Preparation and application of hypochlorite dual-mode sensing platform

Abstract

The invention discloses a dual-mode sensing platform for detecting hypochlorite and a preparation method, and belongs to the technical field of analytical chemistry. The sensing platform is designed and synthesized based on a phenothiazine-chromone fluorescent probe as a photosensitizer, and intelligent integration of fluorescence analysis and photoelectrochemical (PEC) sensing is realized. The sensing platform has the advantages of being high in selectivity, high in sensitivity and easy to prepare, rapid qualitative fluorescence reading and quantitative photoelectrochemical reading of hypochlorite can be achieved, and the fluorescence detection limit and the PEC detection limit are 0.288 mu M and 1.37 nM respectively. Through self-calibration of platform dual-mode signals, interference of interferents in a complex environment can be remarkably improved, and the method can be used for detecting hypochlorite in a real water sample and has good practicability.

Description

Technical Field

[0001] The present invention relates to a dual-mode sensing platform for dual-mode detection of hypochlorite ions, a preparation method thereof, and applications, belonging to the technical field of analytical chemistry. Background Art

[0002] Hypochlorous acid is one of the most important reactive oxygen species (ROS) in organisms and is involved in various physiological and pathological processes. Since the pK of hypochlorous acid a is 7.6, it usually exists as an HOCl / OCl - equilibrium pair under physiological conditions. Endogenous OCl - is produced by the catalysis of hydrogen peroxide and chloride ions by myeloperoxidase, and has strong oxidizing properties and neurotoxicity. The biological concentration of Cl - in the living system is very high. Existing studies have shown that up to 80% of H 2 O 2 in neutrophils can convert Cl - into OCl - at a rate of 20 - 400 μM / h. Since OCl - has strong oxidizing properties, it can react with proteins, DNA, RNA, fatty acids, etc. OCl - is usually used as a protectant for microorganisms. At the same time, the abnormal production of OCl - is closely related to various pathophysiological processes. On the one hand, OCl - participates in multiple immune processes, including resisting microbial invasion, combating pathogens, and regulating apoptosis; on the other hand, excessive OCl - will oxidize thiols, thioethers, and hemoglobin, resulting in a series of adverse effects, and is closely related to the occurrence of diseases such as inflammation, cardiovascular diseases, neurodegenerative diseases, and cancers. Therefore, directly, rapidly, sensitively, and specifically detecting endogenous OCl - in biological systems is crucial for understanding the pathological and physiological functions of OCl - in the living system.

[0003] Fluorescence detection techniques using organic small molecule fluorescent probes have received considerable attention due to their high sensitivity, specificity, fast response time, and structural tunability. Recently, many organic small molecule fluorescent probes have been successfully developed and used for imaging and sensing in living cells, tissues, and organisms. However, quantitative measurements relying on single fluorescence mode readings are easily interfered by factors such as probe concentration, photobleaching, and detection environment, which can lead to "false positive" or "false negative" results, greatly limiting the accuracy and precision of test results.

[0004] To address these issues, several sensing strategies have been designed in recent years, including spatially resolved methods, dual-signal methods, and dual-mode detection methods. Among these methods, sensors based on the dual-mode detection method have relatively independent signal transduction modes due to the combination of two different signal reading mechanisms. This can effectively prevent signal interference and significantly improve the detection accuracy in practical applications. Therefore, it is a logical design to combine fluorescence detection technology with other analytical techniques to form dual-mode analysis to enhance the detection accuracy.

[0005] In recent years, the emerging photoelectrochemical (PEC) analysis technology has attracted great attention because it can be combined with other analytical methods to construct a sensing platform with dual-mode signal output. This technology adopts the "light excitation, electrical detection" mode and has advantages such as low background noise, high sensitivity, and obvious separation of input and output signals. At the same time, fluorescence detection technology also generates fluorescence signals by irradiating fluorescent substances with specific excitation light. Therefore, it is possible to combine fluorescence detection technology with PEC analysis technology to achieve high-precision dual-mode analysis. However, how to integrate these two methods remains a challenge. Summary of the Invention

[0006] Aiming at the problems existing in the prior art, the purpose of the present invention is to provide a proof-of-concept strategy that uses an organic fluorescent probe as a bridge to combine fluorescence detection and PEC analysis to obtain a dual-readout sensing platform. Combining small molecule fluorescence detection and PEC analysis is a pioneering work. Another purpose of the present invention is to provide a preparation method for this dual-mode sensing platform.

[0007] To solve the above technical problems, the present invention provides a dual-mode sensing platform responsive to hypochlorite, and its structure is as follows:

[0008] 。

[0009] The present invention also provides a preparation method for a dual-mode sensing platform responsive to OCl - response, including the following steps:

[0010] (1) Add 2-methoxyphenothiazine, sodium hydroxide, and iodoethane to a reactor, dissolve them in a first solvent, heat up the reaction, and stir for 1 - 4 h to obtain Compound 1, where the molar ratio of 2-methoxyphenothiazine, sodium hydroxide, and iodoethane is 1∶2 - 4∶2.5;

[0011] (2) Add Compound 1, acetyl chloride, and aluminum trichloride to a reactor, dissolve them in a second solvent, react at room temperature, and stop the reaction after stirring for 1 - 2 h to obtain Compound 2, where the molar ratio of Compound 1, acetyl chloride, and aluminum trichloride is 1∶1 - 1.5∶1.5;

[0012] (3) Add compound 2 and aluminum trichloride into the reactor and dissolve them with a second solvent. React at room temperature with stirring for 6 - 12 h to obtain compound 3, where the molar ratio of compound 2 to aluminum trichloride is 1∶5 - 6;

[0013] (4) Add compound 3, sodium hydride and ethyl acetate into the reactor and dissolve them with a third solvent. React at room temperature with stirring for 0.5 - 1 h to obtain a crude product. Dissolve the crude product with a fourth solvent, add hydrochloric acid, and react at room temperature with stirring for 12 - 18 h to obtain compound FPTZ, where the molar ratio of compound 3, sodium hydride to ethyl acetate is 1∶5 - 7∶2.5;

[0014] (5) Add compound FPTZ, benzaldehyde and sodium methoxide into the reactor and dissolve them with a fourth solvent. Heat up the reaction, stop the reaction after stirring for 0.5 - 1 h to obtain the fluorescent probe FPTZ - 1, where the molar ratio of compound FPTZ, benzaldehyde to sodium methoxide is 1∶1.2 - 1.5∶5;

[0015] (6) Dissolve titanium dioxide with a fifth solvent, and at room temperature, drop it onto the FTO glass substrate and air - dry it naturally to form a uniform and stable titanium dioxide nanolayer. Then heat up and calcine for 0.5 - 1 hh to obtain a stable titanium dioxide photoelectrode. Subsequently, soak the obtained photoelectrode in the FPTZ - 1 stock solution for 2 h and dry it at room temperature to obtain the final FTO / TiO 2 / FPTZ - 1 sensing platform.

[0016] The preparation process is as follows:

[0017] .

[0018] Preferably, the temperature for the heating reaction in step (1) is 60 - 70 °C.

[0019] Preferably, the temperature for the heating reaction in step (5) is 70 - 80 °C.

[0020] Preferably, the temperature for the heating reaction in step (6) is 300 - 350 °C.

[0021] Preferably, the first solvent is dimethyl sulfoxide; the second solvent is dichloromethane; the third solvent is tetrahydrofuran; the fourth solvent is methanol; the fifth solvent is ultrapure water.

[0022] Meanwhile, the present invention also provides an application of the dual - mode sensing platform for hypochlorite response or the FTO / TiO 2 / FPTZ - 1 sensing platform with dual - mode response to hypochlorite prepared by the preparation method of the sensing platform with dual - mode response to hypochlorite in a real water sample environment.

[0023] Advantages achieved by the present invention:

[0024] 1. A dual-mode responsive sensing platform of the present invention for OCl - has high selectivity and high sensitivity, and can achieve rapid qualitative fluorescence readout and quantitative photoelectrochemical readout of hypochlorite. The detection limits of fluorescence and PEC are 0.288 μM and 1.37 nM respectively. Through the self-calibration of the dual-mode signals of the platform, the interference of interferents in a complex environment can be significantly reduced, and it can be used for the detection of hypochlorite in real water samples.

[0025] 2. A preparation method of a dual-mode responsive sensing platform of the present invention for OCl - uses easily obtainable raw materials, has mild and easily controllable reaction conditions, saves reaction costs, and ensures the yield of the target product.

[0026] 3. The dual-mode responsive sensing platform of the present invention for OCl - can be applied to the detection of OCl in real water samples - . These results indicate that the sensing platform is a powerful tool for the accurate detection of OCl - and is expected to achieve the accurate detection of hypochlorite in a complex environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 1H NMR spectrum of Compound 1 in the present invention;

[0028] Figure 2 13C NMR spectrum of Compound 1 in the present invention;

[0029] Figure 3 1H NMR spectrum of Compound 2 in the present invention;

[0030] Figure 4 13C NMR spectrum of Compound 2 in the present invention;

[0031] Figure 5 High-resolution mass spectrum of Compound 2 in the present invention;

[0032] Figure 6 1H NMR spectrum of Compound 3 in the present invention;

[0033] Figure 7 13C NMR spectrum of Compound 3 in the present invention;

[0034] Figure 8 High-resolution mass spectrum of Compound 3 in the present invention;

[0035] Figure 9 1H NMR spectrum of Compound FPTZ in the present invention;

[0036] Figure 10 13C NMR spectrum of compound FPTZ in the present invention;

[0037] Figure 11 High-resolution mass spectrum of compound FPTZ in the present invention

[0038] Figure 12 1H NMR spectrum of FPTZ-1 in the present invention;

[0039] Figure 13 13C NMR spectrum of FPTZ-1 in the present invention;

[0040] Figure 14 High-resolution mass spectrum of FPTZ-1 in the present invention;

[0041] Figure 15 Photophysical property diagram of FPTZ-1 in the present invention; Absorption spectra and (B) fluorescence responses (λex = 405 nm) of FPTZ-1 (10 μM) in PBS (containing 20% ethanol) before and after the addition of ClO - ; (C) Time-dependent fluorescence intensity of FPTZ-1 (10 μM) with different concentrations of ClO in PBS at room temperature - ; (D) Fluorescence intensity changes of FPTZ-1 (10 μM) with 50 μM μM of ClO - and other analytes in PBS (containing 20% ethanol) at 553 nm;

[0042] Figure 16 Characterization diagram of the sensing platform in the present invention; (A) Crystal structure and side view of FPTZ-1 (B); H atoms are omitted for clarity; (C) TiO 2 and TiO 2 / FPTZ-1 XPS spectra; (D-F) High-resolution XPS spectra of Ti 2 p, O1s and N1s; (G) Solid-state UV absorption spectrum of FPTZ-1 on the TiO 2 film; (H) FT-IR absorption spectrum and (I) EIS characterization of the preparation process of the photoanode FTO / TiO 2 / FPTZ-1;

[0043] Figure 17 Evaluation diagram of the detection performance of the sensing platform in the present invention for OCl - ; (A) Photocurrent signal of the FTO / TiO - / FPTZ-1 platform after the increase of ClO 2 concentration; (B) Photocurrent change calibration curve; (C) After the increase of ClO - concentration, FTO / TiO2 Fluorescence signal of the / FPTZ-1 platform; (D) Calibration curve of emission intensity at 520 nm

[0044] Figure 18 This is the fluorescence visualization diagram of the sensing platform in the present invention Detailed implementation manners

[0045] The present invention will be further described below in conjunction with specific embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention

[0046] A sensing platform with dual-mode response to OCl - The structure is as shown in the figure

[0047] .

[0048] A preparation method of a sensing platform with dual-mode response to OCl - comprises the following steps

[0049] (1) Add 2-methoxyphenothiazine, sodium hydroxide and iodoethane to the reactor, dissolve with the first solvent, raise the temperature for reaction, and stir for 1-4 h to obtain compound 1, wherein the molar ratio of 2-methoxyphenothiazine, sodium hydroxide and iodoethane is 1∶2-4∶2.5

[0050] (2) Add compound 1, acetyl chloride and aluminum trichloride to the reactor, dissolve with the second solvent, react at room temperature, stop the reaction after stirring for 1-2 h to obtain compound 2, wherein the molar ratio of compound 1, acetyl chloride and aluminum trichloride is 1∶1-1.5∶1.5

[0051] (3) Add compound 2 and aluminum trichloride to the reactor, dissolve with the second solvent. React at room temperature, stir for 6-12 h to obtain compound 3, wherein the molar ratio of compound 2 and aluminum trichloride is 1∶5-6

[0052] (4) Add compound 3, sodium hydride and ethyl acetate to the reactor, dissolve with the third solvent. React at room temperature, stir for 0.5-1 h to obtain the crude product. Dissolve the crude product with the fourth solvent, add hydrochloric acid, react at room temperature, stir for 12-18 h to obtain compound FPTZ, wherein the molar ratio of compound 3, sodium hydride and ethyl acetate is 1∶5-7∶2.5

[0053] (5) Add compound FPTZ, benzaldehyde and sodium methoxide to the reactor, dissolve with the fourth solvent. Raise the temperature for reaction, stop the reaction after stirring for 0.5-1 h to obtain the fluorescent probe FPTZ-1, wherein the molar ratio of compound FPTZ, benzaldehyde and sodium methoxide is 1∶1.2-1.5∶5

[0054] (6) Dissolve titanium dioxide in the fifth solvent, and at room temperature, drop it onto the FTO glass substrate and air-dry it naturally to form a uniform and stable titanium dioxide nanolayer. Then heat it for calcination for 0.5 - 1 h to obtain a stable titanium dioxide photoelectrode. Subsequently, immerse the obtained photoelectrode in the FPTZ-1 stock solution for 2 h and dry it at room temperature to obtain the final FTO / TiO 2 / FPTZ-1 sensing platform.

[0055] Among them, the first solvent is dimethyl sulfoxide, the second solvent is dichloromethane, the third solvent is tetrahydrofuran, the fourth solvent is methanol, and the fifth solvent is ultrapure water.

[0056] The preparation process is as follows:

[0057] .

[0058] Example 1

[0059] (1) Dissolve 1,2-methoxyphenothiazine (2.29 g, 10 mmol) and crushed NaOH (1.2 g, 30 mmol) in DMSO (20 mL). Then add iodoethane (3.9 g, 25 mmol). Under N 2 atmosphere, stir the mixture at 65 °C for 9 h. After the reaction is completed, cool the reaction and pour it into 300 mL of water. Add CH 2 Cl 2 (100 mL×2) for extraction. Wash the combined organic phase with brine and dry it with magnesium sulfate. After evaporating the solvent under reduced pressure, the crude product is purified by silica gel column chromatography using petroleum ether / CH 2 Cl 2 = 5 / 1 as the eluent to obtain a white solid (2.26 g, 88%).

[0060] As Figure 1 shown, 1 1H NMR (600 MHz, CDCl 3 ) δ 7.16 – 7.12 (m, 2H), 7.05 – 7.00(m, 1H), 6.92 (td, J = 7.5, 1.0 Hz, 1H), 6.89 – 6.85 (m, 1H), 6.52 – 6.44 (m,2H), 3.91 (q, J = 7.0 Hz, 2H), 3.79 (s, 3H), 1.43 (t, J = 7.0 Hz, 3H).

[0061] As Figure 2 shown, 13 C NMR (151 MHz, CDCl 3 ) δ 159.71, 146.36, 144.71, 127.49, 127.27, 127.02, 124.89, 122.28, 115.34, 115.13, 106.40, 103.08, 55.44, 41.75, 12.95.

[0062] (2)At 0 °C, acetyl chloride (1.25 mL, 18 mmol) was added to a 100 mL CH 2 Cl 2 solution of compound 1 (3.49 g, 14 mmol). Then anhydrous AlCl 3 (2.7 g, 21 mmol) was added in portions. Under a N 2 atmosphere, the mixture was stirred at room temperature for 1 h. After the reaction was completed, 10% aqueous sodium hydroxide was added to stop the reaction, and then it was poured into 300 mL of water. CH 2 Cl 2 (100 mL×2) was used for extraction. Then the combined organic phases were washed with brine and dried over Na 2 SO 4 . After evaporation of the solvent under reduced pressure, the crude product was purified by silica gel column chromatography using petroleum ether / EA = 15 / 1 as the eluent to give a yellow solid (2.84 g, 70%).

[0063] As Figure 3 shown, 1 H NMR (600 MHz, CDCl 3 ) δ 7.58 (s, 1H), 7.15 – 7.10 (m, 1H), 7.08 (dd, J = 7.6, 1.2 Hz, 1H), 6.91 (t, J = 7.4 Hz, 1H), 6.85 (d, J = 8.2 Hz, 1H), 6.39 (s, 1H), 3.95 (q, J = 7.0 Hz, 2H), 3.90 (s, 3H), 2.54 (s, 3H), 1.44 (t, J = 7.0 Hz, 3H).

[0064] As Figure 4 shown, 13 C NMR (151 MHz, CDCl 3) δ 196.52, 160.08, 150.18, 143.02, 129.06, 127.33, 127.14, 124.19, 123.11, 121.47, 115.38, 114.75, 98.73, 55.56, 42.25, 31.69, 12.90.

[0065] As Figure 5 shown HRMS (ESI + ): Calculated for C 17 H 17 NO 2 S: [M+H] + = 300.1053, found: [M+H] + = 300.1047.

[0066] (3) Aluminum chloride (0.70 g, 5 mmol) was added to a 100 mL round-bottom flask containing 5 mL of anhydrous CH 3 Cl 2 . At 20 °C and with stirring, a solution of compound 2 (0.3 g, 1 mmol) in CH 2 Cl 2 (2 mL) was added dropwise to the mixture. After 12 h, aqueous HCl solution (2 M, 6 mL) was added and the mixture was stirred for 0.5 h. Then most of the CH 2 Cl 2 was removed under reduced pressure, and EtOAc was added for extraction. The combined organic phases were washed with brine and dried over magnesium sulfate. After removal of the solvent by evaporation under reduced pressure, the crude product was purified by silica gel column chromatography using petroleum ether / EtOAc = 5 / 1 as the eluent to give 3 as a yellow viscous material which solidified upon standing (0.2 g, 71%). 2

[0067] As Figure 6 shown 1 H NMR (600 MHz, CDCl 3 ​) δ 12.64 (s, 1H), 7.34 (s, 1H), 7.17 - 7.12 (m, 1H), 7.09 (dd, J = 7.6, 1.4 Hz, 1H), 6.94 (td, J = 7.5, 0.9 Hz,1H), 6.90 (d, J = 8.2 Hz, 1H), 6.37 (s, 1H), 3.92 (q, J = 7.0 Hz, 2H), 2.50(s, 3H), 1.43 (t, J = 7.0 Hz, 3H).

[0068] As Figure 7 shown 13 C NMR (151 MHz, CDCl 3 ) δ 201.64, 163.88, 151.92, 142.32, 128.27, 127.45, 127.29, 123.39, 123.35, 115.64, 114.70, 112.68, 103.12, 42.57, 26.08, 12.64.

[0069] As Figure 8 shown HRMS (ESI + ):Calculated for C 16 H 15 NO 2 S: [M + H] + = 286.0896, found: [M + H] + = 286.0885.

[0070] (4) Sodium hydride (60% dispersion in mineral oil, 0.21 g, 10.5 mmol) was rinsed three times with hexane and suspended in THF (1.5 mL). At room temperature, a mixture of compound 2 (0.5 g, 1.75 mmol) and EtOAc (0.45 mL, 4.38 mmol) in THF (1 mL) was added dropwise to the above suspension. A vigorous reaction was observed and the temperature rose to reflux. After complete addition, the reaction mixture was stirred for an additional 5 min, quenched on ice, and further acidified to pH 6 with 6 M HCl (aqueous solution). The solution was extracted with EtOAc, the combined organic layers were washed with brine, and dried over magnesium sulfate. The solvent was evaporated to give the crude product. Without further purification, the methanol (10 mL) solution of the crude product was concentrated. The mixture was concentrated under reduced pressure, the residue was diluted with ethyl acetate (50 mL), and then washed successively with saturated sodium bicarbonate (aqueous solution), water, and brine solution. The organic layer was then dried over magnesium sulfate and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography using petroleum ether / EtOAc = 2 / 1 as the eluent to give a yellowish-green solid (0.42 g, 77%).

[0071] As Figure 9 shown, 1 1H NMR (600 MHz, DMSO-d 6 ) δ 7.53 (s, 1H), 7.22 (t, J = 7.8 Hz, 1H),7.14 (d, J = 7.6 Hz, 1H), 7.08 (d, J = 8.2 Hz, 1H), 6.99 (d, J = 6.9 Hz, 2H),6.10 (s, 1H), 3.98 (q, J = 6.9 Hz, 2H), 2.33 (s, 3H), 1.31 (t, J = 6.9 Hz,3H).

[0072] As Figure 10 shown, 13 13C NMR (151 MHz, DMSO) δ 175.58, 166.59, 157.24, 149.21, 142.36,128.47, 127.56, 123.89, 122.11, 122.05, 121.07, 118.21, 116.63, 110.14,103.22, 42.39, 20.36, 12.53.

[0073] As Figure 11 shown, HRMS (ESI +) Calculated value C 18 H 15 NO 2 S: [M+H] + = 310.0891, Experimental value: [M+H] + = 310.0892。

[0074] (5) Sodium methoxide (0.22 g, 4.1 mmol) was gradually added to anhydrous methanol (1 mL), and the mixture was stirred until the solution reached room temperature. FPTZ (0.25 g, 0.8 mmol) and benzaldehyde (0.1 g, 0.96 mmol) were added, and the resulting mixture was stirred under reflux for 45 min. After this time, the solution was poured into ice water, and the pH was adjusted to 4 with HCl. Ethyl acetate (100 mL × 2) was added for extraction. Then the combined organic phases were washed with brine and dried over magnesium sulfate. After evaporation of the solvent under reduced pressure, the crude product was purified by silica gel column chromatography using CH 2 Cl 2 / MeOH = 20 / 1 as the eluent to give an orange solid (0.23 g, 70%)

[0075] As Figure 12 shown, 1 H NMR (600 MHz, DMSO) δ 8.87 (s, 2H), 8.14 (s, 2H), 7.80 (s, 2H), 7.55 (s, 1H), 7.23 (t, J = 7.2 Hz, 1H), 7.19 – 7.14 (m, 2H), 7.12 (d, J = 7.8 Hz, 1H), 7.00 (t, J = 7.1 Hz, 1H), 6.51 (s, 1H), 4.02 (q, J = 7.0 Hz, 2H), 1.37 (t, J = 6.4 Hz, 3H).

[0076] As Figure 13 shown, 13 C NMR (151 MHz, DMSO) δ 175.26, 160.23, 156.40, 150.41, 149.17, 142.18, 141.69, 133.14, 128.05, 127.11, 125.17, 123.54, 121.62, 121.57, 121.50, 120.92, 118.35, 116.23, 111.56, 102.77, 42.11, 12.17.

[0077] As Figure 14 shown, HRMS (ESI+): calculated value C 24 H 18 N 2 O 2 S: [M+H] + = 399.1162, experimental value: [M+H] + = 399.1153.

[0078] (6) The FTO glass substrate was cleaned by ultrasonication in acetone, ethanol, and ultrapure water for 30 min, respectively, to remove surface impurities, and then dried with nitrogen. TiO 2 was formulated into an ultrapure aqueous solution of 8 mg / mL and dropped onto the pretreated FTO glass substrate at room temperature, air-dried, and a uniform and stable TiO 2 nanolayer was formed on the surface. Then it was calcined at 300 °C for 1 h to obtain a stable TiO 2 photoanode. At 25 °C, the TiO 2 photoanode was immersed in a 0.3 mM FPTZ-1 stock solution prepared in 2 mL of MeOH for 2 h. Then the unbound FPTZ-1 probe was washed off, and then the electrode was dried at room temperature to obtain the final FTO / TiO 2 / FPTZ-1 sensing platform.

[0079] All the photophysical characterization experiments of the probe FPTZ-1 were carried out at room temperature. All aqueous solutions were prepared with deionized water. The probe was dissolved in dimethyl sulfoxide (DMSO) to make a 10 mM stable stock solution. The probe stock solution was diluted to 10 μM with EtOH / PBS buffer (2:88, v / v, 10 mM, pH = 7.40).

[0080] The PEC test of the sensing platform was carried out in a phosphate buffer solution (10 mM, pH 7.4) containing 0.1 M ascorbic acid (AA) using a platinum sheet counter electrode and an Ag / AgCl reference electrode, and the PEC response of the treated photoanode was recorded on a CHI660E electrochemical workstation. Subsequently, under the optimized experimental conditions, the photocurrents of FTO / TiO 2 / FPTZ-1 in response to ClO- at different concentrations from 0.05 to 40 μM were recorded. The PEC photoelectric signal was tested using a UVGO 78UY type ultraviolet lamp, and a 405 nm laser was used as the excitation source (998 mW).

[0081] As Figure 15As shown, this application evaluated the photophysical properties of FPTZ-1 in EtOH / PBS buffer (v∶v = 2∶8, 10 mM, pH = 7.40) ( Figure 15 ). First, this application investigated the UV-visible absorption spectra of FPTZ-1 after reacting with different equivalents of OCl - . In the absence of OCl - , the maximum absorption peak of this probe was located at 434 nm, and the molar extinction coefficient was 11000 M·cm -1 . After adding OCl - , a new absorption peak appeared at 388 nm ( Figure 15 A). As the concentration of OCl - increased, the intensity of the 434 nm peak decreased, while the intensity of the 388 nm peak increased until the reaction was complete. It is worth noting that during the entire reaction process, the only isosbestic point appeared at 410 nm, confirming that FPTZ-1 was completely converted into the only oxidation product without any side reactions, which was further confirmed by subsequent mechanism studies. Compared with the sulfur atom, the electron-donating ability of the sulfone group decreased, effectively inhibiting the intramolecular CT process, resulting in a blue shift of λ abs in the absorption spectrum.

[0082] Subsequently, this application studied the fluorescence response of FPTZ-1 to OCl - ( Figure 15 B). This probe showed weak fluorescence in PBS buffer (10 mM, pH = 7.40, containing 20% DMSO), with a maximum emission wavelength of 553 nm and a quantum yield of 1.3%. The emission peak was relatively weak and broad, indicating that this emission peak was a CT emission peak. The strong intermolecular CT effect of this probe molecule was the main reason for its fluorescence quenching. After introducing OCl - into the probe solution, the fluorescence at 553 nm increased significantly. After adding 5 equivalents of OCl - , it reached stability, and the fluorescence intensity increased by approximately 3 times at most. The increase in emission intensity was attributed to the significant inhibition of the ICT effect in the oxidation product formed after reacting with OCl - .

[0083] In addition, this application also evaluated the reaction kinetics of FPTZ-1 with OCl - and the specificity of the reaction to OCl - ( Figure 15 C, D). By adding different concentrations of OCl - to the buffer solution of FPTZ-1, FPTZ-1 immediately reacted with OCl - , resulting in a significant increase in the fluorescence intensity at 553 nm. It is worth noting that even at low concentrations of OCl- In the presence of these, these reactions can also be completed within a few seconds, indicating that FPTZ-1 has an ultrafast response ability to OCl - Finally, this application studied the changes in the fluorescence intensity of FPTZ-1 after introducing different bio-related analytes. The results showed that after adding OCl - alone, the fluorescence intensity of FPTZ-1 at 553 nm increased significantly. Except for OCl - , the introduction of other species had a negligible effect on the fluorescence spectrum. These findings indicate that FPTZ-1 can specifically detect OCl - in a complex environment.

[0084] Therefore, based on the above excellent photophysical properties of FPTA-1, this application used it as an organic photosensitive material to construct the subsequent dual-readout signal sensing platform ITO / TiO 2 / FPTZ-1.

[0085] Characterization of the sensing platform, as Figure 16 shown, the chemical structure of FPTZ-1 was determined by X-ray single crystal diffraction ( Figure 16 A, B). Subsequently, the prepared FTO / TiO 2 / FPTZ-1 sensing platform was characterized by X-ray photoelectron spectroscopy (XPS), solid-state ultraviolet-visible absorption spectroscopy (UV-Vis), Fourier transform infrared absorption spectroscopy (FT-IR), and electrochemical techniques. All results fully confirmed the successful preparation of the FTO / TiO 2 / FPTZ-1 sensing platform.

[0086] Application Example 1

[0087] The sensing platform was used to detect OCl - in PBS.

[0088] To gain an in-depth understanding of the PEC and fluorescence dual-mode sensing mechanisms and evaluate the feasibility of the proposed sensing platform, its photocurrent response and fluorescence response to OCl - were studied. As can be seen from Figure 17 , as the concentration of OCl - increased from 0.05 μM to 40 μM, the current signal of the FTO / TiO 2 / FPTZ-1 PEC system gradually decreased. In the range of 0.05 - 40 μM, the change in photocurrent was linearly correlated with the logarithm of the OCl - concentration, and the linear equation was ΔI (μA) = 5.71 log c - 6.16. The proposed FTO / TiO 2 / FPTZ-1 platform had a -The detection has excellent sensitivity, with a detection limit (LOD) of 1.37 nM, as Figure 17 shown in 2 Figure B. Subsequently, this application studied the fluorescence response of the FTO / TiO 2 / FPTZ-1 PEC platform to OCl - . This platform exhibits weak fluorescence in the absence of OCl - , which is a CT emission peak with a weak and broad peak. The strong ICT effect of this probe is the main reason for its fluorescence quenching. After introducing different amounts of OCl - into the probe solution, a significant fluorescence turn-on occurs at 520. It reaches stability after adding 20 μM of OCl - . Compared with the state before the platform response, the fluorescence intensity at 520 nm increases by approximately 14.8 times. And in the range of 0 - 20 μM, the change in the fluorescence signal at 520 nM is linearly correlated with the concentration of OCl - , and the linear equation is F = 0.14 c + 0.22. Using the equation 3σ / k, the detection limit of FTO / TiO 2 / FPTZ-1 at 520 is 0.288 μM. In addition, the naked-eye readout performance of the sensing platform was also examined. Under the irradiation of 365 nm ultraviolet light, the PL intensity increases significantly with the increase in the concentration of OCl - ( Figure 18 ).

[0089] Application Example 2

[0090] The sensing platform was used to detect OCl - in real water samples.

[0091] The feasibility of this dual-mode sensing platform was verified in water samples from Xuanwu Lake (Nanjing, China) using the standard addition method. First, the water samples were pretreated to remove suspended solids; then, different concentrations of ClO - (0.5, 2.5, 5.0 μM) were added to the water samples, and the designed sensing strategy was used for detection. For different ClO - concentrations, the recovery rates of the PL and PEC signals were 97.3% to 101.9% and 98.6% to 100.4% respectively, and the RSDs were less than 5.93% and 2.07% respectively (Table 1).

[0092] Table 1

[0093]

[0094] In addition, traditional DPD colorimetric analysis was performed on actual samples with the same concentration, and the recovery rates were 91.33% to 102.67%. See Table 2 for details.

[0095] Table 2

[0096]

[0097] These experimental results show that the designed FTO / TiO 2 / FPTZ-1 dual-mode sensing platform exhibits selectivity and accuracy in the detection of ClO - in complex real water environments.

Claims

1. A dual-mode sensing platform responsive to hypochlorite, characterized in that: Its structure is: 。 2. The method for preparing a dual-mode hypochlorite response sensing platform according to claim 1, characterized in that: The following steps are involved: (1) Adding 2-methoxyphenothiazine, sodium hydroxide and ethyl iodide into a reactor, adding a first solvent to dissolve, raising the temperature to react, and stirring for 1 to 4 hours to obtain compound 1, wherein the molar ratio of 2-methoxyphenothiazine, sodium hydroxide and ethyl iodide is 1:2 to 4:2.5; (2) Adding compound 1, acetyl chloride and aluminum chloride into a reactor, adding a second solvent to dissolve, reacting at room temperature, stirring for 1 to 2 hours and then stopping the reaction to obtain compound 2, wherein the molar ratio of compound 1, acetyl chloride and aluminum chloride is 1:1 to 1.5:1.5; (3) Add compound 2 and aluminum chloride to the reactor and dissolve them in a second solvent. React at room temperature and stir for 6 to 12 hours to obtain compound 3, wherein the molar ratio of compound 2 to aluminum chloride is 1:5 to 6; (4) Add compound 3, sodium hydride and ethyl acetate to the reactor and dissolve them with the third solvent. React at room temperature and stir for 0.5-1 h to obtain a crude product. Dissolve the crude product with the fourth solvent, add hydrochloric acid, react at room temperature and stir for 12-18 h to obtain compound FPTZ, wherein the molar ratio of compound 3, sodium hydride and ethyl acetate is 1:5-7:2.5; (5) Add compound FPTZ, benzaldehyde and sodium methoxide to the reactor and dissolve them with a fourth solvent. Raise the temperature to react, stir for 0.5 to 1 h and then stop the reaction to obtain the fluorescent probe FPTZ-1, wherein the molar ratio of compound FPTZ, benzaldehyde and sodium methoxide is 1:1.2 to 1.5:5; (6) Titanium dioxide is dissolved in the fifth solvent, added dropwise to the FTO glass substrate at room temperature, and naturally air-dried to form a uniform and stable titanium dioxide nanolayer. Then the temperature is raised and calcined for 0.5-1 h to obtain a stable titanium dioxide photoelectrode. Subsequently, the obtained photoelectrode is soaked in the FPTZ-1 stock solution for 2 h and dried at room temperature to obtain the final FTO / TiO2 / FPTZ-1 sensing platform; The preparation process is: 。 3. The method for preparing a dual-mode hypochlorite response sensing platform according to claim 2, characterized in that: The temperature of the heating reaction in step (1) is 60-70°C.

4. The method for preparing a dual-mode hypochlorite response sensing platform according to claim 2 or 3, characterized in that: The temperature of the heating reaction in step (5) is 60-70°C.

5. The method for preparing a dual-mode hypochlorite-responsive sensing platform according to any one of claims 2 to 4, characterized in that: The temperature of the heating reaction in step (6) is 300-350°C.

6. The method for preparing a dual-mode hypochlorite response sensing platform according to claims 2 to 5, characterized in that: The first solvent is dimethyl sulfoxide; the second solvent is dichloromethane; the third solvent is tetrahydrofuran; the fourth solvent is methanol; and the fifth solvent is ultrapure water.

7. Use of the dual-mode sensing platform responsive to hypochlorite according to claim 1 or the FTO / TiO2 / FPTZ-1 sensing platform with dual-mode response to hypochlorite prepared according to the method for preparing the sensing platform with dual-mode response to hypochlorite according to any one of claims 2 to 6 in detecting hypochlorous acid in a water sample environment.

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