Sensor for detecting sPD-L1 based on surface enhanced Raman scattering

Abstract

The invention discloses a sensor for detecting sPD-L1 based on surface enhanced Raman scattering, a silicon wafer is used as a substrate, the surface of the silicon wafer is modified with an Au (at) 4-MBA (at) Ag core-shell nanometer material, and the surface of an Ag nanometer shell layer is coupled with an sPD-L1 antibody, when the sensor is used for detecting sPD-L1 antigens with different concentrations, the concentration of the sPD-L1 antigens is within the range of 0.1-104 pg / mL, and the concentration of the sPD-L1 antigens is within the range of 0.1-104 pg / mL. The logarithm of the peak intensity and the logarithm of the concentration of the sPD-L1 have a good linear relationship: Y is equal to 0.08465 X + 3.67384 (R2 is equal to 0.9984), and the lower limit of detection is 0.4731 pg / mL; and the sensor has good repeatability, stability and specificity, can successfully distinguish liver cancer positive and negative samples in clinical tests, has good clinical application prospects, and provides a new method technology for sPD-L1 detection.

Description

Technical Field

[0001] The present invention relates to the field of sensing technology, and particularly relates to a sensor for detecting sPD-L1 based on surface-enhanced Raman scattering. Background Art

[0002] Programmed cell death-1 and ligand-1 (PD-1 / PD-L1) is a key pathway for tumor immune escape. After the PD-L1 ligand on the surface of tumor cells binds to the PD-1 receptor on T cells, it will inhibit the immune activity and proliferation of T cells, making them unable to recognize and attack tumors, resulting in the failure of the immune system's "surveillance function". The expression level of soluble PD-L1 (sPD-L1) in the serum of healthy people is low, but many patients with malignant tumors show a high expression trend of sPD-L1 in their serum, and high levels of serum sPD-L1 are positively correlated with poor prognosis. Therefore, sPD-L1 is used clinically as an auxiliary marker for cancer diagnosis, treatment, or prognosis.

[0003] Surface-enhanced Raman scattering (SERS) technology is a highly sensitive, fast, and non-destructive detection spectral technology. By analyzing the scattering spectrum of substances, an information map of the characteristic vibrations of biomacromolecules can be obtained. However, this technology is in the development stage for biological monitoring, and it is urgent to build a spectral database. This technology has the advantages of being free from interference by water molecules, not relying on proliferation culture, achieving accurate, high-throughput, non-damaging to microorganisms, and ultra-fast detection; real-time dynamic monitoring of the content of biomacromolecules, and obtaining rich biological information, and has a wide range of applications. Currently, it has been widely used in biochemical detection, analytical chemistry, disease diagnosis, food safety, microbial detection, traditional Chinese medicine identification, environmental monitoring, biosensing, public safety and other fields. The purpose of the present invention is to provide a new method for detecting sPD-L1 by establishing a biosensor, which is of great significance for early cancer screening, diagnosis, and prognosis judgment. Summary of the Invention

[0004] In view of this, one of the purposes of the present invention is to provide a sensor for detecting sPD-L1 based on surface-enhanced Raman scattering; the second purpose of the present invention is to provide a kit for cancer auxiliary diagnosis; the third purpose of the present invention is to provide a method for using the kit for cancer auxiliary diagnosis.

[0005] To achieve the above purposes, the present invention provides the following technical solutions:

[0006] 1. A sensor for detecting sPD-L1 based on surface-enhanced Raman scattering, comprising the following structures:

[0007] a) A silicon wafer substrate with a positively charged surface modified by aminosilanization;

[0008] b) Au@4-MBA@Ag core-shell nanomaterials loaded on the surface of the silicon wafer, where:

[0009] i. Au is the nanocore, its surface is modified with the Raman tag molecule 4-MBA, and the outermost layer is further coated with an Ag nanoshell layer;

[0010] ii. The weight percentages of the main elements in the Au@4-MBA@Ag core-shell nanomaterials are O 58.42%, Au 28.76, Ag 10.82, C 1.53%, and S 0.47%;

[0011] c) sPD-L1 antibody conjugated to the surface of the Ag nanoshell layer for specifically capturing the target antigen.

[0012] In some embodiments of the present invention, the particle size range of the Au@4-MBA@Ag core-shell nanomaterials is 0.08 - 0.35 μm.

[0013] In some embodiments of the present invention, the sPD-L1 antibody is covalently bound to the Ag shell layer by the EDC / NHS activation method.

[0014] In some embodiments of the present invention, the coupling amount of the sPD-L1 antibody is 10 - 30 ng / cm 2 .

[0015] In some embodiments of the present invention, the preparation method of the Au@4-MBA@Ag core-shell nanomaterials includes the following steps:

[0016] a) Using CTAC as a template agent, preparing Au nanocores by reducing HAuCl4 with NaBH4;

[0017] b) In a PVP ethanol solution, binding 4-MBA to the Au nanocores to form Au@4-MBA;

[0018] c) Growing an Ag nanoshell layer on the surface of Au@4-MBA by reducing AgNO3 with ascorbic acid.

[0019] In some embodiments of the present invention, in step b), the mass-volume fraction of the PVP ethanol solution is 1% - 2%, the reaction temperature is 25 - 30 °C, and the reaction time is 1 - 2 hours.

[0020] 2. A cancer auxiliary diagnosis kit, comprising the following components:

[0021] a) A sensor for detecting sPD-L1 based on surface-enhanced Raman scattering;

[0022] b) An sPD-L1 standard antigen concentration gradient test solution with a concentration range of 0.1 pg / mL - 104 pg / mL.

[0023] 3. The method for using the cancer auxiliary diagnosis kit, which is used for non-disease diagnosis and treatment purposes, includes the following steps:

[0024] a) Contact the sample to be tested with the sensor so that the sPD-L1 antigen in the sample specifically binds to the sPD-L1 antibody;

[0025] b) Use a Raman spectrometer, excited by 785 nm laser, to detect the intensity of the 4-MBA characteristic peak at 1074 cm-1;

[0026] c) Calculate the concentration of sPD-L1 antigen in the sample to be tested according to the linear relationship between the logarithm of the characteristic peak intensity and the logarithm of the sPD-L1 standard antigen concentration.

[0027] The sensor for detecting sPD-L1 based on surface-enhanced Raman scattering described in the present invention uses Au nanoparticles surface-modified with Raman tag molecules and coated with an Ag nanoshell on the surface to form a core-shell nanomaterial with a Raman signal probe. Finally, the core-shell nanoparticles are assembled onto the surface of a Si wafer by electrostatic adsorption to prepare a SERS substrate. Finally, sPD-1 antibody is fixed on the substrate surface to capture the detection target molecule, so that the target molecule is located near the hot spot of the substrate to achieve Raman signal enhancement, thereby detecting the target molecule. In the invention, CTAC and CTAB can provide a templating effect when the nanoparticles are reduced to elemental molecules to form nanoparticles, preventing nanoparticle aggregation, and forming nanoparticles with relatively uniform particle size and shape in the micelle molecular template formed by CTAC and CTAB molecules. When preparing the connection of Raman signal tags, a PVP ethanol solution is used as the reaction solution. PVP can effectively prevent nanoparticle aggregation and sedimentation, and can adjust the gap between the core and the shell, thereby enhancing the Raman signal. The SERS Raman tag molecule is in the hot spot region between the SERS bimetallic core and shell, and can obtain the maximum signal enhancement, effectively improving the sensitivity of sensor detection. In addition, it also has advantages such as anti-photobleaching, narrow spectral bandwidth, and multi-channel detection. Using a Si wafer as the substrate, the surface is smooth and flat, which is easy to modify. During Raman signal detection, the background signal peak is relatively smooth, and has little influence on the signal fingerprint characteristic peak of the Raman probe molecule.

[0028] The beneficial effects of the present invention are as follows: The Au-4-MBA@Ag nanobase material is successfully synthesized and prepared, and a Raman biosensor based on 4-MBA Raman tags is constructed by modifying a silicon wafer with the nanomaterial. When the prepared nanobase detects sPD-L1 antigens at different concentrations, Raman signal molecules 4-MBA can be detected at 513 cm -1 and 1074 cm-1 、 At 1580 cm -1 The fingerprint characteristic peak at the displacement, 1074 cm -1 、 At 1580 cm -1 The two strong SERS fingerprint peaks at [location] are due to the in-plane bending of C-H and symmetric stretching vibration of C=C of 4-MBA, which is consistent with the reported literature, indicating that the Raman substrate is successfully prepared and has a strong surface Raman enhancement effect.

[0029] The performance of the sensor was tested, including its repeatability, stability, and specificity. Clinical samples were detected to study the sensor performance. The results showed that when detecting sPD-L1 antigens at different concentrations, within the range of 0.1 - 10 4 pg / mL, there was a good linear relationship between the logarithm of the peak intensity and the logarithm of the sPD-L1 antigen concentration: Y = 0.08465X + 3.67384 (R 2 = 0.9984), and the lower detection limit was 0.4731 pg / mL. In the presence of non-specific interfering antigens such as DCP, SFLT-1, NES, and PLGF, the characteristic peak signal of the Raman tag molecule of the sensor was significantly enhanced only in the presence of the sPD-L1 antigen, indicating its good specificity. In the clinical trial, we used this sensor to detect 7 clinical serum samples with different concentrations of AFP. The results showed that the sensor could successfully distinguish between positive and negative liver cancer samples and had good clinical application prospects, providing a new method and technology for sPD-L1 detection. Description of the Drawings

[0030] To make the objectives, technical solutions, and beneficial effects of the present invention clearer, the following drawings are provided for description:

[0031] Figure 1 It is a schematic diagram of the experimental design.

[0032] Figure 2 It is the SEM scanning electron micrograph of Au@4-MBA@Ag; the scales are 5μm (a), 5μm (b), 1μm (c), and 500nm (d) respectively.

[0033] Figure 3 It is the particle size distribution of the Au@4-MBA@Ag nanomaterial.

[0034] Figure 4 It is the EDS elemental composition analysis of the Au@4-MBA@Ag nanomaterial.

[0035] Figure 5 It is the X-ray diffraction pattern of Au@4-MBA@Ag.

[0036] Figure 6Effect of PVP concentration on Raman signal.

[0037] Figure 7 (a) Peak intensity displacement diagram of Raman tag signal at different antigen concentrations; (b) Curve of logarithm of Raman tag signal at 1074 cm -1 Peak intensity logarithm vs. logarithm of different antigen concentrations; (c) Linearity of logarithm of Raman tag signal at 1074 cm -1 Peak intensity logarithm vs. logarithm of different antigen concentrations.

[0038] Figure 8 Experimental results of reproducibility (a) and time stability (b) of Raman sensor.

[0039] Figure 9 Specificity experiment of Raman sensor.

[0040] Figure 10 Clinical sample testing of electrochemical sensor. Detailed implementation mode

[0041] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it, but the specific embodiments cited are not intended to limit the present invention.

[0042] As Figure 1 shown, the present invention uses 4-mercaptobenzoic acid (4-MBA)-labeled Au nanoparticles as the core, and then uses ascorbic acid (AA) as a reducing agent and cetylammonium acetate (CTAC) as a capping agent to prepare Au@4-MBA@Ag material with Ag-coated Au nanoparticles embedded with Raman tag molecules, which is used as a SERS substrate. The preparation of the substrate mainly consists of three steps: isomorphism of the plasma core, functionalization of the dye molecule, and overgrowth of the metal shell. The synthesis of these substances is simple and low-cost because the required reagents and instruments are easily available. Importantly, the Raman probe molecules are placed in the hot spot region generated by the nano-gap in the core-shell nanostructure, which can enhance the Raman signal and prevent the Raman tag molecules from bleaching. The obtained nanomaterials are combined with the surface of a 1 cm × 1 cm silicon wafer by electrostatic adsorption, and the sPD-L1 antibody is combined with the SERS substrate through S-Ag bonds to form a Raman biosensor.

[0043] Experimental materials

[0044] The sPD-L1 antigen was prepared and purified by prokaryotic expression. The sPD-L1 monoclonal antibody was purchased from Wuhan Huamei Biological Engineering Co., Ltd. The Au@4-MBA@Ag composite material was synthesized and prepared in the laboratory. The serum sample testing work involved in the present invention has obtained the consent of the patients or their families and the approval of the Medical Ethics Committee of Chongqing University of Technology.

[0045] Experimental reagents

[0046] Tetrachloroauric acid trihydrate (HAuCl4·3H2O) and anhydrous citric acid were purchased from Macklin Co., Ltd. Silver nitrate (AgNO3) was purchased from Xilong Scientific Co., Ltd. Sodium borohydride (NaBH4), cetyltrimethylammonium chloride (CTAC), and polyvinylpyrrolidone (PVP) were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. Cetyltrimethylammonium bromide (CTAB) and hydrochloric acid (HCl) were purchased from Sinopharm Chemical Reagent Co., Ltd. 4-Mercaptobenzoic acid (4-MBA) was purchased from Chengdu Kelong Chemical Co., Ltd., Sichuan. Anhydrous ethanol (CH3CH2OH) was purchased from Shanghai Titan Scientific Co., Ltd. L-Ascorbic acid (AA) was purchased from Shanghai Macklin Biochemical Co., Ltd. 1-Ethyl-(3-dimethylaminopropyl)carbodiimide (EDC) was purchased from Aladdin Holding Group Co., Ltd. N-Hydroxysuccinimide (NHS) was purchased from Shanghai Yuanye Biotechnology Co., Ltd.

[0047] Preparation of Au@4-MBA@Ag composite material in Example 1

[0048] It is prepared by a two-step method to prepare an Au nanoseed solution, then connect the 4-MBA Raman label to the surface of Au nanoparticles, and then coat Ag nanoparticles.

[0049] (1) Preparation of Au nanoseed solution

[0050] Mix 0.1 mL of 1 mM HAuCl4 solution, 0.1 mL of 0.02 M citric acid solution, and 0.01 mL of 0.025 M NaBH4 solution freshly prepared with ice water by magnetic stirring for 5 min. Add 0.2 mL of 0.1 M CTAC solution and stir vigorously for 5 min. Then place the solution in an 80°C water bath and stir gently for aging for 2 h. Then store the solution in the dark at room temperature in a sealed manner.

[0051] (2) Preparation of Au@4-MBA seed solution

[0052] Mix 0.2 mL of 0.01 M HAuCl4 solution, 0.04 mL of 0.01 M AgNO3 solution, 0.08 mL of 1 M HCl solution, and 0.032 mL of 0.1 M ascorbic acid solution by magnetic stirring for 5 min. Add 0.1 mL of the Au nanoseed solution prepared in the first step, add 4 mL of 0.1 M CTAB solution, and stir vigorously for 5 min. Then place the reaction solution in a 30°C water bath and stir for reaction for 4 h. Then centrifuge at 6000 rpm for 5 min to remove the supernatant solution.

[0053] The precipitate was resuspended and dispersed with 5 mL of 1%, 1.5%, 2% (g / mL) PVP ethanol solution, and 50 μL of 0.1 M 4-MBA solution was added respectively. The reaction was stirred at room temperature for 1 h to bind the Raman label to the surface of Au nanoparticles.

[0054] (3) Preparation of Au@4-MBA@Ag nanoparticles

[0055] The Au@4-MBA seed solution was centrifuged at 6000 rpm for 5 min to remove the supernatant. It was resuspended and dispersed with 2 mL of 0.01 M CTAC solution, 0.4 mL of 0.1 M AgNO3 solution and 0.2 mL of 0.1 M ascorbic acid solution were added, and it was vigorously stirred for 5 min. Then the reaction solution was placed in a 60 °C water bath and stirred for 2 h to grow Ag nanoshells on the surface of the Au@4-MBA nanomaterial.

[0056] Example 2. Preparation of a Raman biosensor based on Au@4-MBA@Ag

[0057] (1) Silicon wafer treatment

[0058] The silicon wafer was cut into 1 cm × 1 cm square blocks, and the surface protective film was removed. After ultrasonic cleaning the silicon wafer in absolute ethanol and UP water, the silicon wafer was immersed in piranha solution (volume ratio concentrated sulfuric acid: 30% hydrogen peroxide = 7:3) for 30 min, and then the silicon wafer was ultrasonically cleaned with UP water.

[0059] The treated silicon wafer was immersed in 2 mL of 5% 3-aminopropyltriethoxysilane solution (APTES) for 30 min to make the surface of the silicon wafer positively charged.

[0060] (2) Connecting Au@4-MBA@Ag to the silicon wafer surface

[0061] The prepared Au@4-MBA@Ag nano solution was centrifuged at 4000 rpm for 5 min, the supernatant was discarded, and it was washed three times with 1% PVP ethanol, and then the Au@4-MBA@Ag nanoparticles were dispersed with 1% PVP ethanol solution. The silicon wafer prepared in the previous step was placed in the Au@4-MBA@Ag nanoparticle solution and soaked overnight, so that the negatively charged nanoparticles were adsorbed onto the positively charged silicon wafer surface by electrostatic adsorption.

[0062] (3) sPD-L1 antibody conjugation

[0063] The silicon wafer adsorbed with Au@4-MBA@Ag nanomaterials was rinsed thoroughly with 1ⅹPBS to remove the nanoparticles that were not firmly adsorbed on the surface. The silicon wafer was placed in NHS / EDC activation solution and activated at room temperature for 1 h. The surface of the silicon wafer was rinsed with 1ⅹPBS, and then the silicon wafer was placed in a 2 mL drop of 10 ng / mL sPD-L1 monoclonal antibody solution and left overnight at 4 °C to allow the antibody to bind to the surface of the nanomaterials. After the silicon wafer was rinsed with 1ⅹPBS, it was placed in 2 mL of 1% BSA solution and incubated at 37 °C for 1 h to block the non-specific binding sites of the antibody, thus obtaining the PD-L1 Raman sensor.

[0064] Example 3. Characterization of Au@4-MBA@Ag Nanomaterials

[0065] The microstructure and appearance of the Au@4-MBA@Ag nanomaterials on the Si wafer were characterized using a field emission scanning electron microscope (SEM) under the conditions of resolution: 1.0 nm at 15 kV, electron beam current: 1 pA - 50 nA, magnification: 150 - 1,000,000 times, and imaging probes: SE, T1 (BSE), T2. The structure is as Figure 2 shown. At different positions on the surface of the Si wafer, the Au@4-MBA@Ag nanoparticles are distributed relatively evenly. The nanoparticles are polygonal granular, with relatively uniform particle sizes, and the particle size range is 0.08 - 0.35 μm. The average particle size of the nanoparticles is about 0.20 μm ( Figure 3 ). At the same time, the nanomaterials were scanned by energy-dispersive X-ray spectroscopy (EDS) to analyze the element distribution and content of the nanomaterials. The structure is as Figure 4 shown. The nanoparticles contain Au and Ag elements, and at the same time contain the S element unique to the 4-MBA Raman tag molecule, indicating the successful synthesis of the material. Figure 5 This is the XRD pattern of the Au@4-MBA@Ag nanomaterials. At 38.2°, 44.6°, 64.9°, 77.9°, and 81.8°, they correspond to the (111), (200), (220), (311), and (222) planes of Au and Ag crystals respectively, and 12.1° represents the characteristic peak of carbon (001) plane.

[0066] Example 4. Optimization of the Amount of PVP in the Synthesis of Au@4-MBA@Ag Composite Materials

[0067] During the preparation of the Au@4-MBA seed solution in Reference Example 1, after the gold nanoparticle solution reacted for 4 h, it was centrifuged at 6000 rpm for 5 min. The precipitate was resuspended and dispersed with 5 mL of 1%, 1.5%, and 2% PVP ethanol solutions respectively. 50 μL of 0.1 M 4-MBA solution was added to each, and the mixture was stirred at room temperature for 1 h to bind the Raman label to the surface of the Au nanoparticles. Then, Ag nanoshells were coated under the same conditions respectively, centrifuged, and the nanoparticles were resuspended with absolute ethanol to detect the signal molecule intensity of the nanoparticles prepared at different PVP concentrations. The results are as Figure 6 shown that when the PVP content is 1.5%, the signal of the nanoparticles is the best.

[0068] Example 5. Sensitivity experiment of the sPD-L1 Raman sensor

[0069] The sPD-L1 antigen solution was prepared into antigen solutions with different gradient concentrations of 0.01 pg / mL, 0.1 pg / mL, 1 pg / mL, 10 pg / mL, 100 pg / mL, 1000 pg / mL, 10000 pg / mL, and 100000 pg / mL. The Raman biosensor silicon wafers prepared in Example 2 were taken and placed in antigen solutions with different concentrations, incubated at 37 °C for 30 min, and then the electrode surface was rinsed with PBS to detect the characteristic peak intensity of the Raman signal molecules at different antigen concentrations. For example, the Raman program was selected with the Raman OceanView 2.0.7 software, and the test was carried out with a Raman portable spectrometer under the conditions of 785 nm, 150 W, and an integration time of 5 s to detect the characteristic peak spectrum of 4-MBA and study the relationship between the characteristic peak intensity of 4-MBA and the antigen concentration.

[0070] The results are as Figure 7 shown that the sPD-L1 antigen has a linear relationship between the logarithm of the characteristic peak intensity of the 4-MBA Raman signal molecule and the logarithm of the sPD-L1 antigen concentration in the concentration range of 0.1 pg·mL -1 ~10 4 ng·mL -1 : The linear fitting curve equation is Y = 0.08465X + 3.67384, and the linear correlation coefficient R -1 = 0.99844, with good linearity, and the lower detection limit is 0.4731 pg / mL.. 2

[0071] Example 6. Repeatability and stability experiments of the sPD-L1 Raman sensor

[0072] Five Raman sensing substrate silicon wafers of the same batch prepared by the same method as in Example 2 were subjected to immunosensing tests to measure their reproducibility. According to the same treatment method, an sPD-L1 antigen solution of the same concentration was measured. The Raman signal molecule 1074 cm -1 The signal intensity of the characteristic peak at the displacement was recorded. Another batch of the same prepared Raman sensor silicon wafers was stored at room temperature, sealed, and away from light, and taken out on the 2nd, 4th, 6th, 8th, 10th, 12th, and 14th days for detecting the sPD-L1 antigen solution of the same concentration. The experimental results Figure 8 are shown as follows, further indicating that the sensor has good reproducibility and stability.

[0073] Example 7. Specificity experiment of the sPD-L1 Raman sensor

[0074] To evaluate the specificity of the sensor, the same concentration of des-γ-prothrombin (DCP), soluble fms-like tyrosine kinase-1 (SFLT-1), neuron-specific enolase (NES), placental growth factor (PLGF), and sPD-L1 antigen were detected using the same batch of prepared Raman sensors, and the signal intensity of the characteristic peak of the Raman signal molecule 1074 cm -1 was observed. The results are as Figure 9 shown, indicating that the sensor has good specificity.

[0075] Example 8. Clinical experiment of the sPD-L1 Raman sensor

[0076] To test whether the sPD-L1 Raman immunosensor has recognition performance for clinical samples, clinical serum samples of liver cancer patients and normal healthy people were used for testing, and the intensity of the characteristic peak of the Raman label 4-MBA at 1074 cm -1 displacement was observed. Four positive liver cancer sera (SP1 - SP4) and three negative sera (SN1 - SN3) collected were grouped according to the AFP (alpha-fetoprotein) concentration from high to low. Each group of samples was independently tested three times, and the sPD-L1 Raman sensor was used for detection. The results of the measured characteristic peak intensities are as Figure 10 shown. For the sera of liver cancer patients with high AFP expression, the characteristic peak at 1074 cm -1 displacement of the sPD-L1 Raman sensor was significantly enhanced. For the sera of healthy controls, the characteristic peak at 1074 cm -1 displacement of the sPD-L1 Raman sensor was enhanced less. Table 1 shows the AFP content values in the sera of liver cancer patients and healthy controls detected by chemiluminescence method in Anhui Provincial People's Hospital. Itensity (a.u) is the average value of the characteristic peak intensities at 1074 cm -1 displacement of the sPD-L1 Raman biosensor detecting the sera of the same liver cancer patients and healthy controls three times.

[0077] Table 1 AFP detection values of clinical serum samples and Raman sensor characteristic peak intensities

[0078]

[0079] The above-described embodiments are merely preferred embodiments given to fully illustrate the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art on the basis of the present invention are all within the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. A sensor for detecting sPD-L1 based on surface-enhanced Raman scattering, characterized in that, Comprises the following structures: a) A silicon wafer substrate, the surface of which is modified by aminosilane and is positively charged; b) Au@4-MBA@Ag core-shell nanomaterials loaded on the surface of the silicon wafer, wherein: i. Au is the nanocore, the surface of which is modified with the Raman tag molecule 4-MBA, and the outermost layer is further coated with an Ag nanoshell layer; ii. The weight percentages of the main elements in the Au@4-MBA@Ag core-shell nanomaterials are O 58.42%, Au 28.76, Ag 10.82, C 1.53%, and S 0.47%; c) sPD-L1 antibodies coupled to the surface of the Ag nanoshell layer for specifically capturing target antigens.

2. The sensor according to claim 1, characterized in that, The particle size range of the Au@4-MBA@Ag core-shell nanomaterials is 0.08 - 0.35 μm.

3. The sensor according to claim 1, characterized in that The sPD-L1 antibodies are covalently bound to the Ag shell layer by the EDC / NHS activation method.

4. The sensor according to claim 1, characterized in that The conjugation amount of the sPD-L1 antibody is 10 - 30 ng / cm 2 .

5. The sensor according to claim 1, characterized in that, The preparation method of the Au@4-MBA@Ag core-shell nanomaterials comprises the following steps: a) Using CTAC as a template agent, preparing Au nanocores by reducing HAuCl4 with NaBH4; b) In a PVP ethanol solution, binding 4-MBA to the Au nanocores to form Au@4-MBA; c) Reducing AgNO3 with ascorbic acid to grow an Ag nanoshell layer on the surface of Au@4-MBA.

6. The sensor according to claim 5, characterized in that In step b), the mass-volume fraction of the PVP ethanol solution is 1% - 2%, the reaction temperature is 25 - 30 °C, and the reaction time is 1 - 2 hours.

7. A cancer auxiliary diagnosis kit, characterized in that, Contains the following components: a) The sensor according to any one of claims 1 - 6; b) An sPD-L1 standard antigen concentration gradient test solution with a concentration range of 0.1 pg / mL - 104 pg / mL.

8. The method of using the cancer adjuvant diagnosis kit according to claim 7, wherein the method is for non-disease diagnosis and treatment purposes, and is characterized in that, Comprises the following steps: a) Contacting the sample to be tested with the sensor, so that the sPD-L1 antigen in the sample specifically binds to the sPD-L1 antibody; b) Using a Raman spectrometer, exciting with a 785 nm laser, and detecting the intensity of the 4-MBA characteristic peak at 1074 cm-1; c) Calculating the concentration of the sPD-L1 antigen in the sample to be tested according to the linear relationship between the logarithm of the characteristic peak intensity and the logarithm of the sPD-L1 standard antigen concentration.

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