A sensitized gold-plated tilted fiber Bragg grating SPR sensor and its application

Abstract

The present invention relates to a sensitized gold-plated tilted fiber Bragg grating (SPR) sensor and its application. The present invention discloses a gold-plated tilted fiber Bragg grating (SPR) sensor structure sensitized by AuNPs@Ta2C-Mxene and a SARS-CoV-2 detection and analysis method. Based on the traditional gold film sensitization layer structure, the novel two-dimensional material Ta2C-Mxene is introduced, and an in-situ reduction method is used to achieve uniform doping of AuNPs on the surface of the two-dimensional material. To achieve specific detection of novel coronavirus molecules, Ta2C-Mxene is amino-functionalized to provide binding sites for the covalent immobilization of protein receptors on the surface of the virus spike. An innovative segmented secondary probe modification method is proposed to form a novel probe-type TFBG biosensor platform in which AuNPs@Ta2C-Mxene is coated with a gold film, enabling trace detection of novel coronavirus molecules.

Description

Technical Field

[0001] The present invention belongs to the technical field of tilted Bragg grating biosensors, and specifically relates to a sensitized gold-plated tilted fiber Bragg grating (SPR) sensor, a method for constructing the SPR sensor, a microfluidic chip based on the SPR sensor, and its application in the detection of the new coronavirus. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] Tilted fiber Bragg grating (TFBG) sensors based on surface plasmon resonance (SPR) have become a hot topic of research due to their advantages such as label-free, real-time detection, easy miniaturization, and rapid detection. This type of sensor significantly increases the surface energy state density of the sensor due to the periodic modulation of the core refractive index. It has a high-density narrow-linewidth spectral comb, which can achieve the excitation of SPR signals in a wide refractive index range and achieve ultra-low detection limit measurement. Traditional plasmon (SPP) layers are mostly precious metals such as gold and silver. This type of sensor has the following disadvantages: (1) The structure of the sensitization layer is simple and cannot meet the requirements of trace detection of biomolecules; (2) The bioaffinity is poor and the molecular capture ability is poor; (3) The specific surface area is small and the molecular loading density on the sensor surface is low. Therefore, it is necessary to develop a high-performance TFBG sensor with a new sensitization structure.

[0004] Nanomaterial-enhanced SPR sensing strategies have greatly improved sensing performance. Compared to two-dimensional materials such as graphene, black phosphorus, and MoS2, MXene possesses superior metallic conductivity, surface hydrophilicity, large specific surface area, and broadband light absorption. The novel two-dimensional material Ta2C-MXene is doped with AuNPs to create an AuNPs@Ta2C-MXene sensitizing layer structure. The doped AuNPs, under the action of evanescent wave excitation, can generate localized surface plasmon resonance (LSPR) effects. The strong electromagnetic coupling between the evenly distributed AuNPs and the Au film transforms the sensor response signal from a single SPP enhancement to SPP-LSP coupling, effectively amplifying the SPR propagation efficiency. As a substrate for AuNPs, the large surface area of Ta2C-MXene provides more binding sites for the AuNPs. Furthermore, the metallic properties of Ta2C-MXene introduce stronger carrier mobility, effectively improving the detection performance of the sensor. Currently, AuNPs@Ta2C-Mxene is typically prepared by chemical reduction, where a mixture of NaBH4 and NaOH is reacted with HAuCl4·3H2O as a reducing agent. The resulting AuNPs@Ta2C-Mxene is then self-assembled on Au / TFBG via photoinduced deposition. However, the presence of gold nanoparticles makes the prepared AuNPs@Ta2C-Mxene prone to agglomeration, affecting the material's performance. Furthermore, during the self-assembly process, it is difficult to form a uniform and complete two-dimensional material film. Summary of the Invention

[0005] This invention provides a micron-scale optical fiber that can be packaged into a probe-type TFBG sensor structure, creating a stable and highly sensitive biomolecule detection platform. This probe-type sensing structure overcomes the limitations of traditional transmissive TFBGs in engineering applications, which are limited in size and inability to perform in-situ detection. Furthermore, in a reflective optical path, input light undergoes secondary coupling at the grating region, resulting in greater sensitivity to changes in external parameters compared to single-coupling transmissive gratings, enabling low-concentration detection of biomolecules.

[0006] Based on the above technical effects, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides a sensitized gold-plated tilted fiber Bragg grating (SPR) sensor. The sensor is based on a tilted fiber Bragg grating (FBG). The upper and lower surfaces of the body are sequentially covered with a gold coating and an amino-modified two-dimensional material (N-Ta2C-MXene). The surface of the two-dimensional material is doped with gold nanoparticles (AuNPs) and modified with probe molecules.

[0008] Preferably, the modulation tilt angle of the tilted fiber Bragg grating is 10 to 14°.

[0009] Preferably, the optical fiber is a single-mode quartz optical fiber, including a core and a cladding, wherein the core has a grating inscribed thereon, and the refractive index of the core and the cladding is 1.400-1.500.

[0010] Preferably, the thickness of the gold coating is 50±5 nm, and the particle size of the gold nanoparticles is 20±5 nm.

[0011] The aforementioned SPR sensor incorporates a novel sensitizing composite structure, AuNPs@Ta2C-MXene / Au. The uniformly distributed AuNPs generate a localized plasmon resonance (LSP) effect under the influence of the evanescent field, which couples with the surface plasmon (SPP) resonance in the Au film. The unique metallic two-dimensional material of Ta2C-MXene enhances carrier mobility, further strengthening the resonance effect between the evanescent wave and the surface plasmon. The combined sensitization of the Au film by the LSP+SPP coupling mode and the metallic properties of MXene significantly enhances the SPR signal, significantly improving the sensor's sensitivity and enabling ultra-low detection limits for molecular measurements.

[0012] Preferably, the probe molecule is a marker molecule capable of indicating a specific nucleic acid, protein or cell, including nucleic acid probes, polypeptide probes and probe compounds; further preferably, the probe molecule is a nucleic acid chain or polypeptide chain that specifically binds to a target protein.

[0013] In a second aspect, the present invention provides a method for constructing the sensitized gold-plated tilted fiber Bragg grating (SPR) sensor described in the first aspect. The construction method is characterized in that the gold coating and the amino-modified two-dimensional material are assembled as follows: triethylaminosilane (APTES) is used to perform functional group treatment on the two-dimensional material Ta2C-Mxene to obtain an amino-modified two-dimensional material, and a dispersion containing the amino-modified two-dimensional material is immersed in the gold coating-covered area of the main material to grow the two-dimensional material through photoinduced deposition.

[0014] To address the existing problem of gold nanoparticles easily agglomerating on the surface of two-dimensional materials, the present invention first deposits Ta2C-Mxene onto the Au / TFBG surface through photoinduced deposition. Leveraging the strong metal-carbon coupling between the Mxene and the gold coating, as well as the adsorption of the amino terminus of N-Ta2C-Mxene on the gold surface, the N-Ta2C-Mxene self-assembles onto the bare gold film. The gold particles are then directly reduced on the Ta2C-Mxene / Au / TFBG sensor surface via a self-reduction method, thereby improving the success rate of preparing AuNPs@Ta2C-Mxene / Au / TFBG. This preparation process does not require the introduction of an additional reducing agent, and the resulting AuNPs@Ta2C-Mxene / Au structure is uniform and complete, effectively reducing the probability of gold nanoparticle agglomeration and extending the service life of the SPR sensor.

[0015] Preferably, the specific steps of the functional group treatment are as follows: dispersing Ta2C-Mxene in an ethanol solution, slowly adding APTES to the above dispersion system, and stirring at room temperature for 20 to 30 hours to obtain the product.

[0016] Furthermore, the concentration of the ethanol solution is 18-22% (v / v).

[0017] Furthermore, in the above-mentioned dispersion system, the addition ratio of the Ta2C-Mxene to APTES is 8-12 mg: 75-85 μL.

[0018] Preferably, the assembly method of the above-mentioned amino-modified two-dimensional material and the gold coating is as follows: 0.8-1.2 mg / ml N-Ta2C-MXene dispersion is added to the main material with the gold coating, and the dispersion can immerse the gold coating coverage area, and grow for 1-3 hours at room temperature and under the irradiation of an excitation light source for assembly. After the above-mentioned assembly is completed, the step of cleaning the surface of the gold coating to remove unbound N-Ta2C-MXene is also included.

[0019] Furthermore, the excitation light source is a combination light source of ASE-CL-30-M and SLD-1470-10-B.

[0020] Preferably, the above construction method further includes in-situ doping of gold nanoparticles on the surface of the two-dimensional material. The specific steps are as follows: adding HAuCl4 solution to the main material of the above-mentioned two-dimensional material assembly that has completed the amino treatment and letting it stand.

[0021] Furthermore, the concentration of the HAuCl4 solution is 0.08-0.12 g / mL.

[0022] Furthermore, the standing time is 25 to 35 minutes.

[0023] In addition, the above-mentioned construction method also includes the steps of grating writing on the optical fiber surface and gold coating deposition, which can be constructed using conventional methods in the field. For example, the grating structure can be constructed by phase mask technology, keeping the laser beam, mask, and grating area on the same axis, and using ultraviolet laser to irradiate the mask to produce diffraction stripes of different orders; the gold coating deposition can be performed by thermal evaporation under vacuum conditions. In order to achieve a good coupling effect between the gold coating and the grating structure, in one embodiment provided by the present invention, the film layer is constructed by two deposition methods.

[0024] COVID-19 is a severe acute respiratory infectious disease caused by the novel coronavirus (SARS-CoV-2). Since its outbreak in 2019, the global cumulative number of confirmed cases of COVID-19 has exceeded 53.22 million, and the cumulative number of deaths has exceeded 6.3 million, and the data is still growing. Many studies have shown that COVID-19 can cause pulmonary fibrosis, damage the human metabolic system and central nervous system, etc. Therefore, it is of great significance to develop a method for rapid detection and diagnosis to block the spread of COVID-19. Based on the improvement in detection sensitivity of the above-mentioned SPR sensor, the present invention further provides its application in the detection of new coronavirus.

[0025] In a third aspect, the present invention provides a microfluidic chip for novel coronavirus detection, wherein the sensitized gold-plated tilted fiber Bragg grating (SPR) sensor described in the first aspect is fixed in the microfluidic chip, wherein the probe molecule is angiotensin-converting enzyme II (ACE2) spike protein receptor. The spike protein binds to the peptidase domain (PD) of ACE2 based on the RBD of the S1 subunit.

[0026] In terms of biological detection, the sensors prepared by the present invention show even greater advantages. Unlike graphene structures, the large number of hydrophilic functional groups on the MXene surface can easily bind to most organic solvents and organisms. In addition, the large specific surface area makes the MXene outer sensitive layer a perfect molecule enricher, providing a large number of binding sites for biomolecular probes. However, when performing biomolecule modification, traditional single modification will reduce the affinity of the MXene material for the biomolecule solution due to insufficient discharge of water molecules on the MXene surface, affecting the binding rate of the probe molecules. Therefore, in the construction of the above-mentioned microfluidic chip, the bioprobe modification adopts a "segmented secondary modification" method. Through the "pre-soak + re-soak" mechanism, it compensates for the low biomodification efficiency caused by the van der Waals force of the liquid-based environment under traditional single modification, effectively increasing the loading density of the probe molecules.

[0027] Preferably, the microfluidic chip is constructed as follows: a fiber Bragg grating doped with gold nanoparticles is fixed in a microfluidic chip, a solution containing ACE2 is added and pre-soaked for 1.5 to 2.5 hours, the surface of the optical fiber is cleaned with PBS buffer, and the solution containing ACE2 is added again and allowed to stand for 1.5 to 2.5 hours. After cleaning, a bovine serum albumin solution is added to block the non-specific active sites on the chip surface.

[0028] Furthermore, in the solution containing ACE2, the receptor concentration is 80-120 μg mL -1 .

[0029] Furthermore, the ACE2 is first activated using a mixed solution of EDC and NHS, with an activation time of 10 to 20 minutes and an activation temperature of 3 to 5°C.

[0030] Furthermore, the sequence of the probe molecule is: MSSSSWLLLSLVAVTAA.

[0031] In a fourth aspect, the present invention provides a method for detecting the new coronavirus, which is as follows: the microfluidic chip described in the third aspect is connected to the optical path, so that the optical path includes a light source, a polarizer, a polarization controller, a microfluidic detection chip and a spectrometer in sequence; the solution to be tested is pushed through the SPR sensor and the SPR signal offset of the sensor is recorded.

[0032] Preferably, the above detection method further comprises a step of cleaning the surface of the microfluidic chip before applying the test solution; a specific cleaning method is, for example, to clean the microfluidic chip by pushing deionized water at a flow rate of 3 to 6 μL / min.

[0033] Preferably, the flow rate of the test solution is 3 to 6 μL / min.

[0034] Preferably, the correlation between the concentration of the spike protein solution (pM) and the sensor wavelength signal (nm) is as follows: y=0.00325lgx+1533.49346. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0036] Figure 1 The structure and application flow chart of the AuNPs@Ta2C-Mxene-sensitized gold-plated tilted fiber Bragg grating SPR sensor;

[0037] Figure 2 It is a probe-based biomolecule detection platform;

[0038] Figure 3 Flow chart for biomolecule detection;

[0039] Figure 4 is the reflectance spectrum SPR detection signal;

[0040] Among them, (a) is the sensor signal spectrum; (b) and (c) are the sensor signals of single modification and segmented secondary modification respectively; (d) is the linearity, sensitivity and detection limit of the sensor SPR peak. DETAILED DESCRIPTION

[0041] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0042] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0043] In summary, the present invention proposes a method for preparing an AuNPs@Ta2C-MXene / Au / TFBG biosensor and detecting and analyzing SARS-CoV-2. The amino-treated Ta2C-MXene nanocomposite is assembled on the surface of a gold film, and an in-situ reduction method is used to achieve uniform doping of AuNPs in the Ta2C-MXene. A segmented secondary modification method is used to achieve covalent immobilization of the SARS-CoV-2 spike surface protein receptor (angiotensin converting factor II, ACE2) on the sensor surface. Furthermore, specific and rapid detection of SARS-CoV-2 is achieved by directly identifying the expression of the spike surface protein.

[0044] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0045] Example 1

[0046] This embodiment specifically provides a AuNPs@Ta2C-Mxene-sensitized gold-plated tilted fiber Bragg grating SPR sensor structure and a SARS-CoV-2 detection and analysis method, the implementation steps of which are as follows:

[0047] In this embodiment, the experimental equipment models used are:

[0048] A Yokogawa AQ 63700 spectrometer was used for spectral modulation and analysis.

[0049] The model of the polarizer is MCILP-1550-00-S2-P15-10-L-FA, which is used to ensure the polarization of the light source.

[0050] The polarization controller model is: MP-900UM.

[0051] The spectrometer model is: YOKOGAWA-AQ 63700.

[0052] The microfluidic model is: QHZS-001B. The optical fiber writing light source is complex11pro.

[0053] Source of experimental materials:

[0054] Ta2C-MXene was purchased from Jipu Nano Co., Ltd., gold hypochlorite trihydrate (HAuCl4·3H2O), sodium borohydride (NaBH4), and sodium hydroxide (NaOH) were purchased from Lanyu Co., Ltd., bovine serum albumin solution (BSA), phosphate buffered saline (PBS), and triethylaminosilane (APTES) were purchased from Sinopharm Chemical Reagent Co., Ltd., and N-hydroxysuccinimide (NHS) and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) were purchased from Baiweiling Technology Co., Ltd.

[0055] 1. Preparation of TFBG fiber

[0056] Single-mode quartz fiber is used for inscription, with the following parameters: core diameter: 8.2 μm, refractive index 1.4500; cladding diameter: 125 μm, refractive index 1.4765. The fiber is pre-treated with hydrogen to enhance the core's photosensitivity. A 60-80 cm length of fiber is taken, and a 1.5-2 cm cladding region is removed from the center to inscribe the grating structure. After wiping it clean with alcohol, the fiber is fixed to the inscription platform. The grating structure is obtained using phase mask technology. The laser beam, mask, and grating area are kept on the same axis. A 248 nm wavelength ultraviolet laser is used to illuminate the mask to produce diffraction fringes of different orders, creating a permanent refractive index modulation within the fiber core. A tilted grating structure can be obtained by rotating the mask along the axis by a certain angle.

[0057] The phase mask parameters are as follows: center-to-center spacing = 1099.05 nm, mask length = 10 mm, mask height = 15 mm, substrate length = 17.17 mm, substrate height = 25.4 mm. The grating modulation tilt angle is 12°. An excimer laser operating in the ultraviolet band at 248 nm is used, with the laser operating frequency, voltage, energy, power, and pressure being 50 Hz, 25 kV, 160 MJ, 7.92 W, and 3366 mbar, respectively. To complete the Bragg grating inscription, the polished portion is exposed to UV light for 25 minutes. The prepared TFBG is then stored at 100°C for 48 hours to remove hydrogen.

[0058] 2. Au film deposition

[0059] The gold film is deposited using vacuum thermal evaporation. To ensure good coupling between the TFBG cladding mode and the gold film SPR, a two-step deposition process is employed. The deposited film layers cover the upper and lower reflection directions of the grating, respectively, to achieve maximum light field energy coupling. The specific implementation method is as follows:

[0060] The optical fiber is fixed on the substrate, and then the optical fiber, tungsten evaporation boat, and gold target (purity 99.999%) are placed in the evaporation chamber. When the vacuum degree is lower than 7×10 -5 When the current is below 50A, the deposition rate can be increased gradually. Once the rate stabilizes, the substrate shutter is opened and evaporation begins. The film thickness is monitored using a quartz crystal film thickness monitor. Evaporation is stopped when the thickness reaches 50 nanometers, completing one gold film deposition cycle. The fiber is removed, rotated 180° along its axis, and the above evaporation steps are repeated to obtain a uniformly coated TFBG with a gold film.

[0061] 3. Amino functionalization of Ta2C-Mxene

[0062] First, Ta2C-MXene (10 mg) was dispersed in 10 mL of deionized water and sonicated for 2 h. After standing for 10 minutes and removing the precipitate, Ta2C nanosheets were obtained. Then, the two-dimensional material Ta2C-MXene was functionalized with triethylaminosilane (APTES). 10 mg of Ta2C-MXene was dispersed in ethanol and deionized water (DI) with a volume ratio of 1:4. 80 μL of APTES was then slowly added to the above solution and stirred at room temperature at 800 rpm for 24 h. The obtained product was washed several times with DI water to remove unbound APTES. The purified product was vacuum-dried at 50°C overnight and then dispersed in deionized water to prepare N-Ta2C-MXene (1 mg / ml) solution, which was stored at 4°C for later use.

[0063] 4. In situ reduction preparation of AuNPs@Mxene

[0064] First, the assembly of gold-coated TFBG and N-Ta2C-MXene was achieved through photoinduced deposition. The synthesized N-Ta2C-MXene dispersion was injected into a reaction vessel and completely immersed in the TFBG grating area for 2 hours. The strong metal-carbon coupling between MXene and the gold chip surface and the adsorption of the amino terminus of N-Ta2C-MXene on the gold surface were utilized to complete the autonomous assembly of N-Ta2C-MXene on the bare gold film. DI water was then injected and circulated in the microfluidic chip (at a rate of 6.5 mm / min) for 10 minutes to remove any unbound N-Ta2C-MXene.

[0065] Then, the in-situ doping of AuNPs was achieved by self-reduction method. 300 μL of 0.1 g / mL HAuCl4·3H2O was added to the reaction vessel and allowed to stand for 30 min. The surface of Ta2C-Mxene contains a large number of oxygen-containing groups, among which -OH can directly convert AuCl4 in HAuCl4·3H2O into - Reduction to obtain AuNPs (the particle size of AuNPs is proportional to the reaction time, where the average particle size of Au particles can be concentrated at 20±5nm when the reaction time is 30min):

[0066]

[0067] Finally, the DI water washing process was repeated to remove the excess unreacted HAuCl4, thereby achieving uniform dispersion of AuNPs on Ta2C-Mxene / Au / TFBG.

[0068] 5. Modification of Probe Molecules

[0069] The AuNPs@Ta2C-Mxene / Au / TFBG was immobilized in a microfluidic chip of a biological detection platform. The microfluidic chip channel parameters were as follows: width: 2 μm, height: 2 μm, and length: 3.8 cm.

[0070] First, 500 μL of ACE2 solution (100 μg mL) was treated with EDC (0.2 mol L-1) and NHS (0.05 mol L-1) at 4 °C. -1) was activated for 15 min; then, a “2h+2h” segmented secondary modification method was adopted to fix it on the N-Ta2C-MXene nanosheet based on the covalent bond between the amino group of the N-Ta2C-MXene nanosheet and the carboxyl group at the end of the polypeptide chain of the probe molecule. (1) ACE2 was injected into the microfluidic chip and pre-soaked for 2 hours. The purpose was to squeeze water molecules out of the Ta2C-Mxene surface, thereby greatly reducing the repulsion of water molecules on the Mxene surface to the ACE2 solution; (2) PBS buffer was circulated in the microfluidic chip (speed: 6.5mm / min) for 10 minutes to remove any unbound probe molecules; (3) The TFBG gate area was immersed in the ACE2 solution again and allowed to stand for 2 hours before repeating step (2). In this step, the increased affinity of Mxene for the probe molecules after pre-soaking increased the diffusion rate and reaction efficiency of the probe molecules, thereby effectively ensuring the binding rate of the probe molecules; finally, 10mg / ml bovine serum albumin (BSA) was injected into the microfluidic chip and incubated at room temperature for 20 minutes so that BSA could block non-specific active sites on the sensor chip. Finally, the cleaning process was repeated to ensure that no excess residual molecules affected the detection process.

[0071] To further illustrate the advantages of segmented secondary modification, a comparative experiment was set up, using the "4h" single modification method to complete the surface modification process of the spike protein receptor according to the above steps.

[0072] 6. Biodetection process of AuNPs@Ta2C-Mxene / Au / TFBG sensor

[0073] The segmented secondary modified and single modified AuNPs@Ta2C-MXene / Au / TFBG sensors were fixed in the microfluidic chip, respectively, and then connected to the optical path consisting of a light source, a polarizer, a polarization controller and a spectrometer. Figure 2 During the experiment, the polarization controller was first adjusted to make the sensor work in the TM mode. Then, the microfluidic chip sensing area was cleaned with deionized water (DI) at a flow rate of 5 μL / min. Finally, the test solution of different concentrations was pushed slowly through the sensing area at a speed of 5 μL / min. When the spike protein binds to the probe, the sensor surface quality increases, the medium refractive index increases, and the SPR signal shifts. The entire biological detection process is shown in Figure 2. Figure 3 As shown (it should be noted that each time the sample to be tested is changed, the microfluidic chip sensing area must be thoroughly cleaned with deionized water). The detection spectrum of each concentration of each sample to be tested is recorded, and the SPR signal is analyzed to evaluate the sensor performance. Figure 4 shown.

[0074] analyze Figure 4It can be seen that the concentration of the spike protein solution (lgx, where x is in pM) is linearly related to the wavelength signal of the TFBG sensor (y / nm). The linear relationship after least square fitting is y=0.00185lgx+1533.49122(R 2 =0.99513), the linear relationship of the piecewise quadratic modification is y=0.00325lgx+1533.49346(R 2 =0.99784); wherein the sensitivity of single modification is: The sensitivity of the segmented secondary modification was S = 0.00318; the minimum detection limit for single modification was 1 pM, and the minimum detection limit for segmented secondary modification was 0.1 pM. These results demonstrate that the segmented secondary modification sensor performs better than the single modification in terms of sensitivity, linearity, and detection limit. The secondary modification method can indeed increase the probe loading density and improve the capture ability of biomolecules.

[0075] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A sensitized gold-plated tilted fiber Bragg grating (SPR) sensor, characterized in that: The sensor is based on a tilted fiber Bragg grating, the upper and lower surfaces of which are sequentially covered with a gold coating and an amino-modified two-dimensional material, the surface of which is doped with gold nanoparticles and modified with probe molecules; The method for constructing the sensitized gold-plated tilted fiber Bragg grating (SPR) sensor comprises: The gold coating and the amino-modified two-dimensional material are assembled as follows: the two-dimensional material Ta2C-Mxene is functionalized using triethylaminosilane to obtain the amino-modified two-dimensional material, and the dispersion containing the amino-modified two-dimensional material is immersed in the gold coating-covered area of the main material to grow the two-dimensional material through photoinduced deposition; The method for assembling the amino-modified two-dimensional material and the gold coating is as follows: adding a 0.8-1.2 mg / ml N-Ta2C-MXene dispersion to a main material having a gold coating, wherein the dispersion is capable of immersing the area covered by the gold coating, and growing for 1-3 hours at room temperature under an excitation light source for assembly. After the above assembly is completed, the surface of the gold coating is cleaned to remove unbound N-Ta2C-MXene. The method for constructing the sensitized gold-plated tilted fiber Bragg grating (SPR) sensor further includes in-situ doping of gold nanoparticles on the surface of the two-dimensional material. The specific steps are as follows: adding HAuCl4 solution to the main material of the two-dimensional material assembly after the amino reaction and allowing it to stand.

2. The sensitized gold-plated tilted fiber Bragg grating (SPR) sensor according to claim 1, wherein: The concentration of the HAuCl4 solution is 0.08-0.12 g / mL.

3. The sensitized gold-plated tilted fiber Bragg grating (SPR) sensor according to claim 1, wherein: The standing time is 25 to 35 minutes.

4. The sensitized gold-plated tilted fiber Bragg grating (SPR) sensor according to claim 1, wherein: The modulation tilt angle of the tilted fiber Bragg grating is 10 to 14 degrees; Alternatively, the optical fiber is a single-mode quartz optical fiber, comprising a core and a cladding, wherein the core has a grating inscribed thereon, and the refractive index of the core and the cladding is 1.400 to 1.500; Alternatively, the thickness of the gold coating is 50±5 nm, and the particle size of the gold nanoparticles is 20±5 nm.

5. The sensitized gold-plated tilted fiber Bragg grating (SPR) sensor according to claim 1, wherein: The probe molecules are labeling molecules that can indicate specific nucleic acids, proteins or cells, including nucleic acid probes, polypeptide probes and probe compounds.

6. The sensitized gold-plated tilted fiber Bragg grating (SPR) sensor according to claim 5, characterized in that: The probe molecule is a nucleic acid chain or a polypeptide chain that specifically binds to a target protein.

7. The sensitized gold-plated tilted fiber Bragg grating (SPR) sensor according to claim 1, wherein: The specific steps of the functional group treatment are as follows: dispersing Ta2C-Mxene in an ethanol solution, slowly adding APTES to the above dispersion system, and stirring at room temperature for 20 to 30 hours to obtain the obtained product.

8. The sensitized gold-plated tilted fiber Bragg grating (SPR) sensor according to claim 7, wherein: The concentration of the ethanol solution is 18-22%.

9. The sensitized gold-plated tilted fiber Bragg grating (SPR) sensor according to claim 7, characterized in that: In the dispersed system, the addition ratio of the Ta2C-Mxene to APTES is 8-12 mg: 75-85 μL.

10. A microfluidic chip for detecting the novel coronavirus, wherein the sensitized gold-plated tilted fiber Bragg grating (SPR) sensor according to any one of claims 1 to 9 is fixed in the microfluidic chip, wherein: The probe molecule is the spike protein receptor ACE2.

11. The microfluidic chip for detecting novel coronavirus according to claim 10, characterized in that: The microfluidic chip is constructed as follows: a fiber Bragg grating doped with gold nanoparticles is fixed in the microfluidic chip, a solution containing ACE2 is added and pre-soaked for 1.5 to 2.5 hours, the surface of the fiber Bragg grating is cleaned with PBS buffer, the solution containing ACE2 is added again and allowed to stand for 1.5 to 2.5 hours, and after cleaning, a bovine serum albumin solution is added to block the non-specific active sites on the chip surface.

12. The microfluidic chip for detecting novel coronavirus according to claim 11, characterized in that: In the solution containing ACE2, the ACE2 concentration is 80-120 μg mL -1 .

13. The microfluidic chip for detecting novel coronavirus according to claim 11, characterized in that: The ACE2 is activated in advance using a mixed solution of EDC and NHS, with an activation time of 10 to 20 minutes and an activation temperature of 3 to 5°C.

14. The microfluidic chip for detecting novel coronavirus according to claim 10, characterized in that: The sequence of the probe molecule is: MSSSSWLLLSLVAVTAA.

15. A method for detecting a novel coronavirus, characterized in that: The detection method is as follows: connecting the microfluidic chip described in any one of claims 10 to 14 to an optical path, so that the optical path includes a light source, a polarizer, a polarization controller, a microfluidic detection chip and a spectrometer in sequence; pushing the solution to be tested to flow through the SPR sensor and recording the SPR signal offset of the sensor.

16. The method for detecting the novel coronavirus according to claim 15, wherein: The detection method further includes a step of cleaning the surface of the microfluidic chip before applying the test solution; specifically, the microfluidic chip is cleaned by pushing deionized water at a flow rate of 3 to 6 μL / min.

17. The method for detecting the novel coronavirus according to claim 16, wherein: The flow rate of the solution to be tested is 3-6 μL / min.

18. The method for detecting the novel coronavirus according to claim 16, wherein: The correlation between the concentration of the spike protein solution and the sensor wavelength signal is as follows: y = 0.00325lgx + 1533.49346.

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