Silicon nanowire field effect transistor biosensor and preparation method and application thereof

Abstract

The invention provides a silicon nanowire field effect transistor biosensor and a preparation method and application thereof. The preparation method of the silicon nanowire field effect transistor biosensor comprises the following steps: S1, preparing a silicon nanowire field effect transistor sensor; s2, a PBS solution containing an A beta 1-42 nucleic acid aptamer is prepared, and the base sequence of the A beta 1-42 nucleic acid aptamer is 5 '-NH2-(CH2) 4-UAGCG UAUG < C > CACCUCU < CCUGG > ACCCCCG < C > CGGAUGGCCA-CAUCC-3'; s3, performing surface functionalization treatment on the silicon nanowire of the silicon nanowire field effect transistor sensor; and S4, putting the silicon nanowire of the silicon nanowire field effect transistor sensor into an absolute ethyl alcohol solution containing 3-aminopropyltriethoxysilane for condensation reaction, cleaning with absolute ethyl alcohol after the condensation reaction is completed, heating, finally dropwise adding the PBS solution containing the A beta 1-42 nucleic acid aptamer, standing for 2-4 hours, and storing at 4 DEG C for later use. According to the invention, the surface of the silicon nanowire is modified with the Abeta1-42 nucleic acid aptamer, so that rapid, accurate and high-sensitivity detection of the characteristic biomarker Abeta1-42 can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of biosensors, and in particular to a silicon nanowire field-effect transistor biosensor and a preparation method and application thereof. Background Art

[0002] Alzheimer's disease is the most common neurodegenerative disease.

[0003] Although early diagnosis and treatment of Alzheimer's disease are crucial, current treatment options are still in their infancy, lacking effective medications or therapeutic strategies to prevent and slow disease progression. Most Alzheimer's patients are diagnosed in the middle or late stages of the disease, missing the optimal time for early intervention and exacerbating the burden of the disease.

[0004] Given that there are currently no effective drugs that can prevent or significantly delay the progression of Alzheimer's disease, early diagnosis and intervention are particularly important. Biomarkers, as a key tool, can reveal the stage-specific abnormal biological and pathological processes of Alzheimer's disease. According to the amyloid-beta (Aβ) toxicity hypothesis, the physiological and pathological mechanisms of Alzheimer's disease are closely related to Aβ. The formation of Aβ is the product of the cleavage of Aβ precursor protein by β-secretase and γ-secretase. Different cleavage positions of γ-secretase can produce Aβ with different numbers of amino acids, among which Aβ 1-42 Considered to be a hallmark biomarker of Alzheimer's disease. Early identification of Aβ 1-42 The deposition of leukemia cells is crucial for the early detection and intervention of Alzheimer's disease.

[0005] Currently, there are many methods for Aβ 1-42 There are many methods for detecting Aβ, such as positron emission tomography (PET) and cerebrospinal fluid testing. However, these methods are generally expensive, complex to operate, and rely on specialized equipment, making them difficult to be widely promoted in primary care. In addition, although traditional immunoassays (such as enzyme-linked immunosorbent assay, immunofluorescence chromatography, immunoprecipitation mass spectrometry, and colloidal gold method) can effectively detect Aβ, 1-42 However, these methods generally have problems such as low sensitivity, high cost, and cumbersome operation. In many cases, patients have already experienced irreversible cognitive decline by the time the disease is detected, which seriously affects the effectiveness of intervention for Alzheimer's disease.

[0006] In order to overcome these problems, in recent years, biosensor technology based on nucleic acid aptamers has provided a new solution for the detection of Alzheimer's disease markers. As single-stranded oligonucleotide molecules with high specificity and affinity, nucleic acid aptamers can specifically bind to target molecules. Combining nucleic acid aptamers with semiconductor sensor technology can achieve real-time, label-free, and highly sensitive monitoring of Alzheimer's disease biomarkers. This method can sensitively detect target molecules at lower concentrations, breaking through the limitations of traditional detection methods and having significant advantages in sensitivity and cost. However, this type of sensor is susceptible to nonspecific adsorption on the device surface and the Debye screening effect during actual detection, which limits the accuracy and sensitivity of detection. The device structure and modification methods need to be optimized to overcome this. Summary of the Invention

[0007] In view of the shortcomings of the existing technology, the present invention provides a silicon nanowire field effect transistor biosensor and its preparation method and application, which binds to Aβ through specific nucleic acid aptamers. 1-42 The specific binding of the silicon nanowire field effect transistor enables the biosensor to achieve high-sensitivity detection through the electrical signal changes of the silicon nanowire field effect transistor, solving the problems raised in the above background technology.

[0008] To achieve the above objectives, the present invention is implemented through the following technical solutions: According to a first aspect of the present invention, a method for preparing a silicon nanowire field-effect transistor biosensor is provided, comprising the following steps: S1, preparation of silicon nanowire field effect transistor sensor; S2, configuration containing Aβ 1-42 PBS solution of nucleic acid aptamers, wherein the Aβ 1-42 The base sequence of the nucleic acid aptamer is: 5'-NH2-(CH2)4-UAGCGUAUGCCACUCUCCUGGGACCCCCCGCCGGAUGGCCA-CAUCC-3'; S3, performing surface functionalization treatment on the silicon nanowire of the silicon nanowire field effect transistor sensor; S4, placing the silicon nanowires of the silicon nanowire field effect transistor sensor in an anhydrous ethanol solution containing 3-aminopropyltriethoxysilane for condensation reaction, washing with anhydrous ethanol after the condensation reaction is completed, heating, and finally adding the 1-42 The PBS solution of nucleic acid aptamers was allowed to stand for 2-4 hours and then stored at 4°C for later use.

[0009] Preferably, in step S1, the silicon nanowire field effect transistor sensor is prepared as follows: S1-1, using photolithography technology to define a rectangular photoresist pattern on the surface of the SiO2 layer of the SiO2 / n-type heavily doped silicon substrate; S1-2, using inductively coupled plasma etching technology, alternately using C4F8 and O2 plasma to etch the SiO2 layer to obtain a multi-step guide step structure, and then ultrasonically treating in acetone, ethanol and deionized water in sequence to remove the photoresist on the surface; S1-3, depositing metal indium strips on the surface of the multi-level guide step structure by electron beam evaporation, then performing annealing to reduce the indium oxide strips and condense them into catalytic indium droplets, then introducing SiH4 gas to deposit an amorphous silicon film on the surface of the guide step structure, finally activating the indium droplets to absorb the pre-coated amorphous silicon film, and etching to obtain crystalline silicon nanowires; S1-4. Use a photolithography process to transfer the electrode patterns of the source and drain to a SiO2 / n-type heavily doped silicon substrate, then use a buffered oxide etchant to remove the surface oxide layer of the crystalline silicon nanowires, and then successively evaporate platinum and aluminum on the surface of the SiO2 / n-type heavily doped silicon substrate, prepare the source and drain by a stripping process, and finally use a conductive silver paste to lead out the back gate electrode to obtain the silicon nanowire field effect transistor sensor.

[0010] Preferably, in step S1-3, the annealing method is: using plasma enhanced chemical vapor deposition equipment to perform H2 plasma annealing at 250-270° C. to reduce the indium oxide strips and condense them into catalytic indium droplets; The preparation temperature of the amorphous silicon layer is 100-120°C.

[0011] Preferably, the step of activating the indium droplets to absorb the pre-coated amorphous silicon layer is: raising the temperature to 340-360° C. and maintaining it for 1-2 hours under vacuum or hydrogen atmosphere; The etching step is: removing the remaining amorphous silicon layer by low-temperature H2 plasma.

[0012] Preferably, in step S2, the 1-42 Aptamer Aβ in phosphate buffered saline 1-42 The concentration of the aptamer was 100 nM.

[0013] Preferably, in step S3, the surface functionalization treatment adopts ozone treatment or O2 plasma treatment, and the time of the surface functionalization treatment is 90-110s.

[0014] Preferably, the ozone treatment time is 2 minutes; The parameters of the O2 plasma treatment are: substrate temperature is room temperature, RF power is 20~100W, reactive coupled plasma power is 200~500W, chamber pressure is 0.5~3Pa, O2 flow rate is 20~200sccm, and treatment time is 1~20min.

[0015] Preferably, in step S4, the volume fraction of 3-aminopropyltriethoxysilane in the anhydrous ethanol solution containing 3-aminopropyltriethoxysilane is 2-4%; The condensation reaction temperature is 20-30°C and the time is 30-60 minutes; The heating temperature is 110-130° C. and the heating time is 10-20 minutes.

[0016] According to a second aspect of the present invention, a silicon nanowire field-effect transistor biosensor obtained according to the above preparation method is provided.

[0017] According to a third aspect of the present invention, there is provided an application of a silicon nanowire field-effect transistor biosensor in detecting amyloid protein, a biomarker of Alzheimer's disease.

[0018] The present invention provides a silicon nanowire field-effect transistor biosensor and its preparation method and application. It has the following beneficial effects: (1) This scheme provides a silicon nanowire field-effect transistor biosensor, which modifies Aβ on the surface of the silicon nanowire. 1-42 Aptamers can bind to Aβ 1-42 This characteristic biomarker enables rapid, accurate and highly sensitive detection.

[0019] (2) This proposal provides a method for preparing a silicon nanowire field-effect transistor biosensor, which uses plasma-enhanced chemical vapor deposition to prepare an in-plane nanowire structure with excellent performance and a high specific surface area. In addition, nucleic acid aptamers are modified on its surface, thereby making biomarker detection more sensitive. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the preparation process of the silicon nanowire field effect transistor sensor of the present invention; Figure 2 Schematic diagram of the process of fixing nucleic acid aptamers to the surface of silicon nanowire field-effect transistor sensors according to the present invention; Figure 3 The XPS full spectrum and N 1s high-resolution spectrum of the silicon nanowires of the present invention at different processing steps; Figure 4 The water contact angle changes of the silicon nanowires modified with APTES after different treatments of the present invention; Figure 5 Surface morphology of the silicon nanowire field effect transistor sensor of the present invention, (a) is an optical microscope image, and (b) is a scanning electron microscope image; Figure 6 : This is the output characteristic curve of the silicon nanowire field effect transistor sensor before and after the immobilization of the nucleic acid aptamer of the present invention; Figure 7 This is the transfer characteristic curve of the silicon nanowire field effect transistor sensor before the nucleic acid aptamer is fixed. DETAILED DESCRIPTION

[0021] In order to better illustrate the content of the present invention, a detailed description is given below in conjunction with specific embodiments.

[0022] Example 1 The preparation process of a silicon nanowire field-effect transistor biosensor is as follows: Step 1: Preparation of silicon nanowire field effect transistor sensor, such as Figure 1 As shown: (a) Using photolithography technology to define a rectangular photoresist pattern on the SiO2 surface of a SiO2 / n-type heavily doped silicon substrate; (b) Using an inductively coupled plasma etching device, C4F8 and O2 plasma are alternately used to etch the SiO2 layer multiple times to form a multi-step guide step structure; (c) Then ultrasonically treating in acetone, ethanol, and deionized water in sequence to remove the surface photoresist; (d) Electron beam evaporation is used to deposit metal indium strips of a certain width on the surface of the multi-level guide steps; (e) Using plasma-enhanced chemical vapor deposition equipment, H2 plasma annealing was performed at 250°C to reduce the indium oxide strips and condense them into catalytic indium droplets with uniform diameters; (f) At a reaction temperature of 100°C, SiH4 gas is introduced to deposit an amorphous silicon film on the surface of the guide step; (g) The temperature is then raised to 350°C and maintained in a vacuum or hydrogen atmosphere for 1 hour to activate the indium droplets, causing them to move along the sidewalls, absorbing the coated amorphous silicon film and growing uniform crystalline silicon nanowires along the step sidewalls. After the silicon nanowire growth is completed, the remaining amorphous silicon layer is selectively removed by a low-temperature H2 plasma etching process to obtain high-quality and uniform crystalline silicon nanowires. (h) The electrode patterns of the source and drain are transferred to a SiO2 / n-type heavily doped silicon substrate using a photolithography process. The surface oxide of the crystalline silicon nanowires is then removed using a buffered oxide etchant. Platinum and aluminum are then sequentially evaporated on the surface of the SiO2 / n-type heavily doped silicon substrate. The source and drain are prepared using a lift-off process. Finally, a conductive silver paste is used to lead out the back gate electrode to obtain a silicon nanowire field-effect transistor sensor.

[0023] Step 2: Immobilization of nucleic acid aptamers on silicon nanowire field effect transistor sensors, such as Figure 2 As shown: (a) The surface of the silicon nanowire of the silicon nanowire field-effect transistor sensor was photonized by ozone treatment for 100 s, with the ozone treatment time being 2 min. (b) The silicon nanowires of the silicon nanowire field-effect transistor sensor were placed in an anhydrous ethanol solution containing 2% volume fraction of 3-aminopropyltriethoxysilane and allowed to stand at room temperature for 30 minutes to promote the condensation reaction to form amide bonds. The silicon nanowire field-effect transistor sensor was then rinsed with anhydrous ethanol solution to remove uncoupled APTES and heated at 120°C for 10 minutes to enhance the coupling strength. (c) Aβ at a concentration of 100 nM was added to the silicon nanowires of the silicon nanowire field-effect transistor sensor at room temperature. 1-42 After the nucleic acid aptamer PBS solution was allowed to stand for 2 hours, it was placed in a refrigerator at 4°C for storage. 1-42 The base sequence of the nucleic acid aptamer is: 5'-NH2-(CH2)4-UAGCGUAUGCCACUCUCCUGGGACCCCCCGCCGGAUGGCCA-CAUCC-3'.

[0024] The surface morphology of the silicon nanowire field effect transistor biosensor prepared in this example is shown in FIG. Figure 5 shown.

[0025] Example 2 The preparation method of this embodiment is the same as that of the embodiment, except that, during the process of fixing the nucleic acid aptamer on the silicon nanowire field effect transistor sensor, step (a) uses an inductively coupled plasma etching device to use O2 plasma to surface treat the silicon nanowire for 100s.

[0026] Performance Testing (1) X-ray electron spectroscopy was used to characterize the APTES-modified and aptamer-fixed silicon nanowires by XPS analysis to verify whether the aptamer was successfully fixed on the surface of the silicon nanowires and the changes in the elemental composition before and after fixation. The results were compared with those of the untreated silicon nanowires. Figure 3 shown.

[0027] in, Figure 3 Figure (a) shows the full XPS spectrum of Example 1 after ozone treatment. The red curve in the figure represents the full spectrum of silicon nanowires after any treatment, mainly containing Si 2p and C 1s peaks; the blue curve is the full spectrum of silicon nanowires modified with APTES after ozone treatment, with N 1s and O 1s peaks appearing, indicating that the surface of the silicon nanowires has been successfully amino-modified; the green curve is the full spectrum after further immobilization of nucleic acid aptamers; Figure 3 Figure (b) shows the full XPS spectrum of Example 2 after O2 plasma treatment. The red curve represents the full spectrum of silicon nanowires without any treatment, which mainly contains Si 2p and C 1s peaks; the blue curve is the full spectrum of silicon nanowires modified with APTES after O2 plasma treatment, with N 1s and O 1s peaks appearing, indicating successful amino modification; the green curve shows the full spectrum after further immobilization of nucleic acid aptamers; Figure 3 Comparison of Figures (a) and (b) shows that ozone treatment and O2 plasma treatment can replace each other, and both methods can effectively achieve APTES modification and nucleic acid aptamer immobilization.

[0028] Figure 3 Figure (c) shows the high-resolution N 1s spectrum of untreated silicon nanowires. The N 1s signal is close to the background noise, indicating that no significant nitrogen element is detected on the surface of the original silicon nanowires. Figure 3 Figure (d) shows the high-resolution N 1s spectrum of silicon nanowires modified with APTES after ozone treatment. After APTES modification, the N 1s peak is significantly enhanced, and multiple chemical states of N 1s peaks appear, such as C–NH2 (400.51 eV), C–NH–C (401.59 eV) and NSi x O (399.41 eV) proves that APTES modification is successful; Figure 3 Figure e is the high-resolution N 1s spectrum of silicon nanowires after immobilization of nucleic acid aptamers after ozone treatment, in which the C–NH2 peak is enhanced (400.86 eV), indicating that the nitrogen element in the aptamer molecule has been successfully introduced.

[0029] The combined results of the full XPS spectrum and the high-resolution N 1s spectrum show that after ozone or O2 plasma treatment, the silicon nanowire surface can be successfully modified with APTES and further immobilized with aptamers. During the modification process, the N 1s peak changes significantly, reflecting the chemical characteristics of the APTES modification and aptamer immobilization. These signal changes reflect the chemical characteristics of the modification process, verifying the effectiveness of the functionalization of the silicon nanowire surface and aptamer immobilization, and providing a solid foundation for the development of biosensors based on silicon nanowire field-effect transistors. This result demonstrates that this technology can be used to construct highly sensitive biosensors for detecting Alzheimer's disease-related biomarkers.

[0030] (2) Figure 4 The water contact angle changes of silicon nanowires modified with APTES after different treatments. Specifically, Figure 4 Figure (a) shows the change in water contact angle of Example 1 after ozone treatment and APTES modification. After three measurements, the initial water contact angles of silicon nanowires were 29.9°, 33.9°, and 35.0°, respectively. After ozone treatment, the water contact angles decreased to 21.6°, 26.7°, and 26.6°, indicating that ozone treatment increased the hydrophilicity of the surface. After APTES modification, the water contact angles increased to 65.7°, 50.6°, and 54.1°. Figure 4 Figure (b) shows the change in water contact angle after O2 plasma treatment and APTES modification in Example 2. After three measurements, the water contact angle further decreased to 26.7°, 25°, and 33.7° after O2 plasma treatment. After APYES modification, the water contact angle increased to 25.3°, 31.9°, and 30°. APTES condenses its ethoxy groups with the hydroxyl groups on the silicon surface to form siloxane bonds, introducing amino functional groups on the surface of the silicon nanowires. The introduction of these amino functional groups changes the surface chemical properties, thereby transforming the silicon nanowire surface from hydrophilic to hydrophobic. After APTES modification, the water contact angle of the ozone-treated sample increased significantly, indicating that the modification was successful and made the surface more hydrophobic. In addition, a comparison of Examples 1 and 2 shows that the APTES modification effect of the sample after O2 plasma treatment is slightly worse than that of the ozone treatment.

[0031] (3) Aβ of the silicon nanowire field effect transistor sensor prepared in Example 1 1-42 Aptamer specificity point measurement, measurement from 10 -7 M to 10 -15 Aβ at different concentrations 1-42 The solution is added to the sensor surface so that I ds -V gs change.

[0032] First, Aβ1-42 Solution preparation: Aβ 1-42 The lyophilized powder was dissolved in hexafluoroisopropanol (HFIP) until the powder was completely dissolved to form a clear and transparent solution. The solution was then vortexed and incubated at room temperature for 30 min to obtain a uniform Aβ solution without aggregates. 1-42 To the monomer solution, add 60 μL of 20 μM sodium hydroxide solution and evaporate HFIP with nitrogen to obtain a concentration of 1 mM Aβ 1-42 Monomer solution, diluted to 10 -7 M to 10 -15 M and stored at -20 °C before use.

[0033] Figure 6 Figures (a) and (b) are the output characteristic curves of the silicon nanowire field effect transistor sensor before and after the immobilization of the nucleic acid aptamer, respectively. The drain current I ds As the drain voltage V ds The change relationship at different gate voltages V gs The test is carried out under the following conditions. According to the figure, as the gate voltage V gs The output current increases significantly from 0 V to -6 V, indicating that a larger negative gate bias can enhance the carrier concentration of the channel and thus improve the conductivity. Figure 6 (a), Figure 6 (b) After the aptamer is fixed, the output current shifts to the left, and the drain current I ds significantly reduced, at the same drain voltage V ds and gate voltage V gs Aβ 1-42 The aptamer is negatively charged. When it is fixed on the surface of the silicon nanowire, it will change the surface potential and carrier distribution of the device channel through the charge effect. Under the structure of n-type heavily doped silicon substrate and SiO2 insulating layer, the fixed negatively charged aptamer will reduce the electron density on the surface of the silicon nanowire channel, resulting in a decrease in the conductance of the channel, thereby reducing the drain current I ds The shift of the output characteristic curve further illustrates that the aptamer is successfully immobilized on the device surface. Figure 6 (b) As the gate voltage V gs From 0 V to -6 V, the drain current I dsThe magnitude of the change decreases. This indicates that the negative charge of the aptamer has a certain degree of shielding on the inhibitory effect of the conductivity, which weakens the gate's ability to regulate the device. The decrease in the device's conductivity after the aptamer is immobilized is the basis for its biosensing function. By changing the surface negative charge density after the aptamer binds to the target molecule, the device's conductivity characteristics will further change. This change in the output signal can be used to detect the presence and concentration of the target molecule. This phenomenon demonstrates the sensitivity of the silicon nanowire field-effect transistor to surface modification and also shows that the immobilization of the aptamer is a key step in the biochemical function of the device.

[0034] Figure 6 Figure (c) shows that the drain voltage is constant, and after the nucleic acid aptamer is fixed, different concentrations of Aβ-containing 1-42 Transfer characteristic curve after solution. Figure 6 (c) It can be seen that with the increase of Aβ 1-42 With the increase of concentration, the transfer curve gradually shifts, indicating that the threshold voltage V th With the Aβ 1-42 This is because the specific binding of the target molecule to the aptamer changes the surface charge distribution, thereby regulating the conductance of the device and causing the output signal to change.

[0035] Figure 6 Figure (d) shows the addition of different concentrations of Aβ-containing 1-42 It can be observed that there is an obvious linear relationship between the threshold voltage and the concentration (at 10 -14 M to 10 -11 M) further demonstrated that the aptamer-modified biosensor can detect Aβ 1-42 The concentration was sensitively detected and Aβ at the 10 fM level was detected. 1-42 .

[0036] Figure 7 The red curve (V gs =-0.1 V) and the green curve (V gs =-0.5 V) all exhibit typical p-type field-effect transistor characteristics. The drain voltage V ds As the gate voltage V gs The switching ratio of the device I on / I off ≈10 5 , which shows that the device has high sensitivity and good switching performance.

[0037] Aβ in cerebrospinal fluid of cognitively normal people and patients with Alzheimer's disease 1-42 There were significant differences in the concentration of Aβ 1-42 >325pg / mL (approximately 10 -13 Aβ in plasma of patients with Alzheimer's disease is used as the standard for "amyloid negative", while concentrations below this value may reflect abnormal accumulation of amyloid protein. 1-42 The concentration is usually between 10pg / mL and 100pg / mL) about 2×10 -15 M~2×10 -14 M, the silicon nanowire field effect transistor biosensor prepared by the present invention is sensitive to Aβ 1-42 The lowest concentration detected was 10 -14 M, can provide accurate test results for early detection and intervention of Alzheimer's disease.

[0038] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a silicon nanowire field-effect transistor biosensor, characterized by: The following steps are involved: S1, preparation of silicon nanowire field effect transistor sensor; S2, configuration containing Aβ 1-42 Phosphate buffered saline solution of nucleic acid aptamers, wherein the Aβ 1-42 The base sequence of the nucleic acid aptamer is: 5'-NH2-(CH2)4-UAGCGUAUGCCACUCUCCUGGGACCCCCCGCCGGAUGGCCA-CAUCC-3'; S3, performing surface functionalization treatment on the silicon nanowire of the silicon nanowire field effect transistor sensor; S4, placing the silicon nanowires of the silicon nanowire field effect transistor sensor in an anhydrous ethanol solution containing 3-aminopropyltriethoxysilane for condensation reaction, washing with anhydrous ethanol after the condensation reaction is completed, heating, and finally adding the 1-42 The PBS solution of nucleic acid aptamer is prepared to obtain the silicon nanowire field effect transistor biosensor.

2. The method for preparing a silicon nanowire field-effect transistor biosensor according to claim 1, wherein: In step S1, the silicon nanowire field effect transistor sensor is prepared as follows: S1-1, using photolithography technology to define a rectangular photoresist pattern on the surface of the SiO2 layer of the SiO2 / n-type heavily doped silicon substrate; S1-2, using inductively coupled plasma etching technology, alternately using C4F8 and O2 plasma to etch the SiO2 layer to obtain a multi-step guide step structure, and then ultrasonically treating in acetone, ethanol and deionized water in sequence to remove the photoresist on the surface; S1-3, depositing metal indium strips on the surface of the multi-level guide step structure by electron beam evaporation, then performing annealing to reduce the indium oxide strips and condense them into catalytic indium droplets, then introducing SiH4 gas to deposit an amorphous silicon film on the surface of the guide step structure, finally activating the indium droplets to absorb the pre-coated amorphous silicon film, and etching to obtain crystalline silicon nanowires; S1-4. Use a photolithography process to transfer the electrode patterns of the source and drain to a SiO2 / n-type heavily doped silicon substrate, then use a buffered oxide etchant to remove the surface oxide layer of the crystalline silicon nanowires, and then successively evaporate platinum and aluminum on the surface of the SiO2 / n-type heavily doped silicon substrate, prepare the source and drain by a stripping process, and finally use a conductive silver paste to lead out the back gate electrode to obtain the silicon nanowire field effect transistor sensor.

3. The method for preparing a silicon nanowire field-effect transistor biosensor according to claim 2, wherein: In step S1-3, the annealing method is: using plasma enhanced chemical vapor deposition equipment, performing H2 plasma annealing at 250-270°C to reduce the indium oxide strips and condense them into catalytic indium droplets; The preparation temperature of the amorphous silicon layer is 100-120°C.

4. The method for preparing a silicon nanowire field-effect transistor biosensor according to claim 2, wherein: In step S1-3, the step of activating the indium droplets to absorb the pre-coated amorphous silicon layer is as follows: raising the temperature to 340-360° C. and maintaining it for 1-2 hours under vacuum or hydrogen atmosphere; The etching step is: removing the remaining amorphous silicon layer by low-temperature H2 plasma.

5. The method for preparing a silicon nanowire field-effect transistor biosensor according to claim 1, wherein: In step S2, the Aβ-containing 1-42 Aptamer Aβ in phosphate buffered saline 1-42 The concentration of the aptamer was 100 nM.

6. The method for preparing a silicon nanowire field-effect transistor biosensor according to claim 1, wherein: In step S3, the surface functionalization treatment adopts ozone treatment or O2 plasma treatment, and the time of the surface functionalization treatment is 90-110 seconds.

7. The method for preparing a silicon nanowire field-effect transistor biosensor according to claim 6, characterized in that: The parameters of the O2 plasma treatment are: substrate temperature is room temperature, RF power is 20~100W, reactive coupled plasma power is 200~500W, chamber pressure is 0.5~3Pa, O2 flow rate is 20~200sccm, and treatment time is 1~20min.

8. The method for preparing a silicon nanowire field-effect transistor biosensor according to claim 1, wherein: In step S4, the volume fraction of 3-aminopropyltriethoxysilane in the anhydrous ethanol solution containing 3-aminopropyltriethoxysilane is 2-4%; The condensation reaction temperature is 20-30°C and the time is 30-60 minutes; The heating temperature is 110-130° C. and the heating time is 10-20 minutes.

9. A silicon nanowire field-effect transistor biosensor obtained according to the preparation method according to any one of claims 1 to 8.

10. Use of the silicon nanowire field-effect transistor biosensor according to claim 9 in detecting amyloid protein, a biomarker of Alzheimer's disease.

Images