A method for preparing a self-powered sensor for a light-assisted auxiliary all-solid-state zinc-air battery based on a signal flipping strategy and application of the method in detecting theophylline

Abstract

This invention belongs to the field of photoelectrochemical detection, specifically relating to a method for fabricating a photo-assisted all-solid-state zinc-air battery self-powered sensor based on a signal reversal strategy and its application in detecting theophylline. Using CuInS2 as the photocathode, CdS is loaded onto the photocathode using a split aptamer technique. Polished zinc foil is used as the anode, and PVA gel polymer is used as the solid electrolyte to construct a photo-assisted all-solid-state zinc-air battery self-powered sensor based on a signal reversal strategy. This invention achieves signal reversal by incorporating split aptamer technology, thereby significantly improving the detection sensitivity for antioxidants. The constructed photo-assisted all-solid-state zinc-air battery self-powered sensor based on a signal reversal strategy also has a wide detection range, low detection limit, and low detection cost.

Description

Technical Field

[0001] This invention belongs to the field of photoelectrochemical detection, specifically relating to a method for preparing a self-powered sensor for a photo-assisted all-solid-state zinc-air battery based on a signal reversal strategy and its application in detecting theophylline. Background Technology

[0002] The human body continuously generates free radicals through constant contact with the external environment. When the concentration of oxidatively active substances is too high, it disrupts the balance between oxidation and antioxidation in the body, leading to oxidative stress. At this time, free radicals and other oxidatively active substances damage the structure and function of macromolecules within cells. When the damage to cells reaches an irreparable level, it can trigger a series of serious diseases. Antioxidants can effectively scavenge free radicals within cells, protecting them from oxidative stress and maintaining the body's health and stability. Polyphenols are a mixture of secondary metabolites widely found in plants, exhibiting excellent antioxidant properties, especially in their ability to scavenge free radicals, making them a promising natural antioxidant that has attracted much attention in recent years. Theophylline is a biologically active purine alkaloid, mainly found in plants such as tea and coffee. Theophylline has various physiological functions in organisms, such as bronchodilating and improving respiratory function. Recent studies have shown that theophylline can indirectly exert its antioxidant effect by regulating intracellular signaling pathways or by working synergistically with other antioxidants.

[0003] Traditional methods for detecting theophylline include spectroscopic methods, chromatographic methods, and enzyme-linked immunosorbent assays (ELISA). Spectroscopic methods offer advantages such as simplicity and speed, but suffer from low resistance to interference. Chromatographic methods can accurately distinguish antioxidant components in complex food components and provide concentration information, but the expensive, bulky, and complex instruments limit their widespread adoption. ELISA offers high sensitivity and specificity, but requires the preparation of corresponding antibodies. Therefore, there is an urgent need to develop a low-cost, simple, rapid, highly sensitive, interference-resistant, and reproducible method to overcome these shortcomings.

[0004] A light-assisted self-powered electrochemical sensor is a novel sensor integrating photoelectric conversion and electrochemical sensing technologies. It combines the photoelectric effect with electrochemical reaction processes, using photogenerated electrons and holes generated by light illumination to drive electrochemical sensing. The advantages of a light-assisted self-powered electrochemical sensor lie in its lack of external power supply, thus offering low power consumption, portability, and implantability. Zinc-air batteries, as a common battery type, possess advantages such as high energy density and environmental friendliness, playing a crucial role in light-assisted self-powered electrochemical sensors. The signal inversion strategy, by introducing a specific signal conversion mechanism, achieves high-sensitivity response and rapid identification of target analytes. Combining the signal inversion strategy with a portable self-powered electrochemical sensor enables both highly sensitive detection of analytes and meets the requirements of high integration and miniaturization for portable sensors. However, there are no reports on establishing a self-powered sensing platform for the photoelectrochemical detection of theophylline using a light-assisted all-solid-state zinc-air battery device based on the signal inversion strategy. Summary of the Invention

[0005] This invention aims to provide a method for constructing a light-assisted all-solid-state zinc-air battery self-powered sensor for theophylline detection based on a signal reversal strategy, which combines the advantages of high sensitivity, low detection limit, and wide detection range. A self-powered sensor for theophylline detection is constructed based on a CdS / CuInS2 composite material. This sensor has a simple fabrication process and low cost. Test results show that the sensor has high sensitivity and a low detection limit.

[0006] The present invention discloses a method for preparing a light-assisted all-solid-state zinc-air battery self-powered sensor for detecting theophylline based on a signal reversal strategy, comprising the following steps:

[0007] (1) Disperse CuInS2 powder in ultrapure water to obtain CuInS2 dispersion, drop it onto ITO electrode, then drop split aptamer S1 onto the surface of CuInS2 electrode, incubate at room temperature, and label it as S1-CuInS2; drop bovine serum albumin (BSA) onto the electrode, then drop the analyte solution onto the modified electrode, and label it as CuInS2-S1 / TP;

[0008] (2) CdS@NH2 and split aptamer S2 were shaken to obtain a mixture. The mixture was centrifuged to collect the solid phase, and then dispersed in phosphate buffer solution to obtain CdS-S2 dispersion. CdS-S2 was incubated on CuInS2-S1 / TP electrode, and unbound CdS-S2 was washed away. The electrode was labeled as CuInS2-S1 / TP / S2-CdS electrode.

[0009] (3) Using CuInS2-S1 / TP / S2-CdS electrode as photocathode, polished zinc foil as anode, PVA gel polymer as solid electrolyte, and xenon lamp as light source, a light-assisted all-solid-state zinc-air battery self-powered sensor based on signal reversal strategy is constructed.

[0010] The CuInS2 of this invention is prepared by the following method: cuprous chloride, indium(III) chloride hydrate and thiourea are dissolved in ethylene glycol solution and heated at 180 °C for 24 h; the product is collected by centrifugation, washed, and the collected precipitate is freeze-dried; wherein the molar ratio of cuprous chloride, indium(III) chloride hydrate and thiourea is 1:1:4.

[0011] The CdS@NH2 of this invention is prepared by the following method: thiourea and glutathione are added to a Cd(NO3)2·4H2O solution, and the mixed solution is then hydrothermally treated at 160 °C for 8 h. The precipitate is collected by centrifugation and dried to obtain CdS. The CdS is uniformly dispersed in an ethanol-water solution to obtain a CdS suspension. Concentrated ammonia solution is added and the mixture is stirred evenly under ultrasound. (3-aminopropyl)triethoxysilane is added and stirred at 35 °C for 3 h to obtain CdS@NH2. The molar ratio of Cd(NO3)2·4H2O, glutathione, and thiourea is 84:0.5:10. The mass concentration of the CdS suspension is 1.5 mg / mL, and the volume ratio of the CdS suspension to concentrated ammonia solution and (3-aminopropyl)triethoxysilane is 100:1:5.

[0012] The base sequence of the split aptamer S1 described in this invention is 5'-CGGCUGGGGCGAUACCAGCCGAAA-3'; the base sequence of the split aptamer S2 is 5'-CCAGCCGAAAGGCCCUUGGCAGCGUCGGG-3'.

[0013] The mass ratio of CuInS2 to CdS-S2 modification is 5~25:1~10; preferably, the mass ratio of CuInS2 to CdS-S2 modification is 1~20:6~10; more preferably, the mass ratio of CuInS2 to CdS-S2 modification is 20:6.

[0014] In step (1), the concentration of CuInS2 dispersion was 1~5 mg / mL, the modification amount was 50 μL; the concentration of BSA was 1 wt%; the drop volume was 20 μL. The concentration of the split aptamer (S1) was 2 μM; the modification amount of the split aptamer (S1) was 20 μL.

[0015] In step (2), the concentration of CdS@NH2 in the CdS-S2 dispersion is 1~5 mg / mL, the concentration of the splitting aptamer S2 is 2 μM, and the modification amount of the CdS-S2 dispersion is 20 μL.

[0016] In step (3), the PVA gel polymer is prepared as follows: 3.00 g of PVA is dissolved in 50 mL of deionized water, then stirred vigorously at 85 °C for 4 h, then 10 mL of PBS is slowly poured in, and stirring is continued at 60 °C for 3 h, thus successfully preparing the PVA gel. The PVA gel polymer has an area of ​​1 cm × 1 cm and a thickness of approximately 0.3 cm.

[0017] This invention also provides the application of the light-assisted all-solid-state zinc-air battery self-powered sensor prepared by the above method based on a signal reversal strategy in the photoelectrochemical detection of theophylline. First, a photocathode is prepared using a theophylline standard solution to construct a light-assisted all-solid-state zinc-air battery self-powered sensor. The open-circuit photovoltage response value is tested, and a linear relationship is established between the photovoltage intensity after the addition of theophylline and the logarithm of theophylline concentration, obtaining the corresponding linear regression equation. Then, a photocathode is prepared using the test solution, the open-circuit photovoltage response value is tested, and the value is substituted into the linear regression equation to calculate the concentration of theophylline in the test solution.

[0018] The application of the aforementioned light-assisted zinc-air battery self-powered sensor based on a signal reversal strategy in the detection of theophylline involves the following specific detection steps:

[0019] S1. Plotting the standard curve:

[0020] A series of theophylline solutions of known concentrations were drop-coated onto the prepared CuInS2-S1 electrode and incubated at room temperature. The resulting modified electrode was labeled CuInS2-S1 / TP. CdS-S2 was then incubated onto the electrode and labeled CuInS2-S1 / TP / S2-CdS. Using CuInS2-S1 / TP / S2-CdS as the photocathode, polished zinc foil as the anode, and PVA gel polymer as the solid electrolyte, the light intensity of the xenon lamp as the light source was maintained at 20 mW, and the vertical distance from the light source outlet to the ITO conductive surface was maintained at 15 cm. The open-circuit photovoltage response of this circuit was tested, and a series of concentration-photovoltage correspondences were obtained. A standard curve for theophylline was then obtained, and a linear relationship between the photovoltage intensity after the addition of theophylline and the logarithm of theophylline concentration was established, yielding the corresponding linear regression equation.

[0021] S2. Actual sample testing:

[0022] After testing the photovoltage of the actual sample, the calculation is performed according to the linear regression equation in step S1 above.

[0023] Furthermore, in step S1, the concentration range of the series of different concentrations of theophylline is 1.0 × 10⁻⁶. -8 mol / L~1.0×10 -3 mol / L; the amount of theophylline at a series of different concentrations was 20 μL; the incubation time was 1 h.

[0024] The beneficial effects of this invention are:

[0025] This invention prepares a composite CdS / CuInS2 as a photocathode material, successfully establishes a photoelectrochemical sensing platform, and develops a photoelectrochemical detection method for theophylline. Its features and advantages are described below:

[0026] (1) This invention introduces an all-solid-state zinc-air battery into a photo-assisted self-powered electrochemical sensor. The high energy density and safety stability of this battery provide new possibilities for the development of portable sensors. CuInS2 is used as the photocathode, and CdS is loaded onto the photocathode by combining split aptamer technology, thereby forming a CdS / CuInS2 complex. This causes the photoinduced oxygen reduction reaction to be transformed into an oxygen evolution reaction, resulting in a significant voltage change and successfully realizing the signal reversal, thus significantly improving the detection sensitivity of theophylline.

[0027] (2) Compared with traditional detection methods, the photoelectrochemical detection method proposed in this invention has the characteristics of simple and flexible operation, simple instruments and equipment, high sensitivity, wide linear range, low detection limit and low detection cost. Attached Figure Description

[0028] Figure 1 This is a simplified flowchart of the sensor fabrication and the theophylline detection in this invention;

[0029] Figure 2 The effect of different concentrations of CuInS2 on the open-circuit photovoltage response value;

[0030] Figure 3 The effect of different CdS concentrations on the open-circuit photovoltage response;

[0031] Figure 4 The comparison shows the open-circuit voltage response values ​​of CuInS2 and CdS / CuInS2 electrodes in PVA gel electrolyte, with zinc sheet as anode.

[0032] Figure 5 This is an open-circuit voltage diagram for different concentrations of theophylline. The theophylline concentrations from left to right are 1×10⁻⁶. -8 mol / L, 1×10 -7 mol / L, 1×10 -6 mol / L, 1×10 -5mol / L, 1×10 -4 mol / L, 1×10 -3 mol / L;

[0033] Figure 6 It is a standard curve of open-circuit voltage versus the logarithm of theophylline concentration after the addition of theophylline. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to the embodiments. Example 1

[0035] Comparison of the effects of different concentrations of CuInS2 on the open-circuit photovoltage response.

[0036] (1) Preparation of CuInS2 material:

[0037] 0.045 mol / L cuprous chloride, 0.045 mol / L indium(III) chloride hydrate, and 0.18 mol / L thiourea were dissolved in 60 mL of ethylene glycol solution. The solution was then transferred to a polytetrafluoroethylene reactor and heated at 180 °C for 24 h. The product was collected by centrifugation and repeatedly washed with deionized water. Finally, the collected precipitate was freeze-dried.

[0038] (2) Fabrication of a light-assisted all-solid-state zinc-air battery self-powered sensor:

[0039] The CuInS2 powder obtained in step (1) was dispersed in 1 mL of ultrapure water, and 50 μL of different concentrations were drop-coated onto the ITO electrode. CuInS2 was used as the photocathode, polished zinc foil was used as the anode, PVA gel polymer was used as the solid electrolyte, the light intensity of the xenon lamp as the light source was kept at 20 mW, and the vertical distance from the light source outlet to the ITO conductive surface was kept at 15 cm. The open-circuit photovoltage response value of the circuit was tested using a two-electrode system.

[0040] Depend on Figure 2 As can be seen, the open-circuit photovoltage response increases with the concentration of CuInS2 from 1 mg / mL to 4 mg / mL. The open-circuit photovoltage response reaches its maximum value when the concentration of CuInS2 is 4 mg / mL. Therefore, 4 mg / mL of CuInS2 was used throughout the experiment. Example 2

[0041] Comparing the effects of different CdS concentrations on open-circuit photovoltage response.

[0042] (1) Preparation of CuInS2 material: Same as in Example 1;

[0043] (2) Preparation of CdS@NH2:

[0044] 0.76 g of thiourea and 0.15 g of glutathione were added to a 0.084 M Cd(NO3)2·4H2O solution. The mixture was then hydrothermally treated at 160 °C for 8 h. The yellow precipitate was collected by centrifugation and finally dried under vacuum at 60 °C. 0.15 g of CdS was mixed with 80 mL of ethanol, 1 mL of concentrated ammonia solution (28 wt%), and 20 mL of ultrapure water under ultrasonication. Then, 5 mL of (3-aminopropyl)triethoxysilane was added to the mixture, and the mixture was stirred at 35 °C for 3 h. After filtration and drying, CdS@NH2 was obtained.

[0045] (3) Preparation of CdS-S2:

[0046] CdS@NH2 was dispersed in ultrapure water to prepare CdS@NH2 at different concentrations. Then, the prepared CdS@NH2 at different concentrations and the splitting aptamer (S2) were shaken and incubated overnight at 4 °C. Finally, the mixture was centrifuged and then dispersed in phosphate buffered saline (PBS) (0.1 M, pH = 7.4) to obtain a CdS-S2 dispersion with a final concentration of 2 μM for the splitting aptamer (S2).

[0047] (4) Fabrication of a light-assisted all-solid-state zinc-air battery self-powered sensor:

[0048] Weigh 4 mg of CuInS2 powder obtained in step (1), disperse it in 1 mL of ultrapure water, and drop 50 μL onto an ITO electrode. Then, drop 20 μL of 2 μM split aptamer (S1) onto the surface of the CuInS2 electrode and incubate at room temperature for 5 h, labeling it as CuInS2-S1. Next, drop 20 μL of BSA (1 wt%) onto the electrode, and then fix 20 μL of theophylline of known concentration onto the modified electrode for 1 h, labeling it as CuInS2-S1 / TP. Finally, drop 20 μL of CdS-S2 of different concentrations obtained in step (3) onto the ITO electrode, and then wash away the unbound CdS-S2 with PBS, labeling it as CuInS2-S1 / TP / S2-CdS. Using CuInS2-S1 / TP / S2-CdS as the photocathode, polished zinc foil as the anode, and PVA gel polymer as the solid electrolyte, the light intensity of the xenon lamp as the light source was kept at 20 mW, and the vertical distance from the light source outlet to the ITO conductive surface was kept at 15 cm. The open-circuit photovoltage response of the circuit was tested using a two-electrode system.

[0049] Depend on Figure 3 As can be seen, the open-circuit photovoltage response decreases with increasing CdS concentration, and remains almost unchanged after the concentration exceeds 3 mg / mL. Therefore, a CdS concentration of 3 mg / mL was chosen. Example 3

[0050] Compare the open-circuit voltage response curves of CuInS2 and CdS / CuInS2 as photoanodes.

[0051] 50 μL of a CuInS2 dispersion with a concentration of 4 mg / mL was drop-coated onto an ITO electrode and labeled as CuInS2 / ITO. 20 μL of a CdS dispersion with a concentration of 3 mg / mL was drop-coated onto the CuInS2 / ITO surface and labeled as CdS / CuInS2 / ITO.

[0052] CuInS2 / ITO and CdS / CuInS2 / ITO were used as photocathodes for photoelectrochemical testing, respectively. A zinc sheet was used as the anode, and PVA gel polymer was used as the solid electrolyte. The light intensity of the xenon lamp as the light source was maintained at 20 mW, and the vertical distance from the light source outlet to the ITO conductive surface was maintained at 15 cm. The open-circuit photovoltage response of the circuit was measured using a two-electrode system. Figure 4 These are voltage-time curves for different photocathodes used in the sensor. Example 4

[0053] like Figure 1 As shown, a light-assisted all-solid-state zinc-air battery self-powered sensor based on a signal reversal strategy is constructed using a zinc sheet as the anode and CuInS2-S1 / TP / S2-CdS as the photocathode to form a self-powered system for theophylline detection.

[0054] The fabrication method of a light-assisted all-solid-state zinc-air battery self-powered sensor based on a signal reversal strategy includes the following steps:

[0055] (1) Preparation of CuInS2 material: Same as in Example 1;

[0056] (2) Preparation of CdS@NH2: Same as in Example 2;

[0057] (3) Preparation of CdS-S2:

[0058] CdS@NH2 and the splitting aptamer (S2) were mixed and incubated overnight at 4 °C. Finally, the mixture was centrifuged and then dispersed in phosphate buffered saline (PBS) (0.1 M, pH = 7.4) to obtain a CdS-S2 dispersion containing 3 mg / mL CdS@NH2 and 2 μM splitting aptamer (S2).

[0059] (4) Fabrication and standard curve plotting of a light-assisted all-solid-state zinc-air battery self-powered sensor based on a signal reversal strategy:

[0060] Weigh 4 mg of the CuInS2 powder obtained in step (1), disperse it in 1 mL of ultrapure water, and drop 50 μL onto an ITO electrode. Then, drop 20 μL of 2 μM split aptamer (S1) onto the surface of the CuInS2 electrode and incubate at room temperature for 5 h, labeling it as S1-CuInS2. Next, drop 20 μL of BSA (1 wt%) onto the electrode, and then add a series of known concentrations (1 × 10⁻⁶) of different concentrations. -8 mol / L, 1×10 -7 mol / L, 1×10 -6 mol / L, 1×10 -5 mol / L, 1×10 -4 mol / L, 1×10 -3 20 μL of theophylline (mol / L) was immobilized on the modified electrode for 1 h and labeled as CuInS2-S1 / TP. Finally, 20 μL of CdS-S2 was incubated on the electrode, and unbound CdS-S2 was washed away with PBS, labeled as CuInS2-S1 / TP / S2-CdS. Using CuInS2-S1 / TP / S2-CdS as the photocathode, polished zinc foil as the anode, and PVA gel polymer as the solid electrolyte, the light intensity of the xenon lamp as the light source was maintained at 20 mW, and the vertical distance from the light source outlet to the ITO conductive surface was maintained at 15 cm. The open-circuit photovoltage response of this circuit was tested using the two-electrode system, and a series of concentration-photovoltage correspondences were obtained. Figure 5 ), thus obtaining the standard curve of theophylline ( Figure 6 The regression equation is: y = 0.4598 - 0.0769Log C TP (mol / L), with a detection range of 1.0 × 10⁻⁶. -8 ~1.0×10 -3 mol / L, the limit of detection is 3.22 × 10⁻⁶. -9 mol / L.

[0061] (5) Actual sample testing:

[0062] Different concentrations of theophylline were added to two tap water samples and then fixed on CuInS2-S1 electrodes and incubated for 1 hour. The open-circuit voltage of the circuit was tested using a two-electrode system. The concentration of theophylline in the sample to be tested was calculated according to the linear regression equation corresponding to step (3) above. The results are listed in Table 1.

[0063] Table 1. Detection results of theophylline in tap water

[0064]

[0065] As shown in Table 1, the samples were measured in triplicate, and the recoveries ranged from 99% to 105%, with relative standard deviations of less than 7%. These results validate that this method can be used to detect samples in real-world applications.

[0066] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for fabricating a light-assisted all-solid-state zinc-air battery self-powered sensor based on a signal reversal strategy, characterized in that, The preparation method includes the following steps: (1) Disperse CuInS2 powder in ultrapure water to obtain CuInS2 dispersion, and drop it onto ITO electrode. Then drop split aptamer S1 onto the surface of CuInS2 electrode and incubate at room temperature. Label it as CuInS2-S1. Drop bovine serum albumin onto the electrode and then drop the analyte solution onto the modified electrode. Label it as CuInS2-S1 / TP. (2) CdS@NH2 and split aptamer S2 were shaken to obtain a mixture. The mixture was centrifuged to collect the solid phase, and then dispersed in phosphate buffer solution to obtain CdS-S2 dispersion. CdS-S2 was incubated on CuInS2-S1 / TP electrode, and unbound CdS-S2 was washed away. The electrode was labeled as CuInS2-S1 / TP / S2-CdS electrode. (3) Using CuInS2-S1 / TP / S2-CdS electrode as photocathode, polished zinc foil as anode, PVA gel polymer as solid electrolyte, and xenon lamp as light source, a light-assisted all-solid-state zinc-air battery self-powered sensor based on signal reversal strategy is constructed. The CdS@NH2 in step (2) is prepared by the following method: thiourea and glutathione are added to a Cd(NO3)2·4H2O solution, and the mixed solution is hydrothermally treated at 160 °C for 8 h. The precipitate is collected by centrifugation and dried to obtain CdS. CdS is uniformly dispersed in an ethanol-water solution to obtain a CdS suspension. Concentrated ammonia solution is added and mixed uniformly under ultrasonication. (3-aminopropyl)triethoxysilane is added and stirred at 35 °C for 3 h to obtain CdS@NH2. The molar ratio of Cd(NO3)2·4H2O, glutathione and thiourea is 84:0.5:

10. The mass concentration of the CdS suspension is 1.5 mg / mL, and the volume ratio of the CdS suspension to concentrated ammonia solution and (3-aminopropyl)triethoxysilane is 100:1:

5. The base sequence of the split aptamer S1 is 5'-CGGCUGGGGCGAUACCAGCCGAAA-3'; the base sequence of the split aptamer S2 is 5'-CCAGCCGAAAGGCCCUUGGCAGCGUCGGG-3'.

2. The fabrication method of the light-assisted all-solid-state zinc-air battery self-powered sensor based on a signal reversal strategy as described in claim 1, characterized in that, The CuInS2 was prepared by the following method: cuprous chloride, indium(III) chloride hydrate and thiourea were dissolved in ethylene glycol solution and heated at 180 °C for 24 h; the product was collected by centrifugation, washed, and the collected precipitate was freeze-dried; wherein the molar ratio of cuprous chloride, indium(III) chloride hydrate and thiourea was 1:1:

4.

3. The method for fabricating a light-assisted all-solid-state zinc-air battery self-powered sensor based on a signal reversal strategy as described in claim 1, characterized in that, The mass ratio of CuInS2 to CdS-S2 modification is 5~25:1~10.

4. The method for fabricating a light-assisted all-solid-state zinc-air battery self-powered sensor based on a signal reversal strategy as described in claim 3, characterized in that, The mass ratio of CuInS2 to CdS-S2 modification is 1~20:6~10.

5. The method for fabricating a light-assisted all-solid-state zinc-air battery self-powered sensor based on a signal reversal strategy as described in claim 1, characterized in that, In step (1), the concentration of CuInS2 dispersion is 1~5 mg / mL, the modification amount is 50 μL; the mass concentration of bovine serum albumin is 1 wt%, the drop volume is 20 μL; the concentration of split aptamer S1 is 2 μmol / L, and the modification amount is 20 μL.

6. The method for fabricating a light-assisted all-solid-state zinc-air battery self-powered sensor based on a signal reversal strategy as described in claim 1, characterized in that, In step (2), the concentration of CdS@NH2 in the CdS-S2 dispersion is 1~5 mg / mL, the concentration of the splitting aptamer S2 is 2 μmol / L, and the modification amount of the CdS-S2 dispersion is 20 μL.

7. The method for fabricating a light-assisted all-solid-state zinc-air battery self-powered sensor based on a signal reversal strategy as described in claim 1, characterized in that, The PVA gel polymer has dimensions of 1 cm × 1 cm × 0.3 cm.

8. An application of a light-assisted all-solid-state zinc-air battery self-powered sensor based on a signal reversal strategy, prepared by the method described in any one of claims 1-7, in the photoelectrochemical detection of theophylline, characterized in that... A photocathode was prepared using a theophylline standard solution, and a photo-assisted all-solid-state zinc-air battery self-powered sensor was constructed. The open-circuit photovoltage response value was tested, and a linear relationship between the photovoltage intensity after the addition of theophylline and the logarithm of theophylline concentration was established, resulting in the corresponding linear regression equation. A photocathode was prepared using the solution to be tested, and the open-circuit photovoltage response was measured. The result was then substituted into a linear regression equation to calculate the concentration of theophylline in the solution to be tested.

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