanning conditions are 50mV / s, the detection potential range is -0.2V to 0.8V, the potential increment is 5mV, and the temperature is room temperature. The DPV results are as follows: Figure 1 As shown.
[0042] A standard curve for estradiol was established with the concentration of estradiol in the standard solution as the x-axis and the corresponding peak current as the y-axis. The linear range for detecting estradiol was then determined to be 2–100 μM.
[0043] Before use, the glassy carbon electrode requires surface cleaning. The specific steps are as follows: Rinse the electrode surface with deionized water and ethanol for 5 seconds, then sonicate for 3 minutes to remove residual electrolyte or adsorbents. Next, polish in a figure-eight motion for a total of 6 minutes on a damp polishing cloth with 1, 0.2, and 0.05 μm alumina suspensions added, respectively. Finally, rinse with water and dry with nitrogen. All glassy carbon electrodes involved in the following examples require the above treatment before use.
[0044] Example 2 In this embodiment, a working electrode for an electrochemical sensor for estradiol detection is prepared using iron oxide and carbon nanotubes as modifying materials and a glassy carbon electrode as the electrode substrate. Then, an electrochemical sensor is constructed using this electrode, and electrochemical characterization is performed. The specific implementation method is as follows: 1. Add 4 mg of iron(III) oxide (10-30 nm) to a mixed solution of 125 μL of anhydrous ethanol and 375 μL of deionized water, and sonicate for 3 minutes to mix the material evenly.
[0045] 2. Add 1 mg of carbon nanotubes to the mixed solution obtained in step 1 and sonicate for 3 minutes to mix the materials evenly to obtain the electrode modified material.
[0046] 3. Add 10 μL of Nafion reagent (the mass concentration of perfluorosulfonic acid polymer in Nafion reagent is 5.0%~5.4%) to the electrode modification material mixture obtained in step 2, and sonicate in a room temperature water bath for 30 minutes to ensure that the material is mixed evenly.
[0047] 4. Take 2.5 μL of the material obtained in step 3 and drop it onto the glassy carbon electrode (3 mm in diameter) and let it stand for a period of time to wait for film formation. After film formation, repeat this step to obtain the electrode modified with iron oxide and carbon nanotube (CNT) doped material (i.e., the working electrode for the estradiol detection electrochemical sensor).
[0048] 5. The electrode modified with iron(III) oxide and carbon nanotube (CNT) doped material obtained in step 4 is used as the working electrode, forming a three-electrode system with the counter electrode (platinum mesh electrode) and the reference electrode (silver chloride electrode), and is connected to a chemical working station to construct an electrochemical sensor.
[0049] 6. Connect the electrochemical sensor constructed in step 5 to an electrochemical workstation. Add a standard solution of estradiol molecules to an appropriate amount of electrolyte (0.01M PBS buffer solution) to prepare a series of standard solutions of different concentrations; inject these solutions into the electrolytic cell for differential pulse voltammetry detection. The DPV scanning conditions are 50mV / s, the detection potential range is -0.2V to 0.8V, the potential increment is 5mV, and the temperature is room temperature. The DPV results are as follows: Figure 2 As shown.
[0050] A standard curve for estradiol was established with the concentration of estradiol in the standard solution as the x-axis and the corresponding peak current as the y-axis. The linear range for detecting estradiol was then determined to be 5–100 μM.
[0051] Example 3 In this embodiment, a working electrode for an electrochemical sensor for estradiol detection is prepared using porous tin oxide (porous tin oxide prepared according to literature, DOI: 10.1021 / jp0620522) as a modifying material and a glassy carbon electrode as the electrode substrate. Then, an electrochemical sensor is constructed using this electrode, and electrochemical characterization is performed. The specific implementation method is as follows: 1. Add 4 mg of porous tin oxide (20-30 nm) to a mixed solution of 125 μL of anhydrous ethanol and 375 μL of deionized water, and sonicate for 3 minutes to mix the material evenly to obtain the electrode modified material.
[0052] 2. Add 10 μL of Nafion reagent (the mass concentration of perfluorosulfonic acid polymer in Nafion reagent is 5.0%~5.4%) to the electrode modification material mixture obtained in step 1, and sonicate in a room temperature water bath for 30 minutes to ensure that the material is mixed evenly.
[0053] 3. Take 2.5 μL of the material obtained in step 2 and drop it onto the glassy carbon electrode (3 mm in diameter) and let it stand for a period of time to wait for film formation. After film formation, repeat this step to obtain a porous tin oxide modified electrode (i.e., the working electrode for the estradiol detection electrochemical sensor).
[0054] The porous tin oxide-modified electrode was observed using a scanning electron microscope, such as... Figure 3 As shown in the figure, the tin oxide is porous tin oxide with a pore size of 50-100 nm and a specific surface area increased to 200 m² / g.
[0055] 4. The porous tin oxide and carbon nanotube (CNT) doped material modified electrode obtained in step 3 is used as the working electrode, forming a three-electrode system with the counter electrode (platinum mesh electrode) and the reference electrode (silver chloride electrode), and is connected to a chemical working station to construct an electrochemical sensor.
[0056] 5. Connect the electrochemical sensor constructed in step 4 to an electrochemical workstation. Add a standard solution of estradiol molecules to an appropriate amount of electrolyte (0.01M PBS buffer solution) to prepare a series of standard solutions of different concentrations; inject these solutions into the electrolytic cell for differential pulse voltammetry detection. The DPV scanning conditions are 50mV / s, the detection potential range is -0.2V to 0.8V, the potential increment is 5mV, and the temperature is room temperature. The DPV results are as follows: Figure 4 As shown.
[0057] A standard curve for estradiol was established with the concentration of estradiol in the standard solution as the x-axis and the corresponding peak current as the y-axis. The linear range for detecting estradiol was then determined to be 0.2–1 μM.
[0058] Example 4 In this embodiment, a working electrode for an electrochemical sensor for estradiol detection is prepared using tin oxide and carbon nanotubes as modifying materials and a glassy carbon electrode as the electrode substrate. Then, an electrochemical sensor is constructed using this electrode, and electrochemical characterization is performed. The specific implementation method is as follows: 1. Add 4 mg of tin oxide (20-30 nm) to a mixed solution of 125 μL of anhydrous ethanol and 375 μL of deionized water, and sonicate for 3 minutes to mix the material evenly.
[0059] 2. Add 1 mg of carbon nanotubes to the mixed solution obtained in step 1 and sonicate for 3 minutes to mix the materials evenly to obtain the electrode modified material.
[0060] 3. Add 10 μL of Nafion reagent (the mass concentration of perfluorosulfonic acid polymer in Nafion reagent is 5.0%~5.4%) to the electrode modification material mixture obtained in step 2, and sonicate in a room temperature water bath for 30 minutes to ensure that the material is mixed evenly.
[0061] 4. Take 2.5 μL of the material obtained in step 3 and drop it onto the glassy carbon electrode (3 mm in diameter) and let it stand for a period of time to wait for film formation. After film formation, repeat this step to obtain the tin oxide and carbon nanotube (CNT) doped material modified electrode (i.e., the working electrode for the estradiol detection electrochemical sensor).
[0062] 5. The electrode modified with tin oxide and carbon nanotube (CNT) doped material obtained in step 4 is used as the working electrode, forming a three-electrode system with the counter electrode (platinum mesh electrode) and the reference electrode (silver chloride electrode), and is connected to a chemical working station to construct an electrochemical sensor.
[0063] 6. Connect the electrochemical sensor constructed in step 5 to an electrochemical workstation. Add a standard solution of estradiol molecules to an appropriate amount of electrolyte (0.01M PBS buffer solution) to prepare a series of standard solutions of different concentrations; inject these solutions into the electrolytic cell for differential pulse voltammetry detection. The DPV scanning conditions are 50mV / s, the detection potential range is -0.2V to 0.8V, the potential increment is 5mV, and the temperature is room temperature. The DPV results are as follows: Figure 5 As shown.
[0064] A standard curve for estradiol was established with the concentration of estradiol in the standard solution as the x-axis and the corresponding peak current as the y-axis. Figure 6 As shown in the figure, the linear range for detecting estradiol was found to be 0.6~10μM.
[0065] II. Specific embodiments of the application of the working electrode of the estradiol detection electrochemical sensor of the present invention or the estradiol detection electrochemical sensor in estradiol detection: Example 5 In this embodiment, a working electrode for an electrochemical sensor for estradiol detection is prepared using porous tin oxide (prepared according to literature, DOI: 10.1021 / jp0620522) and carbon nanotubes as modifying materials and a glassy carbon electrode as the electrode substrate. The electrochemical sensor is then constructed using this electrode, and electrochemical characterization is performed. The specific implementation method is as follows: 1. Add 4 mg of porous tin oxide (20-30 nm) to a mixed solution of 125 μL of anhydrous ethanol and 375 μL of deionized water, and sonicate for 3 minutes to mix the material evenly.
[0066] 2. Add 1 mg of carbon nanotubes to the mixed solution obtained in step 1 and sonicate for 3 minutes to mix the materials evenly to obtain the electrode modified material.
[0067] 3. Add 10 μL of Nafion reagent (the mass concentration of perfluorosulfonic acid polymer in Nafion reagent is 5.0%~5.4%) to the electrode modification material mixture obtained in step 2, and sonicate in a room temperature water bath for 30 minutes to ensure that the material is mixed evenly.
[0068] 4. Take 2.5 μL of the material obtained in step 3 and drop it onto the glassy carbon electrode (3 mm in diameter) and let it stand for a period of time to wait for film formation. After film formation, repeat this step to obtain a porous tin oxide and carbon nanotube (CNT) doped material modified electrode (i.e., the working electrode for the estradiol detection electrochemical sensor).
[0069] 5. The porous tin oxide and carbon nanotube (CNT) doped material modified electrode obtained in step 4 is used as the working electrode, forming a three-electrode system with the counter electrode (platinum mesh electrode) and the reference electrode (silver chloride electrode), and is used in conjunction with a chemical working station to construct an electrochemical sensor.
[0070] 6. Connect the electrochemical sensor constructed in step 5 to an electrochemical workstation. Add standard solutions of estradiol, testosterone, cortisol, and cortisone to appropriate amounts of electrolyte solution (0.01M PBS buffer) to prepare 1μM standard solutions of estradiol, testosterone, cortisone, and cortisol, respectively. Inject these solutions into the electrolytic cell for differential pulse voltammetry (DPV) detection. The DPV scan conditions are 50mV / s, the detection potential range is -0.2V to 0.8V, the potential increment is 5mV, and the temperature is room temperature. The DPV results are as follows: Figure 7 As shown.
[0071] As shown in the figure, porous tin oxide responds to different substances. At the same concentration, it has a significant response to estradiol but no significant response to other substances (testosterone, cortisone, and cortisol), which reflects the selectivity of tin dioxide for estradiol.
[0072] Example 6 In this embodiment, zinc oxide and carbon nanotubes with different mass ratios were used as modifying materials, and glassy carbon electrodes were used as electrode substrates to prepare working electrodes for an electrochemical sensor for estradiol detection. Then, an electrochemical sensor was constructed using these electrodes, and their sensitivity in detecting estradiol molecules was compared. The specific implementation method is as follows: 1. Add 4 mg of zinc oxide (50±10 nm) to a mixed solution of 125 μL of anhydrous ethanol and 375 μL of deionized water, and sonicate for 3 minutes to mix the material evenly.
[0073] 2. Add 1 mg, 2 mg, 3 mg or 4 mg of carbon nanotubes to the mixed solution obtained in step 1 and sonicate for 3 minutes to mix the materials evenly to obtain the electrode modified material.
[0074] 3. Add 10 μL of Nafion reagent (the mass concentration of perfluorosulfonic acid polymer in Nafion reagent is 5.0%~5.4%) to the electrode modification material mixture obtained in step 2, and sonicate in a room temperature water bath for 30 minutes to ensure that the material is mixed evenly.
[0075] 4. Take 2.5 μL of the material obtained in step 3 and drop it onto the glassy carbon electrode (3 mm in diameter) and let it stand for a period of time to wait for film formation. After film formation, repeat this step to obtain the zinc oxide and carbon nanotube (CNT) doped material modified electrode (i.e., the working electrode for the estradiol detection electrochemical sensor).
[0076] 5. The zinc oxide and carbon nanotube (CNT) doped material modified electrode obtained in step 4 is used as the working electrode, forming a three-electrode system with the counter electrode (platinum mesh electrode) and the reference electrode (silver chloride electrode), and is connected to a chemical working station to construct an electrochemical sensor.
[0077] 6. Connect the electrochemical sensor constructed in step 5 to the electrochemical workstation. Add a standard solution of estradiol molecules to an appropriate amount of electrolyte (0.01M PBS buffer solution) to prepare a series of standard solutions of different concentrations; inject these solutions into the electrolytic cell for differential pulse voltammetry detection. The DPV scan conditions are 50mV / s, the detection potential range is -0.2V to 0.8V, the potential increment is 5mV, and the temperature is room temperature. Specific detection results are as follows: Figure 8 As shown.
[0078] As shown in the figure, the response of zinc oxide and carbon nanotube mixtures with different mass ratios (4:1, 4:2, 4:3, 4:4) to estradiol is different, with the largest response current observed when the mass ratio is 4:1.
[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A working electrode for an electrochemical sensor for the detection of estradiol comprising an electrode substrate, characterised in that: The electrode substrate is modified with an electrode material layer; the electrode material layer is composed of an oxide and a perfluorosulfonic acid type polymer, or composed of an oxide, carbon nanotubes and a perfluorosulfonic acid type polymer; the oxide is one of zinc oxide, tin dioxide and triiron tetroxide.
2. The working electrode for an electrochemical sensor for estradiol detection according to claim 1, characterized in that: The mass ratio of the oxide and the carbon nanotubes is (4-4.5):
1.
3. The working electrode for an electrochemical sensor for estradiol detection according to claim 1 or 2, characterized in that: The modification is to prepare the material to be modified into a dispersion liquid, and then coat on the surface of the electrode substrate to dry to form the electrode material layer.
4. The working electrode for an electrochemical sensor for estradiol detection according to claim 3, wherein: 10 μL of the perfluorosulfonic acid type polymer solution is used per (4-4.5) mg of the oxide.
5. The working electrode for electrochemical sensor for estradiol detection according to claim 3, wherein: The mass concentration of the perfluorosulfonic acid type polymer in the solution is 5.0%-5.4%.
6. The working electrode for electrochemical sensor for estradiol detection according to claim 3, wherein: The solvent of the dispersion liquid is a mixed solution of ethanol and water; the volume ratio of the ethanol and water is (1-1.2):(3-3.5).
7. The working electrode for an electrochemical sensor for estradiol detection according to claim 1 or 2, characterized in that: The particle size of the oxide is 10-60 nm.
8. An electrochemical sensor for estradiol detection comprising a working electrode, a reference electrode, a counter electrode, characterized in that: The working electrode is the working electrode of the estradiol detection electrochemical sensor according to any one of claims 1-7.
9. Use of the working electrode of an electrochemical sensor for the detection of estradiol according to any one of claims 1 to 7 or of the electrochemical sensor for the detection of estradiol according to claim 8 for the detection of estradiol, characterized in that: The application is not for the purpose of disease diagnosis and treatment.
10. The working electrode for an electrochemical sensor for detecting estradiol or use of an electrochemical sensor for detecting estradiol in the detection of estradiol according to claim 9, characterized in that: The application comprises the following steps: (1) placing the working electrode, the reference electrode and the counter electrode in the same electrolyte, adding estradiol standard solutions with different concentrations to change the concentration of estradiol in the electrolyte, detecting by differential pulse voltammetry, taking the estradiol concentration as the horizontal coordinate and the corresponding peak current as the vertical coordinate, and establishing a standard curve of estradiol molecules; (2) placing the working electrode, the reference electrode and the counter electrode in the electrolyte of the sample to be detected, performing differential pulse voltammetry scanning, recording the peak current, and combining the standard curve obtained in step (1) to obtain the content of estradiol molecules in the sample to be detected.