An interdigital electrode-based serotonin surface stress biosensor and a preparation method thereof

Abstract

The application belongs to the technical field of biological detection sensors, and particularly relates to a serotonin surface stress biosensor based on an interdigital electrode and a preparation method thereof. The biosensor comprises a reaction layer, a sensing layer, an insulation layer and an interdigital electrode layer. The upper surface of the interdigital electrode layer is provided with the sensing layer. The upper surface of the sensing layer is provided with the insulation layer. The upper surface of the insulation layer is provided with the reaction layer. The reaction layer is fixed with a transferrin layer. The formed serotonin surface stress biosensor is a non-suspended or non-suspended structure. The biosensor is prepared by spin coating, sputtering and other methods according to the structure of the biosensor. The application can directly convert the concentration signal of serotonin into an electric signal through specific combination of transferrin and serotonin. Compared with the traditional detection method of serotonin, the sensor is simple to prepare, has low detection lines, fast response time, simple operation and low cost.

Description

Technical Field

[0001] This invention belongs to the field of biosensor technology, specifically a serotonin surface stress biosensor based on interdigital electrodes and its preparation method. Background Technology

[0002] The neurotransmitter serotonin (5-HT), also known as hydroxytryptamine, participates in the regulation of various gastrointestinal functions and is an important component of the gut-brain communication system. Even minute changes in 5-HT concentration (nmoL) can cause intestinal motility disorders. Therefore, dynamic monitoring of 5-HT provides crucial information for understanding the causes of intestinal motility disorders and developing therapeutic neuromodulation strategies. However, bioelectronic tools for monitoring the dynamics of neurotransmitters in vivo, especially those for the enteric nervous system, are still underdeveloped.

[0003] To date, mass spectrometry has been the primary method for quantitative analysis of 5-HT in clinical settings, but this method is costly and slow. In recent years, laboratory detection of 5-HT has mainly relied on instruments using voltammetry-based neurotransmitter sensing, supplemented by carbon fiber probes. However, rigid probes can lead to early equipment failure, severely reduced sensitivity, and high equipment costs, limiting their widespread application. Therefore, achieving highly sensitive and low-cost electrical measurements of 5-HT dynamics remains a long-standing challenge. Summary of the Invention

[0004] This invention overcomes the shortcomings of the prior art and proposes a serotonin surface stress biosensor based on interdigital electrodes and its preparation method; solving the problems of low sensitivity and high cost of current biosensors.

[0005] This invention is achieved through the following technical solution:

[0006] A serotonin surface stress biosensor based on interdigitated electrodes includes a reaction layer, a sensing layer, an insulating layer, and an interdigitated electrode layer. The sensing layer is disposed on the upper surface of the interdigitated electrode layer. An insulating layer is disposed on the upper surface of the sensing layer. A reaction layer is disposed on the upper surface of the insulating layer. A transferrin layer is immobilized on the reaction layer. The transferrin layer is used to bind with the serotonin molecules to be detected, generating surface stress to achieve the detection of serotonin. The reaction layer is a chitosan layer, and the chitosan layer and the transferrin layer are bonded by stable amide bonds. The electrode width on the interdigitated electrode layer is 2-3 μm, and the length is 4-5 mm.

[0007] Preferably, the insulating layer is a flexible insulating material.

[0008] More preferably, the flexible insulating material is polydimethylsiloxane, silicone, or polylactic acid.

[0009] Preferably, the sensing layer is a conductive material, and the conductive material is one of palladium, platinum, terbium, and dysprosium.

[0010] Preferably, the interdigitated electrode layer is formed by printing interlaced electrode materials on PET.

[0011] More preferably, the electrode material is conductive silver paste.

[0012] A method for fabricating a serotonin surface stress biosensor based on interdigital electrodes includes the following steps:

[0013] S1. Prepare a PET with conductive silver paste interdigitated electrodes and coat the electrodes with a palladium layer;

[0014] S2. Coat the palladium layer with a layer of polydimethylsiloxane;

[0015] S3. Coat the other side of the polydimethylsiloxane with a layer of chitosan;

[0016] S4. Modify the other side of the chitosan layer with transferrin so that serotonin can be specifically recognized by the sensor;

[0017] S5. Remove the excess solution after the reaction and drop the serotonin concentration to be tested onto the functionalized chitosan layer.

[0018] Preferably, the step of preparing the PET with conductive silver paste interdigitated electrodes in step S1 is as follows: using an inkjet printer to print conductive silver paste onto the PET, and placing it on a heating stage at 150-170°C for 30-40 minutes to cure; the palladium layer is obtained directly by sputtering using a magnetron sputtering machine.

[0019] Preferably, the polydimethylsiloxane layer is obtained directly by spin coating using a spin-coating machine.

[0020] Preferably, the specific steps for modifying the other side of the chitosan layer with transferrin in step S4 are as follows:

[0021] Mix 50-100 mmol / L citric acid solution with 40-60 mmol / L glutaraldehyde solution at a volume ratio of 1:5, and drop the mixture onto the surface of chitosan and let it stand for 3-6 hours; then drop 20-50 mmol / L transferrin aqueous solution onto the surface of chitosan and let it stand for 2-4 hours to complete the transferrin modification.

[0022] The beneficial effects of this invention compared to the prior art are as follows:

[0023] This invention utilizes the specific binding of transferrin to serotonin, directly converting the serotonin concentration signal into an electrical signal. Compared to traditional methods of serotonin detection, this sensor is simple to fabricate, has a low detection limit, fast response time, is easy to operate, and is low in cost. The sensor of this invention can be integrated, miniaturized, and portable, effectively meeting the practical application needs in the field of biochemical detection. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating the fabrication process of the biosensor described in Example 2;

[0025] Figure 2 This is a cross-sectional view of the biosensor of the present invention;

[0026] Figure 3 This is a schematic diagram of the transferrin modified on the reaction layer of the biosensor of the present invention;

[0027] Figure 4 This is a schematic diagram illustrating the binding process of the biosensor of the present invention with serotonin;

[0028] In the diagram: 1 is PET, 2 is conductive silver paste, 3 is palladium layer, 4 is polydimethylsiloxane film, 5 is chitosan film, 6 is transferrin, and 7 is serotonin solution. Detailed Implementation

[0029] To make the technical problems to be solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail with reference to the embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. The technical solutions of this invention are described in detail below with reference to the embodiments and accompanying drawings, but the scope of protection is not limited thereto.

[0030] like Figures 1 to 4As shown, this invention provides a serotonin surface stress biosensor based on interdigitated electrodes, comprising a PET layer 1, a reaction layer, a sensing layer, an insulating layer, and an interdigitated electrode layer. Specifically, in this embodiment, the reaction layer is a chitosan film 5, the sensing layer is a palladium layer 3, the insulating layer is a polydimethylsiloxane film 4, and the interdigitated electrode layer is formed by printing conductive silver paste 2 onto the PET layer 1 in an interdigitated structure; that is, the conductive silver paste 2 is printed from both sides of the PET layer 1 to the other side, so that the conductive silver paste 2 on both sides is staggered; a palladium layer 3 is disposed on the upper surface of the interdigitated electrode layer as a sensing layer; a polydimethylsiloxane film 4 is disposed on the upper surface of the palladium layer 3 as an insulating layer; a chitosan film 5 is spin-coated on one side of the polydimethylsiloxane film 4 as a reaction layer, and transferrin 6 is fixed on the chitosan film 5 through stable amide bonds. Surface stress is generated by adding the serotonin solution 7 to be detected, causing it to bind with the transferrin 6. The serotonin surface stress biosensor is a non-suspended or non-levitated structure.

[0031] The surface stress generated by the chitosan film 5 causes the polydimethylsiloxane film 4 to deform; the deformation of the polydimethylsiloxane film 4 causes the palladium layer 3 to also deform, which increases the distance between palladium particles, thereby changing the resistance of the palladium layer and converting the concentration signal of serotonin into an electrical signal.

[0032] The sensing layer is a conductive material. The surface stress generated by the reaction layer causes the electrode layer to deform through the sensing layer, which changes the distance between the conductive nanoparticles and thus changes the resistance value of the conductive material.

[0033] The insulating film in the insulating layer is not limited to polydimethylsiloxane; other flexible insulating materials such as silicone and polylactic acid can also be used. The materials used in the sensing layer are not limited to palladium; platinum, terbium, dysprosium, etc., can also be used. The conductive material in the electrode layer is conductive silver paste or other conductive materials.

[0034] This embodiment also proposes a method for fabricating a serotonin surface stress biosensor based on interdigital electrodes, specifically by following these steps:

[0035] (1) Mix polydimethylsiloxane A and B adhesives at a mass ratio of 10:1, let stand at -20℃ for 2 hours, and then spin coat them onto a glass plate using a spin coater (speed of 5000 rpm, acceleration of 100 rad / s). 2 (The time is 1 minute). The glass plate is heated in a heating box at 70°C for 40 minutes to cure the polydimethylsiloxane film 4.

[0036] (2) Spin-coating the obtained polydimethylsiloxane film 4 using a spin-coating machine (rotation speed 4000 rpm, acceleration 50 rad / s). 2A 0.5 g / mL chitosan aqueous solution was heated in a 60°C heating oven for 15 minutes (time: 1 min) to solidify the chitosan film.

[0037] (3) Use a magnetron sputtering machine (7.4 × 10) −5 A palladium layer 3 was sputtered on the other side of the polydimethylsiloxane film 4 under a vacuum of Pa, an argon atmosphere of 0.3 Pa, and a DC power supply of 80 W for 30 min.

[0038] (4) Use an inkjet printer to print conductive silver paste 2 onto PET layer 1 in an interdigitated structure. The width of the printed electrode is set to 3 μm and the length is set to 5 mm. After printing, place the PET on a heating table at 160°C and heat for 40 minutes to cure.

[0039] (5) The polydimethylsiloxane film 4, which is assembled with chitosan film 5 and palladium layer 3, is fixed to the interdigitated electrode layer by electric welding machine.

[0040] (6) Mix 80 mmol / L citric acid solution and 50 mmol / L glutaraldehyde solution at a volume ratio of 1:5, and drop the mixture onto the surface of chitosan film 5 and let it stand for 5 hours; then drop 30 mmol / L transferrin aqueous solution onto the surface of chitosan and let it stand for 3 hours to complete the modification of transferrin 6.

[0041] (10) Packaging and testing.

[0042] Example 2

[0043] See Figure 1 This embodiment proposes a method for preparing a serotonin surface stress biosensor based on interdigitated electrodes. The only difference is the assembly order of each layer compared to Embodiment 1. In this embodiment, conductive silver paste 2 is first printed onto PET layer 1 in an interdigitated structure. After curing, palladium layer 3 is sputtered onto conductive silver paste 2. Then, polydimethylsiloxane film 4 is spin-coated onto palladium layer 3, and chitosan film 5 is spin-coated onto polydimethylsiloxane film 4 and cured.

[0044] The above description is a further detailed explanation of the present invention in conjunction with specific preferred embodiments. It should not be considered that the specific embodiments of the present invention are limited to this. For those skilled in the art, several simple deductions or substitutions can be made without departing from the present invention, and all of these should be considered to fall within the scope of patent protection determined by the submitted claims.

Claims

1. A serotonin surface stress biosensor based on interdigital electrodes, characterized in that, The device comprises a reaction layer, a sensing layer, an insulating layer, and an interdigitated electrode layer. A sensing layer is disposed on the upper surface of the interdigitated electrode layer. An insulating layer is disposed on the upper surface of the sensing layer. A reaction layer is disposed on the upper surface of the insulating layer. A transferrin layer is fixed on the reaction layer. The transferrin layer is used to bind with the serotonin molecules to be detected, generating surface stress to achieve the detection of serotonin. The reaction layer is a chitosan layer, and the chitosan layer and the transferrin layer are bonded by stable amide bonds. The electrode width on the interdigitated electrode layer is 2-3 μm, and the length is 4-5 mm. The insulating layer is a flexible insulating material; the interdigitated electrode layer is formed by printing interlaced electrode materials on PET; the sensing layer is a conductive material, which is one of palladium, platinum, terbium, and dysprosium.

2. The serotonin surface stress biosensor based on interdigital electrodes according to claim 1, characterized in that, The flexible insulating material is polydimethylsiloxane, silicone, or polylactic acid.

3. A serotonin surface stress biosensor based on interdigital electrodes according to claim 1, characterized in that, The electrode material is conductive silver paste.

4. A method for preparing a serotonin surface stress biosensor based on interdigitated electrodes as described in any one of claims 1-3, characterized in that, Includes the following steps: S1. Prepare a PET with conductive silver paste interdigitated electrodes and coat the electrodes with a palladium layer; S2. Coat the palladium layer with a layer of polydimethylsiloxane; S3. Coat the other side of the polydimethylsiloxane with a layer of chitosan; S4. Modify the other side of the chitosan layer with transferrin so that serotonin can be specifically recognized by the sensor; S5. Remove the excess solution after the reaction and drop the serotonin concentration to be tested onto the functionalized chitosan layer.

5. The method for fabricating a serotonin surface stress biosensor based on interdigitated electrodes according to claim 4, characterized in that, The steps in step S1 for preparing the PET with conductive silver paste interdigitated electrodes are as follows: the conductive silver paste is printed onto the PET using an inkjet printer, and then the PET is placed on a heating stage and heated at 150-170℃ for 30-40 minutes to cure; the palladium layer is obtained directly by sputtering using a magnetron sputtering machine.

6. The method for fabricating a serotonin surface stress biosensor based on interdigitated electrodes according to claim 4, characterized in that, The polydimethylsiloxane layer was obtained directly by spin coating using a spin-coating machine.

7. The method for fabricating a serotonin surface stress biosensor based on interdigitated electrodes according to claim 4, characterized in that, The specific steps for modifying the other side of the chitosan layer with transferrin in step S4 are as follows: Mix 50-100 mmol / L citric acid solution with 40-60 mmol / L glutaraldehyde solution at a volume ratio of 1:5, and drop the mixture onto the surface of chitosan and let it stand for 3-6 hours; then drop 20-50 mmol / L transferrin aqueous solution onto the surface of chitosan and let it stand for 2-4 hours to complete the transferrin modification.

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