A biosensor based on screen-printed electrode and its preparation method and application

Abstract

The application provides a biosensor based on a screen-printed electrode and a preparation method and application thereof. The preparation method comprises the following steps: a, depositing a silicon thin film transition layer on the surface of a working electrode of a screen-printed electrode by using a PECVD device; b, spin-coating a tin dioxide solution on the surface of the silicon thin film transition layer to form a tin dioxide layer; c, first performing hydrogen reduction on the surface of the tin dioxide layer, and then performing silicon nanowire growth to obtain a silicon nanowire layer; d, first performing ultraviolet ozone treatment on the silicon nanowire layer, then placing the silicon nanowire layer in an alcohol solution containing 3-aminopropyl triethoxysilane to perform condensation reaction, cleaning, then performing heating to enhance the coupling strength, and finally placing the silicon nanowire layer in a phosphate buffer solution containing a nucleic acid aptamer to fix the nucleic acid aptamer, so as to obtain the biosensor. The application prepares silicon nanowires on a screen-printed electrode, then fixes a nucleic acid aptamer, and constructs an electrochemical sensor for detecting Alzheimer's disease, and the electrochemical sensor has excellent conductivity, biocompatibility and detection sensitivity.

Description

Technical Field

[0001] This invention relates to the field of biosensor technology, specifically to a biosensor based on screen-printed electrodes, its fabrication method, and its application. Background Technology

[0002] Alzheimer's disease (AD) is a progressive, irreversible degenerative disease of the central nervous system, characterized by gradual cognitive loss, accompanied by a decline in daily living abilities and behavioral disorders. AD not only severely impacts the quality of life of patients but also places enormous pressure on families, society, and the healthcare system.

[0003] Typical case features of Alzheimer's disease (AD) include: (1) extensive deposition of amyloid plaques (formed by Aβ peptide deposition) in the cerebral cortex and hippocampus; (2) neurofibrillary tangles (mainly composed of hyperphosphorylated Tau protein); (3) a significant reduction in the number of neurons and loss of synapses; (4) activation of neuroinflammatory responses; and (5) brain atrophy. Recent studies have shown that amyloid protein (Aβ peptide), especially Aβ... 1-42 The formation and clearance of transitional barriers are early initiating factors that trigger changes in AD cases.

[0004] Aβ 1-42 It is a short peptide produced by the cleavage of β-amyloid precursor protein (APP) by β and γ secretases, and is related to Aβ. 1-40 In contrast, it is more likely to aggregate into fibrous structures and form highly neurotoxic amyloid deposits. Aβ 1-42 It can deposit between neuronal synapses, triggering glial cell activation, free radical release, and upregulation of inflammatory factors, ultimately inducing neuronal apoptosis, constituting an early biological event in Alzheimer's disease (AD). Therefore, Aβ... 1-42 It plays a crucial role in the diagnosis and pathogenesis research of Alzheimer's disease (AD). AD typically begins more than 10 years before the onset of clinical symptoms, with a "latent period" or "preclinical stage" during which pathological changes have occurred but obvious cognitive impairment has not yet appeared. Accurate detection of abnormal Aβ accumulation during this stage would provide a valuable window for intervention and treatment. Therefore, developing a highly sensitive, low-cost, easy-to-operate detection technology suitable for preclinical screening has significant social and medical value.

[0005] Current mainstream AD detection technologies have significant drawbacks, such as: 1) Cerebrospinal fluid testing requires invasive sampling, leading to poor patient compliance and hindering its widespread adoption for early screening; 2) PET imaging relies on expensive equipment and radioactive tracers, making it costly and also limiting its use for early screening; 3) Traditional electrochemical / immunoassay methods are ineffective for detecting low concentrations of Aβ in the blood. 1-42 (usually below 10) -9M) has insufficient sensitivity and suffers from complex operation and poor reproducibility.

[0006] In recent years, silicon nanowires have been widely used in biosensor design due to their high specific surface area, excellent electron transport properties, and ease of surface modification. However, existing silicon nanowire growth methods require temperatures exceeding 400°C, making them suitable only for high-temperature resistant rigid substrates such as silicon wafers and incompatible with flexible, low-cost sensing platforms. While screen-printed electrodes are ideal flexible sensing platforms, the commonly used polyimide substrates have a temperature limit of approximately 250°C, and the high-temperature growth process of silicon nanowires can lead to substrate deformation and failure.

[0007] Although some studies have attempted to achieve flexible integration through nanowire transfer processes, the transfer process is prone to interface instability, leading to decreased signal stability and difficulty in controlling manufacturing consistency. Therefore, developing a technique for in-situ low-temperature growth of silicon nanowires on screen-printed carbon electrodes (SPCE) is of great significance. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a biosensor based on screen-printed electrodes, its fabrication method, and its application, thus solving the problems mentioned in the background section.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] According to a first aspect of the present invention, a method for fabricating a biosensor based on a screen-printed electrode is provided, comprising the following steps:

[0011] Step 1: Deposit a silicon thin film transition layer on the surface of the working electrode of the screen-printed electrode using a PECVD device;

[0012] Step 2: Spin-coat tin dioxide solution onto the surface of the silicon thin film transition layer to form a tin dioxide layer;

[0013] Step 3: First, hydrogen reduction is performed on the surface of the tin dioxide layer, and then silicon nanowires are grown to obtain a silicon nanowire layer.

[0014] Step 4: First, the silicon nanowire layer is treated with ultraviolet ozone, then placed in an alcohol solution containing 3-aminopropyltriethoxysilane for condensation reaction. After washing, it is heated to enhance the coupling strength. Finally, it is fixed in a phosphate buffer containing nucleic acid aptamers to obtain the biosensor. The base sequence of the nucleic acid aptamer is 5'-NH2-(CH2)4-UAGCGUAUGCCACUCUCCUGGGACCCCCCGCCGGAUGGCCA-CAUCC-3'.

[0015] Preferably, in step 1, the deposition conditions of the silicon thin film transition layer are as follows: the deposition conditions of the silicon thin film transition layer are as follows: at a temperature of 25~300℃, a radio frequency power of 1~50 W, and a pressure of 50~1000 Pa, hydrogen, silane, and phosphine are introduced for deposition for 2~180 min, wherein the flow rate of the hydrogen is 50~500 sccm, the flow rate of the silane is 0.1~50 sccm, and the flow rate of the phosphine is 0.1~10 sccm.

[0016] Preferably, in step 2, the concentration of the tin dioxide solution is 0.01~10%;

[0017] The spin coating speed is 100~5000 RPM, and the spin coating time is 10~120 s.

[0018] Preferably, in step 3, the conditions for hydrogen reduction are: a temperature of 25~300 ℃, a radio frequency power of 10~100 W, a pressure of 100~1000 Pa, and hydrogen reduction for 2~30 min, wherein the hydrogen flow rate is 50~500 sccm.

[0019] The conditions for growing silicon nanowires are as follows: the silicon nanowires are prepared by introducing hydrogen, silane, and phosphine at a temperature of 232~350 ℃, a radio frequency power of 5~50 W, a pressure of 150~1000 Pa, and by passing hydrogen gas, silane, and phosphine through the gas. The flow rate of hydrogen gas is 100~500 sccm, the flow rate of silane is 1~20 sccm, the flow rate of phosphine is 0.1~10 sccm, and the growth time is 1~40 min.

[0020] Preferably, in step 4, the volume fraction of 3-aminopropyltriethoxysilane in the alcohol solution containing 3-aminopropyltriethoxysilane is 0.5% to 5%.

[0021] The concentration of nucleic acid aptamers in the phosphate buffer containing nucleic acid aptamers is 50~1000 nM, and the pH of the phosphate buffer is 7.4.

[0022] Preferably, in step 4, the ultraviolet ozone treatment time is 50~500 s.

[0023] Preferably, in step 4, the condensation reaction is carried out at room temperature for 20 to 60 minutes.

[0024] The temperature for heating to enhance coupling strength is 100~120℃, and the time is 10~30 min.

[0025] Preferably, in step 4, the fixed time is 1 to 3 hours.

[0026] According to a second aspect of the present invention, a biosensor obtained according to the above-described preparation method is provided, comprising a screen-printed electrode and a biorecognition layer loaded on the surface of the working electrode of the screen-printed electrode, the biorecognition layer comprising a silicon thin film transition layer and a silicon nanowire growth layer, wherein a nucleic acid aptamer is immobilized on the surface of the silicon nanowire growth layer.

[0027] According to a third aspect of the present invention, there is an application of a biosensor based on an electrochemical method in the detection of amyloid protein, a biomarker for Alzheimer's disease.

[0028] This invention provides a biosensor based on screen-printed electrodes, its fabrication method, and its application. It offers the following advantages:

[0029] (1) The present invention provides a method for preparing a biosensor based on screen-printed electrodes. Low-melting-point tin is used as a catalyst and combined with silicon-tin eutectic reaction. Silicon nanowires can be grown on a polyimide flexible substrate with a temperature limit of ≤250℃. This avoids cross-sectional defects caused by nanowire transfer, significantly improves stability and reproducibility during the process. Silicon nanowires are embedded in the electrode interface, reducing interface resistance, improving the response speed of electrochemical signals, and increasing detection sensitivity.

[0030] (2) The method for preparing a biosensor based on screen-printed electrodes provided in this solution prepares a silicon thin film before spin-coating the tin dioxide layer, which can control the wettability of tin and prevent the problem of tin diffusion failure on the carbon electrode surface.

[0031] (3) The present solution provides a biosensor based on screen-printed electrodes, which is integrated in one piece. Silicon nanowires are grown in situ on the working electrode of SPCE, and nucleic acid aptamers are fixed on the surface of silicon nanowires. It can be applied to flexible wearable biosensors and is portable.

[0032] (4) The biosensor provided in this scheme is based on the application of electrochemical methods in the detection of amyloid protein, a biomarker of Alzheimer's disease. Through electrochemical methods, the chemical energy generated after the biomarker and the biorecognition layer on the electrode surface are combined in an electrolyte solution is converted into electrical energy, generating a detectable current signal. Due to the unique one-dimensional structure of silicon nanowires, electrons can be transported axially, making the electrochemical signal faster and the response more sensitive. Thus, it is possible to accurately and quickly detect Alzheimer's disease biomarkers. β Amyloid protein content can be detected with high sensitivity. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the process steps for preparing silicon nanowires in Example 1 of the present invention;

[0034] Figure 2 This is a scanning electron microscope image of the working electrode surface of the screen-printed electrode in Embodiment 1 of the present invention;

[0035] Figure 3 This is a schematic diagram of the process steps for immobilizing nucleic acid aptamers on the surface of silicon nanowires in Embodiment 1 of the present invention;

[0036] Figure 4 This is a scanning electron microscope image of the working electrode surface without a transition layer in Comparative Example 1 of the present invention;

[0037] Figure 5 This is a comparison of cyclic voltammetry curves at various stages of the preparation process in Example 1 of the present invention. Curve 1 is the cyclic voltammetry curve of the screen-printed electrode SPCE with a conductive substrate, curve 2 is the cyclic voltammetry curve of SiNWs / SPCE with grown silicon nanowires (SiNWs), and curve 3 is the cyclic voltammetry curve of APTES+Aβ after immobilization with nucleic acid aptamers. 1-42 Cyclic voltammetry curves of / Si NWs / SPCE;

[0038] Figure 6 The differential pulse voltammetry (DPV) performance of the biosensor prepared in Example 1 of this invention was tested, wherein (a) the figure shows different concentrations of Aβ. 1-42 The DPV curves after solution preparation, (b) shows the addition of different concentrations of Aβ. 1-42 Linear relationship between solution concentration and peak current;

[0039] Figure 7 The DPV performance of the biosensor prepared in Comparative Example 2 of this invention was detected, wherein (a) Figure shows different concentrations of Aβ. 1-42 The DPV curves after solution preparation, (b) shows the addition of different concentrations of Aβ. 1-42 Linear relationship between solution concentration and peak current;

[0040] Figure 8 The peak current and Aβ of the biosensor prepared in Example 1 of this invention 1-42 Linear fitting curve of concentration;

[0041] Figure 9 The DPV performance of the biosensor prepared in Comparative Example 3 of this invention was detected, wherein (a) Figure shows different concentrations of Aβ. 1-42 The DPV curves after solution preparation, (b) shows the addition of different concentrations of Aβ. 1-42 Linear relationship between solution concentration and peak current;

[0042] Figure 10The DPV performance of the biosensor prepared in Example 1 of the present invention was tested. (a) The figure shows the DPV curves after adding bovine serum albumin solution of different concentrations, and (b) The figure shows the linear relationship between the concentration and the peak current after adding bovine serum albumin solution of different concentrations. Detailed Implementation

[0043] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0044] Example 1

[0045] A method for fabricating a biosensor based on screen-printed electrodes, combined with Figure 1 and Figure 3 It is prepared by the following method:

[0046] (a) Provides the working electrode for screen printing electrodes;

[0047] (b) A transition layer is prepared on the working electrode using PECVD process;

[0048] The specific steps are as follows: A silicon thin film transition layer is deposited on the working electrode surface of the screen-printed electrode using a PECVD equipment. The deposition conditions of the silicon thin film transition layer are: temperature 150℃, RF power 10W, pressure 150Pa, H2 is introduced at a flow rate of 200sccm, SiH4 at a flow rate of 5sccm, and PH3 at a flow rate of 0.5sccm, and the deposition time is 30min. H2 is used as the carrier gas, SiH4 as the silane, and PH3 as the dopant. The 150℃ condition helps to control the deposition rate and quality of silicon, resulting in excellent crystal quality of the silicon thin film.

[0049] (c) Treat the surface of the transition layer with ultraviolet ozone cleaning agent;

[0050] The specific steps are as follows: Clean the surface of the silicon film using an ultraviolet ozone cleaner for 10 minutes;

[0051] (d) Spin-coating tin dioxide solution onto the surface of the transition layer;

[0052] The specific steps are as follows: a 3% tin dioxide solution is spin-coated onto the surface of the silicon thin film transition layer using a spin coater at a speed of 3000 RPM for 10 seconds, so that the tin dioxide solution is uniformly covered on the surface of the silicon thin film, providing a catalyst for the growth of silicon nanowires.

[0053] (e) Silicon nanowires are grown on the surface of the working electrode using PECVD;

[0054] The specific steps are as follows: At a temperature of 250℃, an RF power of 10W, and a pressure of 150Pa, hydrogen gas is introduced at a flow rate of 100 sccm for 10 minutes for reduction treatment. Then, under the same temperature, RF power, and pressure, hydrogen gas is introduced at a flow rate of 200 sccm, silane at a flow rate of 5 sccm, and phosphine at a flow rate of 0.5 sccm for 10 minutes to grow silicon nanowires. Figure 2 As shown;

[0055] (f) The surface of the silicon nanowires was cleaned with ultraviolet ozone cleaner for 100 s. Then, the working electrode was placed in a 2% (v / v) APTES anhydrous ethanol solution to form amide bonds through a condensation reaction. After standing at room temperature for 30 min, it was rinsed with anhydrous ethanol to remove uncoupled APTES. Then, it was heated at 120 °C for 10 min to enhance the coupling strength. Finally, a 100 nM Aβ solution was dropped onto the surface of the working electrode. 1-42 The PBS solution of the nucleic acid aptamer was allowed to stand for 2 hours, and the treated electrode was stored in a 4°C refrigerator for later use.

[0056] Comparative Example 1

[0057] The preparation method of this comparative example is the same as that of Example 1, except that the coating treatment in step (b) was not performed.

[0058] according to Figure 2 and Figure 4 The comparison shows that silicon nanowires can be successfully fabricated on the electrode surface after the preparation of the transition layer. The prepared silicon nanowires have a high surface area-to-volume ratio and high electron mobility, which is beneficial for immobilizing more nucleic acid aptamers and improving the performance of the sensor.

[0059] Comparative Example 2

[0060] The preparation method of this comparative example is the same as that of Example 1, except that Aβ is directly applied to the working electrode surface of the screen-printed electrode. 1-42 Immobilization of nucleic acid aptamers.

[0061] Comparative Example 3

[0062] The preparation method of this comparative example is the same as that of Example 1, except that Aβ was not performed. 1-42 Immobilization of nucleic acid aptamers.

[0063] Performance testing

[0064] Electrochemical tests were performed on the biosensor after the nucleic acid aptamer was successfully immobilized on the electrode surface. The tests involved the interaction between the nucleic acid aptamer and Aβ. 1-42 The specific binding of the substance causes a change in the interfacial resistance, which in turn causes a change in the intensity of the current signal. This change can be detected and recorded by an electrochemical electrode.

[0065] First, perform Aβ 1-42 Solution preparation:

[0066] Hexafluoroisopropanol was used as a solvent to mix with β-amyloid protein, and a conformational change in β-amyloid protein was induced under room temperature to obtain β-amyloid protein monomers.

[0067] Specifically: Aβ 1-42 The lyophilized powder was dissolved in hexafluoroisopropanol. After complete dissolution to form a clear and transparent solution, the solution was incubated under moderate vortexing at room temperature for 30 minutes to obtain a uniformly dispersed Aβ. 1-42 The monomer solution was then followed by the addition of 60 μL of a 20 μM sodium hydroxide solution. The solution was then dried under nitrogen to remove the hexafluoroisopropanol solvent, ultimately yielding 1 mM Aβ. 1-42 Monomer solution. And further serially diluted to 10. -5 M to 10 -17 All solutions of different concentrations of M must be stored at -20°C for later use.

[0068] Cyclic voltammetry was performed on the bare electrode, the electrode with grown silicon nanowires, and the electrode with successfully immobilized nucleic acid aptamers from Example 1 in a 0.2 M KCl electrolyte solution containing 5 mM K3[Fe(CN)6] / [Fe(CN)6]. Figure 5 It can be seen that the redox peaks of the Si NWs-grown electrode are significantly higher than those of the bare electrode, indicating that silicon nanowires have good conductivity and can provide electrochemical signals. Furthermore, silicon nanowires have a large specific surface area, which can accelerate electron transport rates. The peak current decreases after modification with nucleic acid aptamers. This is because the nucleic acid aptamers, once immobilized on the electrode surface, hinder electron transfer at the electrode-electrolyte interface, thus reducing the redox peak.

[0069] Electrodes with successfully immobilized nucleic acid aptamers were tested using differential pulse voltammetry in a 0.2 M KCl electrolyte solution containing 5 mM K3[Fe(CN)6] / [Fe(CN)6]. The voltage range was -0.4 to 0.6 V, the pulse potential was 0.05 V, and the pulse duration was 0.5 s.

[0070] Figure 6 and Figure 7 The measurements will be 10 respectively. -7 M to 10 -14 M at different concentrations of Aβ 1-42 DPV diagrams showing the changes in current signals caused by droplets being added to the surfaces of the biosensor prepared in Example 1 and Comparative Example 2. Wherein, as... Figure 6 The oxidation peak shown in figure a increases with Aβ 1-42 The concentration of Aβ increases and decreases, resulting in the peak current being related to Aβ. 1-42The concentration shows a linear relationship (e.g.) Figure 6 As shown in b), the linear fitting results are as follows: Figure 8 As shown, the linear regression equation is I (μA) = -40.4logC - 206.84, and the overall fit is relatively high, with a correlation coefficient R. 2 =0.94576. Compared to SPCE without silicon nanowire growth (e.g., Figure 7 As shown), the electrode on which silicon nanowires are grown (e.g.) Figure 6 (As shown) It has good performance in Alzheimer's disease detection.

[0071] Experimental results show that the electrode for detecting β-amyloid protein, a biomarker of Alzheimer's disease, constructed in this application is an electrochemical immunosensor with high sensitivity and quantitative detection capabilities, created by growing silicon nanowires on a screen-printed carbon electrode and then performing biological modification.

[0072] 10 -7 M to 10 -14 Aβ at different concentrations of M 1-42 The sample was dropped onto the surface of the sensor electrode prepared in Comparative Example 3. To verify that the biosensor surface must be immobilized with nucleic acid aptamers, differential pulse voltammetry was used for testing. The test results are as follows: Figure 9 As shown, it can be seen that with Aβ 1-42 As the concentration increases, the peak current follows an infinitely regular pattern.

[0073] 10 -7 M to 10 -14 Bovine serum albumin (BSA) at different concentrations was dropped onto the surface of the sensor electrode prepared in Example 1. To verify the specificity of the electrochemical sensor based on the base complementary pairing principle, differential pulse voltammetry was used for testing. The test results are as follows: Figure 10 As shown, according to Figure 10 It can be seen that the peak current does not change significantly with the increase of bovine serum albumin concentration. This is because the non-complementary sequence cannot completely hybridize with the nucleic acid aptamer, so it does not cause a significant change in the peak current on the electrode surface.

[0074] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for fabricating a biosensor based on screen-printed electrodes, characterized in that: Includes the following steps: Step 1: Deposit a silicon thin film transition layer on the surface of the working electrode of the screen-printed electrode using a PECVD device; Step 2: Spin-coat tin dioxide solution onto the surface of the silicon thin film transition layer to form a tin dioxide layer; Step 3: First, hydrogen reduction is performed on the surface of the tin dioxide layer, and then silicon nanowires are grown to obtain a silicon nanowire layer. Step 4: First, the silicon nanowire layer is treated with ultraviolet ozone, then placed in an alcohol solution containing 3-aminopropyltriethoxysilane for condensation reaction. After washing, it is heated to enhance the coupling strength. Finally, it is fixed in a phosphate buffer containing nucleic acid aptamers to obtain the biosensor. The base sequence of the nucleic acid aptamer is 5'-(CH2)4-UAGCGUAUGCCACUCUCCUGGGACCCCCCGCCGGAUGGCCA-CAUCC-3'.

2. The method for fabricating a biosensor based on a screen-printed electrode according to claim 1, characterized in that: In step 1, the deposition conditions for the silicon thin film transition layer are as follows: at a temperature of 25~300℃, a radio frequency power of 1~50 W, and a pressure of 50~1000 Pa, hydrogen, silane, and phosphine are introduced for deposition for 2~180 min, wherein the flow rate of hydrogen is 50~500 sccm, the flow rate of silane is 0.1~50 sccm, and the flow rate of phosphine is 0.1~10 sccm.

3. The method for fabricating a biosensor based on a screen-printed electrode according to claim 1, characterized in that: In step 2, the concentration of the tin dioxide solution is 0.01% to 10%. The spin coating speed is 100~5000 RPM, and the spin coating time is 10~120 s.

4. The method for fabricating a biosensor based on a screen-printed electrode according to claim 1, characterized in that: In step 3, the conditions for hydrogen reduction are: a temperature of 25~300 ℃, a radio frequency power of 10~100 W, a pressure of 100~1000 Pa, and hydrogen reduction for 2~30 min, wherein the hydrogen flow rate is 50~500 sccm. The conditions for growing silicon nanowires are as follows: the silicon nanowires are prepared by introducing hydrogen, silane, and phosphine at a temperature of 232~350 ℃, a radio frequency power of 5~50 W, a pressure of 150~1000 Pa, and by passing hydrogen gas, silane, and phosphine. The flow rate of hydrogen gas is 100~500 sccm, the flow rate of silane is 1~20 sccm, the flow rate of phosphine is 0.1~10 sccm, and the growth time is 1~40 min.

5. The method for fabricating a biosensor based on a screen-printed electrode according to claim 1, characterized in that: In step 4, the volume fraction of 3-aminopropyltriethoxysilane in the alcohol solution containing 3-aminopropyltriethoxysilane is 0.5% to 5%. The concentration of nucleic acid aptamers in the phosphate buffer containing nucleic acid aptamers is 50~1000 nM, and the pH of the phosphate buffer is 7.

4.

6. The method for fabricating a biosensor based on a screen-printed electrode according to claim 1, characterized in that: In step 4, the ultraviolet ozone treatment time is 50~500 s.

7. The method for fabricating a biosensor based on a screen-printed electrode according to claim 1, characterized in that: In step 4, the condensation reaction is carried out at room temperature for 20-60 minutes. The temperature for heating to enhance coupling strength is 100~120℃, and the time is 10~30 min.

8. The method for fabricating a biosensor based on a screen-printed electrode according to claim 1, characterized in that: In step 4, the fixed time is 1 to 3 hours.

9. A biosensor obtained by the method according to any one of claims 1 to 8, characterized in that: The invention includes a screen-printed electrode and a biometric layer loaded on the surface of the working electrode of the screen-printed electrode. The biometric layer includes a silicon thin film transition layer and a silicon nanowire growth layer, and nucleic acid aptamers are immobilized on the surface of the silicon nanowire growth layer.

10. The application of the biosensor as described in claim 9 in the detection of amyloid protein, a biomarker of Alzheimer's disease, based on an electrochemical method.

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