A photoelectric immunosensor based on silicon nanowire array@polydopamine composite structure and a preparation method thereof

Abstract

The application discloses a kind of photoelectric immunosensor and preparation method based on silicon nanowire array @ polydopamine composite structure, comprising: the composite structure is polydopamine and is coated on the surface of silicon nanowire array.This application also discloses the application of the above-mentioned sensor in photoelectric immunodetection myocardial infarction biomarker-troponin.Silicon nanowire array has excellent photoelectric conversion performance;Polydopamine has good biocompatibility, and the surface has abundant amine functional groups, and is easy to modify.The composite structure obtained by combining the two materials.According to the application, the complexity of the photoelectric immunosensor structure is effectively reduced, and the stability and sensitivity of the immunosensor are improved, which is used for detecting cardiac troponin I, has high sensitivity and good specificity.

Description

Technical Field

[0001] This invention relates to the technical field of biosensors, and in particular to a photoelectric immunosensor based on a silicon nanowire array@polydopamine composite structure and its preparation method. Background Technology

[0002] Photoelectroimmunosensing is a novel sensing technology that combines photoelectric conversion with the recognition of biomolecules. In the sensor detection process, a light source acts as the excitation source, exciting photoactive materials, and an electrical signal is output as the detection signal. Using two different signal forms for excitation and detection offers the advantage of low background signal, resulting in higher sensitivity. In photoelectroimmunoassay, steric hindrance has become an important signal amplification strategy. Most biomolecules, such as proteins, have poor conductivity. Therefore, when target molecules (mainly proteins) are modified onto the electrode surface, a steric hindrance effect is generated, hindering electron transfer and transmission, thus affecting the generation of photocurrent. The electrodes of photoelectroimmunosensors generally involve two main parts: photoactive materials and biorecognition probes. Photoactive materials are fundamental to sensor construction, and their photoelectric conversion efficiency directly affects the intensity of the photocurrent, which in turn affects the sensor's detection sensitivity. While loading other materials onto the photoelectrode can further increase the photocurrent, it also makes the electrode structure more complex and reduces stability. In addition, a bio-friendly interface is required for probe antibody immobilization, making the entire photoelectroimmunoelectrode construction process more cumbersome, resulting in poor device stability and reproducibility. Therefore, there is a need for a photoelectroimmunosensor with high photoelectric conversion efficiency, simple electrode structure, and reliable performance. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a photoelectric immunosensor based on a silicon nanowire array@polydopamine composite structure. This effectively reduces the structural complexity of the photoelectric immunosensor while improving the stability and sensitivity of the immunosensing, enabling the detection of cardiac troponin I with high sensitivity and specificity. To achieve the above-mentioned objectives and other advantages of the present invention, a photoelectric immunosensor based on a silicon nanowire array@polydopamine composite structure is provided, comprising:

[0004] A silicon nanowire array electrode, comprising a substrate on which a silicon nanowire array is etched, wherein the substrate is a silicon wafer.

[0005] A silicon nanowire array@PDA electrode, wherein the silicon nanowire array@PDA electrode is formed by in-situ modification of a polydopamine film on the surface of a silicon nanowire array electrode;

[0006] The test electrode is formed by immobilizing antibody molecules on a silicon nanowire array@PDA electrode.

[0007] Preferably, the silicon wafer is of type n-type silicon or p-type silicon.

[0008] A method for fabricating a photoelectric immune sensor based on a silicon nanowire array@polydopamine composite structure includes the following steps:

[0009] S1. Prepare silicon nanowire array electrodes. Cut silicon wafers into appropriate sizes, clean them, and place them face up in a container containing etching solution. Etch at 15-45℃ for 0.5-6 hours. Finally, rinse the etched silicon nanowire array and blow it dry to obtain silicon nanowire array electrodes.

[0010] S2. Place the silicon nanowire array electrode obtained in step S1 into the prepared mixed solution and stir for 0.5–24 h to obtain a polydopamine-coated silicon nanowire array. Take out the silicon nanowire array electrode, rinse it and blow it dry to obtain a silicon nanowire array@PDA electrode.

[0011] S3. Immerse the silicon nanowire array @PDA electrode obtained in step S2 in the antibody solution for 0.5-24 hours. After rinsing the silicon nanowire array @PDA electrode, immerse it in bovine serum albumin solution for 0.5-24 hours. After rinsing the silicon nanowire array @PDA electrode, the test electrode of the photoelectric immunosensor is obtained.

[0012] Preferably, the etching solution in step S1 is of two types. One etching solution is prepared by mixing 0.08 mol / L silver nitrate and 10 mol / L hydrofluoric acid solution at a volume ratio of 1:1. The other etching solution is prepared by mixing 0.6 mol / L hydrogen peroxide and 10 mol / L hydrofluoric acid solution at a volume ratio of 1:1.

[0013] Preferably, in step S1, the crystal plane type is <100> Silicon nanowire arrays are etched on the surface of an n-type silicon wafer. The cleaned silicon wafer with the polished side facing up is placed in a container containing an etching solution. After etching for 1 minute, the silicon wafer is removed and placed in a container containing another etching solution. After etching for 1 hour, the etched silicon wafer is rinsed clean and dried with nitrogen to obtain a silicon nanowire array electrode.

[0014] In step S2, a polydopamine film is grown on the silicon nanowire array electrode. The silicon nanowire array electrode obtained in step S1 is immersed in the dopamine solution for 0.5-24 hours. The silicon nanowire array electrode is then taken out, rinsed, and dried to obtain the silicon nanowire array@PDA electrode.

[0015] In step S3, antibody molecules are immobilized on the silicon nanowire array @PDA electrode. The silicon nanowire array @PDA electrode prepared in step S2 is immersed in the antibody solution for 0.5-24 hours. The silicon nanowire array @PDA electrode is then removed and rinsed. It is then immersed in bovine serum albumin solution for 30 minutes. After rinsing, the test electrode of the photoelectric immunosensor is obtained.

[0016] Preferably, the rinsing in steps S1 and S2 is rinsing with deionized water. The cleaning in step S1 is ultrasonic treatment in acetone, anhydrous ethanol, deionized water, piranha solution, and water in sequence. The ultrasonic treatment is ultrasonic cleaning three times each in acetone, anhydrous ethanol, and deionized water cleaning solution, 10 minutes each time, and ultrasonic cleaning once in piranha solution cleaning solution for 30 minutes.

[0017] Preferably, the concentration of the dopamine solution in step S2 is 1-5 mg / mL, and the preparation method is to dissolve dopamine in a tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution with pH=8.5.

[0018] Preferably, the rinsing in S3 involves rinsing with TBS washing solution and PBS buffer sequentially; the TBS washing solution is prepared by dissolving 6g of tris(hydroxymethyl)aminomethane hydrochloride, 8g of sodium chloride, and 0.2g of potassium chloride in 1L of water, adjusting the pH to 8, and then adding 500μL of Tween 20.

[0019] Preferably, the concentration of the bovine serum albumin solution is 1 mg / mL, and it is prepared by dissolving bovine serum albumin in 0.01 M PBS buffer.

[0020] Compared with existing technologies, the advantages of this invention are as follows: It utilizes polydopamine and silicon nanowire arrays to construct a photoelectric immunosensor. Silicon nanowire arrays are excellent semiconductor materials; compared to traditional oxide semiconductors, they exhibit broad absorption in the visible and near-infrared light range. The large aspect ratio of silicon nanowires promotes charge separation. Therefore, using silicon nanowire arrays as the electrode substrate material increases the sensor's photocurrent response from the source without requiring additional modification to enhance photocurrent, thus reducing the complexity of the electrode structure. Furthermore, while polydopamine and silicon nanowire arrays achieve energy level matching and enhance photocurrent response, the abundant amino functional groups on polydopamine's surface can react with carboxyl groups in proteins to form stable covalent bonds, effectively immobilizing biological probe molecules and ensuring the stability of the photoelectric immunosensor, resulting in high sensitivity. When the photoelectric immunosensor constructed using polydopamine-modified silicon nanowire arrays was used for the detection of cTnI in mice, its detection limit was 2 pg / mL, exhibiting a linear distribution within the concentration range of 5 pg / mL-10 ng / mL, demonstrating excellent specificity and stability. The photoelectric immunosensor constructed from polydopamine-modified silicon nanowire array material in this invention is suitable for the detection of all proteins and can also be used for the detection of other biomolecules such as DNA and cells. Attached Figure Description

[0021] Figure 1 The images show scanning electron microscope (SEM) images of the photoelectric immunosensor based on the silicon nanowire array@polydopamine composite structure and preparation method according to the present invention, and transmission electron microscope (TEM) images of the polydopamine-silicon nanowire array on the SiNWs@PDA electrode.

[0022] Figure 2 The image shows the X-ray diffraction pattern of the silicon nanowire array on the SiNWs electrode in Example 1 of the photoelectric immune sensor based on the silicon nanowire array@polydopamine composite structure and preparation method according to the present invention.

[0023] Figure 3 Raman plots of the SiNWs electrode and SiNWs@PDA electrode in Example 1 of the photoelectric immune sensor based on the silicon nanowire array@polydopamine composite structure and preparation method according to the present invention.

[0024] Figure 4 The transient current curves of the SiNWs@PDA electrode after each step of surface modification in Example 2 of the photoelectric immune sensor based on silicon nanowire array@polydopamine composite structure and preparation method according to the present invention.

[0025] Figure 5The photocurrent response diagrams of the photoelectric immunosensor (BSA / mouse anti-cTnI / SiNWs@PDA electrode) after reacting with different concentrations of mouse cardiac troponin I in Example 3 of the photoelectric immunosensor based on silicon nanowire array@polydopamine composite structure and preparation method according to the present invention are shown.

[0026] Figure 6 This is a diagram illustrating the specificity of the photoelectric immunosensor based on the silicon nanowire array@polydopamine composite structure and its preparation method according to Example 4 of the present invention for different protein antigens at a concentration of 10 ng / mL. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Reference Figure 1-6 A photoelectric immune sensor based on a silicon nanowire array@polydopamine composite structure includes: a silicon nanowire array electrode, wherein the silicon nanowire array electrode includes a substrate, and the silicon nanowire array is etched on the substrate, wherein the substrate is a silicon wafer;

[0029] A silicon nanowire array@PDA electrode, wherein the silicon nanowire array@PDA electrode is formed by in-situ modification of a polydopamine film on the surface of a silicon nanowire array electrode;

[0030] The test electrode is formed by immobilizing antibody molecules on a silicon nanowire array@PDA electrode.

[0031] Furthermore, the silicon wafer is of type n-type silicon or p-type silicon.

[0032] A method for fabricating a photoelectric immune sensor based on a silicon nanowire array@polydopamine composite structure includes the following steps:

[0033] S1. Prepare silicon nanowire array electrodes. Cut silicon wafers into appropriate sizes, clean them, and place them face up in a container containing etching solution. Etch at 15-45℃ for 0.5-6 hours. Finally, rinse the etched silicon nanowire array and blow it dry to obtain silicon nanowire array electrodes.

[0034] S2. Place the silicon nanowire array electrode obtained in step S1 into the prepared mixed solution and stir for 0.5–24 h to obtain a polydopamine-coated silicon nanowire array. Take out the silicon nanowire array electrode, rinse it and blow it dry to obtain a silicon nanowire array@PDA electrode.

[0035] S3. Immerse the silicon nanowire array @PDA electrode obtained in step S2 in the antibody solution for 0.5-24 hours. After rinsing the silicon nanowire array @PDA electrode, immerse it in bovine serum albumin solution for 0.5-24 hours. After rinsing the silicon nanowire array @PDA electrode, the test electrode of the photoelectric immunosensor is obtained.

[0036] Furthermore, the etching solution in step S1 is divided into two types. One etching solution is prepared by mixing 0.08 mol / L silver nitrate and 10 mol / L hydrofluoric acid solution at a volume ratio of 1:1. The other etching solution is prepared by mixing 0.6 mol / L hydrogen peroxide and 10 mol / L hydrofluoric acid solution at a volume ratio of 1:1.

[0037] Furthermore, in step S1, the crystal plane type is... <100> Silicon nanowire arrays are etched on the surface of an n-type silicon wafer. The cleaned silicon wafer with the polished side facing up is placed in a container containing an etching solution. After etching for 1 minute, the silicon wafer is removed and placed in a container containing another etching solution. After etching for 1 hour, the etched silicon wafer is rinsed clean and dried with nitrogen to obtain a silicon nanowire array electrode.

[0038] In step S2, a polydopamine film is grown on the silicon nanowire array electrode. The silicon nanowire array electrode obtained in step S1 is immersed in the dopamine solution for 0.5-24 hours. The silicon nanowire array electrode is then taken out, rinsed, and dried to obtain the silicon nanowire array@PDA electrode.

[0039] In step S3, antibody molecules are immobilized on the silicon nanowire array @PDA electrode. The silicon nanowire array @PDA electrode prepared in step S2 is immersed in the antibody solution for 0.5-24 hours. The silicon nanowire array @PDA electrode is then removed and rinsed. It is then immersed in bovine serum albumin solution for 30 minutes. After rinsing, the test electrode of the photoelectric immunosensor is obtained.

[0040] Furthermore, the rinsing in steps S1 and S2 is rinsing with deionized water. The cleaning in step S1 is to sequentially pass through acetone, anhydrous ethanol, deionized water, piranha solution, and water for ultrasonic treatment. The ultrasonic treatment is to ultrasonically clean three times each in acetone, anhydrous ethanol, and deionized water cleaning solutions, each time for 10 minutes, and ultrasonically clean once in the piranha solution cleaning solution for 30 minutes.

[0041] Furthermore, in step S2, the concentration of the dopamine solution is 1-5 mg / mL, and the preparation method is to dissolve dopamine in a tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution with pH=8.5.

[0042] Furthermore, the rinsing in S3 involves rinsing with TBS washing solution and PBS buffer in sequence; the TBS washing solution is prepared by dissolving 6g of tris(hydroxymethyl)aminomethane hydrochloride, 8g of sodium chloride, and 0.2g of potassium chloride in 1L of water, adjusting the pH to 8, and then adding 500μL of Tween 20.

[0043] Furthermore, the concentration of the bovine serum albumin solution is 1 mg / mL, and it is prepared by dissolving bovine serum albumin in 0.01 M PBS buffer.

[0044] Example 1

[0045] The specific steps for constructing a photoelectric immune sensor using a polydopamine-modified silicon nanowire array are as follows:

[0046] (1) In crystal plane type <100> Etching silicon nanowire arrays on the surface of an n-type silicon wafer: First, the silicon wafer is sequentially ultrasonically treated with acetone, anhydrous ethanol, deionized water, piranha solution, and water. The ultrasonic treatment involves ultrasonic cleaning three times each in acetone, anhydrous ethanol, and deionized water cleaning solutions, 10 minutes each time, and ultrasonic cleaning once in piranha solution cleaning solution for 30 minutes. Then, the cleaned silicon wafer is placed with the polished side facing up in a container containing etching solution No. 1 for 1 minute. Then, the silicon wafer is removed and placed in a container containing etching solution No. 2 for 1 hour. Finally, the etched silicon wafer is rinsed clean and dried with nitrogen gas to obtain SiNWs electrodes. The etching solution No. 1 is prepared by mixing 0.08 mol / L silver nitrate and 10 mol / L hydrofluoric acid solution in a volume ratio of 1:1. The etching solution No. 2 is prepared by mixing 0.6 mol / L hydrogen peroxide and 10 mol / L hydrofluoric acid solution in a volume ratio of 1:1.

[0047] (2) Growth of polydopamine shell on SiNWs electrode: The SiNWs electrode obtained in step (1) is immersed in dopamine solution for 12 hours, the SiNWs electrode is taken out, rinsed and dried to obtain SiNWs@PDA electrode; the concentration of dopamine solution is 1 mg / mL, and the preparation method is to dissolve dopamine in tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution at pH=8.5.

[0048] (3) Immobilizing mouse cTnI monoclonal antibody on SiNWs@PDA electrode: Immerse the SiNWs@PDA electrode obtained in step (2) in antibody solution for 1 h, take out the SiNWs@PDA electrode and wash it with TBS washing solution and PBS buffer to obtain mouse cTnI monoclonal antibody / SiNWs@PDA electrode; then immerse the mouse cTnI monoclonal antibody SiNWs@PDA electrode in bovine serum albumin solution for 30 min, take out the mouse cTnI monoclonal antibody / SiNWs@PDA electrode and wash it with TBS washing solution and PBS buffer to obtain photoelectric immunosensor (BSA / mouse cTnI monoclonal antibody / SiNWs@PDA electrode). The concentration of the bovine serum albumin solution is 1 mg / mL, and it is prepared by dissolving bovine serum albumin in 0.01 M PBS buffer. The TBS washing solution is prepared by dissolving 6 g of tris(hydroxymethyl)aminomethane hydrochloride, 8 g of sodium chloride, and 0.2 g of potassium chloride in 1 L of deionized water, adjusting the pH to 8, and then adding 500 μL of Tween 20.

[0049] Figure 1 In Figures a and b, we see scanning electron microscope (SEM) images of silicon nanowire arrays on SiNWs electrodes. As can be seen from the images, the silicon nanowire arrays are well grown, with uniform nanowire diameter distribution, uniform orientation, and uniform density.

[0050] Figure 2 The image shows the X-ray diffraction pattern of the silicon nanowire array on the SiNWs electrode. As can be seen from the image, the original silicon crystal structure is not destroyed in the silicon nanowire array.

[0051] Figure 3 The figures show the Raman spectroscopy of the SiNWs electrode and the SiNWs@PDA electrode. As can be seen from the figures, the Raman spectroscopy of the SiNWs array after PDA modification shows the characteristic peak of PDA.

[0052] Figure 1 c and d are scanning electron microscope (SEM) and transmission electron microscope (TEM) images of the polydopamine-silicon nanowire array on the SiNWs@PDA electrode, respectively. As can be seen from the figures, the short-term polydopamine growth process does not cause corrosion to the silicon nanowire array, and polydopamine can form a continuous and uniformly thick thin film on the surface of the silicon nanowires.

[0053] Example 2

[0054] 1. Using the SiNWs@PDA electrode prepared in Example 1 as the working electrode, a platinum sheet and a silver chloride electrode as the counter electrode and reference electrode, respectively, 0.1M PBS as the electrolyte, an applied voltage of 1V, and a xenon lamp (150W power, 100mW / cm2 power density) as the light source, the transient current curve was recorded. The results are as follows: Figure 4 (a);

[0055] 2. Using the mouse cTnI monoclonal antibody / SiNWs@PDA electrode prepared in Example 1 as the working electrode, a platinum sheet and a silver chloride electrode as the counter and reference electrodes, respectively, 0.1M PBS as the electrolyte, an applied voltage of 1V, and a xenon lamp (150W power, 100mW / cm2) as the light source, transient current curves were recorded. The results are as follows: Figure 4 (b);

[0056] 3. Using the BSA / mouse cTnI monoclonal antibody / SiNWs@PDA electrode prepared in Example 1 as the working electrode, a platinum sheet and a silver chloride electrode as the counter electrode and reference electrode, respectively, 0.1M PBS as the electrolyte, an applied voltage of 1V, and a xenon lamp (150W power, 100mW / cm2) as the light source, the transient current curve was recorded. The results are as follows: Figure 4 (c);

[0057] 4. The BSA / mouse cTnI monoclonal antibody / SiNWs@PDA electrode prepared in Example 1 was immersed in mouse cTnI solution for 1 hour. The electrode was then removed and washed sequentially with TBS washing solution and PBS buffer to obtain the mouse cTnI / BSA / mouse cTnI monoclonal antibody / SiNWs@PDA electrode. This electrode was used as the working electrode, with a platinum sheet and a silver chloride electrode as the counter and reference electrodes, respectively. 0.1M PBS was used as the electrolyte, with an applied voltage of 1V, and a xenon lamp (150W power, 100mW / cm²) as the light source. The transient current curve was recorded, and the results are as follows: Figure 4 (d);

[0058] Depend on Figure 4 As shown in (a), (b), (c), and (d), the photocurrent of the electrode gradually decreases after the protein is gradually connected, indicating that the SiNWs@PDA electrode itself can connect to the protein, and the specific binding of the protein will affect the generation of the photocurrent, indicating that it can be used as a photoelectric immunosensor to detect proteins.

[0059] Example 3

[0060] The BSA / mouse cTnI monoclonal antibody / SiNWs@PDA electrode prepared in Example 1 was used as the working electrode, the platinum sheet and silver chloride electrode were the counter electrode and reference electrode, respectively, 0.1M PBS was used as the electrolyte, the applied voltage was 1V, and the xenon lamp (power of 150W, power density of 100mW / cm2) was used as the light source to record the transient current I0.

[0061] The BSA / mouse cTnI monoclonal antibody / SiNWs@PDA electrode prepared in Example 1 was then immersed in mouse cTnI solutions with concentrations of 0 ng / mL, 0.005 ng / mL, 0.05 ng / mL, 0.5 ng / mL, 1 ng / mL, 5 ng / mL, and 10 ng / mL, respectively. After reacting for 1 hour, the electrode was washed with TBS wash buffer and PBS buffer, and the transient current I was recorded again. The ratio of the decrease in photocurrent in the two transient current curves, i.e., (I0-I) / I0, was compared and analyzed. The results are as follows: Figure 5 As shown, by Figure 5 It can be seen that the lowest detection limit of this photoelectric immunosensor for mouse cTnI is 2 pg / mL, and it exhibits a linear distribution in the antibody concentration range of 0.005 ng / mL to 10 ng / mL.

[0062] Example 4

[0063] The BSA / mouse cTnI monoclonal antibody / SiNWs@PDA electrode prepared in Example 1 was used as the working electrode, the platinum sheet and silver chloride electrode were the counter electrode and reference electrode, respectively, 0.1M PBS was used as the electrolyte, the applied voltage was 1V, and the xenon lamp (power of 150W, power density of 100mW / cm2) was used as the light source to record the transient current I0.

[0064] The BSA / mouse cTnI monoclonal antibody / SiNWs@PDA electrode prepared in Example 1 was then immersed in PBS buffer, procalcitonin (10 ng / mL), bovine serum albumin (10 ng / mL), N-terminal pro-brain natriuretic peptide (10 ng / mL), and cardiac troponin I (10 ng / mL) solutions, respectively. After reacting for 1 hour, the electrode was washed with TBS wash buffer and PBS buffer, and the transient current I was recorded again. The ratio of the decrease in photocurrent in the two transient current curves, i.e., (I0-I) / I0, was compared and analyzed. The results are as follows: Figure 6 As shown, by Figure 6 It can be seen that the photoelectric immunosensor has high sensitivity to troponin I and good specificity and stability to interfering proteins.

[0065] The photoelectric immunosensor of this invention can be used not only for the detection of troponin I, but also for the detection of other proteins and biomolecules such as DNA and cells.

[0066] The number of devices and processing scale described herein are for the purpose of simplifying the description of the invention, and applications, modifications and variations thereof will be apparent to those skilled in the art.

[0067] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A photoelectric immunosensor based on a silicon nanowire array@polydopamine composite structure, characterized in that, include: A silicon nanowire array electrode, comprising a substrate on which a silicon nanowire array is etched, wherein the substrate is a silicon wafer. A silicon nanowire array@PDA electrode, wherein the silicon nanowire array@PDA electrode is formed by in-situ modification of a polydopamine film on the surface of a silicon nanowire array electrode; The test electrode is an antibody immobilized on a silicon nanowire array@PDA electrode, wherein the antibody is formed from cardiac troponin I antibody molecules. The silicon nanowire array was prepared by a stepwise etching method: first, it was etched for 1 minute with an etching solution containing a mixture of 0.08 mol / L silver nitrate and 10 mol / L hydrofluoric acid in a volume ratio of 1:1, and then etched for 1 hour with an etching solution containing a mixture of 0.6 mol / L hydrogen peroxide and 10 mol / L hydrofluoric acid in a volume ratio of 1:

1. The sensor has a detection limit of 2 pg / mL for cardiac troponin I and exhibits a linear distribution within the antibody concentration range of 5 pg / mL to 10 ng / mL.

2. The photoelectric immunosensor as described in claim 1, characterized in that, The silicon wafer is of type n-type silicon or p-type silicon.

3. A method for preparing a photoelectric immune sensor as described in any one of claims 1-2, characterized in that, Includes the following steps: S1. Preparation of silicon nanowire array electrodes: Cut silicon wafers to appropriate sizes, clean them, and place them face up. First, place them in a container containing an etching solution of 0.08 mol / L silver nitrate and 10 mol / L hydrofluoric acid mixed in a 1:1 volume ratio, and etch for 1 minute. After removing them, place them in a container containing an etching solution of 0.6 mol / L hydrogen peroxide and 10 mol / L hydrofluoric acid mixed in a 1:1 volume ratio, and etch for 1 hour. The etching is carried out at a temperature of 15-45 ℃, and the total etching time is 0.5-6 h. Finally, rinse the etched silicon nanowire array clean and blow it dry to obtain the silicon nanowire array electrode. S2. Preparation of silicon nanowire array @PDA electrode: Place the silicon nanowire array electrode obtained in step S1 into a dopamine solution and stir for 0.5-24 h. Take it out, rinse and dry it to obtain the silicon nanowire array @PDA electrode. S3. Preparation of test electrode: Immerse the silicon nanowire array@PDA electrode obtained in step S2 in cardiac troponin I antibody solution for 0.5-24 h, take it out and rinse it, then immerse it in bovine serum albumin solution for 30 min, take it out and rinse it to obtain the test electrode.

4. The method for fabricating a photoelectric immunosensor based on a silicon nanowire array@polydopamine composite structure as described in claim 3, characterized in that, In step S1, the silicon wafer is of the crystal plane type. <100> n-type silicon wafers.

5. The method for fabricating a photoelectric immune sensor based on a silicon nanowire array@polydopamine composite structure as described in claim 3, characterized in that, The rinsing in steps S1 and S2 is rinsing with deionized water. The cleaning in step S1 is ultrasonic treatment in acetone, anhydrous ethanol, deionized water, piranha solution and water in sequence. The ultrasonic treatment is ultrasonic cleaning three times each in acetone, anhydrous ethanol and deionized water cleaning solution, 10 minutes each time, and ultrasonic cleaning once in piranha solution cleaning solution for 30 minutes.

6. The method for fabricating a photoelectric immunosensor based on a silicon nanowire array@polydopamine composite structure as described in claim 3, characterized in that, In step S2, the concentration of the dopamine solution is 1-5 mg / mL, and the preparation method is to dissolve dopamine in a tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution with pH=8.

5.

7. The method for fabricating a photoelectric immunosensor based on a silicon nanowire array@polydopamine composite structure as described in claim 3, characterized in that, The rinsing in S3 involves sequential rinsing with TBS washing solution and PBS buffer. The TBS washing solution is prepared by dissolving 6 g of tris(hydroxymethyl)aminomethane hydrochloride, 8 g of sodium chloride, and 0.2 g of potassium chloride in 1 L of water, adjusting the pH to 8, and then adding 500 μL of Tween 20.

8. The method for fabricating a photoelectric immunosensor based on a silicon nanowire array@polydopamine composite structure as described in claim 3, characterized in that, The concentration of the bovine serum albumin solution is 1 mg / mL, and it is prepared by dissolving bovine serum albumin in 0.01 M PBS buffer.

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