A thin film biosensor based on magnetoelectric coupling and its preparation method

Abstract

The invention belongs to the technical field of biosensors, and relates to a thin film biosensor based on magnetoelectric coupling and a preparation method thereof; the invention comprises a flexible substrate, wherein the flexible substrate is provided with a hollow area, one side of the flexible substrate carries a sandwich structure film, and the other side carries a conductive layer; one side of the sandwich structure film located in the hollow area is provided with a sensing layer, and the other side is provided with a nano gold layer; the sensing layer and the conductive layer are located on the same side of the sandwich structure film; the sandwich structure film is composed of upper and lower PDMS films and a magnetic film arranged in the middle; the biosensor is placed in a magnetic field, and the invention generates surface stress under the action of the magnetic field to make the film deform more violently, thereby realizing magnetoelectric coupling in the biosensor; the addition of a uniform magnetic field improves the sensitivity of the biosensor.

Description

Technical Field

[0001] The invention belongs to the technical field of biosensors and relates to a thin film biosensor based on magnetoelectric coupling and a preparation method thereof. Background Art

[0002] With the development of bio-MEMS technology, microstructures have received extensive attention and application in the field of biochemical sensing. Surface stress biosensor is a type of biosensor that can be used in clinical medical diagnosis, biochemical detection, new drug discovery and other fields. The detection principle of surface stress biosensor is to modify the sensor with specific probes to achieve qualitative analysis of the biological molecules to be tested; after the molecules to be tested combine with their corresponding probes, the sensitive parts of the sensor will produce a slight deformation, and the stress generated by the combination of molecules to be tested with probes of different concentrations is different. By detecting the electrical signals of different deformations, quantitative analysis of the concentration of the molecules to be tested can be achieved.

[0003] Micromechanical biosensors are widely used in medical diagnosis due to their high sensitivity, good repeatability and strong anti-interference ability, and have therefore become a research hotspot in the field of biosensors. Micromechanical biosensors are analytical devices for qualitative detection of biomolecules. The biosensor system consists of a sensitive layer and a conversion layer. Surface stress derived from hydrogen bonds, van der Waals forces, electrostatic forces or chemical adsorption between molecules causes the sensitive elements of the biosensor to deform, thereby converting biological signals into physical signals and realizing the analysis of biomolecules. Thin-film biosensors have become the main research target due to their high sensitivity, repeatability and strong anti-interference ability.

[0004] As a new type of sensing device, force-magnetic coupling biosensor can realize intelligent human-machine interaction and monitor chronic diseases and other health conditions in real time. It is a scientific technology with important innovations. As a strategic emerging industry in various countries, it has gradually penetrated into various fields such as medicine, pharmaceuticals, food, agriculture, and security defense. At present, how to achieve effective conversion of biological signals to surface stress and magnetic force on MXene / PDMS composite films, as well as the coupling of surface stress and magnetic force, and fundamentally improve the sensitivity of surface stress biosensors has become the main research direction. Summary of the invention

[0005] The present invention overcomes the shortcomings of the prior art, proposes a thin film biosensor based on magnetoelectric coupling and a preparation method thereof, and solves the problem of low sensitivity of current biosensors.

[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions.

[0007] A thin film biosensor based on magnetoelectric coupling comprises a flexible substrate, wherein the flexible substrate is provided with a hollow area, one side of the flexible substrate carries a sandwich structure film, and the other side carries a conductive layer;

[0008] The part of the sandwich structure film located in the hollow area is provided with a sensing layer on one side and a nano-gold layer on the other side; the sensing layer and the conductive layer are located on the same side of the sandwich structure film;

[0009] The nano-gold layer is used to modify antibodies; the antibodies are bound to the proteins to be tested;

[0010] The sandwich structure film is composed of upper and lower PDMS films and a magnetic film arranged between the upper and lower PDMS films.

[0011] Preferably, a flexible substrate having a hollow area is provided on one side of the sandwich structure film having the nano-gold layer, and the nano-gold layer is located in the hollow area.

[0012] Preferably, the sensing layer is a MXene or carbon nanotube film layer.

[0013] Preferably, the magnetic film is ferroferric oxide or terbium dysprosium iron film material.

[0014] Preferably, the conductive layer includes a second flexible substrate and a conductive silver paste attached to the second flexible substrate.

[0015] A method for preparing a thin film biosensor based on magnetoelectric coupling comprises the following steps:

[0016] 1) preparing a sandwich structure film, and transferring the sandwich structure film to one side of a flexible substrate; the upper surface of the sandwich structure film is bonded to the flexible substrate, and a nano-gold layer is prepared on the lower surface of the sandwich structure film located in the hollow area;

[0017] 2) preparing a conductive layer on the other side of the flexible substrate;

[0018] 3) preparing a sensing layer on the upper surface of the sandwich structure film located in the hollow area;

[0019] 4) immersing the sandwich structure film prepared in step 3) in a CYS solution to generate an aminated self-assembled monolayer to prepare a biosensor;

[0020] 5) Modify the antibody molecules onto the gold nanoparticle layer;

[0021] 6) Bind the protein to be tested to the antibody molecule;

[0022] 7) Placing the biosensor in a magnetic field and performing packaging testing.

[0023] Preferably, the method for preparing the sandwich structure film is to first spin-coat the magnetic material on the PDMS film to form a magnetic film, and then spin-coat another layer of PDMS film on the magnetic film.

[0024] Preferably, the nano-gold layer is prepared by immersing the sandwich structure film transferred to the flexible substrate in a mixed solution of chloroauric acid, glucose and potassium bicarbonate for 12-24 hours to obtain the nano-gold layer.

[0025] Preferably, conductive silver is offset-printed onto the upper surface of the second flexible substrate to obtain a conductive layer, and then the lower surface of the second flexible substrate is adhered to the other side of the flexible substrate carrying the sandwich structure film.

[0026] Preferably, the method for preparing the sensing layer is to drop the MXene solution into the hollow area.

[0027] The beneficial effects of the present invention compared with the prior art are as follows:

[0028] The surface stress generated by the specific binding of antibodies and proteins causes the biosensor to undergo mechanical deformation, resulting in changes in the pathway of the MXene film on the conversion layer of the biosensor, and then changes in the resistance of the biosensor, thereby achieving the function of converting biological signals into force signals and electrical signals. Afterwards, when the biosensor is placed in a uniform magnetic field, the ferroferric oxide film generates surface stress under the action of the magnetic field, further amplifying the film deformation.

[0029] The present invention increases the deformation of the PDMS film by introducing surface stress generated by antibody-modified proteins; the biosensor is placed in a magnetic field, and ferroferric oxide generates surface stress under the action of the magnetic field, making the film deformation more intense, thereby realizing magnetoelectric coupling in the biosensor; the addition of a uniform magnetic field improves the sensitivity of the biosensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the preparation of the sandwich structure film of the present invention;

[0031] Figure 2 is a cross-sectional view of the biosensor of the present invention;

[0032] Figure 3 This is a schematic diagram of the biosensor nanogold layer modified antibody molecule of the present invention;

[0033] In the figure: 1 is a flexible substrate, 2 is a sandwich structure film, 3 is a sensing layer, 4 is a nano-gold layer, 5 is a conductive layer, 6 is an antibody molecule, 7 is human serum albumin, and 8 is a second flexible substrate. DETAILED DESCRIPTION

[0034] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention is further described in detail in conjunction with the embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. The technical solutions of the present invention are described in detail below in conjunction with the embodiments and the accompanying drawings, but the scope of protection is not limited thereto.

[0035] Example 1

[0036] Reference Figure 2 and Figure 3 This embodiment discloses a thin film biosensor based on magnetoelectric coupling, including a flexible substrate 1, the flexible substrate 1 is provided with a hollow area, one side of the flexible substrate 1 carries a sandwich structure film 2, and the other side carries a conductive layer 5. Among them, the material of the flexible substrate 1 is PET, and the flexible substrate 1 in this embodiment is a ring-shaped structure with a hollow area in the middle. The sandwich structure film 2 is composed of upper and lower layers of PDMS films and a magnetic film arranged between the upper and lower layers of PDMS films, and the magnetic film is a magnetic film material such as ferroferric oxide or terbium dysprosium iron. The conductive layer 5 is a conductive silver glue layer.

[0037] The part of the sandwich structure film 2 located in the hollow area is provided with a sensing layer 3 on one side and a nano-gold layer 4 on the other side; the sensing layer 3 and the conductive layer 5 are located on the same side of the sandwich structure film 2; the side of the sandwich structure film 2 having the nano-gold layer 4 is also provided with a flexible substrate 1 having a hollow area, and the nano-gold layer 4 is located in the hollow area. The nano-gold layer 4 is used to modify the antibody molecule 6. Among them, the sensing layer 3 is a MXene or carbon nanotube film layer. The conductive layer 5 includes a second flexible substrate 8 and a conductive silver glue attached to the second flexible substrate 8. The structure of the second flexible substrate 8 is the same as that of the flexible substrate 1.

[0038] Example 2

[0039] A method for preparing a thin film biosensor based on magnetoelectric coupling, specifically comprising the following steps:

[0040] S1, preparation of sandwich structure film 2 (such as Figure 1 shown)

[0041] S1.1. Using Sylgard 184, Dow Corning as raw materials, mix the prepolymer and curing agent in a weight ratio of 10:1 and stir evenly. Use a degassing machine to remove bubbles from the mixture. Then let it stand for 10-15 minutes, and use a spin coater to spin-coat PDMS on a glass substrate to form a thin film. Put the film on a drying table at 110-130℃ and cure it for 10-15 minutes.

[0042] S1.2. Disperse the ferrosoferric oxide powder into deionized water at a ratio of 0.05 g / ml using an ultrasonic disperser. After the powder is evenly dispersed, a film is prepared on the PDMS film using a spin coater.

[0043] S1.3. Use a spin coater to spin-coat PDMS on the prepared ferroferric oxide film to form a thin film, and place the film on a drying table at 110-130° C. for 10-15 min.

[0044] S2, transferring the prepared sandwich structure film 2 onto the flexible substrate 1, specifically, pasting the flexible substrate 1 on both the upper and lower surfaces of the sandwich structure film 2. In this embodiment, the flexible substrate 1 is a ring-shaped structure with a hollow area in the middle; then immersing the sandwich structure film 2 with the flexible substrate 1 attached on the upper and lower surfaces in a mixed solution of chloroauric acid, glucose, and potassium bicarbonate for 12 to 24 hours, and obtaining a nano-gold layer 4 in the hollow area on the lower surface of the sandwich structure film 2 (refer to Figure 2 ).

[0045] S3, preparing the conductive layer 5: printing a small glass rod dipped in 3812 conductive silver glue onto the second flexible substrate 8. In this embodiment, the second flexible substrate 8 is a circular ring structure with a hollow area in the middle; heating the printed substrate at 140-160° C. for 30-40 minutes to prepare a conductive silver glue layer.

[0046] S4, attaching the second flexible substrate 8 to the flexible substrate 1 located on the upper surface of the sandwich structure film 2; and filling the bonding gap with nano silver glue;

[0047] S5. Drop a MXene solution dissolved in deionized water onto the hollow portion of the upper surface of the sandwich structure film 2 to prepare a sensing layer 3 and obtain a biosensor.

[0048] S6. Immerse the sensor prepared in the previous step in a 4 mmol / L CYS solution to generate an aminated self-assembled monolayer. After 8-9 hours, remove the CYS solution and wash the sensor with deionized water.

[0049] S7. Mix 50 mmol / L EDC and NHS solution in a volume ratio of 1:1, and drop the antibody solution, place the biosensor in the antibody mixed solution with EDC / NHS for 2-3 hours, so that the antibody molecules 6 are modified onto the nanogold layer 4.

[0050] S8. The biosensor was then placed in a BSA buffer solution and kept for 1 hour to inhibit nonspecific adsorption.

[0051] S9. Use the biosensor to detect 0-50 μg / mL human serum albumin 7, so that human serum albumin 7 binds to the antibody molecules 6 on the sensor.

[0052] S10. Place the biosensor in a uniform magnetic field.

[0053] S11, packaging and testing.

[0054] The above content is a further detailed description of the present invention in combination with a specific preferred embodiment. It cannot be determined that the specific embodiments of the present invention are limited to this. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the present invention, which should be regarded as belonging to the present invention and the scope of patent protection determined by the submitted claims.

Claims

1. A thin film biosensor based on magnetoelectric coupling, characterized in that: It comprises a flexible substrate (1), wherein the flexible substrate (1) is provided with a hollow area, one side of the flexible substrate (1) carries a sandwich structure film (2), and the other side carries a conductive layer (5); A portion of the sandwich structure film (2) located in the hollow area is provided with a sensing layer (3) on one side and a nano-gold layer (4) on the other side; the sensing layer (3) and the conductive layer (5) are located on the same side of the sandwich structure film (2); The nanogold layer (4) is used to modify antibody molecules (6); The sandwich structure film (2) is composed of upper and lower PDMS films and a magnetic film arranged between the upper and lower PDMS films; The sandwich structure film (2) has a flexible substrate (1) with a hollow area on one side thereof having the nano-gold layer (4), and the nano-gold layer (4) is located in the hollow area; The conductive layer (5) comprises a second flexible substrate and conductive silver paste attached to the second flexible substrate.

2. A thin film biosensor based on magnetoelectric coupling according to claim 1, characterized in that: The sensing layer (3) is a MXene or carbon nanotube film layer.

3. The thin film biosensor based on magnetoelectric coupling according to claim 1, characterized in that: The magnetic film is made of ferroferric oxide or terbium dysprosium iron film material.

4. A method for preparing a thin film biosensor based on magnetoelectric coupling according to any one of claims 1 to 3, characterized in that: The following steps are involved: 1) preparing a sandwich structure film (2), transferring the sandwich structure film (2) to one surface of a flexible substrate (1); laminating the upper surface of the sandwich structure film (2) with the flexible substrate (1), and preparing a nano-gold layer (4) on the lower surface of the sandwich structure film (2) located in the hollow area; 2) preparing a conductive layer (5) on the other side of the flexible substrate (1), i.e., offset printing conductive silver onto the upper surface of a second flexible substrate to obtain the conductive layer (5), and then pasting the lower surface of the second flexible substrate onto the other side of the flexible substrate (1) carrying the sandwich structure film (2); 3) preparing a sensing layer (3) on the upper surface of the sandwich structure film (2) located in the hollow area; 4) The sandwich structure film (2) prepared in step 3) is immersed in a CYS solution to generate an aminated self-assembled monolayer to prepare a biosensor.

5. The method for preparing a thin film biosensor based on magnetoelectric coupling according to claim 4, characterized in that: The preparation method of the sandwich structure film (2) is to first spin-coat a magnetic material on a PDMS film to form a magnetic film, and then spin-coat another layer of PDMS film on the magnetic film.

6. The method for preparing a thin film biosensor based on magnetoelectric coupling according to claim 4, characterized in that: The method for preparing the nano-gold layer (4) is to immerse the sandwich structure film (2) transferred onto the flexible substrate in a mixed solution of chloroauric acid, glucose and potassium bicarbonate for 12-24 hours to obtain the nano-gold layer.

7. The method for preparing a thin film biosensor based on magnetoelectric coupling according to claim 4, characterized in that: The method for preparing the sensing layer (3) is to drop the MXene solution onto the hollow area.

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