Ratio-type photoelectrochemical microsensor based on competitive absorption regulation and preparation method and application thereof

Abstract

The application discloses a ratio type photoelectrochemical microsensor based on competitive absorption regulation, which uses cadmium telluride quantum dots as photoelectric active material and energy donor, and uses an organic small molecule probe as a recognition unit and energy acceptor, and can specifically recognize target objects to change light absorption intensity. The ratio type photoelectrochemical microsensor is prepared by adding a small molecule probe solution into a cadmium telluride quantum dot aqueous solution to obtain a compound, and then modifying the compound to an electrode surface through a self-assembly method. The ratio type photoelectrochemical microsensor is mainly used for sensitive detection of hypochlorous acid, and the detection purpose is achieved through the combination between the small molecule probe and the target object, thereby greatly improving the specificity of the photoelectrochemical sensor, and solving the problem that a traditional photoelectrochemical sensor cannot detect non-electrochemical active substances. Meanwhile, the ratio signal can be better applied to a complex environment, so that the whole system has strong anti-interference ability.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochemical analysis, and in particular to a ratiometric photoelectrochemical microsensor based on competitive absorption regulation, and a preparation method and application thereof. Background Art

[0002] Electrochemical (EC) analysis is a promising analytical tool due to its advantages such as high spatiotemporal resolution and good sensitivity. However, the detection of non-electrochemically active substances using EC sensors remains a considerable challenge. In addition, when faced with many structurally similar substances, the specificity of EC sensing is insufficient. As a branch of EC analysis, photoelectrochemical (PEC) analysis has developed rapidly in recent years. Compared with EC analysis methods, it has higher compatibility with living organisms because it uses light rather than bias voltage as the excitation source. However, PEC sensing also faces the problem of insufficient specificity, so PEC sensing is not widely used in complex environments.

[0003] Hypochlorous acid, a type of reactive oxygen species, participates in various physiological and pathological processes in the body. Real-time detection of hypochlorous acid levels can help study the mechanisms of various diseases and achieve prevention and treatment. However, as a non-electrochemically active substance, hypochlorous acid is difficult to detect photoelectrochemically via direct redox methods. Therefore, a stable and reliable method for hypochlorous acid detection remains to be developed. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the purpose of the present invention is to provide a highly specific, widely applicable, and universal ratiometric photoelectrochemical microsensor based on competitive absorption regulation. The detection purpose is achieved through the binding between organic small molecule probes and the target object, which greatly improves the specificity of the photoelectrochemical sensor and solves the problem that traditional photoelectrochemical sensors cannot detect non-electrochemically active substances. At the same time, the ratiometric signal can be better applied to complex environments, giving the entire system a strong anti-interference ability.

[0005] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0006] A ratiometric photoelectrochemical microsensor based on competitive absorption regulation uses cadmium telluride quantum dots as photoelectrically active materials and energy donors, and organic small molecule probes as recognition units and energy acceptors. The cadmium telluride quantum dots and the organic small molecule probes are compositely modified on electrodes to form a ratiometric photoelectrochemical microsensor. Among them, competitive absorption can occur between the cadmium telluride quantum dots and the organic small molecule probes under the irradiation of dual excitation light sources. The organic small molecule probes can undergo a specific recognition reaction on the target and change the light absorption intensity to cause a change in the photocurrent signal, thereby realizing the detection of the target.

[0007] According to the above scheme, the absorption capacity of cadmium telluride quantum dots and organic small molecule probes for excitation light is comparable, that is, the difference in molar absorption coefficient does not exceed two orders of magnitude.

[0008] Furthermore, the organic small molecule probe is: (E)-O-(4-(2-(3-(dicyano)-5,5-dimethylcyclohex-1-en-1-yl)vinyl)phenyl)dimethylaminosulfate (abbreviated as CN-MTC), with the chemical formula: The target substance in this case is hypochlorous acid.

[0009] Another object of the present invention is to provide a method for preparing the above-mentioned ratiometric photoelectrochemical microsensor based on competitive absorption regulation, comprising the following steps:

[0010] (1) dissolving cadmium telluride quantum dots in water to prepare an aqueous solution;

[0011] (2) dissolving the organic small molecule probe in an aqueous solution of dimethyl sulfoxide to obtain an organic small molecule probe solution;

[0012] (3) mixing the organic small molecule probe solution with the cadmium telluride quantum dot aqueous solution to obtain a composite;

[0013] (4) The complex is modified onto the electrode surface by self-assembly, and the electrode of the modified complex is a ratiometric photoelectrochemical microsensor regulated by competitive absorption.

[0014] According to the above scheme, in step (3), the concentration of the cadmium telluride quantum dot aqueous solution is in the range of 0.2 to 1 mg / mL; the concentration of the organic small molecule probe solution is in the range of 20 to 100 μM, and the solvent is a dimethyl sulfoxide aqueous solution with a volume concentration not exceeding 5%; the small molecule probe solution and the cadmium telluride quantum dot aqueous solution are mixed in a volume ratio of 1:(0.8 to 1.2).

[0015] According to the above scheme, in step (4), the specific process of modifying the complex onto the electrode surface by self-assembly is as follows: insert the electrode upside down on the foam board, take the complex solution and drop it on the end of the electrode, and dry it. The drop amount is 1-2 μL / mm 2 The electrodes are microelectrodes, such as metal needles, etc., and generally have a tip diameter of less than 200 μm.

[0016] The last object of the present invention is to provide the application of the above-mentioned ratiometric photoelectrochemical microsensor based on competitive absorption regulation. Under the irradiation of dual excitation light sources, competitive light absorption can occur between cadmium telluride quantum dots and organic small molecule probes, causing the level fluctuation of the target object to bring about changes in the light absorption intensity of the organic small molecule probe, and the detection of the target object is achieved by the linear relationship between the ratio of the photocurrent signal under dual excitation light and the target object level (concentration, content, etc.). Wherein, the wavelength of the dual excitation light source corresponds to the wavelength of the position where the absorption spectra of cadmium telluride quantum dots and organic small molecule probes overlap. Preferably, the wavelengths of the dual excitation light sources are 395-415nm and 510-540nm, respectively.

[0017] The present invention uses the small molecule probe CN-MTC, which can specifically bind to hypochlorous acid, as an example to specifically provide a method for detecting hypochlorous acid using the aforementioned ratiometric photoelectrochemical microsensor based on competitive absorption regulation. The method comprises: using a three-electrode system comprising a working electrode, a reference electrode, and a counter electrode, with the ratiometric photoelectrochemical microsensor as the working electrode, a phosphate buffer solution as the electrolyte, and excitation light from a dual light source with wavelengths of 395-415 nm and 510-540 nm. The working electrode is then incubated with hypochlorous acid at different concentrations by immersion, and then tested using the three-electrode system. The photocurrent changes under the dual-wavelength light source are recorded to obtain a ratiometric signal of the photocurrent intensity under the dual-wavelength light source. A standard curve is then established between the hypochlorous acid concentration and the photocurrent ratio signal under the dual-wavelength light source, thereby enabling detection of hypochlorous acid using the standard curve. The linear relationship range of the standard curve is 0-10 μM.

[0018] The technical principle behind the above-mentioned technical solution of the present invention is as follows: In this photoelectrochemical microsensor, cadmium telluride quantum dots and organic small molecule probes have spectral matching. When irradiated with excitation light whose absorption spectra overlap, competitive absorption occurs between the two, resulting in a decrease in the photocurrent signal. Organic small molecule probes are structurally flexible small molecules that can specifically recognize targets, including reactive oxygen species, reactive sulfur species, enzymes, and other bioactive substances. The present invention uses CN-MTC, a small molecule probe that specifically binds to hypochlorous acid, as an example. Upon binding with hypochlorous acid, it converts to CN-OH, resulting in a significant change in its absorption spectrum. The photoelectric material, cadmium telluride quantum dots, and the organic small molecule probe are co-modified onto a microelectrode. Under irradiation with excitation light of a specific wavelength, different photocurrent signals are generated due to competitive absorption between the photoelectric material and the organic small molecule probe, as well as changes in light absorption intensity caused by fluctuations in the target hypochlorous acid level. The specific chemical reaction between the organic small molecule probe and hypochlorous acid addresses, to some extent, the lack of specificity and universality of traditional photoelectrochemical sensors.

[0019] Since hypochlorous acid itself is a non-electroactive substance, and substances such as H2O2 and OH- will interfere with its detection, it is difficult to perform photoelectrochemical detection through direct oxidation-reduction methods. The present invention selects it as a concept verification target. When the organic small molecule probe is CN-MTC, the competitive absorption between cadmium telluride quantum dots and the organic small molecule probe causes the photocurrent signal to weaken. After the target hypochlorous acid undergoes a specific chemical reaction with CN-MTC, the light absorption properties of the organic small molecule probe change, the competitive absorption effect changes, and it is ultimately manifested as a change in photocurrent intensity. Based on this principle, the ratio-type energy transfer-regulated photoelectrochemical sensing strategy based on competitive absorption regulation proposed in the present invention can achieve specific recognition and sensitive response to the target.

[0020] Ratio signals are rarely used in PEC sensing. However, to further enhance the sensor's reliability in complex environments and improve its anti-interference capabilities, the present invention uses ratio signals to record fluctuations in hypochlorous acid levels. By establishing a linear relationship between the ratio of the photocurrent signal under dual-excitation light and the target level (concentration, content, etc.), the effects of environmental factors and sensor performance can be eliminated to a certain extent. This not only enables self-calibration measurement but also simplifies the control of the photoelectrode, greatly improving the reliability of the sensor.

[0021] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0022] (1) The present invention is based on a competitive absorption design and relies on the specific binding between an organic small molecule probe and the target hypochlorous acid to achieve detection, which greatly improves the specificity of the photoelectrochemical sensor. Compared with traditional photoelectrochemical detection methods, it not only has higher specificity but also solves the problem that traditional photoelectrochemical sensors cannot detect non-electrochemically active substances.

[0023] (2) Compared with other methods for detecting hypochlorous acid, such as chromatography analysis and fluorescence imaging, the present invention has the advantages of strong anti-interference ability, high specificity, high sensitivity, simple and convenient operation, etc.; and the use of ratio signals can eliminate the influence of environmental factors and sensor performance factors to a certain extent, making it more suitable for detection in complex environments, and making the entire system have strong anti-interference ability;

[0024] (3) The present invention is universal and can be applied to the detection of other non-electrochemically active substances. It only requires replacing the organic small molecule probe that specifically binds to the target hypochlorous acid with other qualified small molecules. This reduces the limitations of the photoelectrochemical sensing method to a certain extent, expands the application scope of photoelectrochemical detection, and provides new ideas for photoelectrochemical detection methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1Schematic diagram of the ratiometric photoelectrochemical microsensor constructed based on competitive absorption in the present invention.

[0026] Figure 2 This is the XRD pattern of cadmium telluride quantum dots in the present invention.

[0027] Figure 3 The small molecule probe CN-MTC of the present invention 1 H NMR spectrum.

[0028] Figure 4 The UV-visible absorption spectra of the cadmium telluride quantum dots and small molecule probes in the present invention.

[0029] Figure 5 The UV-visible absorption spectra of the small molecule probes of the present invention after incubation with hypochlorous acid at different concentrations.

[0030] Figure 6 The photocurrent response diagrams of different materials in the present invention are as follows; curves a to e are:

[0031] (a) Initial electrode;

[0032] (b) Initial electrode modified with CdTe quantum dots;

[0033] (c) Initial electrode modified with CdTe quantum dots and then incubated in 10 μM sodium hypochlorite solution for 30 seconds;

[0034] (d) Complex of modified CdTe quantum dots and probe CN-MTC on the initial electrode;

[0035] (e) The photoelectrochemical sensor was incubated in 10 μM sodium hypochlorite solution for 30 s.

[0036] Figure 7 Graphs showing the photocurrent responses of the photoelectrochemical microsensor of the present invention when incubated with hypochlorous acid at different concentrations.

[0037] Figure 8 The standard curve diagram is obtained when the photoelectrochemical microsensor of the present invention is incubated with hypochlorous acid of different concentrations. DETAILED DESCRIPTION

[0038] In order to make the purpose, process conditions and advantages of the present invention more clear, the present invention is further described in detail with reference to the following examples. However, the embodiments of the present invention are not limited thereto. Without departing from the above technical ideas of the present invention, various replacements and changes can be made according to common technical knowledge and customary means in this field, which should be included in the scope of the present invention. The embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0039] In the following embodiments, the specific synthesis process of the cadmium telluride quantum dots used is as follows:

[0040] (1.1) Dissolve 100 mg of sodium citrate, 59 mg of cadmium nitrate, and 25 μL of mercaptopropionic acid in deionized water and sonicate for 3 min to disperse them evenly.

[0041] (1.2) Adjust the mixed solution to pH 11 and transfer it to a round-bottom flask;

[0042] (1.3) Add 18.9 mg of sodium borohydride and 11.1 mg of sodium tellurite, disperse them uniformly by ultrasonication, and then place the round-bottom flask containing the mixture in an oil bath at 100°C and reflux with stirring for 3 h.

[0043] (1.4) After 3 h of reaction, the mixed solution was cooled to room temperature and an equal amount of isopropanol was added. Precipitation was observed in the round-bottom flask. The mixture was allowed to stand until precipitation was complete and then centrifuged at 10,000 rpm for 10 min. The solid was then washed with isopropanol three times. The solid was collected to obtain cadmium telluride quantum dots and dried in an oven at 60°C.

[0044] like Figure 2 As shown in the figure, the XRD pattern shows that the sharp diffraction peaks of cadmium telluride nanocrystals at 2θ=25.54, 41.75 and 49.17° are attributed to the (111), (220) and (311) crystal planes, respectively, which can be indexed to the cubic sphalerite structure (JCPDS card number 65-1046), proving that the prepared quantum dots are cadmium telluride quantum dots.

[0045] In the following examples, the chemical structure of the organic small molecule probe used is: Used for sensitive detection of hypochlorous acid.

[0046] The organic small molecule probe can be synthesized using the following synthetic route:

[0047]

[0048] The specific synthesis process includes the following steps:

[0049] (2.1) Synthesis of compound 1

[0050] Isophosphatone (276 mg, 2 mmol) and malononitrile (62.4 mg, 2.4 mmol) were dissolved in 50 mL of ethanol, and 2-3 drops of piperidine were added. The resulting mixture was stirred and refluxed at 80°C, and the reaction progress was monitored by thin-layer chromatography. Before the reaction was complete, the solvent was removed under vacuum, and then the product was purified by chromatography using petroleum ether and dichloromethane (volume ratio 1:3) as eluent to obtain compound 1 (334 mg, 90%).

[0051] (2.2) Synthesis of compound 2

[0052] Hydroxybenzaldehyde (244 mg, 2 mmol), dimethylthiocarbamoyl chloride (307 mg, 2.5 mmol), and triethylenediamine (392 mg, 3.5 mmol) were dissolved in 30 mL of dimethylformamide. The resulting mixture was heated to 70°C with stirring. Completion of the reaction was confirmed by thin-layer chromatography. The reaction mixture was then extracted with ethyl acetate and saturated sodium chloride, followed by purification by column chromatography using petroleum ether and dichloromethane (volume ratio 1:3) as eluents to yield compound 2 (334 mg, 80%).

[0053] (2.3) Synthesis of CN-MTC

[0054] Compound 1 (372 mg, 2 mmol) and compound 2 (502 mg, 2.4 mmol) were dissolved in 50 mL of ethanol, 2-3 drops of piperidine were added, and the resulting mixture was stirred at 80°C and then cooled to room temperature. The yellow precipitate was CN-MTC (600 mg, 80%).

[0055] The organic small molecule probe synthesized by the above method 1 H NMR spectrum, such as Figure 3 shown. 1 H NMR (400MHz, CDCl3) δ7.55–7.53(m,2H),7.10–7.12(m,2H),7.03(s,1H),6.93–6.97(m,1H ),6.84–6.87(m,1H),3.47(s,3H),3.36(s,3H),2.61(s,2H),2.47(s,2H),1.08(s,6H);.The 1 H NMR spectrum confirmed that the organic small molecule probe was successfully synthesized.

[0056] The light absorption capabilities of the above-mentioned cadmium telluride quantum dots and organic small molecule probes are comparable, that is, the difference in the molar absorption coefficient σ does not exceed two orders of magnitude, as shown in Table 1.

[0057] Table 1 Molar absorption coefficients of CdTe quantum dots and organic small molecule probes

[0058]

[0059] Example 1

[0060] A ratiometric photoelectrochemical microsensor based on competitive absorption regulation uses cadmium telluride quantum dots as the photoactive material and energy donor, and an organic small molecule probe CN-MTC as the recognition unit and energy acceptor. The cadmium telluride quantum dots and the organic small molecule probe are compositely modified on an electrode to form a ratiometric photoelectrochemical microsensor. The specific preparation method includes the following steps:

[0061] i) Dissolve the probe CN-MTC in 1% dimethyl sulfoxide solution to a concentration of 50 μM; dissolve cadmium telluride powder in water to a concentration of 500 μM; mix the two in equal volumes and sonicate;

[0062] ii) Place the electrode upside down on the foam board and drop 3 μL of the mixed solution obtained in step i) onto the end of the electrode. The drop amount is 1-2 μL / mm 2 , the droplet area is 3.14~6.28mm 2 ; Then it was dried in an oven at 60℃ to obtain a ratiometric photoelectrochemical microsensor.

[0063] Figure 4 and Figure 5 It can be proved that energy transfer occurs between CdTe quantum dots and CN-MTC. Figure 4 As shown in Figure 2, the absorption spectra of the small molecule probe CN-MTC and the cadmium telluride quantum dots are highly matched, achieving the premise of competitive absorption. Figure 5 As shown, the chemical reaction between the target hypochlorous acid and the small molecule probe will reduce the absorption intensity at 405nm, while the absorption intensity at 525nm will increase, confirming that it is feasible to regulate the photocurrent by changing the absorption intensity.

[0064] like Figure 6 As shown, the successful construction of the photoelectrochemical microsensor was demonstrated by detecting the photocurrent response of the photoelectrochemical microsensor. First, there was no photocurrent response in the initial electrode, but after modification with cadmium telluride quantum dots, there was a relatively obvious photocurrent under both excitation lights. After modifying the complex of cadmium telluride and probe CN-MTC on the electrode, the photocurrent signal decreased, proving that the presence of competitive absorption can reduce the photocurrent, indicating the successful construction of the photoelectrochemical sensor of the present invention. After incubating the photoelectrochemical sensor with hypochlorous acid, the photocurrent increased under 405nm light excitation, proving that the chemical reaction between hypochlorous acid and the small molecule probe CN-MTC reduced the light absorption capacity of CN-MTC at 405nm, thereby weakening the competitive absorption and ultimately leading to an increase in photocurrent. Under 525nm light excitation, the photocurrent decreased, proving that the chemical reaction between hypochlorous acid and the small molecule probe CN-MTC enhanced the light absorption capacity of CN-MTC at 525nm, thereby enhancing competitive absorption and ultimately leading to a decrease in photocurrent. The above results prove that the photoelectrochemical sensing strategy based on competitive absorption is feasible.

[0065] Example 2

[0066] This example uses the ratiometric photoelectrochemical microsensor prepared in Example 1 to detect hypochlorous acid. The specific steps are as follows:

[0067] (1) Because hypochlorous acid is unstable and easily decomposes when exposed to light, the present invention uses a method of diluting sodium hypochlorite to prepare a hypochlorous acid solution, and then determines the hypochlorous acid concentration by ultraviolet absorbance measurement. The concentrations of different hypochlorous acid concentrations are 0, 1, 2.5, 5, 7.5, and 10 μM.

[0068] (2) A conventional three-electrode system was used on a CHI 730E electrochemical workstation, including a working electrode, a reference electrode, and a counter electrode. The ratiometric photoelectrochemical microsensor prepared in Example 1 was used as the working electrode, the reference electrode was a silver / silver chloride electrode, the counter electrode was a platinum wire electrode, a phosphate buffer solution with a pH value of 7.4 was used as the electrolyte, and the excitation light was 405nm violet light and 525nm green light. The working electrode was then incubated with hypochlorous acid of different concentrations at 25°C for 30 seconds, and then tested using the above three-electrode system. The photocurrent changes under the dual-wavelength light source were recorded, and the ratio signal of the photocurrent changes under the dual-wavelength light source was obtained (the average value of three parallel measurements was taken), as shown in Table 2. A standard curve of the hypochlorous acid concentration and the photocurrent ratio signal under the dual-wavelength light source was established, as shown in Table 2. Figure 8 shown.

[0069] Table 2 Changes in dual-channel photocurrent and ratio at different hypochlorous acid concentrations

[0070]

[0071]

[0072] Figure 7 The photocurrent signals obtained after the photoelectrochemical sensor was incubated with different concentrations of hypochlorous acid (0, 1, 2.5, 5, 7.5, 10 μM) for 8 minutes under the excitation of two light sources are shown. The results show that as the concentration of hypochlorous acid gradually increases, I 405 and I 525 The ratio of is also gradually increasing, and has a good linear relationship in the range of 0μM to 10μM, and the linear equation is I=2.41+0.082C ClO- (R 2 =0.9937), such as Figure 8 The results show that the ratiometric photoelectrochemical sensor proposed in the present invention can be used for sensitive detection of hypochlorous acid.

[0073] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A ratiometric photoelectrochemical microsensor based on competitive absorption regulation, characterized in that: Cadmium telluride quantum dots are used as photoelectric active materials and energy donors, and organic small molecule probes are used as recognition units and energy acceptors. The cadmium telluride quantum dots and the organic small molecule probes are compositely modified on an electrode to form a ratiometric photoelectrochemical microsensor. Competitive light absorption can occur between the cadmium telluride quantum dots and the organic small molecule probes. The organic small molecule probes can undergo a specific recognition reaction on the target and change the light absorption intensity to cause a change in the photocurrent signal, thereby achieving detection of the target. The chemical structure of the organic small molecule probe is: .

2. The photoelectrochemical microsensor based on small molecule probes according to claim 1, characterized in that: The target substance is hypochlorous acid.

3. The photoelectrochemical microsensor based on small molecule probes according to claim 1, characterized in that: Under the irradiation of dual excitation light sources, competitive absorption occurs between cadmium telluride quantum dots and organic small molecule probes, causing the level fluctuation of the target object and the change of the light absorption intensity of the organic small molecule probe. The photocurrent signal ratio of the target object under the dual excitation light source at different concentrations is obtained, thereby realizing the detection of the target object; wherein, the wavelength of the dual excitation light source corresponds to the wavelength of the overlapping position of the absorption spectra of the cadmium telluride quantum dots and the organic small molecule probe.

4. The photoelectrochemical microsensor based on small molecule probes according to claim 3, characterized in that: The wavelengths of the dual excitation light sources are 395~415nm and 510~540nm respectively.

5. The method for preparing a ratiometric photoelectrochemical microsensor based on competitive absorption regulation according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) Dissolving cadmium telluride quantum dots in water to prepare an aqueous solution; (2) dissolving the organic small molecule probe in an aqueous solution of dimethyl sulfoxide to obtain an organic small molecule probe solution; (3) mixing the small molecule probe solution with the cadmium telluride quantum dot aqueous solution to obtain a complex; (4) The complex is modified onto the electrode surface by self-assembly, and the electrode of the modified complex is a ratiometric photoelectrochemical microsensor regulated by competitive absorption.

6. The method for preparing a ratiometric photoelectrochemical microsensor based on competitive absorption regulation according to claim 5, characterized in that: In step (3), the concentration of the cadmium telluride quantum dot aqueous solution is in the range of 0.2~1 mg / mL; the concentration of the organic small molecule probe solution is in the range of 20~100 μM, and the solvent is a dimethyl sulfoxide aqueous solution with a volume concentration not exceeding 5%; the organic small molecule probe solution and the cadmium telluride quantum dot aqueous solution are mixed in a volume ratio of 1:(0.8~1.2).

7. The method for preparing a ratiometric photoelectrochemical microsensor based on competitive absorption regulation according to claim 5, characterized in that: In step (4), the method for modifying the complex onto the electrode surface by self-assembly is as follows: insert the electrode upside down on the foam board, take a solution of the complex and drop it on the end of the electrode, and dry it.

8. The method for preparing a ratiometric photoelectrochemical microsensor based on competitive absorption regulation according to claim 5, characterized in that: The light absorption capabilities of cadmium telluride quantum dots and organic small molecule probes are comparable, that is, the difference in molar absorption coefficients does not exceed two orders of magnitude; the absorption spectra of cadmium telluride quantum dots and organic small molecule probes overlap.

9. The method for detecting hypochlorous acid using a ratiometric photoelectrochemical microsensor based on competitive absorption regulation according to claim 2, wherein: A three-electrode system is used, including a working electrode, a reference electrode, and a counter electrode. The ratiometric photoelectrochemical microsensor is used as the working electrode, a phosphate buffer solution is used as the electrolyte, and the excitation light is a dual light source with wavelengths of 395-415 nm and 510-540 nm. The working electrode is then immersed and incubated with hypochlorous acid of different concentrations, and then tested using the three-electrode system. The photocurrent change under the dual-wavelength light source is recorded to obtain a ratio signal of the photocurrent change under the dual-wavelength light source. A standard curve of hypochlorous acid concentration and the photocurrent ratio signal under the dual-wavelength light source is established, and the standard curve is used to detect hypochlorous acid.

10. The method for detecting hypochlorous acid using a ratiometric photoelectrochemical microsensor based on competitive absorption regulation according to claim 9, wherein: The linear range of the standard curve was 0~10 μM.

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