A method for preparing a prostate cancer sensing electrode

Abstract

The application belongs to the field of biochemical technology clinical diagnosis, and relates to a prostate cancer sarcosine detection sensing electrode based on a prussian blue wrapped tungsten oxide composite material. Sodium tungstate is used as a tungsten source, oxalic acid is used as a structure directing agent, and hydrochloric acid is used as an etching agent. The sodium tungstate, the oxalic acid and the hydrochloric acid are mixed to prepare a mixed solvent. After a hydrothermal synthesis reaction, tungsten oxide nanosheets are obtained. A micro-speed synthesis method is used to drop a mixed solution of two precursors of prussian blue into a tungsten oxide dispersion liquid. A composite material of prussian blue wrapped tungsten oxide is obtained through the reaction. The composite material solution is drop-coated on a bare gold working electrode, and is dried at room temperature. Sarcosine oxidase cross-linked with glutaraldehyde is added dropwise on the electrode surface, and is stored in a refrigerator. The aptamer electrode can realize rapid trace detection of sarcosine in prostate cancer, and is suitable for early detection of prostate cancer in medicine.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of biochemistry and clinical diagnosis, and relates to a preparation method of a prostate cancer sensing electrode. BACKGROUND

[0002] Sarcosine is an amino acid derivative existing in all cells of the human body, and is a product of glycine synthesis and metabolism, which can be detected in blood and urine. Sarcosine, as a biomarker of prostate cancer, plays an important role in the diagnosis of prostate cancer. The specificity of the enzymatic reaction between sarcosine oxidase and sarcosine can be used for rapid and specific determination of sarcosine.

[0003] Therefore, early screening and diagnosis of prostate cancer is crucial for later treatment. It is necessary to develop a simple, convenient and reliable prostate cancer screening method to improve people's enthusiasm for disease screening and help them get treatment as soon as possible. Electrochemical biosensors are a new type of technology and are considered an attractive alternative analytical tool for the manufacture of point-of-care diagnostics. They have the characteristics of high selectivity, high sensitivity, rapid detection, low cost and easy use and handling, which can help early diagnosis and management of diseases, thereby helping to make timely treatment decisions. However, there is no ideal prostate cancer sensing electrode reported at present. SUMMARY

[0004] The application proposes a preparation method of a novel prostate cancer sensing electrode aiming at the problems existing in the traditional prostate cancer detection system.

[0005] In order to achieve the above purpose, the application is implemented by using the following technical solutions:

[0006] A preparation method of a prostate cancer sarcosine sensing electrode, the steps are as follows:

[0007] (1) Preparation of tungsten oxide nanomaterials

[0008] Sodium tungstate is used as tungsten source, oxalic acid is used as structure directing agent, and hydrochloric acid is used as etching agent. Sodium tungstate aqueous solution is mixed with hydrochloric acid solution uniformly to obtain solution A; oxalic acid solution is added, and after stirring for 30 minutes, the mixture is transferred to a 100ml Teflon-lined stainless steel autoclave for hydrothermal synthesis reaction. After the reaction is completed, the reaction product is centrifuged and washed, and dried to obtain tungsten oxide powder.

[0009] (2) Preparation of prussian blue coated tungsten oxide composite material

[0010] The tungsten oxide powder is added to deionized water to obtain a dispersion liquid, and potassium ferricyanide solution and potassium ferrocyanide solution are respectively added dropwise into the dispersion liquid to carry out a micro-speed reaction to obtain a composite precipitate.

[0011] (3) The complex precipitate is added into a suspension liquid composed of water and chitosan to obtain a mixed liquid B, the working electrode is cleaned, the mixed liquid B is added dropwise onto the surface of the working electrode, the working electrode is dried at room temperature, and then the surface of the working electrode is cleaned with ultrapure water to obtain a sensing electrode.

[0012] Preferably, in step (1), the concentration of sodium tungstate in solution A is 50-100 mM, the concentration of hydrochloric acid is 1-4 M, the molar ratio of sodium tungstate to oxalic acid is 2:1, the mixing and stirring time is 30 min, the hydrothermal synthesis reaction temperature is 140-180 DEG C, the hydrothermal synthesis reaction time is 4-12 h, the washing liquid is anhydrous ethanol and deionized water, and the washing procedure is to wash twice with anhydrous ethanol and centrifuge, and then wash twice with deionized water and centrifuge.

[0013] Preferably, in step (2), the concentration of potassium ferricyanide solution and potassium ferrocyanide solution is 5-10 mM, the concentration of tungsten oxide powder in the dispersion liquid is 0.01-0.25 g / ml, the dropwise adding speed of potassium ferricyanide solution and potassium ferrocyanide solution is 0.1-1 ml / min, and the micro-speed reaction temperature is 45 DEG C.

[0014] Preferably, in step (3), the working electrode is a gold electrode, the mass fraction of chitosan in the suspension liquid is 1-5%, the mass concentration of the complex precipitate in the mixed liquid B is 3-15 mg / mL, and the dropwise coating amount is 2-5 μL; the drying time at room temperature is 60-120 min.

[0015] The application provides application of the sensing electrode prepared by the method in detection of sarcosine.

[0016] A detection method of sarcosine, which uses the sensing electrode prepared by the method.

[0017] Preferably, 2-4 microliters of sarcosine oxidase solution is dropped on the surface of the working electrode during detection, the enzyme solution concentration is 0.1-10 U / μL, the working electrode is dried at room temperature for 2 hours and then directly used, or is stored in a 4-8 DEG C environment for standby.

[0018] The application provides a prostate cancer sarcosine detection sensing electrode based on a prussian blue wrapped tungsten oxide composite material, and the electrode surface is loaded with sarcosine oxidase.

[0019] The prussian blue wrapped tungsten oxide composite material in the application needs to strictly control the concentration ratio of sodium tungstate and oxalic acid in the synthesis process, and only high enough concentration of oxalic acid can synthesize tungsten oxide nanosheet, and too low concentration of oxalic acid will cause the product to appear incomplete sheet, but too high concentration of oxalic acid will cause the product to appear agglomeration phenomenon. The tungsten metal in the sensing material tungsten oxide is in high valence state, is easy to lose electrons and has good oxidizability, can promote the oxidation of sarcosine oxidase and shorten the response time of the electrode. Prussian blue is a natural hydrogen peroxide oxidase, which can directly detect target objects without introducing other auxiliary detection enzyme preparations, and there is no system error caused by the mixing of two enzymes, so that the sensing electrode prepared by the application has good detection specificity. The tungsten oxide used in the application has small electron transport capacity and large semiconductor band gap as an oxide, and the band gap of prussian blue is very narrow, and the mutual interaction solves the problem of poor conductivity of tungsten oxide and improves the sensitivity of the sensing electrode. The tungsten oxide and prussian blue are combined by van der waals force, which increases the stability of the material and improves the stability of the sensing electrode. The sensing electrode prepared by the application can produce sensing signals to trace markers by using the catalytic oxidation method of oxidase, realizes trace detection and widens the detection limit of the sensing electrode. Therefore, the application uses the prussian blue wrapped tungsten oxide composite material with high catalytic activity and high oxidizability as the electrode modification material, uses sarcosine as the detection material, and has high accuracy, specificity and sensitivity for early detection of prostate cancer, low response time and wide detection range.

[0020] Compared with the prior art, the application has the advantages and positive effects that:

[0021] The prussian blue wrapped tungsten oxide composite material synthesized by the application has obvious advantages, the tungsten metal in the tungsten oxide is in high valence state, loses electrons and has good oxidizability, can promote the oxidation of sarcosine oxidase, and the prussian blue is a natural hydrogen peroxide oxidase, which can reduce the error caused by the mixing of two enzymes. And the tungsten oxide is an oxide with small electron transport capacity and large semiconductor band gap, and the band gap of prussian blue is very narrow, which solves the problem of poor conductivity of tungsten oxide. The material has good catalytic activity and biocompatibility, and can better realize biosensing detection. The combination of the two materials solves the problems of poor catalytic activity, low sensitivity and poor conductivity in electrochemical sensing, and provides better biocompatibility for subsequent detection, overcomes the problems of long detection time and large side effects in traditional detection, and can meet the requirements of prostate cancer sarcosine detection in clinic, and is suitable for large-scale popularization and application. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The scanning electron microscope image of the prussian blue wrapped tungsten oxide composite material synthesized by the micro-speed synthesis method in Example 1.

[0023] Figure 2 I-T scan of the prostate cancer sarcosine sensor prepared in Example 1 for different concentrations of sarcosine. DETAILED DESCRIPTION

[0024] In order to make the above-mentioned objects, features and advantages of the present application more clearly understood, the present application will be further described below with specific examples. It should be noted that the examples of the present application and the features in the examples can be combined with each other without conflict.

[0025] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present application, however, the present application can also be implemented in other ways different from those described herein, and therefore, the present application is not limited to the specific examples disclosed in the following description.

[0026] In the following examples, the preparation of the prostate cancer sarcosine electrode is as follows: sodium tungstate is used as the tungsten source, oxalic acid is used as the structure directing agent, and hydrochloric acid is used as the etching agent. The sodium tungstate, oxalic acid and hydrochloric acid are mixed to form a mixed solvent (all the above-mentioned chemicals are purchased from Macklin Biochemical Technology Co., Ltd.). After the mixed solvent is stirred at room temperature for 30 minutes, it is transferred to a 100-milliliter Teflon-lined stainless steel autoclave. After the hydrothermal synthesis reaction, a tungsten oxide nanomaterial solution is obtained. The solution is centrifuged and washed to obtain a tungsten oxide nanomaterial precipitate. A portion of the tungsten oxide powder is dispersed in deionized water under ultrasonic to obtain a dispersion liquid. Two solutions of potassium ferricyanide and potassium ferrocyanide are respectively transferred to 100-milliliter syringes. The two solutions of potassium ferricyanide and potassium ferrocyanide are respectively added dropwise to the tungsten oxide dispersion liquid by using the micro-speed synthesis method. A Prussian blue-coated tungsten oxide composite material is obtained by reaction. The solution is centrifuged and washed to obtain a composite material precipitate. A certain amount of the composite material is dispersed in a mixed solution of ultrapure water and chitosan to obtain a composite material mixed solution. A gold electrode is used as the working electrode, an Ag / AgCl electrode is used as the reference electrode, and a platinum wire electrode is used as the counter electrode. A certain amount of the composite material mixed solution is drop-coated onto the bare gold working electrode, and dried at room temperature overnight.

[0027] Sarcosine oxidase is dissolved in a phosphate (PBS) buffer solution, and the enzyme concentration is 0.1-10 U / μL. The PBS buffer solution has a pH of 6.5, and the composition is 0.1 M potassium chloride, 0.5 M potassium dihydrogen phosphate, and 0.5 M dipotassium hydrogen phosphate. 2-4 microliters of the sarcosine oxidase solution is dropped on the gold electrode, and the electrode is dried at room temperature for two hours. Then, the electrode is placed in a 4-8°C refrigerator for standby.

[0028] In the following examples, the concentration range of the detected sarcosine is 0.1-20 μM, and the detection is performed from low concentration to high concentration. Example 1

[0029] The embodiment provides a preparation method of a prostate cancer sarcosine sensing electrode based on a tungsten oxide composite material wrapped by Prussian blue, and steps are as follows.

[0030] (1) 0.2473 g of sodium tungstate is dissolved in 15 ml of deionized water, stirred for 10 minutes until the particles are completely dissolved, then 5 ml of 1M hydrochloric acid solution is added to generate a yellow precipitate. Then 0.0338 g of oxalic acid is added to 10 ml of deionized water, stirred until clear, and then added to the above precipitate solution, stirred at room temperature for 30 minutes, and then transferred to a 100 ml Teflon-lined stainless steel autoclave. The hydrothermal synthesis reaction is carried out at 140°C for 12 hours to obtain a tungsten oxide nanomaterial solution. The solution is centrifuged, the supernatant is discarded, and the tungsten oxide precipitate is left. The precipitate is first washed twice with anhydrous ethanol by centrifugation, and then washed twice with deionized water by centrifugation. The centrifugal speed in this step is 8000 r / min, and the centrifugal time is 6 min. After centrifugation, the supernatant is discarded to obtain the tungsten oxide nanomaterial precipitate, which is taken out and dried in a 60°C oven for 12 hours.

[0031] (2) The tungsten oxide nanomaterial obtained in step (1) is placed in a beaker, 80 ml of water is added, and ultrasonic treatment is performed for 10 minutes to obtain a tungsten oxide dispersion solution. 80 ml of 5 mM potassium ferrocyanide solution and 80 ml of 5 mM potassium ferricyanide solution are prepared, and a micro-rate synthesis method is used to slowly drop the two solutions into the ultrasonic-treated tungsten oxide dispersion solution: a syringe is fixed on a double-channel syringe pump, then a 200 ml beaker is placed in a heated magnetic stirrer as a reaction container, the tungsten oxide dispersion solution is added to the beaker, and the rotor is started to stir and heat at a speed of 250 r / min. When the temperature stabilizes at 45°C, the two solutions are simultaneously injected into the beaker at a rate of 0.1 ml / min through the syringe pump. After the dropwise addition is completed, the stirring and heating buttons are turned off. The reaction solution is taken out, centrifuged to remove the supernatant, and then washed with deionized water four times by centrifugation. The centrifugal speed is 8000 r / min, and the centrifugal time is 6 min. After centrifugation, the supernatant is discarded to obtain the Prussian blue-wrapped tungsten oxide nanomaterial precipitate. If necessary, the precipitate can be dispersed in deionized water to prepare a 6 mg / mL dispersion solution. Figure 1 The electron microscope results show that the tungsten oxide is uniformly wrapped with a layer of Prussian blue on the outer surface.

[0032] (3) The composite material prepared in step (2) is dispersed in deionized water to prepare a 6 mg / mL dispersion solution, and a 6 mg / mL chitosan aqueous solution is prepared. 500 μL of each of the two liquids is mixed together, 2 μL of the mixed solution is dropped on the gold electrode, and the electrode is dried at room temperature for 60 min. Sarcosine oxidase is dissolved in a phosphate (PBS) buffer solution to obtain a sarcosine oxidase solution, and the enzyme solution concentration is 0.1 U / μL. 2 μL of the enzyme solution is dropped on the gold electrode, which is dried at room temperature for two hours, and then the electrode is stored in a 4°C refrigerator for standby. The detection lower limit of the sensor reaches 0.1 μM. Example 2

[0033] This example provides a method for detecting prostate cancer sarcosine based on Prussian blue coated tungsten oxide composite material. The aspects not specifically explained in this example are consistent with Example 1. The steps are as follows.

[0034] (1) 0.3711 grams of sodium tungstate was weighed into 15 milliliters of deionized water, stirred for 10 minutes until the particles were completely dissolved, then 5 milliliters of 1M hydrochloric acid solution was added to produce a yellow precipitate. 0.0506 grams of oxalic acid was weighed into 10 milliliters of deionized water, stirred until clear, and then added to the above precipitate solution. After stirring at room temperature for 30 minutes, it was transferred to a 100 milliliter Teflon-lined stainless steel autoclave. The hydrothermal synthesis reaction was carried out at 160°C for 8 hours to obtain a tungsten oxide nanomaterial solution. The solution was centrifuged, the supernatant was discarded, and the tungsten oxide precipitate was left. The precipitate was first washed twice with anhydrous ethanol by centrifugation, and then washed twice with deionized water by centrifugation. The centrifugal speed in this step was 8000 r / min, and the centrifugal time was 6 min. After centrifugation, the supernatant was discarded to obtain the tungsten oxide nanomaterial precipitate, which was taken out and placed in a 60°C oven for drying for 12 hours.

[0035] (2) The tungsten oxide nanomaterial obtained in step (1) was placed in a beaker, 80 milliliters of water was added, and ultrasonic was performed for 10 minutes to obtain a tungsten oxide dispersion solution. 80 milliliters of 8 mM potassium ferrocyanide solution and 80 milliliters of 8 mM potassium ferricyanide solution were prepared, and a micro-rate synthesis method was used to slowly drop the two solutions into the ultrasonic tungsten oxide dispersion solution: a syringe was fixed on a double-channel syringe pump, then a 200ml beaker was placed in a heated magnetic stirrer as a reaction container, the tungsten oxide dispersion solution was added to the beaker, and the rotor was started to stir and heat at a speed of 250 revolutions / min. When the temperature stabilized at 45°C, both solutions were injected into the beaker at a rate of 0.5 ml / min simultaneously through the syringe pump. After the drop was completed, the stirring and heating buttons were turned off. The reaction solution was taken out, centrifuged to remove the supernatant, and then washed with deionized water four times by centrifugation. The centrifuge speed was 8000 r / min, and the centrifugal time was 6 min. After centrifugation, the supernatant was discarded to obtain the Prussian blue coated tungsten oxide nanomaterial precipitate. As Figure 1 The electron microscope results show that the tungsten oxide is uniformly coated with a layer of Prussian blue on the outer surface.

[0036] (3) The composite material prepared in step (2) was dispersed in deionized water to prepare a dispersion liquid of 16 mg / mL, and a chitosan aqueous solution of 16 mg / mL was prepared. 500 μL of each liquid was mixed together, and 3 μL of the mixed liquid was dropped on a gold electrode and dried at room temperature for 90 min. Sarcosine oxidase was dissolved in a phosphate (PBS) buffer to obtain a sarcosine oxidase solution, and the enzyme solution had a concentration of 5 U / μL. 3 μL of the enzyme solution was dropped on the gold electrode, and the electrode was dried at room temperature for two hours and then stored in a refrigerator at 6°C for standby. It was detected that the lower limit of detection of the sensor reached 0.1 μM. Example 3

[0037] This example provides a method for detecting prostate cancer sarcosine based on a Prussian blue wrapped tungsten oxide composite material. The places not specially explained in this example are consistent with example 1. The steps are as follows.

[0038] (1) 0.4948 g of sodium tungstate was dissolved in 15 ml of deionized water, stirred for 10 minutes until the particles were completely dissolved, and then 5 ml of 1M hydrochloric acid solution was added to produce a yellow precipitate. Then 0.0675 g of oxalic acid was weighed and added to 10 ml of deionized water, stirred until clear, and then added to the above precipitate solution. After stirring at room temperature for 30 minutes, it was transferred to a 100 ml Teflon-lined stainless steel autoclave. The hydrothermal synthesis reaction was carried out at 180°C for 4 hours to obtain a tungsten oxide nanomaterial solution. The solution was centrifuged, the supernatant was discarded, and the tungsten oxide precipitate was left. The precipitate was first centrifuged with anhydrous ethanol twice, and then with deionized water twice. The centrifugal speed in this step was 8000 r / min, and the centrifugal time was 6 min. After centrifugation, the supernatant was discarded to obtain the tungsten oxide nanomaterial precipitate, which was taken out and dried in a 60°C oven for 12 hours.

[0039] (2) The tungsten oxide nanomaterial obtained in step (1) was placed in a beaker and 80 ml of water was added and ultrasonicated for 10 minutes to obtain a tungsten oxide dispersion liquid. 80 ml of 10 mM potassium ferrocyanide solution and 80 ml of 10 mM potassium ferricyanide solution were prepared, and a micro-rate synthesis method was used to slowly drop the two solutions into the ultrasonicated tungsten oxide dispersion liquid: a syringe was fixed on a double-channel syringe pump, then a 200 ml beaker was placed in a heated magnetic stirrer as a reaction container, the tungsten oxide dispersion liquid was added to the beaker, and the rotor was started to stir and heat at a speed of 250 r / min. When the temperature stabilized at 45°C, the two solutions were simultaneously injected into the beaker at a rate of 1 ml / min through the syringe pump. After the drop was completed, the stirring and heating buttons were turned off. The reaction liquid was taken out and centrifuged to remove the supernatant, and then washed with deionized water four times by centrifugation. The centrifugal speed was 8000 r / min, and the centrifugal time was 6 min. After centrifugation, the supernatant was discarded to obtain the Prussian blue wrapped tungsten oxide nanomaterial precipitate.Figure 1 The electron microscope results show that the outer surface of the tungsten oxide is uniformly wrapped with a layer of Prussian blue.

[0040] (3) The composite material prepared in step (2) is dispersed in deionized water to prepare a dispersion liquid of 30 mg / mL, and a chitosan aqueous solution of 30 mg / mL is prepared, 500 μL of each of the two liquids is mixed together, 5 μL of the mixed liquid is dropped on the gold electrode, and dried at room temperature for 120 min. The sarcosine oxidase is dissolved in a phosphate (PBS) buffer to obtain a sarcosine oxidase solution, and the enzyme solution has a concentration of 10 U / μL. 4 μL of the enzyme solution is dropped on the gold electrode, and after drying at room temperature for two hours, the electrode is stored in an 8°C refrigerator for standby. It is detected that the lower limit of detection of the sensor reaches 0.1 μM.

[0041] Verification of the performance of the sensing electrode.

[0042] 1. I-T characterization

[0043] 40 mL of PBS buffer (pH = 6.5, composition: 0.1 M potassium chloride, 0.5 M potassium dihydrogen phosphate, 0.5 M dihydrogen potassium phosphate) is taken, the three electrodes are completely immersed in the electrolytic cell filled with the buffer, are respectively connected to the interfaces on the electrochemical workstation, the working potential is set to -0.3 V, when the bottom current is stable, the amount of the measured substance is changed by adding sarcosine with different concentrations into the electrolytic cell, and the current signal generated by the enzymatic reaction is received by the electrochemical workstation. It can be observed that the response time is 5.0 seconds. By investigating the linear range of the sarcosine concentration and the detection response, the results are as follows Figure 2 , from Figure 2 It can be seen that the sensor has a wide detection line.

[0044] 2. Real sample detection

[0045] The real sample blood comes from Gulou Hospital in Nanjing, and the blood sampling site is venous blood. The serum of a healthy male volunteer and a patient with prostate cancer detected by routine physical examination is detected (the patient is aware and agrees). The detection process is as follows: the enzyme is dropped on the sensing electrode, 1 ml of serum is taken and added to 100 ml of PBS buffer, and then the electrode is placed in, the sarcosine existing in the serum is detected, and the concentration of sarcosine in each serum sample is calculated. It is found that the measured sarcosine level of the biosensor in the serum of the patient with prostate cancer is significantly higher than that of the obviously healthy person, and the patient has no any discomfort, indicating that the electrode prepared by the application is suitable for early detection of prostate cancer. The results are shown in Table 1.

[0046] Table 1 Real sample detection results

[0047]

[0048] 3. Accuracy test:

[0049] The electrode prepared in Example 1 was verified for accuracy by preparing a standard sample, sarcosine was added to the PBS buffer, and sarcosine solution concentrations of 0.1 μM, 1 μM, 5 μM, 10 μM, 15 μM, and 20 μM were prepared in turn, and the electrode prepared in Example 1 was used to detect the solution. Three sets of samples were prepared for each concentration, and the average value was taken after testing. The detection value was compared with the actual value, and the results are shown in Table 2. As can be seen from Table 2, the detection value deviates slightly from the actual value, proving that the sensing electrode has good accuracy.

[0050] Table 2 Accuracy test results

[0051]

[0052] 4. Stability test

[0053] The electrode was soaked in PBS buffer for 300 h, and then used after being taken out. The difference between the detection results of the electrode before and after soaking was tested. The results showed that after soaking, the detection results and response time of the sensing electrode and the new electrode were not much different, proving that the electrode has good stability.

[0054] Comparative Example 1

[0055] The difference between this comparative example and Example 1 is that the amount of sodium tungstate added is 0.2473 g, and the amount of oxalic acid added is 0.1352 g. The other operating conditions are the same as in Example 1. It was found that the synthesized tungsten oxide appeared to be agglomerated, resulting in a decrease in specific surface area, which is not conducive to sensing.

[0056] Comparative Example 2

[0057] The difference between this comparative example and Example 1 is that the amount of sodium tungstate added is 4.2136 g, and the amount of oxalic acid added is 0.0225 g. The other operating conditions are the same as in Example 1. It was found that the synthesized tungsten oxide had a large number of particles, only a small amount of plate-like structure, and the size of the nano-plate was not uniform, which is not conducive to the synthesis of composite materials.

[0058] The above is only a preferred embodiment of the present application, and is not intended to limit the present application in other forms. Any skilled person in the art can modify or change the above disclosed technical content to equivalent embodiments applied to other fields, but any simple modification, equivalent change, and modification of the above embodiments made in accordance with the technical essence of the present application still falls within the protection scope of the present application.

Claims

1. A method for preparing a sarcosine sensor electrode for prostate cancer, characterized by, The steps are as follows: (1) Preparation of tungsten oxide nanomaterials Sodium tungstate aqueous solution is mixed with hydrochloric acid solution to obtain solution A; oxalic acid solution is added and stirred, and then hydrothermal synthesis reaction is carried out. After the reaction, the reaction product is centrifuged and washed, and dried to obtain tungsten oxide powder; (2) Preparation of Prussian blue coated tungsten oxide composite material The tungsten oxide powder is added to deionized water to obtain a dispersion liquid, and potassium ferricyanide solution and potassium ferrocyanide solution are added dropwise into the dispersion liquid respectively to carry out a micro-speed reaction to obtain a composite precipitate; (3) The composite precipitate is added to a suspension liquid composed of water and chitosan to obtain a mixed liquid B, the working electrode is cleaned, the mixed liquid B is added dropwise to the surface of the working electrode, and the working electrode surface is dried at room temperature, and then washed with ultrapure water to obtain a sensing electrode; During detection, 2-4 μL of sarcosine oxidase solution with a concentration of 0.1-10 U / μL is added dropwise to the surface of the working electrode, and the enzyme solution is dried at room temperature for 2 hours and then used directly or stored in a 4-8℃ environment for standby.

2. The method of claim 1, wherein the prostate cancer sarcosine sensor electrode is prepared by the steps of: In step (1), the concentration of sodium tungstate in solution A is 50-100 mM, and the concentration of hydrochloric acid solution is 1-4 M; the molar ratio of sodium tungstate to oxalic acid is 2:1, the mixing and stirring time is 30 min; the hydrothermal synthesis reaction temperature is 140-180℃, the hydrothermal synthesis reaction time is 4-12 h, the washing liquid is anhydrous ethanol and deionized water, and the washing procedure is to wash and centrifuge twice with anhydrous ethanol, and then wash and centrifuge twice with deionized water.

3. The method for preparing the prostate cancer sarcosine sensing electrode according to claim 1, characterized in that, In step (2), the concentrations of potassium ferricyanide solution and potassium ferrocyanide solution are both 5-10 mM, the concentration of tungsten oxide powder in the dispersion liquid is 0.01-0.25 g / ml, the dropwise addition rate of potassium ferricyanide solution and potassium ferrocyanide solution is both 0.1-1 ml / min, and the micro-speed reaction temperature is 45℃.

4. The method for preparing the prostate cancer sarcosine sensing electrode according to claim 1, characterized in that, In step (3), the working electrode is a gold electrode, the mass fraction of chitosan in the suspension liquid is 1-5%, the mass concentration of the composite precipitate in the mixed liquid B is 3-15 mg / mL, and the dropwise coating amount is 2-5 μL; the room temperature drying time is 60-120 min.

5. The sensing electrode prepared by the method of any one of claims 1-4.

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