Micromolecule detection method and device based on photoelectric response gel substrate

Abstract

The invention discloses a micromolecule detection method and device based on a photoelectric response gel substrate. The method comprises the following steps: preparing a metal ion modified xanthan gel substrate; dropwise adding a to-be-detected small molecule solution to the surface of the metal ion modified xanthan gel substrate; irradiating the metal ion modified xanthan gel substrate by using a red light source, and recording a photocurrent response value; through the linear relation between the light current and the concentration of the small molecules, the concentration detection of the small molecules is realized. Photocurrent response is generated under red light irradiation by utilizing the photoelectric characteristic of the gel substrate, so that rapid and sensitive detection on the concentration of small molecules is realized, and the method has the characteristics of simple equipment, convenience in operation, low cost, high sensitivity and the like, is particularly suitable for field detection in an environment with limited resources, and has a wide application prospect. The method can be widely applied to the fields of medical diagnosis, biosensing, environment monitoring and the like.

Description

Technical Field

[0001] The present invention belongs to the field of small molecule detection, relates to photocurrent detection technology, and specifically relates to a method and device for detecting small molecules based on a photoelectric response gel substrate. Background Art

[0002] Currently, commonly used small molecule detection methods include gas chromatography, mass spectrometry, high performance liquid chromatography, ultraviolet-visible spectroscopy analysis, capillary electrophoresis, etc. Although these methods have high sensitivity and accuracy, they usually require expensive equipment and complex operation procedures, and have high requirements for the experimental environment and the technical level of operators. This limits the application of these technologies in resource-poor areas or on-site detection scenarios, and it is difficult to meet the requirements of portability, rapidity, and economy.

[0003] Point-of-Care (POC) technology has gradually become a research hotspot in the field of small molecule detection due to its characteristics of portability, simple operation, and rapid response. POC detection methods usually achieve real-time detection at the sampling point through low-cost portable instruments and reagents. However, existing POC technologies still have deficiencies in terms of sensitivity, detection range, and anti-interference ability, and it is difficult to meet the requirements for detection accuracy and reliability in complex application scenarios.

[0004] Therefore, a new technical solution is needed to solve these problems. Summary of the Invention

[0005] Object of the Invention: In order to overcome the deficiencies in the prior art, the present invention provides a method and device for detecting small molecules based on a photoelectric response gel substrate. By utilizing the photoelectric characteristics of the gel substrate, a photocurrent response is generated under red light irradiation, thereby realizing rapid and sensitive detection of the concentration of small molecules. The present invention has the characteristics of simple equipment, convenient operation, low cost, high sensitivity, etc., and is particularly suitable for on-site detection in environments with limited resources, and can be widely applied in fields such as medical diagnosis, biosensing, and environmental monitoring.

[0006] Technical Solution: To achieve the above object, the present invention provides a method for detecting small molecules based on a photoelectric response gel substrate, including the following steps:

[0007] S1: Prepare a metal ion-modified xanthan gum gel substrate;

[0008] S2: Drop the small molecule solution to be detected onto the surface of the metal ion-modified xanthan gum gel substrate;

[0009] S3: Use a red light source to irradiate the metal ion-modified xanthan gum gel substrate and record the photocurrent response value;

[0010] S4: Detect the concentration of small molecules through the linear relationship between photocurrent and small molecule concentration.

[0011] Further, the preparation of the metal ion-modified xanthan gum gel substrate in step S1 includes the following steps:

[0012] A1: Add xanthan gum to ultrapure water and stir evenly to obtain a xanthan gum solution;

[0013] A2: Add a metal reagent to ultrapure water and stir evenly to obtain a metal ion solution;

[0014] A3: Add the metal ion solution to the xanthan gum solution and stir evenly to obtain a metal ion-modified xanthan gum gel;

[0015] A4: Coat the metal ion-modified xanthan gum gel on the surface of a plastic substrate and dry it to form a metal ion-modified xanthan gum gel substrate.

[0016] Further, the metal reagent in step A2 includes: ferric chloride hexahydrate, manganese chloride, holmium(III) chloride hexahydrate, ytterbium(III) chloride hexahydrate, chromium(III) nitrate anhydrous, cerium(III) chloride heptahydrate, samarium(III) chloride hexahydrate. The best metal ion can be selected for modification according to different small molecules.

[0017] Further, the xanthan gum gel modified by iron ions in step A3 is named gel-Fe, the xanthan gum gel modified by manganese ions is named gel-Mn, the xanthan gum gel modified by holmium ions is named gel-Ho, the xanthan gum gel modified by ytterbium ions is named gel-Yb, the xanthan gum gel modified by chromium ions is named gel-Cr, the xanthan gum gel modified by cerium ions is named gel-Ce, and the xanthan gum gel modified by samarium ions is named gel-Sm.

[0018] Further, the small molecule solution to be detected in step S2 is one of N-phenyl-2-naphthylamine small molecule solution, L-phenylalanine small molecule solution, L-(+)-arabinose small molecule solution, D-mannose small molecule solution and L-methionine small molecule solution.

[0019] Further, the preparation of the N-phenyl-2-naphthylamine small molecule solution includes: dissolving N-phenyl-2-naphthylamine in N,N-dimethylformamide to prepare 8.6×10 -5 mol / mL, 3.4×10 -4 mol / mL, 5.6×10 -4 mol / mL, 9.5×10 - 4 mol / L, 1.4×10 -3 mol / mL and 1.7×10 -3Solutions with five concentrations of mol / mL; setting five different concentrations of solutions to form a concentration gradient is to verify the linear relationship between photocurrent and small molecule concentration.

[0020] The preparation of L-(+)-arabinose small molecule solution includes: L-(+)-arabinose is dissolved in ultrapure water to prepare solutions with five concentrations of 1.3×10 -5 mol / mL, 5.3×10 -5 mol / mL, 8.7×10 -5 mol / mL, 1.5×10 -4 mol / mL, 2.1×10 -4 mol / mL, and 2.7×10 -4 mol / mL;

[0021] The preparation of D-mannose small molecule solution includes: D-mannose is dissolved in ultrapure water to prepare solutions with five concentrations of 1.1×10 - 4 mol / mL, 4.4×10 -4 mol / mL, 7.2×10 -4 mol / mL, 1.2×10 -3 mol / mL, 1.8×10 -3 mol / mL, and 2.2×10 -3 mol / mL;

[0022] The preparation of L-phenylalanine small molecule solution includes: L-phenylalanine is dissolved in ultrapure water to prepare solutions with five concentrations of 1.2×10 -5 mol / mL, 4.8×10 -5 mol / mL, 7.9×10 -5 mol / mL, 1.3×10 -4 mol / L, 1.9×10 -4 mol / mL, and 2.4×10 -4 mol / mL. Heating is required using a heating plate at 80 °C during preparation; L-phenylalanine is slightly soluble in water at room temperature, so heating is needed to increase solubility.

[0023] The preparation of L-methionine small molecule solution includes: L-methionine is dissolved in ultrapure water to prepare solutions with five concentrations of 1.3×10 - 5 mol / mL, 5.4×10 -5 mol / mL, 8.7×10 -5 mol / mL, 1.5×10 -4 mol / mL, 2.1×10 -4 mol / mL, and 2.7×10-4 Solutions with five concentrations of mol / mL need to be heated on a hot plate at 80 °C during preparation; L-methionine is slightly soluble in water at room temperature, so heating is required to increase its solubility.

[0024] Further, in step S3, the red light source is generated by an incandescent lamp combined with a red light filter, and the wavelength range of the light source is 620 - 680 nm. In the present invention, metal ions have the best photoelectric responsiveness in the range of 620 - 680 nm, and the wavelength of this red light source exactly matches it.

[0025] Further, in step S1, two copper wires are taken, one end is inserted into both sides of the gel substrate, and the other end is connected to the measuring probes of a multimeter.

[0026] Further, in step S3, the photocurrent response value is obtained through the measuring probes of the multimeter.

[0027] The present invention provides a small molecule detection device based on a photoelectric response gel substrate, including: a metal ion-modified xanthan gum gel substrate, a red light source, and measuring probes of a multimeter; the red light source is used to provide a light source to the metal ion-modified xanthan gum gel substrate, and the measuring probes of the multimeter are used to measure the photocurrent response value. The device of the present invention has the advantages of high sensitivity, low cost, and environmental friendliness.

[0028] Under the action of light, the gel material induces the separation of photo-generated electron-hole pairs through surface defects, thereby generating a photocurrent. Introducing different metal ions can further enhance the defect effect and built-in electric field on the gel surface, thereby significantly improving the photoelectric response performance. In the present invention, xanthan gum has good flexibility and processability. By doping metal ions, sensitive detection of various small molecules can be achieved. Therefore, the small molecule detection method based on a photoelectric response gel substrate has the advantages of simple and easy device availability, low cost, convenient operation, and fast response, providing an efficient and reliable technical solution for fields such as medical diagnosis, biosensing, and environmental monitoring.

[0029] The present invention uses xanthan gum gel as the substrate, and through doping and modification with metal ions, enhances the photoelectric response characteristics of the gel. After the small molecule solution to be measured is dropped onto the surface of the gel substrate, under red light irradiation, surface defects in the gel substrate induce the separation of photo-generated electrons and holes, thereby generating a photocurrent. By measuring the linear relationship between the photocurrent and the change in the concentration of small molecules, the concentration detection of small molecules is realized.

[0030] Advantageous effects: Compared with the prior art, the present invention utilizes the optoelectronic properties of the gel substrate to generate a photocurrent response under red light irradiation, thereby achieving rapid and sensitive detection of the concentration of small molecules. The present invention has the characteristics of simple equipment, convenient operation, low cost, and high sensitivity, and is particularly suitable for on-site detection in environments with limited resources. It can be widely applied in the fields of medical diagnosis, biosensing, and environmental monitoring, etc. Description of the Drawings

[0031] Figure 1 It is a schematic diagram of a method and device for detecting small molecules based on an optoelectronic response gel substrate.

[0032] Figure 2 It is a graph showing the change of the photocurrent of the gel-Mn substrate with the increase in the concentration of N-phenyl-2-naphthylamine.

[0033] Figure 3 It is a graph showing the change of the photocurrent of the gel-Fe substrate with the increase in the concentration of N-phenyl-2-naphthylamine.

[0034] Figure 4 It is a graph showing the change of the photocurrent of the gel-Fe substrate with the increase in the concentration of L-(+)-arabinose.

[0035] Figure 5 It is a graph showing the change of the photocurrent of the gel-Ho substrate with the increase in the concentration of L-(+)-arabinose.

[0036] Figure 6 It is a graph showing the change of the photocurrent of the gel-Mn substrate with the increase in the concentration of D-mannose.

[0037] Figure 7 It is a graph showing the change of the photocurrent of the gel-Yb substrate with the increase in the concentration of D-mannose.

[0038] Figure 8 It is a graph showing the change of the photocurrent of the gel-Cr substrate with the increase in the concentration of D-mannose.

[0039] Figure 9 It is a graph showing the change of the photocurrent of the gel-Sm substrate with the increase in the concentration of L-phenylalanine.

[0040] Figure 10 It is a graph showing the change of the photocurrent of the gel-Yb substrate with the increase in the concentration of L-phenylalanine.

[0041] Figure 11 It is a graph showing the change of the photocurrent of the gel-Fe substrate with the increase in the concentration of L-phenylalanine.

[0042] Figure 12Graph of the change in photocurrent of the gel-Ce substrate with the increase in the concentration of L-phenylalanine.

[0043] Figure 13 Graph of the change in photocurrent of the gel-Sm substrate with the increase in the concentration of L-methionine.

[0044] Figure 14 Graph of the change in photocurrent of the gel-Cr substrate with the increase in the concentration of L-methionine. Detailed implementation manners

[0045] The present invention will be further clarified below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. After reading the present invention, various equivalent modifications of the present invention by those skilled in the art fall within the scope defined by the appended claims of this application.

[0046] Example 1:

[0047] In this example, the concentration of N-phenyl-2-naphthylamine was detected, and the specific process was as follows:

[0048] (1) Preparation of metal ion-modified xanthan gum gel substrate: Dissolve 8 g of xanthan gum in 300 ml of ultrapure water and stir for 30 min to form a uniform xanthan gum gel; dissolve 0.02 g of metal compounds (ferric chloride hexahydrate and manganese chloride) in 5 ml of ultrapure water respectively to form metal solutions; mix the xanthan gum gel with the metal solutions and stir evenly to obtain metal ion-modified xanthan gum gel; uniformly coat the metal ion-modified xanthan gum gel on the surface of a plastic substrate to obtain a metal ion-modified xanthan gum gel substrate (gel-Mn, gel-Fe).

[0049] (2) Preparation of N-phenyl-2-naphthylamine small molecule solution: Dissolve N-phenyl-2-naphthylamine in N,N-dimethylformamide to prepare five solutions with concentrations of 8.6×10-5 mol / mL, 3.4×10-4 mol / mL, 5.6×10-4 mol / mL, 9.5×10-4 mol / L, 1.4×10-3 mol / mL and 1.7×10-3 mol / mL.

[0050] (3) Refer to Figure 1 , build a small molecule detection device based on a photoelectric response gel substrate: Uniformly coat 0.5 g of gel-Mn and gel-Fe on the surface of a plastic substrate (3 cm in length and 2 cm in width) respectively. Insert 20 cm copper wires at both ends of the gel, with one end of the copper wire inserted into both sides of the gel substrate and the other end connected to the measuring pen of a multimeter. Use a mobile phone white light to generate red light through a red light filter, and the light power is 100 mW.

[0051] (4) Take 2 ml of five concentration solutions of N-phenyl-2-naphthylamine and drop them on gel-Mn and gel-Fe respectively, and record the current values shown on the multimeter.

[0052] Figure 2 It shows that the photocurrent of gel-Mn is linearly inhibited with the increase of the concentration of N-phenyl-2-naphthylamine, while Figure 3 it shows that the photocurrent of gel-Fe is linearly enhanced with the increase of the concentration of N-phenyl-2-naphthylamine. In this embodiment, by setting five different concentration small molecule solutions of N-phenyl-2-naphthylamine to form a concentration gradient, it is verified that the photocurrents generated by small molecules with different concentrations are different and approximately linear.

[0053] The sensitivity can be calculated from the absolute value of the slope of the fitting line, and the absolute values of gel-Mn and gel-Fe are 2254.3 and 9506.8 respectively.

[0054] Example 2

[0055] In this example, the concentration detection of L-(+)-arabinose is carried out, and the specific process is as follows:

[0056] (1) Preparation of metal ion modified xanthan gum gel substrate: Dissolve 8 g of xanthan gum in 300 ml of ultrapure water and stir for 30 min to form a uniform xanthan gum gel; Dissolve 0.02 g of metal compounds (ferric chloride hexahydrate and holmium chloride hexahydrate) in 5 ml of ultrapure water respectively to form metal solutions; Mix the xanthan gum gel with the metal solutions and stir evenly to obtain metal ion modified xanthan gum gel; Uniformly coat the metal ion modified xanthan gum gel on the surface of a plastic substrate to obtain a metal ion modified xanthan gum gel substrate (gel-Fe, gel-Ho).

[0057] (2) Preparation of L-(+)-arabinose small molecule solution: Dissolve L-(+)-arabinose in ultrapure water to prepare five concentration solutions of 1.3×10 -5 mol / mL, 5.3×10 -5 mol / mL, 8.7×10 -5 mol / mL, 1.5×10 -4 mol / mL, 2.1×10 -4 mol / mL and 2.7×10 -4 mol / mL.

[0058] (3) Refer to Figure 1, Set up a small molecule detection device based on a photoelectric response gel substrate: Uniformly coat 0.5 g of gel-Fe and gel-Ho on the surface of a plastic substrate (3 cm long and 2 cm wide). Insert 20 cm copper wires at both ends of the gel for connecting the measuring probes of the multimeter. Use a mobile phone white light to generate red light through a red light filter, and the light power is 100 mW.

[0059] (4) Take 2 ml of five concentration solutions of L-(+)-arabinose and drop them on gel-Fe and gel-Ho respectively, and record the current values shown on the multimeter.

[0060] Figure 4 It shows that the photocurrent of gel-Fe increases linearly with the increase of the concentration of L-(+)-arabinose. Figure 5 It shows that the photocurrent of gel-Ho is linearly inhibited with the increase of the concentration of L-(+)-arabinose. When using gel-Ho and gel-Fe, the sensitivities of the device to detect the concentration change of L-(+)-arabinose solution are 7594.0 and 356273.5 respectively.

[0061] Example 3:

[0062] In this example, the D-mannose concentration is detected, and the specific process is as follows:

[0063] (1) Preparation of metal ion-modified xanthan gum gel substrate: Dissolve 8 g of xanthan gum in 300 ml of ultrapure water and stir for 30 min to form a uniform xanthan gum gel; dissolve 0.02 g of metal compounds (manganese chloride, ytterbium trichloride hexahydrate, and chromium nitrate anhydrous) in 5 ml of ultrapure water respectively to form metal solutions; mix the xanthan gum gel with the metal solutions and stir evenly to obtain metal ion-modified xanthan gum gels; uniformly coat the metal ion-modified xanthan gum gels on the surface of a plastic substrate to obtain metal ion-modified xanthan gum gel substrates (gel-Mn, gel-Yb, gel-Cr).

[0064] (2) Preparation of D-mannose small molecule solution: Dissolve D-mannose in ultrapure water to prepare solutions with five concentrations of 1.1×10 -4 mol / mL, 4.4×10 -4 mol / mL, 7.2×10 -4 mol / mL, 1.2×10 -3 mol / mL, 1.8×10 -3 mol / mL, and 2.2×10 - 3 mol / mL.

[0065] (3) Refer to Figure 1, Set up a small molecule detection device based on a photoelectric response gel substrate: Uniformly coat 0.5 g of gel-Mn, gel-Yb, and gel-Cr on the surface of a plastic substrate (3 cm long and 2 cm wide). Insert 20 cm copper wires at both ends of the gel for connecting the measuring probes of the multimeter. Use a mobile phone white light to generate red light through a red light filter, and the light power is 100 mW.

[0066] (4) Take 2 ml of five concentration solutions of D-mannose and drop them on gel-Mn, gel-Yb, and gel-Cr respectively, and record the current values shown on the multimeter.

[0067] Figures 6 - 8 It shows that the photocurrents of gel-Mn, gel-Yb, and gel-Cr basically increase linearly with the increase of D-mannose concentration. When using gel-Mn, gel-Yb, and gel-Cr, the sensitivities of the device for detecting the concentration change of D-mannose solution are 3422.3, 3128.0, and 2252.3 respectively.

[0068] Example 4:

[0069] In this example, the L-phenylalanine concentration is detected, and the specific process is as follows:

[0070] (1) Preparation of a metal ion-modified xanthan gum gel substrate: Dissolve 8 g of xanthan gum in 300 ml of ultrapure water and stir for 30 min to form a uniform xanthan gum gel; dissolve 0.02 g of metal compounds (samarium trichloride hexahydrate, ytterbium trichloride hexahydrate, ferric chloride hexahydrate, cerium trichloride heptahydrate) in 5 ml of ultrapure water respectively to form metal solutions; mix the xanthan gum gel with the metal solutions and stir evenly to obtain a metal ion-modified xanthan gum gel; uniformly coat the metal ion-modified xanthan gum gel on the surface of a plastic substrate to obtain a metal ion-modified xanthan gum gel substrate (gel-Sm, gel-Yb, gel-Fe, gel-Ce).

[0071] (2) Preparation of L-phenylalanine small molecule solution: Dissolve L-phenylalanine in ultrapure water to prepare solutions with five concentrations of 1.2×10 - 5 mol / mL, 4.8×10 -5 mol / mL, 7.9×10 -5 mol / mL, 1.3×10 -4 mol / L, 1.9×10 -4 mol / mL, and 2.4×10 - 4 mol / mL.

[0072] (3) Refer to Figure 1, Set up a small molecule detection device based on a photoelectric response gel substrate: Uniformly coat 0.5 g of gel-Sm, gel-Yb, gel-Fe, and gel-Ce on the surface of a plastic substrate (3 cm long and 2 cm wide). Insert 20 cm copper wires at both ends of the gel for connecting the measuring probes of the multimeter. Use a mobile phone white light to generate red light through a red light filter, and the light power is 100 mW.

[0073] (4) Take 2 ml of five concentration solutions of L-phenylalanine and drop them on gel-Sm, gel-Yb, gel-Fe, and gel-Ce respectively, and record the current values shown on the multimeter.

[0074] Figure 10 and Figure 11 show that the photocurrents of gel-Yb and gel-Fe increase basically linearly with the increase of the L-phenylalanine concentration. Figure 9 and Figure 12 respectively show that the photocurrents of gel-Sm and gel-Ce are basically linearly inhibited with the increase of the L-phenylalanine concentration. The sensitivities of the L-phenylalanine solution concentration changes when gel-Sm, gel-Yb, gel-Fe, and gel-Ce are used as detection materials are 14834.5, 7174.5, 15871.3, and 14126.2 respectively.

[0075] Example 5:

[0076] In this example, the L-methionine concentration is detected, and the specific process is as follows:

[0077] (1) Preparation of a metal ion-modified xanthan gum gel substrate: Dissolve 8 g of xanthan gum in 300 ml of ultrapure water and stir for 30 min to form a uniform xanthan gum gel; dissolve 0.02 g of metal compounds (samarium trichloride hexahydrate, chromium nitrate anhydrous) in 5 ml of ultrapure water respectively to form metal solutions; mix the xanthan gum gel with the metal solutions and stir evenly to obtain a metal ion-modified xanthan gum gel; uniformly coat the metal ion-modified xanthan gum gel on the surface of a plastic substrate to obtain a metal ion-modified xanthan gum gel substrate (gel-Sm, gel-Cr).

[0078] (2) Preparation of L-methionine small molecule solution: Dissolve L-methionine in ultrapure water to prepare 1.3×10 -5 mol / mL, 5.4×10 -5 mol / mL, 8.7×10 -5 mol / mL, 1.5×10 -4 mol / mL, 2.1×10 -4 mol / mL, and 2.7×10 - 4Solutions with five concentrations of mol / mL.

[0079] (3) Refer to Figure 1 , and build a small molecule detection device based on a photoelectric response gel substrate: uniformly coat 0.5 g of gel-Sm and gel-Cr on the surface of a plastic substrate (3 cm long and 2 cm wide). Insert 20 cm copper wires at both ends of the gel for connecting the measuring probes of the multimeter. Use a mobile phone incandescent light source to generate red light through a red light filter, and the light power is 100 mW.

[0080] (4) Take 2 mL of five concentrations of L-methionine solutions and drop them on gel-Sm and gel-Cr respectively, and record the current values shown on the multimeter.

[0081] Figure 14 It shows that the photocurrent of gel-Cr basically increases linearly with the increase of the L-methionine concentration. Figure 13 It shows that the photocurrent of gel-Sm is basically linearly inhibited with the increase of the L-methionine concentration, and the sensitivities of the L-methionine solution concentration change when gel-Sm and gel-Cr are used as detection materials are 62908.8 and 10161.3 respectively.

Claims

1. A small molecule detection method based on a photoelectrically responsive gel substrate, characterized in that: The steps include: S1: Preparation of metal ion modified xanthan gum gel substrate; S2: adding the small molecule solution to be tested dropwise onto the surface of the metal ion-modified xanthan gum gel substrate; S3: Use a red light source to irradiate the metal ion-modified xanthan gum gel substrate and record the photocurrent response value; S4: The concentration of small molecules can be detected through the linear relationship between photocurrent and small molecule concentration.

2. A small molecule detection method based on a photoelectrically responsive gel substrate according to claim 1, characterized in that: The preparation of the metal ion modified xanthan gum gel substrate in step S1 comprises the following steps: A1: Add xanthan gum into ultrapure water and stir evenly to obtain a xanthan gum solution; A2: Add the metal reagent into ultrapure water and stir evenly to obtain a metal ion solution; A3: adding the metal ion solution into the xanthan gum solution and stirring evenly to obtain the metal ion modified xanthan gum gel; A4: The metal ion-modified xanthan gum gel is coated on the surface of a plastic substrate and then dried to form a metal ion-modified xanthan gum gel substrate.

3. A small molecule detection method based on a photoelectrically responsive gel substrate according to claim 2, characterized in that: The metal reagents in step A2 include: ferric chloride hexahydrate, manganese chloride, holmium chloride hexahydrate, ytterbium chloride hexahydrate, anhydrous chromium nitrate, cerium chloride heptahydrate, and samarium chloride hexahydrate.

4. The small molecule detection method based on a photoelectric responsive gel substrate according to claim 1, characterized in that: The small molecule solution to be tested in step S2 is one of N-phenyl-2-naphthylamine small molecule solution, L-phenylalanine small molecule solution, L-(+)-arabinose small molecule solution, D-mannose small molecule solution and L-methionine small molecule solution.

5. A small molecule detection method based on a photoelectrically responsive gel substrate according to claim 4, characterized in that: The preparation of the N-phenyl-2-naphthylamine small molecule solution comprises: dissolving N-phenyl-2-naphthylamine in N,N-dimethylformamide to prepare a solution; The preparation of the L-(+)-arabinose small molecule solution includes: dissolving L-(+)-arabinose in ultrapure water to prepare a solution; The preparation of the D-mannose small molecule solution includes: dissolving D-mannose in ultrapure water to prepare a solution; The preparation of the L-phenylalanine small molecule solution includes: dissolving L-phenylalanine in ultrapure water, preparing the solution, and heating the solution at 80° C. using a heating plate during the preparation; The preparation of the L-methionine small molecule solution includes: dissolving L-methionine in ultrapure water, preparing the solution, and heating the solution at 80° C. using a heating plate during the preparation.

6. A small molecule detection method based on a photoelectrically responsive gel substrate according to claim 1, characterized in that: In step S3, the red light source is generated by an incandescent lamp combined with a red light filter, and the wavelength range of the light source is 620-680nm.

7. The small molecule detection method based on photoelectric responsive gel substrate according to claim 1, characterized in that: In step S1, two copper wires are taken, one end of which is inserted into two sides of the gel substrate, and the other end is connected to the multimeter measuring probe.

8. The small molecule detection method based on photoelectric responsive gel substrate according to claim 7, characterized in that: In step S3, the photocurrent response value is obtained by measuring the test leads of a multimeter.

9. A small molecule detection device based on a photoelectrically responsive gel substrate, characterized in that: include: Metal ion modified xanthan gum gel substrate, red light source and multimeter measuring probe; The red light source is used to provide a light source to the metal ion-modified xanthan gum gel substrate, and the multimeter measuring probe is used to measure the photocurrent response value.

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