Method for preparing metal-organic framework / bismuth vanadate composite material based on electrodeposition and application thereof in detecting biomarker

Abstract

The application discloses a method for preparing a metal organic framework / bismuth vanadate composite material based on an electrodeposition method and application of the metal organic framework / bismuth vanadate composite material in detection of biomarkers. The composite material is prepared by using bismuth vanadate prepared by an electrochemical deposition method as a substrate, and a porphyrin-based metal organic framework prepared by one-step electrochemical deposition is used for surface modification, so as to form a heterojunction. The structure significantly accelerates the separation and migration of photo-generated carriers, and improves photoelectric performance. In the application, the metal organic framework (MOFs) film prepared by the electrochemical deposition method has a large specific surface area, high porosity and excellent structure adjustment capability, and can be used as a photo / electric active material for detection of different biomarkers. In addition, the application uses photoelectrochemical-electrochemical dual-mode detection, and combines light-enzyme action to amplify signals, so that the application has great potential in photoelectric and electrochemical sensing, and can effectively detect low-concentration biomarkers, and has good application prospect.

Description

Technical Field

[0001] This invention relates to a method for preparing metal-organic framework / bismuth vanadate composite materials based on electrodeposition and its application in the detection of biomarkers, belonging to the field of biosensor technology. Background Technology

[0002] Myocardial infarction (MI) is one of the leading causes of death and disability worldwide, and early diagnosis is crucial for improving patient prognosis. In recent years, miRNAs (microRNAs) have shown great potential as biomarkers in the early detection of MI, particularly the significantly elevated expression of specific miRNAs such as miRNA-133a in MI patients, making their detection an important clinical need. Biosensors, as an emerging detection technology, offer advantages such as high sensitivity, rapid response, simple operation, low cost, good reproducibility, and stability. Combining biosensor technology with the characteristics of miRNAs can enable early diagnosis of MI, providing important decision support for clinical practice.

[0003] Photoelectrochemical (PEC) and electrochemical (EC) biosensors have become mainstream methods for miRNA detection in recent years due to their high sensitivity, low background noise, and ease of operation. To further improve detection performance, dual-mode biosensors developed in recent years combine PEC and EC detection modes, utilizing different signal amplification mechanisms to significantly improve detection sensitivity and specificity. This multi-mode sensor design offers new possibilities for improving the reliability of detecting complex biological samples and is considered an important direction for future biosensor research.

[0004] Bismuth vanadate is an important photocatalytic material due to its excellent photoelectric properties. Its moderate band gap energy allows it to effectively absorb visible light and generate charge carriers, thereby promoting electrochemical reactions. Bismuth vanadate exhibits good stability and compatibility in biological environments, making it suitable for applications in biosensors. Through combination with other materials, bismuth vanadate can enhance the signal response and improve the sensitivity of photoelectrochemical and electrochemical sensors.

[0005] Metal-organic frameworks (MOFs) possess large specific surface areas, high porosity, and good structural tunability, making them suitable as photoactive and electroactive materials for constructing PEC and EC biosensors. Porphyrin-based metal-organic frameworks (PMOFs), due to their excellent electrocatalytic activity, porous structure, and highly ordered metal-ligand interactions, are widely used in electrochemical biosensors.

[0006] Therefore, combining bismuth vanadate with porphyrin-based MOFs, leveraging the advantages of both, holds promise for improving the detection sensitivity and selectivity of myocardial infarction-related miRNAs, providing a new approach to enhancing biosensor performance. However, there are currently no reports on the preparation of biosensors using bismuth vanadate combined with porphyrin-based MOFs.

[0007] Currently, most commonly used methods for preparing porphyrin-based MOFs are hydrothermal methods, which have drawbacks such as long synthesis time, the need for heating, and complex operation. Electrodeposition methods, on the other hand, typically offer advantages such as ease of operation, high time efficiency, no need for heating, and strong adjustability. However, there are currently no reports on methods for preparing porphyrin-based MOFs / bismuth vanadate via electrodeposition. Traditional biosensors are usually single-mode detectors, suffering from problems such as excessively high detection limits and insufficient sensitivity at low concentrations. Therefore, there is an urgent need to develop a biosensor that is simple to prepare, safe, and has good detection performance for detecting myocardial infarction-related biomarkers. Summary of the Invention

[0008] The purpose of this invention is to provide a method for preparing metal-organic framework (MOF) / bismuth vanadate composite materials by electrodeposition and its application in the detection of biomarkers. This invention modifies the surface of bismuth vanadate with metal-organic framework materials by electrodeposition, which significantly improves the photoelectric and electrical properties, accelerates the separation and migration rate of photogenerated carriers, enables effective detection of low concentrations of biomarkers, and enables dual-mode sensing and amplification of the detection signal through photo-nanozyme technology.

[0009] To address the aforementioned technical problems, this invention provides a method for preparing metal-organic framework / bismuth vanadate composite materials based on electrodeposition, comprising the following steps:

[0010] Step 1: Prepare a mixed solution of ethanol and N,N-dimethylformamide. Disperse metal nitrate salt, tetra(4-carboxyphenyl)porphyrin and tetrabutylammonium perchlorate in an organic solvent to obtain a metal-organic framework precursor solution.

[0011] Step 2: Deposit bismuth vanadate on conductive glass to obtain a bismuth vanadate modified working electrode. Using the metal-organic framework precursor solution prepared in Step 1 as the electrolyte, perform electrochemical deposition in a three-electrode system to prepare an electrode with a metal-organic framework / bismuth vanadate composite material deposited on a conductive substrate.

[0012] Preferably, the organic solvent in step 1 is a mixture of ethanol and N,N-dimethylformamide;

[0013] And / or; the conductive glass in step 2 is FTO conductive glass or ITO conductive glass.

[0014] Preferably, the nitrate metal salt in step 1 is selected from at least one of copper nitrate, gadolinium nitrate, zinc nitrate and their hydrates;

[0015] And / or, in step 2, the three-electrode system uses platinum as the counter electrode and silver / silver chloride as the reference electrode.

[0016] Preferably, the molar ratio of the metal nitrate salt, tetra(4-carboxyphenyl)porphyrin, and tetrabutylammonium perchlorate in step 1 is 3-4:1:50-70;

[0017] And / or, the preparation method of the bismuth vanadate modified working electrode in step 2 includes: electrochemically depositing bismuth oxy iodide (BiOI) on conductive glass to obtain a bismuth oxy iodide electrode, adding a solution of vanadium diacetylacetonate, then taking out the electrode and calcining it for annealing treatment, and finally washing and drying the obtained electrode to obtain the bismuth vanadate modified working electrode.

[0018] Preferably, the electrochemical deposition of bismuth oxyiodide employs a three-electrode system: FTO as the working electrode, a platinum sheet as the counter electrode, and silver / silver chloride as the reference electrode. The working electrolyte is prepared as follows: weigh bismuth nitrate or its hydrate, dissolve it and potassium iodide in deionized water, adjust the pH to acidic, then add an ethanol solution containing p-benzoquinone, and stir until homogeneous.

[0019] Preferably, the washing process includes: first washing away excess vanadium oxide compound on the electrode surface with an alkaline solution, and then washing with pure water.

[0020] Preferably, the annealing conditions are: 1–3 °C / min -1 The temperature is increased to 400-500℃ and annealed for 1-3 hours.

[0021] This invention also provides the application of the metal-organic framework / bismuth vanadate composite material prepared by the above method in the detection of biomarkers.

[0022] Preferably, the biomarker is a nucleic acid biomarker, including miRNA.

[0023] This invention also provides a method for detecting biomarkers. This method is based on modifying aldehyde groups with a metal-organic framework / bismuth vanadate composite material prepared as described above, and binding it to an amino-modified capture probe. The specific hybridization of the capture probe with the biomarker is utilized to detect different biomarkers. The method specifically includes the following steps:

[0024] S21. Chitosan solution is dropped onto the surface of metal-organic framework / bismuth vanadate / FTO electrode, dried, and then soaked in glutaraldehyde to modify the aldehyde group.

[0025] S22. After rinsing with PBS buffer, add an aqueous solution of the capture probe to immobilize the capture probe by binding with aldehyde and amino groups, and then incubate.

[0026] S23. Add bovine serum albumin solution to block unbound active sites;

[0027] S24. Add the corresponding concentration of biomarker to the electrode;

[0028] S25. Using PBS as the electrolyte, the photocurrent or electrochemical performance of each step is tested. The quantitative or qualitative detection of biomarkers is achieved by detecting the change in current signal intensity before and after hybridization.

[0029] Preferably, the photocurrent test in step S25 uses a xenon lamp as the light source.

[0030] Preferably, the quantitative detection further includes: fitting a linear fitting curve between the photocurrent signal intensity change ratio (ΔI / I0) in the photoelectrochemical mode and different concentrations of biomarkers, or fitting a linear fitting curve between the current signal intensity change ratio (ΔI / I0) in the electrochemical mode and different concentrations of biomarkers.

[0031] Preferably, in step S25, photoelectrochemical signal amplification is achieved through photo-nanozyme amplification technology, that is, PBS and hydrogen peroxide are used as electrolytes, a three-electrode system is adopted, the photocurrent signal is tested, and the quantitative or qualitative detection of biomarkers is achieved by calculating the ratio of photocurrent signal intensity change before and after hybridization (ΔI / I0).

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] (1) This invention modifies the surface of bismuth vanadate with metal-organic framework material by electrochemical deposition. The composite material prepared by this method has a large specific surface area, high porosity and excellent structural adjustment ability, which significantly improves photoelectric and electrochemical performance. It can realize photoelectric and electrochemical dual-mode sensing and detection of nucleic acid biomarkers, and the detection sensitivity is significantly improved. It solves the problems of traditional biosensors, which are usually single-mode detection, such as excessively high detection limit and insufficient sensitivity for low concentration detection.

[0034] (2) The present invention can detect different biomarkers by capturing probe molecules and regulating them; in addition, the detection performance can be further improved by using photo-nanozyme technology. Attached Figure Description

[0035] Figure 1Scanning electron microscope (SEM) images of bismuth vanadate and copper-based metal-organic framework / bismuth vanadate composites; (ab) are 1 μm SEM images of bismuth vanadate (a) and copper-based metal-organic framework / bismuth vanadate (b), respectively; (cd) are 3 μm SEM images of bismuth vanadate (c) and copper-based metal-organic framework / bismuth vanadate (d), respectively.

[0036] Figure 2 Comparison of transient photocurrent densities measured under chopper light irradiation (light on / off cycle: 3s) and at a potential of 0.1V (vs. Ag / AgCl).

[0037] Figure 3 Electrochemical comparison of bismuth vanadate and copper-based metal-organic framework / bismuth vanadate composites at potentials of 0-0.5V (vs. Ag / AgCl).

[0038] Figure 4 Photocurrent response during electrode assembly.

[0039] Figure 5 : DPV current response during electrode assembly process.

[0040] Figure 6 Linear fitting curves of different concentrations of miRNA-133a detected by copper-based metal-organic framework / bismuth vanadate composite material in photoelectrochemical mode; the ordinate ΔI represents the difference in surface photocurrent before (I0) and after (I) hybridization of bovine serum albumin / capture probe / glutaraldehyde / chitosan / copper-based metal-organic framework / bismuth vanadate with miRNA-133a.

[0041] Figure 7 Linear fitting curves of different concentrations of miRNA-133a were detected in electrochemical mode using copper-based metal-organic framework / bismuth vanadate composite material; the ordinate ΔI represents the difference in DPV current between bovine serum albumin / capture probe / glutaraldehyde / chitosan / copper-based metal-organic framework / bismuth vanadate and miRNA-133a before (I0) and after (I) hybridization.

[0042] Figure 8 : Comparison of current changes of copper-based metal-organic framework / bismuth vanadate composite material after the addition of different interfering substances in photoelectrochemical mode; the vertical axis ΔI represents the difference in surface photocurrent before (I0) and after (I) hybridization of bovine serum albumin / capture probe / glutaraldehyde / chitosan / copper-based metal-organic framework / bismuth vanadate with miRNA-133a.

[0043] Figure 9The DPV current changes of copper-based metal-organic framework / bismuth vanadate composite material after the addition of different interfering substances in electrochemical mode; the vertical axis ΔI represents the difference in DPV current between bovine serum albumin / capture probe / glutaraldehyde / chitosan / copper-based metal-organic framework / bismuth vanadate and miRNA-133a before (I0) and after (I) hybridization.

[0044] Figure 10 Comparison of transient photocurrent densities of bismuth vanadate and copper-based metal-organic framework / bismuth vanadate composites under chopped light irradiation (light on / off cycle: 3s) in the presence of hydrogen peroxide and at a potential of 0.1V (vs. Ag / AgCl).

[0045] Figure 11 Photocurrent response during electrode assembly in the presence of hydrogen peroxide.

[0046] Figure 12 Linear fitting curves of different concentrations of miRNA-133a were detected by photoelectrochemical mode in the presence of hydrogen peroxide using a copper-based metal-organic framework / bismuth vanadate composite material. The ordinate ΔI represents the difference in surface photocurrent before (I0) and after (I) hybridization between bovine serum albumin / capture probe / glutaraldehyde / chitosan / copper porphyrin-based metal-organic framework / bismuth vanadate and miRNA-133a.

[0047] Figure 13 : Comparison of photocurrent changes of copper-based metal-organic framework / bismuth vanadate composite material after the addition of different interfering substances in photoelectrochemical mode in the presence of hydrogen peroxide; The vertical axis ΔI represents the difference in surface photocurrent before (I0) and after (I) hybridization of bovine serum albumin / capture probe / glutaraldehyde / chitosan / copper porphyrin-based metal-organic framework / bismuth vanadate with miRNA-133a. Detailed Implementation

[0048] To make the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0049] Example 1

[0050] MOF materials were prepared by electrodeposition, and metal-organic frameworks (MOFs) were deposited on bismuth vanadate to obtain excellent photoelectrochemical and electrochemical properties.

[0051] (1) Preparation of bismuth vanadate / FTO electrode: Before electrodeposition, the FTO glass slide was ultrasonically cleaned for 20 min each with pure water, acetone, and ethanol solutions, and then dried with nitrogen gas for subsequent use. 0.97 g of bismuth nitrate pentahydrate and 3.32 g of potassium iodide were weighed and dissolved in 50 mL of deionized water, stirred for 20 min, and then the pH was adjusted to approximately 1.7. Then, an ethanol solution containing 0.49 g of p-benzoquinone was added, and the mixture was stirred for 20 min. Potentiostatic deposition of bismuth oxyiodide was performed at room temperature using a three-electrode system with FTO as the working electrode, a platinum sheet as the counter electrode, and silver / silver chloride as the reference electrode. The deposition was carried out at a potential of -0.1 V (vs. Ag / AgCl) for 5 min. The prepared bismuth oxyiodide pre-electrode was rinsed several times with pure water to remove excess plating solution adhering to the electrode surface and dried at room temperature. To convert bismuth iodide to bismuth vanadate, 100 μL of a dimethyl sulfoxide solution containing 0.4 M vanadium diacetylacetonate was uniformly added dropwise to the surface of the bismuth iodide electrode. The electrode was then placed in a muffle furnace and incubated at 2 °C for 1 minute. -1 The electrode was annealed for 2 hours after reaching a heating rate of 450℃. Finally, the resulting bismuth vanadate electrode was immersed in 1M NaOH solution for 20 minutes to remove excess vanadium pentoxide from the surface. The bismuth vanadate electrode was rinsed with pure water and dried at room temperature for subsequent experiments.

[0052] (2) Preparation of electrolyte: Weigh 10.845 mg of copper nitrate, 11.9 mg of tetra(4-carboxyphenyl)porphyrin and 308 mg of tetrabutylammonium perchlorate and sonicate for 10 min to disperse them evenly in 10 ml of a mixed solution of ethanol and N,N-dimethylformamide to prepare the electrolyte. The volume ratio of ethanol to N,N-dimethylformamide is 7 mL: 3 mL.

[0053] (3) Electrodeposition of copper-based metal-organic frameworks using a three-electrode system: using bismuth vanadate / FTO as the working electrode, a platinum sheet as the counter electrode, and silver / silver chloride as the reference electrode, and using the solution prepared in the above steps as the electrolyte, deposition was carried out at a potential of -0.7V (vs. Ag / AgCl) for 10 minutes. Copper-based metal-organic frameworks / bismuth vanadate / FTO were obtained.

[0054] Bismuth vanadate / FTO

[0055] from Figure 1 ab and Figure 1 cd are scanning electron microscope images of bismuth vanadate and copper-based metal-organic frameworks / bismuth vanadate at 1 μm and 3 μm, respectively. It can be seen that bismuth vanadate exhibits a typical one-dimensional nanoworm-like, hollow structure. In contrast, the two-dimensional copper-based metal-organic framework is loaded on the bismuth vanadate surface, presenting a two-dimensional thin film structure with a relatively thin thickness. The two-dimensional copper-based metal-organic framework is more uniformly distributed on the bismuth vanadate substrate surface, exhibiting good flatness.

[0056] In a three-electrode system, PBS was used as the electrolyte, a xenon lamp as the light source, a copper-based metal-organic framework / bismuth vanadate as the working electrode, a platinum sheet as the counter electrode, and silver / silver chloride as the reference electrode. The potential was set to 0.1V (vs. Ag / AgCl). The transient photocurrent density was measured under chopper light irradiation (light on / off cycle: 3s) and at a potential of 0.1V (vs. Ag / AgCl).

[0057] from Figure 2 It can be seen that the transient photocurrent density of bismuth vanadate measured under chopper light irradiation (photo-on / off cycle: 3s) and a potential of 0.1V (vs. Ag / AgCl) is approximately 36 μA cm⁻¹. -2 The transient photocurrent density of the copper-based metal-organic framework / bismuth vanadate composite material, measured under chopper light irradiation (light on / off cycle: 3s) and a potential of 0.1V (vs. Ag / AgCl), is approximately 52 μA / cm². -2 The copper-based metal-organic framework / bismuth vanadate composite material showed a significant increase in transient photocurrent density compared to bismuth vanadate under chopper light irradiation (light on / off cycle: 3s) and at a potential of 0.1V (vs. Ag / AgCl).

[0058] In a three-electrode system, PBS was used as the electrolyte, copper-based metal-organic framework / bismuth vanadate as the working electrode, platinum sheet as the counter electrode, and silver / silver chloride as the reference electrode. The potential was set to 0-0.5V (vs. Ag / AgCl), and the electrochemical performance was tested using differential pulse voltammetry (DPV).

[0059] from Figure 3 It can be seen that the DPV current response of bismuth vanadate is 20 μA cm⁻¹. -2 The DPV current response of the copper-based metal-organic framework / bismuth vanadate is 50 μA cm⁻¹. -2 The DPV current response of copper-based metal-organic frameworks / bismuth vanadate is significantly improved compared to that of bismuth vanadate.

[0060] Example 2

[0061] By modifying groups with metal-organic frameworks / bismuth vanadate composite materials and modulating the capture probe molecules, dual-mode detection of different biomarkers in photoelectrochemical (PEC) and electrochemical (EC) modes can be achieved:

[0062] Based on the copper-based metal-organic framework / bismuth vanadate / FTO electrode prepared in Example 1, 43 μL of 0.5% chitosan solution was dropped onto the surface of the copper-based metal-organic framework / bismuth vanadate electrode. After drying, it was soaked in 5% glutaraldehyde for 2 hours. After rinsing with PBS buffer, 50 μL of a 10 nM aqueous solution of the capture probe (NH2-CAGCUGGUUGAAGGGGACCAAA) was added, and the electrode was incubated at 4°C for 6 hours. After another PBS rinse, 2% bovine serum albumin solution was added. Finally, different concentrations of miRNA-133a were dropped onto the electrode surface. The photocurrent and DPV current were measured at each step using a three-electrode system.

[0063] from Figure 4 and Figure 5 It can be seen that each step in the electrode assembly process reduces the photocurrent and DPV current, proving the successful assembly of the electrode.

[0064] from Figure 6 It can be seen that the photocurrent signal decreases as the miRNA concentration gradually increases; the photocurrent density decreases after adding miRNA-133a solution. The miRNA-133a concentration and the photocurrent signal show an excellent correlation, with a linear correlation between the photocurrent signal and the logarithm of the miRNA-133a concentration (lgCmiRNA). The linear equation is y = 24.5136 - 7.67687 * lgCmiRNA, R 2 The value is 0.987 (N=5), Y is ΔI / I0, ΔI represents the difference in surface photocurrent between bovine serum albumin / capture probe / glutaraldehyde / chitosan / copper-based metal-organic framework / bismuth vanadate and miRNA-133a before (I0) and after (I) hybridization; the detection limit is 0.052 pM (S / N=3).

[0065] from Figure 7 It can be seen that the DPV current signal decreases as the miRNA concentration gradually increases; the DPV current density decreases after adding miRNA-133a solution. The miRNA-133a concentration and the DPV current signal show an excellent correlation, with a linear correlation between the DPV current signal and the logarithm of the miRNA-133a concentration (lgCmiRNA). The linear equation is y = 26.77711 - 5.20398 * lgCmiRNA, R 2 The value was 0.976 (N=5), and Y was ΔI / I0, where ΔI represents the difference in surface DPV current before (I0) and after (I) hybridization of bovine serum albumin / capture probe / glutaraldehyde / chitosan / copper-based metal-organic framework / bismuth vanadate with miRNA-133a; the detection limit was 0.078 pM (S / N=3).

[0066] from Figure 8 and Figure 9 The changes in photocurrent and DPV current when different concentrations of biomarkers are dropped onto the electrode surface can be observed, demonstrating that the electrode has excellent selectivity for detecting miRNA-133a.

[0067] Example 3: Implementing a photo-nanozyme amplification strategy to improve sensor detection performance:

[0068] Based on the copper-based metal-organic framework / bismuth vanadate / FTO electrode prepared in Example 1, a three-electrode system was used to test the photocurrent. 30 mM hydrogen peroxide was added, and 43 μL of 0.5% chitosan solution was dropped onto the surface of the copper-based metal-organic framework / bismuth vanadate electrode. After drying, it was soaked in 5% glutaraldehyde for 2 hours. After rinsing with PBS buffer, 50 μL of a 10 nM aqueous solution of the capture probe (NH2-CAGCUGGUUGAAGGGGACCAAA) was added, and the electrode was incubated at 4°C for 6 hours. After another PBS rinse, 2% bovine serum albumin solution was added. Finally, different concentrations of miRNA-133a were dropped onto the electrode surface. The photocurrent in each step was measured using the three-electrode system.

[0069] from Figure 10 It can be seen that the transient photocurrent density of bismuth vanadate irradiated by chopper light in the presence of hydrogen peroxide (photo-on / off cycle: 3s) and at a potential of 0.1V (vs. Ag / AgCl) is 32 μA cm⁻¹. -2 The transient photocurrent density of the copper-based metal-organic framework / bismuth vanadate composite material under chopper light irradiation (photo-on / off cycle: 3s) in the presence of hydrogen peroxide and at a potential of 0.1V (vs. Ag / AgCl) is 80 μA cm⁻¹. -2 The photo-nanozyme amplification technology strategy enables the amplification of photocurrent.

[0070] from Figure 11 It can be seen that each step in the electrode assembly process reduces the photocurrent, proving the successful assembly of the electrode.

[0071] from Figure 12 It can be seen that the photocurrent signal decreases as the miRNA concentration gradually increases; the photocurrent density decreases after adding miRNA-133a solution. The miRNA-133a concentration and the photocurrent signal show an excellent correlation, with a linear correlation between the photocurrent signal and the logarithm of the miRNA-133a concentration (lgCmiRNA). The linear equation is y = 68740 - 1260 * lgCmiRNA, R 2 The value was 0.99 (N=5). The detection limit was 0.003 fM (S / N=3).

[0072] from Figure 13The changes in photocurrent when different concentrations of biomarkers are dropped onto the electrode surface demonstrate that the electrode, combined with a specific capture probe, has excellent selectivity for detecting miRNA-133a.

[0073] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention in any form or substance. It should be noted that those skilled in the art can make several improvements and additions without departing from the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A method for detecting biomarkers based on a metal-organic framework / bismuth vanadate composite material prepared by electrodeposition, characterized in that, Includes the following steps: Step 1: Prepare a mixed solution of ethanol and N,N-dimethylformamide. Copper nitrate, tetrakis(4-carboxyphenyl)porphyrin and tetrabutylammonium perchlorate are mixed and dispersed in an organic solvent to obtain a metal-organic framework precursor solution. Step 2: Using conductive glass as a substrate, a working electrode modified with bismuth vanadate is prepared. Using the metal-organic framework precursor solution prepared in Step 1 as the electrolyte, electrochemical deposition is performed in a three-electrode system to prepare an electrode with metal-organic framework / bismuth vanadate composite material deposited on a conductive substrate. Step 3: Modify the metal-organic framework / bismuth vanadate composite material with aldehyde groups and bind it to an amino-modified capture probe. Detect the biomarker by utilizing the specific hybridization of the capture probe with the biomarker. Specifically, this includes: S1. Chitosan solution is dropped onto the surface of metal-organic framework / bismuth vanadate / FTO electrode, dried, and then soaked in glutaraldehyde to modify the aldehyde group. S2. After rinsing with PBS buffer, add an aqueous solution of the capture probe to immobilize the capture probe by binding with aldehyde and amino groups, and then incubate. S3. Add bovine serum albumin solution to block unbound active sites; S4. Add the corresponding concentration of biomarker to the electrode; S5. Using PBS as the electrolyte, the photocurrent and electrochemical performance of each step were tested. The quantitative or qualitative detection of biomarkers was achieved by calculating the change ratio of photocurrent signal intensity before and after hybridization. The biomarker is miRNA; In step S5, photoelectrochemical signal amplification is achieved through photo-nanozyme amplification technology, that is, PBS and hydrogen peroxide are used as electrolytes, a three-electrode system is adopted, and the photocurrent signal is tested.

2. The method as described in claim 1, characterized in that, The organic solvent in step 1 is a mixture of ethanol and N,N-dimethylformamide; and / or; the conductive glass in step 2 is FTO conductive glass or ITO conductive glass.

3. The method as described in claim 1, characterized in that, In step 1, the molar ratio of copper nitrate, tetra(4-carboxyphenyl)porphyrin, and tetrabutylammonium perchlorate is 3~4:1:50~70; and / or, in step 2, the three-electrode system uses platinum as the counter electrode and silver / silver chloride as the reference electrode.

4. The method as described in claim 1, characterized in that, The preparation method of the bismuth vanadate modified working electrode in step 2 includes: depositing bismuth oxy iodide (BiOI) on conductive glass to obtain a bismuth oxy iodide electrode, adding a solution of vanadium diacetylacetonate, then taking out the electrode and calcining it for annealing treatment, and finally washing and drying the obtained electrode to obtain the bismuth vanadate modified working electrode.

5. The method as described in claim 1, characterized in that, In step S5, the photocurrent is tested using a xenon lamp as the light source.

6. The method as described in claim 1, characterized in that, The quantitative detection also includes: fitting linear fitting curves between the photocurrent signal intensity change ratio in the photoelectrochemical mode and different concentrations of miRNA, and fitting linear fitting curves between the current signal intensity change ratio in the electrochemical mode and different concentrations of miRNA.

Images