Preparation method of a hypochlorous acid photoelectrochemical sensor and its application in detecting hypochlorous acid

Abstract

The present invention discloses a preparation method of a hypochlorous acid photoelectrochemical sensor and its application in detecting hypochlorous acid. The hypochlorous acid photoelectrochemical sensor of the present invention is obtained by chemically bonding and coupling a designed and synthesized D‑π‑A photoelectric probe molecule with a titanium dioxide substrate. The phenothiazine sulfur atom on the hypochlorous acid photoelectric probe molecule can react specifically with hypochlorous acid to achieve direct recognition of the target analyte. After the introduction of hypochlorous acid, the photoelectric conversion efficiency of the photoelectric probe molecule changes significantly, causing the current response of the photoelectrochemical sensor to change, thereby achieving detection of the target object. The hypochlorous acid photoelectrochemical sensor of the present invention has the advantages of high selectivity and high sensitivity to hypochlorous acid, and has a fast response speed, a wide response linear range, and a detection limit as low as 0.18 μmol·L ‑1 .

Description

Technical Field

[0001] The present invention relates to a photoelectrochemical sensor, and in particular to a preparation method of a hypochlorous acid photoelectrochemical sensor and an application thereof in detecting hypochlorous acid. Background Art

[0002] Hypochlorous acid (HClO) has strong oxidizing ability and is a commonly used bleaching agent and disinfectant in our daily lives. HClO is also an important reactive oxygen species in organisms, involved in various physiological and pathological processes, and plays a vital role in the immune system, fighting various pathogens and maintaining normal physiological processes. However, excessive HClO may cause tissue damage and various diseases such as arthritis, cardiovascular disease, kidney disease, neurodegeneration and cancer. Therefore, there is an urgent need to develop an efficient and sensitive method for detecting hypochlorous acid. Several methods are mentioned in the existing literature, such as electroanalysis (Anal. Chim. Acta 2020, 1106, 168), chromatography (Chromatographia 2013, 76, 363) and fluorescence (Dyes Pigments 2021, 190, 109344). However, these methods are generally time-consuming and involve complex and tedious sample processing.

[0003] Photoelectrochemical analysis is a type of electroanalytical chemical method based on the photoelectric conversion effect. In the process of photoelectrochemical detection, the excitation signal is light radiation, which is then converted into an electrical signal by a photosensitive substance. This achieves a complete separation of the excitation signal and the detection signal, thereby greatly reducing the background signal and improving the sensitivity of the detection. Currently, photoelectrochemical methods have been widely used in the detection of biological molecules and metal ions. However, most of these methods use inorganic nanomaterials as photosensitizers and utilize biological molecules (such as antibodies, nucleic acids, etc.) to identify the target detection object. This makes it difficult to achieve precise control of the photosensitizing material and maintain the long-term stability of the sensor. Summary of the Invention

[0004] To address the technical issues that photoelectrochemical analysis methods have difficulty in achieving precise control of photosensitizing materials and maintaining the long-term stability of sensors, the present invention provides a method for preparing a hypochlorous acid photoelectrochemical sensor and its application in detecting hypochlorous acid. A photoelectrochemical sensor based on an organic photoelectric probe molecule is constructed, and the direct recognition of hypochlorous acid by the probe molecule can achieve rapid detection of the target.

[0005] The technical solutions of the present invention are as follows:

[0006] A method for preparing a hypochlorous acid photoelectrochemical sensor comprises the following steps:

[0007] (1) Synthesize the following structure of hypochlorous acid photoelectric probe molecule:

[0008]

[0009] (2) Preparation of titanium dioxide substrate:

[0010] The FTO conductive glass substrate is sequentially placed in concentrated sulfuric acid, ethanol, and deionized water for ultrasonic treatment, then rinsed with deionized water and dried with nitrogen. The reaction solution and the cleaned FTO glass substrate are then placed in a high-pressure reactor for hydrothermal reaction. The composition of the reaction solution is as follows: sodium chloride, n-butyl titanate, concentrated hydrochloric acid, and deionized water in a ratio of 1-1.5 g: 0.2-2.0 mL: 25-35 mL: 25-35 mL. The temperature is controlled at 150-200°C and the reaction time is 4-20 h. After the reaction is completed, a titanium dioxide substrate, namely FTO / TiO2, is obtained.

[0011] (3) Preparation of photoelectrochemical electrodes:

[0012] The titanium dioxide substrate FTO / TiO2 obtained in step (2) is placed in an acetonitrile solution containing a silane coupling reagent and the hydrazine photoelectric probe molecule obtained in step (1), and reflux reaction is performed to obtain an electrode. The electrode is taken out and rinsed with dimethyl sulfoxide and secondary water to remove the dye adsorbed on the electrode, thereby obtaining a photoelectrochemical sensor electrode for detecting hypochlorous acid, namely, a hypochlorous acid photoelectrochemical sensor FTO / TiO2 / Dye-HClO.

[0013] Furthermore, in step (1), the method for synthesizing the hypochlorous acid photoelectric probe molecule comprises the following steps:

[0014] Aldehyde phenothiazine, 4-pyridineacetonitrile and a coupling catalyst are added to a solvent, heated for reaction, and purified to obtain the target product, hypochlorous acid photoelectric probe molecule Dye-HClO.

[0015] Furthermore, the solvent is one of methanol, ethanol, acetonitrile, and tetrahydrofuran, preferably ethanol or tetrahydrofuran; the coupling catalyst is one or more of piperidine, acetic acid, and sodium acetate, preferably piperidine or acetic acid; the reaction temperature is 60-100° C., preferably 80-90° C.; and the reaction time is 1-24 h, preferably 8-12 h.

[0016] Furthermore, in step (2), the concentrated sulfuric acid, ethanol, and deionized water are ultrasonically treated 1 to 3 times, each time for 20 to 40 minutes.

[0017] Furthermore, in step (2), the usage ratio of sodium chloride, n-butyl titanate, concentrated hydrochloric acid, and deionized water is preferably 1-1.2 g: 0.3-1.0 mL: 28-32 mL: 28-32 mL.

[0018] Furthermore, in step (3), the structure of the silane coupling reagent is as follows:

[0019]

[0020] Wherein, R1, R2, and R3 are independently selected from one of alkyl chains of 1 to 18 carbon atoms, n is an integer from 0 to 18, and X is F, Cl, Br or I.

[0021] Further, the preferred structure of the silane coupling agent is

[0022]

[0023] The hypochlorous acid photoelectrochemical sensor prepared by the above preparation method is used in the detection of hypochlorous acid, specifically: the FTO / TiO2 / Dye-HClO electrode is treated in a hypochlorous acid test solution for 1 to 60 minutes (preferably 5 to 10 minutes), and an electrochemical workstation is used to test the three-electrode system, wherein the FTO / TiO2 / Dye-HClO electrode is used as the working electrode, the saturated calomel electrode is used as the reference electrode, the platinum wire electrode is used as the counter electrode, and the test solution system contains ascorbic acid (0.01-1 mol·L -1 , preferably 0.1 to 0.5 mol·L -1 ) of a phosphate buffer solution, and a bias voltage of -0.4-0 V (preferably -0.4 V to -0.2 V) is applied.

[0024] The beneficial effects of the present invention are:

[0025] The present invention constructs a photoelectrochemical sensor for detecting hypochlorous acid based on a designed and synthesized photoelectric probe molecule, exhibiting superior performance. In the presence of hypochlorous acid, hypochlorous acid reacts specifically with the photoelectric probe molecule, altering its structure and properties, thereby significantly reducing the photocurrent response. The hypochlorous acid photoelectrochemical sensor of the present invention exhibits excellent selectivity, specific recognition of hypochlorous acid, high detection sensitivity, and a fast response speed (less than 2 minutes). Under optimal conditions, the detection limit can reach 0.18 μmol·L. -1 . BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of the molecular probe synthesized in Example 1 of the present invention;

[0027] Figure 2 Schematic diagram of the principle of the photoelectrochemical sensor synthesized by the present invention;

[0028] Figure 3 The infrared spectrum (A) and X-ray spectrum (B) of the photoelectrochemical sensor electrode synthesized in Example 2 of the present invention;

[0029] Figure 4 The photocurrent response diagram of the sensor of the present invention after being treated with hypochlorous acid solutions of different concentrations is shown in Figure 1. The concentrations of hypochlorous acid added from a to h are 0 and 1 μmol·L, respectively. -1 , 5.0 μmol·L -1 , 10 μmol·L -1 , 15 μmol·L -1 , 20 μmol·L -1 , 30 μmol·L -1 , 40 μmol·L -1 The solution system contains 0.1 mol·L -1 Ascorbic acid phosphate buffer solution (pH 7.4, 10 mmol·L -1 ) of aqueous solution, the horizontal axis is time and the vertical axis is current value;

[0030] Figure 5 It is a standard curve of hypochlorous acid concentration, that is, the linear relationship between the change of photocurrent and hypochlorous acid concentration; the horizontal axis is the concentration of hypochlorous acid, and the vertical axis is the photocurrent value;

[0031] Figure 6 The probe is selective for hypochlorous acid; the sensor is selective for 50 μmol·L -1 Thiophenol and different interfering substances (Al 3+ 、Fe 2 + 、Cu 2+ 、Zn 2+ Mg 2+ 、Mn 2+ , alanine (Ala), NaNO3, NH4Cl, KBrO3, K2SO4, H2O2, C2H5OH); the abscissa is the tested analyte and the ordinate is the photocurrent value. DETAILED DESCRIPTION

[0032] The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0033] Example 1 Synthesis of Hypochlorous Acid Photoelectric Probe Molecules

[0034] In a 10 mL round-bottom flask, add aldehyde phenothiazine (241 mg, 1.0 mmol), cyanopyridine (118 mg, 1.0 mmol) and 4 mL of anhydrous ethanol and heat under reflux for 5 h. After the reaction, the solvent was distilled off under reduced pressure and the residue was further purified by silica gel chromatography to obtain the purple-red target product, Dye-HClO. The H NMR spectrum is shown in Figure 2. Figure 1 The description of the map is as follows: 1H NMR (400 MHz, DMSO) δ 8.67 (d, J = 6.1 Hz, 2H), 8.19 (s, 1H), 7.91 (dd, J = 8.6, 1.9 Hz, 1H), 7.81 (d, J = 1.9 Hz, 1H), 7.69 (d, J = 6.1 Hz, 2H), 7.26 (t, J = 7.7 Hz, 1H), 7.20 (d, J = 7.4 Hz, 1H), 7.13 (d, J = 8.7 Hz, 1H), 7.03 (t, J = 7.3 Hz, 2H), 3.39 (s, 3H). MS: m / z, Required: [M+H] + 342.1;Measurement value:342.1.

[0035] Example 2 Preparation of Hypochlorous Acid Photoelectrochemical Sensor Electrode

[0036] First, the conductive glass (FTO) was pretreated. The specific steps are as follows: (i) Soak the glass in concentrated sulfuric acid and ultrasonically treat it for 30 minutes; (ii) Ultrasonicate it with ethanol for 30 minutes to remove any organic impurities that may exist on the glass surface; (iii) Ultrasonicate it with deionized water three times, each for 30 minutes. Finally, place the glass in a vacuum drying oven to dry for later use. Measure 30mL of deionized water and 30mL of concentrated hydrochloric acid and mix them in a beaker. Then add 1.2g of sodium chloride. After stirring thoroughly until the sodium chloride dissolves, add 1mL of n-butyl titanate and stir again until the solution is clear and transparent. Then, place the cleaned FTO conductive surface facing down into the inner liner of a polytetrafluoroethylene high-pressure reactor filled with the above solution. Seal the reactor and place it in a 160℃ forced air drying oven for 10 hours. After the reaction is completed, it is naturally cooled to room temperature. The impurities on the surface of TiO2 are rinsed with deionized water and then dried. The dried titanium dioxide nanorods are placed in a muffle furnace, heated to 450°C at a rate of 2°C / min and kept warm for 30 minutes. After cooling to room temperature, a titanium dioxide substrate with a stable structure is obtained, namely FTO / TiO2. The hypochlorous acid photoelectric probe molecules Dye-HClO (1mM) and (3-bromopropyl)trimethoxysilane (0.5mM) obtained in Example 1 are added to 10mL of dry acetonitrile. After dissolution, the FTO / TiO2 substrate is placed in this solution and refluxed for 5 hours. Next, the electrode is taken out and rinsed with dimethyl sulfoxide (DMSO) and secondary water to remove the dye adsorbed on the electrode. The obtained photoelectrochemical sensor electrode is named FTO / TiO2 / Dye-HClO. The preparation process, infrared characterization and X-ray energy spectrum characterization of the electrode are as follows. Figure 2 、 Figure 3 shown.

[0037] Example 3 Photoelectrochemical Detection of Hypochlorous Acid

[0038] The prepared FTO / TiO2 / Dye-HClO electrode was used as the working electrode, the saturated calomel electrode was used as the reference electrode, and the platinum wire was used as the counter electrode to assemble a photoelectrochemical detection system for hypochlorous acid. The working electrode was treated with hypochlorous acid solutions of different concentrations and its photoelectrochemical response was tested. The results are shown in Figure 2. Figure 4 The photocurrent value is plotted against the hypochlorous acid concentration, and the hypochlorous acid concentration is 1.0–20.0 μmol·L -1 Within the range, the photocurrent and the concentration of hypochlorous acid show a good linear relationship ( Figure 5 ), so it can achieve quantitative detection of hypochlorous acid within this concentration range. And the detection of hypochlorous acid by the photoelectric chemical sensor is not affected by some other common interfering substances, such as: Al 3+ 、Fe 2+ 、Cu 2+ 、Zn 2+ Mg 2+ 、Mn 2+ , alanine (Ala), NaNO3, NH4Cl, KBrO3, K2SO4, H2O2, C2H5OH. In the presence of the above interfering substances, the sensor still has good selectivity and sensitivity to hypochlorous acid ( Figure 6 ).

Claims

1. A method for preparing a hypochlorous acid photoelectrochemical sensor, characterized in that: The following steps are involved: (1) Synthesize the following structure of hypochlorous acid photoelectric probe molecule: (2) Preparation of titanium dioxide substrate: The FTO conductive glass substrate is sequentially placed in concentrated sulfuric acid, ethanol, and deionized water for ultrasonic treatment, then rinsed with deionized water and dried with nitrogen. The reaction solution and the cleaned FTO glass substrate are then placed in a high-pressure reactor for hydrothermal reaction. The composition of the reaction solution is as follows: sodium chloride, n-butyl titanate, concentrated hydrochloric acid, and deionized water in a ratio of 1-1.5 g: 0.2-2.0 mL: 25-35 mL: 25-35 mL. The temperature is controlled at 150-200°C and the reaction time is 4-20 h. After the reaction is completed, a titanium dioxide substrate, namely FTO / TiO2, is obtained. (3) Preparation of photoelectrochemical electrodes: The titanium dioxide substrate FTO / TiO2 obtained in step (2) is placed in an acetonitrile solution containing a silane coupling reagent and the hydrazine photoelectric probe molecule obtained in step (1), and reflux reaction is performed to obtain an electrode. The electrode is taken out and rinsed with dimethyl sulfoxide and secondary water to remove the dye adsorbed on the electrode, thereby obtaining a photoelectrochemical sensor electrode for detecting hypochlorous acid, namely, a hypochlorous acid photoelectrochemical sensor FTO / TiO2 / Dye-HClO.

2. The method for preparing the hypochlorous acid photoelectrochemical sensor according to claim 1, wherein: In step (1), the method for synthesizing the hypochlorous acid photoelectric probe molecule comprises the following steps: Aldehyde phenothiazine, 4-pyridineacetonitrile and a coupling catalyst are added to a solvent, heated for reaction, and purified to obtain the target product, hypochlorous acid photoelectric probe molecule Dye-HClO.

3. The method for preparing the hypochlorous acid photoelectrochemical sensor according to claim 2, wherein: The solvent is one of methanol, ethanol, acetonitrile and tetrahydrofuran; the coupling catalyst is one or more of piperidine, acetic acid and sodium acetate; the reaction temperature is 60-100° C.; and the reaction time is 1-24 hours.

4. The method for preparing the hypochlorous acid photoelectrochemical sensor according to claim 1, wherein: In step (2), the product is ultrasonically treated in concentrated sulfuric acid, ethanol, and deionized water for 1 to 3 times, each time for 20 to 40 minutes.

5. The method for preparing the hypochlorous acid photoelectrochemical sensor according to claim 1, wherein: In step (2), the usage ratio of sodium chloride, n-butyl titanate, concentrated hydrochloric acid and deionized water is 1-1.2 g: 0.3-1.0 mL: 28-32 mL: 28-32 mL.

6. The method for preparing the hypochlorous acid photoelectrochemical sensor according to claim 1, wherein: In step (3), the structure of the silane coupling reagent is as follows: Wherein, R1, R2, and R3 are independently selected from one of alkyl chains of 1 to 18 carbon atoms, n is an integer from 0 to 18, and X is F, Cl, Br or I.

7. The method for preparing the hypochlorous acid photoelectrochemical sensor according to claim 1, wherein: The structure of the silane coupling reagent is 8. Use of the hypochlorous acid photoelectrochemical sensor obtained by the preparation method according to any one of claims 1 to 7 in detecting hypochlorous acid.

9. The use according to claim 8, characterized in that The application is specifically as follows: treating the FTO / TiO2 / Dye-HClO electrode in a hypochlorous acid test solution for 1 to 60 minutes, and using an electrochemical workstation to test using a three-electrode system, wherein the FTO / TiO2 / Dye-HClO electrode is a working electrode, a saturated calomel electrode is a reference electrode, and a platinum wire electrode is a counter electrode. The test solution system contains 0.01-1 mol·L -1 Ascorbic acid in phosphate buffer solution, with a bias voltage of -0.4-0V.

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