Natural light driven portable photoelectrochemical paper chip sensing system and construction method thereof

Abstract

The invention discloses a portable photoelectrochemical paper chip sensing system driven by natural light and a construction method of the portable photoelectrochemical paper chip sensing system, and belongs to the technical field of photoelectrochemical sensing. According to the invention, the integrated portable photoelectrochemical sensing paper chip with a self-correction function and the handheld multimeter are integrated, and by means of the exquisite design of the paper chip and the construction of the high-performance composite photoelectrode, natural light is used as an excitation light source, and the handheld multimeter is used for directly reading a photocurrent signal to detect a target object; therefore, the serious dependence of the traditional photoelectrochemical sensing on an expensive and heavy artificial light source and an electrochemical workstation is eliminated, and the conversion of the photoelectrochemical sensing technology from a laboratory technical prototype to a practical application product is facilitated.

Description

Technical Field

[0001] This invention discloses a portable photoelectrochemical paper chip sensing system driven by natural light and its construction method, belonging to the field of photoelectrochemical sensing technology. Background Technology

[0002] Photoelectrochemical sensing, as an active branch of chemical sensing, uses light as the excitation source and photocurrent as the detection signal, and has been widely applied to the detection of various chemical / biomolecules, such as environmental pollutants, disease biomarkers, and pesticide residues. Compared with traditional analytical methods such as fluorescence analysis, electrochemical analysis, and surface-enhanced Raman spectroscopy, PEC sensing, due to the fundamental difference between its energy input (light) and output (current) forms, not only inherits the advantages of low cost and simple operation of electrochemical analysis, but also has the characteristics of low background signal and outstanding sensitivity, thus becoming a current research hotspot.

[0003] Currently, rapid, economical, and easy-to-operate point-of-care (POC) detection technologies are attracting significant attention due to application needs in fields such as environmental monitoring, disease diagnosis, and food safety assessment. Therefore, developing portable PEC sensing systems suitable for on-site detection while maintaining excellent analytical performance is of great importance. However, traditional photoelectrochemical detection technologies heavily rely on bulky and expensive artificial physical light sources and electrochemical workstations (used to excite photoelectric materials and collect output signals, respectively). This equipment dependence poses a major challenge to the transformation of photoelectrochemical sensing technology from the laboratory to on-site detection scenarios. Summary of the Invention

[0004] To address the existing technical problems, this invention provides a portable photoelectric chemical paper chip sensing system driven by natural light and its construction method.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] One of the technical solutions: This invention discloses a portable photoelectrochemical paper chip sensing system driven by natural light, which integrates a self-calibrating portable photoelectrochemical sensing paper chip with a handheld multimeter. Through its ingenious paper chip design, this system enables the detection of target objects by using natural light as the excitation source and directly reading the photocurrent signal with a handheld multimeter. This successfully replaces the expensive and bulky xenon lamp and electrochemical workstation in traditional photoelectrochemical systems. This innovative design eliminates the heavy reliance of traditional photoelectrochemical sensing on high-cost, large-scale instruments, and promotes the transformation of photoelectrochemical sensing technology from laboratory prototypes to practical application products. To achieve the above-mentioned technical effects, the present invention adopts the following key technologies: 1. A Bi2O3-CuInS2 nanomesh photoelectrode with excellent photoelectric conversion efficiency was constructed on a photoelectrochemical sensing paper chip, which can generate a high-intensity photocurrent signal that can be directly read by a handheld multimeter even under natural light excitation with weak irradiation energy. 2. By integrating a photoelectric correction functional area onto the photoelectrochemical sensing paper chip, the system is endowed with self-correction capabilities. This design effectively eliminates background signal interference caused by changes in natural light intensity over time, thereby ensuring the accuracy and stability of the detection results.

[0007] Technical Solution Two: A method for constructing a portable photoelectrochemical paper chip sensing system driven by natural light includes the following steps:

[0008] (1) Preparation of photoelectrochemical sensing paper chip: The photoelectrochemical sensing paper chip disclosed in this invention consists of a sensing photoelectrode, a photoelectric correction region, a hydrophobic region, and a counter electrode (as shown in the attached figure). Figure 1 (As shown in the figure) First, the hydrophilic and hydrophobic regions of the paper chip are constructed using wax printing technology; then, gold nanoparticles are modified in the sensing photoelectrode and photoelectric correction region using the gold seed-assisted method to impart good conductivity; then, carbon counter electrode is modified in the counter electrode region using conductive carbon paste as raw material and screen printing technology.

[0009] (2) Functionalization of sensing photoelectrode and photoelectric correction region: Bi2O3-CuInS2 nano-mesh photoelectrode is modified with a combination of electrochemical deposition technology and solvothermal technology to obtain sensing photoelectrode and photoelectric correction region in step (1).

[0010] (3) Construction of the sensing interface: The target antibody is crosslinked and fixed on the sensing photoelectrode modified with Bi2O3-CuInS2 nanonet obtained in step (2) by glutaraldehyde crosslinking method, while keeping the photoelectric correction area unmodified; the target is including but not limited to alpha-fetoprotein, prostate-specific antigen and carcinoembryonic antigen.

[0011] Further, the gold seed-assisted method described in step (1) for modifying gold nanoparticles in the sensing photoelectrode and photoelectric correction area includes the following steps: mixing chloroauric acid solution and sodium citrate solution in equal amounts to obtain mixture A, adding mixture A dropwise to the sensing photoelectrode and photoelectric correction area, drying, repeating 3 times, and then adding mixture B containing hydroxylamine hydrochloride and chloroauric acid solution with a molar concentration ratio of (2-8):1 in two separate drops, letting stand for 30 min, and washing with water 3 times;

[0012] Furthermore, the ratio of the volume of the mixed solution A added each time to the area of ​​the sensing photoelectrode and the photoelectric correction area is 1 mL : (1-2) cm². 2The volume ratio of the mixture B to the area of ​​the sensing photoelectrode and the photoelectric correction area is 1 mL : (1-2) cm. 2

[0013] Further, the electrochemical deposition technique described in step (2) includes the following steps: First, prepare an electrolyte solution by dissolving 20-500 mmol Bi(NO3)3 and 0.1-0.5 mol of electrolyte in 50 mL of deionized water, and adjust the pH to 9-11 using an alkali; then place the resulting solution in a water bath at 40-80 ℃, immerse the photoelectrochemical sensing paper chip obtained in step (1) and the photoelectric correction area in the solution, and build a three-electrode system with the two as working electrodes, Ag / AgCl as the reference electrode, and Pt wire as the counter electrode, and perform electrochemical deposition of Bi2O3 under an applied bias voltage of -2 - 2 V for 20-60 min; the electrolyte includes, but is not limited to, KCl, NaCl and NaNO3; the alkali includes, but is not limited to, NaOH and KOH, with a concentration of 0.1 M;

[0014] Further, the solvothermal technology in step (2) includes the following steps: first, prepare the growth solution by dissolving 0.1-2 mmol CuCl2·2H2O and 0.1-2 mmol InCl3·4H2O in 15 mL of deionized water, adding 2-50 mmol mercaptopropionic acid under vigorous stirring, then adjusting the pH to 9-11 with an alkali, continuing stirring for 10 min, and then adding 0.2-4 mmol thiourea; subsequently, transfer the above growth solution to a 25 mL hydrothermal reactor containing an electrodeposited photoelectrochemical sensing paper chip, and react at 100-150 °C for 5-20 hours to complete the modification of the sensing photoelectrode and the photoelectric correction region Bi2O3-CuInS2 nanomesh photoelectrode; the alkali includes, but is not limited to, NaOH and KOH, with a concentration of 0.1 M;

[0015] Furthermore, the molar ratio of CuCl2·2H2O to InCl3·4H2O and thiourea in the growth solution is 1:1:2; the molar ratio of CuCl2·2H2O to mercaptopropionic acid is 1:(15-20).

[0016] Further, the glutaraldehyde crosslinking method for immobilizing the target antibody in step (3) includes the following steps: First, add an aqueous solution containing 1-3% (3-aminopropyl)triethoxysilane to the photoelectrode modified with Bi2O3-CuInS2 nanonet obtained in step (2), incubate for 1.5-2.5 h, and then wash 3 times with deionized water; then, add 2-10% glutaraldehyde solution, incubate for 1.5-2.5 h, and then wash 3 times with deionized water; then, add 40 µL of 5-20 mg / mL target antibody, incubate for 1.5-2.5 h, and then wash 3 times with PBS buffer (1 M, pH = 7.4); finally, add 40 µL of 20-50 mg / mL bovine serum albumin to the photoelectrode, incubate for 1 h, and then wash 3 times with PBS buffer (1 M, pH = 7.4), and store at 4 ℃ for later use.

[0017] This invention further protects a method for using the above-mentioned natural light-driven portable photoelectrochemical paper chip sensing system to detect cancer biomarkers, comprising the following steps:

[0018] 40 µL of the test solution containing the target analyte was added dropwise to the photoelectrode of the prepared photoelectrochemical paper chip and incubated at room temperature for 1 h. After rinsing three times with PBS buffer (1 M, pH = 7.4), 100 µL of 150-340 µM hydrogen peroxide solution was added dropwise to both the photoelectrode and the photocorrection area. Subsequently, the photoelectrochemical paper chip was placed under natural light, and a handheld multimeter was connected to both the photoelectrode and the photocorrection area to record their photocurrent signals. The photocurrent signal of the photoelectrode was divided by the photocurrent signal of the photocorrection area to eliminate signal fluctuations caused by changes in natural light intensity, thus obtaining a detection signal that is only related to the concentration of the target analyte.

[0019] Compared with the prior art, the present invention has the following advantages and technical effects:

[0020] (1) Replacing the expensive and bulky xenon lamp and electrochemical workstation in the traditional photoelectrochemical system with natural light and a handheld multimeter eliminates the serious dependence of photoelectrochemical sensing on high-cost, large-scale instruments, greatly facilitating the transformation of photoelectrochemical sensing technology from laboratory technology prototypes to practical application products.

[0021] (2) The highly integrated photoelectrochemical sensor paper chip design requires only one photoelectrochemical sensor paper chip and a handheld multimeter to complete the target detection, which greatly reduces the cost and operation complexity of the detection system and improves the portability of the system.

[0022] (3) A Bi2O3-CuInS2 nano-mesh photoelectrode with excellent photoelectric conversion efficiency was constructed, which enabled the sensing system to maintain high analytical performance under natural light excitation with weak irradiation energy.

[0023] (4) The portable photoelectrochemical sensing system provided by the present invention has a highly modular design and excellent versatility. By selectively replacing the bio-identification elements modified on the sensing photoelectrode, the system can detect a variety of target analytes. Attached Figure Description

[0025] Appendix Figure 1 This is a schematic diagram of the structure of the integrated portable photoelectrochemical sensing paper chip.

[0026] Appendix Figure 2 This is a SEM image of the Bi2O3-CuInS2 nanomesh photoelectrode obtained in Example 1.

[0027] Appendix Figure 3 The image shows an HRTEM image of the Bi2O3-CuInS2 nanomesh photoelectrode obtained in Example 1.

[0028] Appendix Figure 4 The photocurrent response of the Bi2O3-CuInS2 nanomesh photoelectrode obtained in Example 1 under natural light excitation.

[0029] Appendix Figure 5 This illustrates the linear relationship between the photoelectric signal and the alpha-fetoprotein concentration in the portable photoelectric chemical paper chip sensing system driven by natural light in Example 3. Detailed Implementation

[0031] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the present invention is not limited to the following embodiments.

[0032] Example 1 This embodiment provides a method for constructing a portable alpha-fetoprotein photoelectrochemical paper chip sensing system driven by natural light. The specific steps are as follows:

[0033] (1) First, the hydrophilic and hydrophobic regions of the photoelectrochemical sensing paper chip were constructed using wax printing technology. Then, 8 mM chloroauric acid solution and 8 mM sodium citrate solution were mixed at a volume ratio of 1:1 to obtain mixture A. 1 mL of mixture A was added dropwise to the sensing photoelectrode and photoelectric correction area, dried, and repeated 3 times. Then, 1 mL of mixture B containing 5 mmol hydroxylamine hydrochloride and 1 mmol chloroauric acid solution was added dropwise twice, and the mixture was allowed to stand for 30 min and washed 3 times with water. Then, using conductive carbon paste as raw material, carbon counter electrode was modified in the counter electrode area using screen printing technology.

[0034] (2) Dissolve 50 mmol Bi(NO3)3 and 0.2 mol NaNO3 in 50 mL of deionized water and adjust the pH to 10 with 0.1 M NaOH. Then place the resulting solution in a 60 °C water bath and immerse the photoelectrochemical sensing paper chip obtained in step (1) and the photoelectrochemical correction area into the solution. Use the two as working electrodes, Ag / AgCl as reference electrodes, and Pt wire as counter electrodes to build a three-electrode system. Electrochemical deposition of Bi2O3 is carried out under an applied bias voltage of 2 V for 30 min.

[0035] (3) Dissolve 0.2 mmol CuCl2·2H2O and 0.2 mmol InCl3·4H2O in 15 mL of deionized water, add 3 mmol mercaptopropionic acid under vigorous stirring, then adjust the pH to 10 with 0.1 M NaOH, continue stirring for 10 min and add 0.4 mmol thiourea; then transfer the above growth solution to 25 mL of hydrothermal reactor containing photoelectrochemical sensing paper chip that has been electrodeposited, and react at 150 °C for 8 hours to achieve modification of the sensing photoelectrode and the photoelectric correction region Bi2O3-CuInS2 nanomesh photoelectrode;

[0036] (4) Add an aqueous solution containing 2% (3-aminopropyl)triethoxysilane to the photoelectrode modified with Bi2O3-CuInS2 nanomesh, incubate for 2 h and wash three times with deionized water; then add 5% glutaraldehyde solution, incubate for 2 h and wash three times with deionized water; then add 40 µL of 5 mg / mL alpha-fetoprotein antibody, incubate for 1 h and wash three times with PBS buffer (1M, pH = 7.4); finally, add 40 µL of 20 mg / mL bovine serum albumin to the photoelectrode, incubate for 1 h and wash three times with PBS buffer (1M, pH = 7.4), store at 4 ℃ for later use, and obtain a portable alpha-fetoprotein photoelectrochemical paper chip sensing system driven by natural light.

[0037] The SEM image of the Bi2O3-CuInS2 nanomesh photoelectrode prepared in Example 1 is attached. Figure 2 As shown, the sample grows uniformly and densely on the paper substrate surface, forming a sheet-like network structure. This nanostructure can significantly increase the specific surface area of ​​the sensor, endowing it with a large number of reactive sites, thereby improving the sensor's analytical performance; the HRTEM image of this photoelectrode is attached. Figure 3 As shown, a large number of CuInS2 quantum dots are uniformly distributed on the surface of the Bi2O3 nanomesh carrier, proving the successful preparation of Bi2O3-CuInS2; in addition, the photocurrent response of the prepared Bi2O3-CuInS2 nanomesh photoelectrode under natural light excitation is shown in the attached figure. Figure 4As shown, the photoelectrode exhibits excellent photocurrent signals under natural light, providing a foundation for the sensing system to achieve high analytical performance.

[0038] Example 2 This embodiment provides a method for constructing a portable prostate-specific antigen photoelectrochemical paper chip sensing system driven by natural light. The specific steps are as follows:

[0039] (1) First, the hydrophilic and hydrophobic regions of the photoelectrochemical sensing paper chip were constructed using wax printing technology. Then, 8 mM chloroauric acid solution and 8 mM sodium citrate solution were mixed at a volume ratio of 1:1 to obtain mixture A. 500 µL of mixture A was added dropwise to the sensing photoelectrode and photoelectric correction area, dried, and repeated 3 times. Then, 500 µL of mixture B containing 8 mmol hydroxylamine hydrochloride and 1 mmol chloroauric acid solution was added dropwise twice. After standing for 30 min, the mixture was washed 3 times with water. Then, using conductive carbon paste as raw material, carbon counter electrode was modified in the counter electrode area using screen printing technology.

[0040] (2) Dissolve 100 mmol Bi(NO3)3 and 0.5 mol NaNO3 in 50 mL of deionized water and adjust the pH to 10 with 0.1 M KOH. Then place the resulting solution in a 60 °C water bath and immerse the photoelectrochemical sensing paper chip obtained in step (1) and the photoelectrochemical correction area in the solution. Use the two as working electrodes, Ag / AgCl as reference electrodes, and Pt wire as counter electrodes to build a three-electrode system. Electrochemical deposition of Bi2O3 is carried out under an applied bias voltage of 1 V for 60 min.

[0041] (3) Dissolve 1 mmol CuCl2·2H2O and 1 mmol InCl3·4H2O in 15 mL of deionized water, add 20 mmol mercaptopropionic acid under vigorous stirring, then adjust the pH to 10 with 0.1 M KOH, continue stirring for 10 min and add 2 mmol thiourea; then transfer the above growth solution to 25 mL of hydrothermal reactor containing photoelectrochemical sensing paper chip that has been electrodeposited, and react at 120 °C for 12 hours to achieve modification of the sensing photoelectrode and the photoelectric correction region Bi2O3-CuInS2 nanomesh photoelectrode;

[0042] (4) Add an aqueous solution containing 3% (3-aminopropyl)triethoxysilane to the photoelectrode modified with Bi2O3-CuInS2 nanomesh, incubate for 2.5 h and then wash with deionized water 3 times; then add 5% glutaraldehyde solution, incubate for 2.5 h and then wash with deionized water 3 times; then add 40 µL of 10 mg / mL prostate-specific antigen antibody, incubate for 1 h and then wash with PBS buffer (1 M, pH = 7.4) 3 times; finally, add 40 µL of 50 mg / mL bovine serum albumin to the photoelectrode, incubate for 1 h and then wash with PBS buffer (1 M, pH = 7.4) 3 times and store at 4 ℃ for later use to obtain a portable prostate-specific antigen photoelectrochemical paper chip sensing system driven by natural light.

[0043] Example 3 This embodiment provides a method for using the natural light-driven portable photoelectrochemical paper chip sensing system constructed according to the present invention to detect the cancer biomarker alpha-fetoprotein, including the following steps:

[0044] (1) 40 µL of the test solution containing the target alpha-fetoprotein was dropped onto the sensing photoelectrode of the portable alpha-fetoprotein photoelectrochemical paper chip sensing system prepared in Example 1, and incubated at room temperature for 1 h before being rinsed 3 times with PBS buffer (1 M, pH = 7.4).

[0045] (2) At the same time, 100 µL of 340 µM hydrogen peroxide solution was added to the sensing photoelectrode and the photoelectric correction area; then the photoelectrochemical sensing paper chip was placed under natural light, and the handheld multimeter was connected to the sensing photoelectrode and the photoelectric correction area in turn to record the photocurrent signals of the two.

[0046] (3) Divide the obtained photocurrent signal of the sensing photoelectrode by the photocurrent signal of the photoelectric correction zone to eliminate the signal fluctuation caused by the change in natural light intensity, and obtain a detection signal that is only related to the concentration of the target substance.

[0047] Appendix Figure 5 The sensor system detected the signal (I) 传感光电极 / I 光电校正区 The linear relationship between alpha-fetoprotein (AFP) concentration and the linear equation is I. 传感光电极 / I 光电校正区 = -0.52 - 0.08 log c The detection limit was 0.01 pM, indicating that the constructed sensing system can be driven by natural light to perform stable and reliable high-sensitivity target detection, and has good application prospects in the detection of cancer biomarkers.

Claims

1. A portable photoelectrochemical paper chip sensing system driven by natural light, characterized in that... It integrates a portable photoelectrochemical sensor paper chip with self-calibration function with a handheld multimeter. It uses natural light as the excitation source and directly reads the photocurrent signal using the handheld multimeter to detect the target object.

2. The portable photoelectrochemical paper chip sensing system driven by natural light according to claim 1, characterized in that... A high photoelectric conversion efficiency Bi2O3-CuInS2 nanomesh is used as the photoelectrode to achieve high photoelectric response under natural light excitation; at the same time, a photoelectric correction functional area is configured to realize the system self-correction function, eliminate the background signal caused by natural light intensity fluctuations, thereby ensuring high sensitivity and accuracy of detection.

3. The portable photoelectrochemical paper chip sensing system driven by natural light according to claim 1, characterized in that... The integrated portable photoelectrochemical sensor paper chip with self-calibration function consists of a sensing photoelectrode, a photoelectric calibration region, a hydrophobic region, and a counter electrode.

4. A method for constructing a portable photoelectrochemical paper chip sensing system driven by natural light as described in claim 1, characterized in that, Includes the following steps: (1) Preparation of photoelectrochemical sensing paper chip: First, the hydrophilic and hydrophobic regions of the paper chip are constructed by wax printing technology; Subsequently, gold nanoparticles were modified into the sensing photoelectrode and photoelectric correction region using the gold seed-assisted method to impart good conductivity; then, using conductive carbon paste as raw material, carbon counter electrode was modified into the counter electrode region using screen printing technology. (2) Functionalization of the sensing photoelectrode and photoelectric correction region: Bi2O3-CuInS2 nano-mesh photoelectrode is modified with a combination of electrochemical deposition and solvothermal techniques to obtain the sensing photoelectrode and photoelectric correction region in step (1); (3) Construction of the sensing interface: The target antibody is crosslinked and fixed on the sensing photoelectrode modified with Bi2O3-CuInS2 nanonet obtained in step (2) by glutaraldehyde crosslinking method, while keeping the photoelectric correction region unmodified; the target is including but not limited to alpha-fetoprotein, prostate-specific antigen and carcinoembryonic antigen.

5. The method for constructing a portable photoelectrochemical paper chip sensing system driven by natural light according to claim 4, characterized in that, Step (1) of the gold seed-assisted method includes the following steps: chloroauric acid solution and sodium citrate solution are mixed in equal amounts to obtain mixture A. Mixture A is added dropwise to the sensing photoelectrode and photoelectric correction area, dried, and repeated 3 times. Then, a mixture B containing hydroxylamine hydrochloride and chloroauric acid with a molar concentration ratio of (2-8):1 is added dropwise to the sensing photoelectrode and photoelectric correction area. The mixture is allowed to stand, washed, and the desired good conductivity is achieved. The volume of mixture A added each time is in the ratio of 1 mL to (1-2) cm² of the sensing photoelectrode and photoelectric correction area. 2 The volume ratio of the mixture B to the area of ​​the sensing photoelectrode and the photoelectric correction area is 1 mL : (1-2) cm. 2 .

6. The method for constructing a portable photoelectrochemical paper chip sensing system driven by natural light according to claim 4, characterized in that, The electrochemical deposition technique in step (2) includes the following steps: First, prepare an electrolyte solution by dissolving 20-500 mmol Bi(NO3)3 and 0.1-0.5 mol of electrolyte in 50 mL of deionized water and adjusting the pH to 9-11 with an alkali. Then, place the resulting solution in a water bath at 40-80 ℃ and immerse the photoelectrochemical sensing paper chip obtained in step (1) and the photoelectric correction area into the solution. Use the two as working electrodes, Ag / AgCl as the reference electrode, and Pt wire as the counter electrode to build a three-electrode system. Electrochemical deposition of Bi2O3 is carried out under an applied bias voltage of -2 - 2 V for 20-60 min. The electrolyte includes, but is not limited to, KCl, NaCl, and NaNO3. The alkali includes, but is not limited to, NaOH and KOH, with a concentration of 0.1 M.

7. The method for constructing a portable photoelectrochemical paper chip sensing system driven by natural light according to claim 4, characterized in that, Step (2) of the solvothermal technology includes the following steps: First, prepare the growth solution by dissolving 0.1-2 mmol CuCl2·2H2O and 0.1-2 mmol InCl3·4H2O in 15 mL of deionized water, adding 2-50 mmol mercaptopropionic acid under vigorous stirring, then adjusting the pH to 9-11 with an alkali, continuing stirring for 10 min, and then adding 0.2-4 mmol thiourea; subsequently, transfer the above growth solution to a 25 mL hydrothermal reactor containing an electrodeposited photoelectrochemical sensing paper chip, and react at 100-150 °C for 5-20 hours; the alkali includes, but is not limited to, NaOH and KOH, with a concentration of 0.1 M; the molar ratio of CuCl2·2H2O to InCl3·4H2O and thiourea in the growth solution is 1:1:2; the molar ratio of CuCl2·2H2O to mercaptopropionic acid is 1:(15-20).

8. A method for using a portable photoelectrochemical paper chip sensing system, prepared by the method according to any one of claims 4-7, to detect cancer biomarkers.

9. A method for detecting cancer biomarkers using a portable photoelectrochemical paper chip sensing system driven by natural light, prepared by the method according to any one of claims 4-7, characterized in that, Includes the following steps: (1) 40 µL of the test solution containing the target analyte was dropped onto the photoelectrode of the prepared photoelectrochemical sensing paper chip, and incubated at room temperature for 1 h. Then it was rinsed 3 times with PBS buffer (1 M, pH = 7.4). (2) At the same time, add 100 µL of 150-340 µM hydrogen peroxide solution to the sensing photoelectrode and the photoelectric correction area; then place the photoelectrochemical sensing paper chip under natural light, and connect the handheld multimeter to the sensing photoelectrode and the photoelectric correction area one after the other to record the photocurrent signals of the two. (3) Divide the obtained photocurrent signal of the sensing photoelectrode by the photocurrent signal of the photoelectric correction zone to eliminate the signal fluctuation caused by the change in natural light intensity, and obtain a detection signal that is only related to the concentration of the target substance.

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