Organic electrochemical transistors for detecting protein-like substances, their preparation methods and applications

Abstract

This invention relates to an organic electrochemical transistor for detecting protein-like substances, its preparation method, and its application, belonging to the field of protein detection technology. The organic electrochemical transistor for detecting protein-like substances of this invention includes a substrate, a source electrode, a drain electrode, a channel layer, an electrolyte, and a functionalized porous carbon-based gate. The source electrode and drain electrode are disposed parallel to each other on the substrate, forming a channel. The functionalized porous carbon-based gate includes a porous carbon-based gate, a self-assembled layer, and a protein-specific recognition layer stacked sequentially. The self-assembled layer is formed on the surface of the porous carbon-based substrate through the self-assembly of a carboxyl-containing thiol compound. The protein-specific recognition layer is covalently bonded to the surface of the self-assembled layer via amide bonds. The functionalized porous carbon-based gate achieves specific recognition of target protein-like substances through the protein-specific recognition layer. The organic electrochemical transistor of this invention exhibits good sensing stability, consistency, and high sensitivity.

Description

Technical Field

[0001] This invention relates to the field of protein detection technology, and in particular to organic electrochemical transistors for detecting protein substances, their preparation methods, and applications. Background Technology

[0002] Organic electrochemical transistors (OECTs) are transistor devices based on ion-electron coupling. They have attracted widespread attention in the field of biosensing due to their high transconductance, low operating voltage, compatibility with aqueous solutions, and good biocompatibility. OECT devices, combined with biospecific modification techniques, can be directly applied to the real-time detection of biological substances such as ions, glucose, proteins, and DNA. Proteins are important components of the human body, and many proteins are important biomarkers for human diseases, such as immunoglobulins, C-reactive proteins, or amyloid proteins. Their low-dose, high-precision detection is crucial for clinical diagnosis. Traditional detection methods such as chromatography, fluorescence, and enzyme-linked immunosorbent assays (ELISA) suffer from problems such as large equipment, complex preparation, long measurement times, and limited sensitivity. OECT-based transistor sensors offer advantages such as signal amplification, flexibility, miniaturization, ease of specific modification, and integration, and hold promise for achieving portable, rapid, and highly sensitive biosensing.

[0003] To construct sensor devices with specific responses, gate modification is the most common process for transistors. However, there are relatively few materials in existing biomodification technologies that combine high-performance OECT and highly specific biofunctionalization, resulting in current OECT-based protein sensors still facing challenges such as low sensitivity, poor stability, and complex fabrication processes.

[0004] Current OECT-based protein biosensing primarily relies on gold gate biofunctionalization modification technology. Antibodies are immobilized on Au gate electrodes through self-assembled monolayers (SAMs), utilizing the antibodies' specific recognition of immunoglobulins. When the target immunoglobulin binds to the antibody, it alters the gate / electrolyte interface capacitance, thereby modulating the channel current signal. However, the inertness of traditional Au electrodes limits capacitance and antibody immobilization, restricting OECT device performance and sensing sensitivity. Carbon-based thin film materials (such as carbon nanotubes, CNTs) leverage the high conductivity and specific surface area of ​​CNTs to enhance biosensing performance, promising the construction of highly sensitive OECT sensors. However, single CNT gates are prone to aggregation and structural instability, have low specific receptor modification density, and undergo complex fabrication processes (requiring precise control of CNT dispersion), limiting improvements in sensor performance.

[0005] Furthermore, existing gold-gate or carbon-based gate OECT sensors still suffer from drawbacks such as low sensitivity and poor stability, and most OECT channel layers are still based on PEDOT:PSS material, resulting in high static power consumption. Therefore, there is an urgent need to provide an organic electrochemical transistor for detecting protein-like substances that is highly sensitive, has high transconductance, and low power consumption. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides an organic electrochemical transistor for detecting protein substances, its fabrication method, and its applications. It aims to overcome the shortcomings of traditional gold or carbon-based gates, such as insufficient sensitivity and high detection limits due to small specific surface area, low conductivity, and low receptor modification density, as well as the problems of poor stability and high cost caused by complex gate structures and fabrication processes. The biofunctionalized gate suitable for OECT provided by this invention is fabricated using extrusion printing technology. The material composition is a graphene oxide / carbon nanotube composite material (rGO / CNTs). The gate has a porous structure, featuring a large specific surface area, high conductivity, and ease of mass production. Simultaneously, a two-component thiol surface self-assembly technique is used to enhance the specific receptor modification density, forming a highly specific biofunctionalized gate. This achieves a high-sensitivity, high-transconductance, and low-power cumulative OECT protein sensor with a detection limit below 1 fM.

[0007] This invention is achieved through the following technical solution:

[0008] The first objective of this invention is to provide an organic electrochemical transistor for detecting protein-like substances, comprising a substrate, a source electrode, a drain electrode, a channel layer, an electrolyte, and a functionalized porous carbon-based gate: the source electrode and the drain electrode are disposed parallel to each other on the substrate and form a channel;

[0009] The functionalized porous carbon-based gate comprises a porous carbon-based gate, a self-assembled layer, and a protein-specific recognition layer stacked sequentially. The self-assembled layer is formed on the surface of the porous carbon-based substrate through the self-assembly of a carboxyl-containing thiol compound. The protein-specific recognition layer is covalently bonded to the surface of the self-assembled layer via amide bonds. The functionalized porous carbon-based gate achieves specific recognition of target protein substances through the protein-specific recognition layer.

[0010] The porous carbon-based gate electrode is prepared by the following method:

[0011] A porous carbon-based gate electrode was obtained by mixing reduced graphene oxide with multi-walled carbon nanotubes, 3D printing, freeze-drying, and sintering.

[0012] In one embodiment of the present invention, the substrate is one or more of silicon, silicon oxide, glass, polyimide (PI), polyethylene naphthalate (PEN), and polyethylene terephthalate (PET).

[0013] In one embodiment of the present invention, the source electrode and the drain electrode are each independently Au and Cr.

[0014] In one embodiment of the present invention, the organic semiconductor material of the channel layer is P(g2T-T), P3HT, Pg2T-TT, or PrC. 60 One or more of MA and BBL.

[0015] In one embodiment of the present invention, the raw material for the electrolyte is phosphate buffer solution (PBS), potassium chloride solution, sodium chloride solution, physiological saline or human serum solution.

[0016] In one embodiment of the present invention, the mass ratio of the reduced graphene to the multi-walled carbon nanotube is 1:2-1:5;

[0017] And / or, the porous carbon-based gate is a cylindrical carbon material with a diameter of 500 μm-2000 μm; the pore size of the porous carbon-based gate is at the micro-nano level;

[0018] And / or, the parameters of the 3D printing are: nozzle diameter of 100 μm-800 μm and printing speed of 30 mm / s-60 mm / s.

[0019] In one embodiment of the present invention, the functionalized porous carbon-based gate is prepared by the following method:

[0020] A porous carbon-based gate is placed in an alcohol solution containing 11-mercaptoundecanoic acid and 3-mercaptopropionic acid to form a self-assembled layer; the resulting self-assembled layer is activated in an aqueous solution containing 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide; the activated self-assembled layer is placed in a buffer solution containing protein-specific receptors, so that the protein-specific receptors bind to the self-assembled layer to form a protein-specific recognition layer, thus obtaining a functionalized porous carbon-based gate.

[0021] In one embodiment of the present invention, the mass ratio of 11-mercaptoundecanoic acid to 3-mercaptopropionic acid is 0.2 to 0.21;

[0022] And / or, the molar ratio of 1-ethyl-(3-dimethylaminopropyl)carbodiimide to N-hydroxysuccinimide is 0.36 to 0.40;

[0023] And / or, the activation conditions are: a mass ratio of 1-ethyl-(3-dimethylaminopropyl)carbodiimide to N-hydroxysuccinimide of 0.50 to 0.55, and an activation time of 2 to 3 h.

[0024] In one embodiment of the present invention, the protein is one or more of immunoglobulin A, immunoglobulin G, immunoglobulin M, amyloid protein, C-reactive protein, and troponin.

[0025] A second objective of this invention is to provide a method for fabricating the aforementioned organic electrochemical transistor, comprising the following steps:

[0026] (1) Deposit metallic materials on the substrate as source and drain electrodes;

[0027] (2) A uniform organic semiconductor material thin film is deposited using a solution method as the channel layer;

[0028] (3) Cover the channel layer with electrolyte;

[0029] (4) A functionalized porous carbon-based gate is coated on the electrolyte to construct an organic electrochemical transistor for detecting protein substances.

[0030] A third objective of this invention is to provide the application of the described organic electrochemical transistor in the detection of protein-like substances, wherein the application does not involve the diagnosis and treatment of diseases.

[0031] In one embodiment of the present invention, the concentration of the protein substance is 10. -15 mol / L-10 -9 mol / L.

[0032] OECT protein sensor devices based on porous carbon-based gates need to include functionalized porous carbon-based gates based on surface self-assembly modification and cumulative OECT to achieve highly sensitive sensing of typical protein markers.

[0033] Compared with the prior art, the above-described technical solution of the present invention has the following advantages:

[0034] This invention provides an organic electrochemical transistor for detecting protein-like substances (structural schematic diagram shown below). Figure 1 The invention relates to a method for preparing and applying a biofunctionalized porous carbon-based gate. A chemically self-assembled layer is formed on the high specific surface area carbon-based gate, and antibodies capable of specifically recognizing proteins are grafted onto it, achieving a higher density of antibody loading and facilitating highly sensitive and stable protein sensing. The amplification characteristics of organic electrochemical transistors are utilized to amplify the weak potential signal from the biofunctionalized gate. The prepared sensor exhibits good sensing stability, consistency, and high sensitivity, achieving high-sensitivity sensing of immunoglobulins and amyloid proteins down to 1 fM, with a detection time of less than 15 minutes. Furthermore, by using extrusion 3D printing technology and optimizing the surface self-assembly modification steps, gate preparation can be simplified, costs reduced, and it is suitable for large-scale production. Attached Figure Description

[0035] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0036] Figure 1 This is a schematic diagram of the device structure of the organic electrochemical transistor immunoglobulin sensor of the present invention. The reference numerals are as follows: 1-substrate; 2-source / drain electrode; 3-channel layer; 4-electrolyte layer; 5-porous carbon-based gate; the channel layer is a p-type or n-type accumulator material with low drive.

[0037] Figure 2 This is a SEM morphology diagram of a porous carbon-based gate fabricated by extrusion 3D printing in Embodiment 1 of the present invention; wherein, (a) is a surface view of the porous carbon-based gate, and (b) is a cross-sectional view of the porous carbon-based gate.

[0038] Figure 3 The electrochemical characterization of the functionalized sensing gate prepared in Example 1 of this invention includes: (a) cyclic voltammetry (CV) curves of each biofunctionalization modification stage of the gate; and (b) the electrochemical impedance spectroscopy (EIS) response of the gate after biofunctionalization modification to different concentrations of human immunoglobulin G (IgG) solution to be detected.

[0039] Figure 4 This document describes the structure and electrical performance of the OECT device tested in Example 1 of the present invention; wherein, (a) is a schematic diagram of the OECT structure; (b) is the molecular formula of the accumulator channel material; (c) is the transfer curve under 0.1 M PBS electrolyte conditions; and (d) is the output curve under 0.1 M PBS electrolyte conditions.

[0040] Figure 5 The biosensing performance of Example 2 and Comparative Example 1 of the present invention was compared by adding different concentrations of IgG solution to 0.1 M PBS electrolyte.

[0041] Figure 6 This is a biosensing performance diagram of Example 3 and Comparative Example 2 of the present invention with different concentrations of amyloid protein solution added to 0.1 M PBS electrolyte. Detailed Implementation

[0042] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0043] This invention provides an organic electrochemical transistor for detecting protein-like substances. It utilizes a printed porous rGO / CNT composite material as the base gate, employs surface self-assembly modification to load specific receptors to form a biofunctionalized gate, and uses a cumulative semiconductor material as the OECT active layer to construct a highly sensitive OECT sensor device targeting proteins. The device structure includes a substrate, source electrode, drain electrode, channel layer, electrolyte, and functionalized porous carbon-based gate.

[0044] Furthermore, the substrate is silicon, silicon oxide, glass, polyimide (PI), polyethylene naphthalate (PEN), and polyethylene terephthalate (PET), etc.

[0045] Furthermore, the channel layer is mainly a thin film formed of cumulative organic semiconductor materials such as P(g2T-T), P3HT, Pg2T-TT, PrC60MA, and BBL.

[0046] Furthermore, the electrolytes are solutions such as phosphate buffered saline (PBS), potassium chloride, sodium chloride, physiological saline, and human serum.

[0047] Furthermore, the porous carbon-based gate is a composite material of reduced graphene oxide (rGO) and multi-walled carbon nanotubes (CNTs) with adjustable ratios.

[0048] Furthermore, the biofunctionalization process uses a two-component thiol-based approach to introduce COOH, which is then used to modify the process protein antibody as a specific recognition receptor.

[0049] Furthermore, protein detection solutions of different concentrations were added to the electrolyte, incubated, and then used for sensing tests.

[0050] The present invention also provides a method for fabricating the above-mentioned organic electrochemical transistor device, comprising the following steps:

[0051] (1) A patterned Au / Cr metal is deposited on the substrate using photolithography as the source and drain electrodes;

[0052] (2) A uniform organic thin film was prepared using a solution method as the channel layer;

[0053] (3) Cover the channel layer with electrolyte;

[0054] (4) Construct an organic electrochemical crystal sensor with a suspended gate structure by covering the electrolyte with a biofunctionalized porous carbon-based gate.

[0055] Furthermore, in step (1), the source and drain are fabricated using photolithography for patterning design. The photoresist is soft-baked at 105°C for 180 s, exposed for 2.5 s, and developed for 5 s. Then, Au / Cr electrode material is deposited using vacuum sublimation, with the vacuum level maintained at 10 during the deposition process. -4 -10 -5 Pa, deposition rate of 0.2-1 nm / min. Finally, the substrate was immersed in acetone solution and ultrasonically stripped of the photoresist to complete the patterned source and drain electrodes;

[0056] Further, in step (1), the source and drain electrode patterns adopt interdigitated electrodes, with an electrode channel length of 5 μm-50 μm, a width of 100 μm-1340 μm, and an electrode width-to-length ratio of 10-134:1.

[0057] Further, in step (2), the preparation of the channel layer is completed by spin coating or blade coating. The solvent used is chloroform or chlorobenzene, the concentration of the solution is 6-10 mg / mL, the atmosphere for spin coating is N2, and the spin coating rate is 1000-3000 rpm and the spin coating time is 30-60 s, depending on the thickness requirement.

[0058] Furthermore, in step (3), the electrolyte solution needs to be directly added to the exposed channel after a patterned polydimethylsiloxane (PDMS) film is first attached;

[0059] Further, in step (4), the porous carbon-based gate is prepared as follows: Reduced graphene oxide and multi-walled carbon nanotubes (rGO / CNTs) are centrifuged and mixed in a certain mass ratio (range: 0.2~0.5), then printed into cylindrical shapes with adjustable diameters using an extrusion printing method. Subsequently, they are freeze-dried in liquid nitrogen at low temperature and sintered to form a porous gate structure. The gate is then further modified with biofunctionalization. Specifically, the porous carbon-based gate is placed in an ethanol solution of 11-mercaptoundecanoic acid / 3-mercaptopropionic acid (11MUA / 3MPA, mass ratio 1:4.8 mg / mL) for 18 hours under a light-protected N2 atmosphere to form a self-assembled layer. Then, the carbon-based gate is activated in an aqueous solution of 1-ethyl-(3-dimethylaminopropyl)carbodiimide / N-hydroxysuccinimide (EDC / NHS, molar ratio 20:50 mM) for 2 hours. Next, the carbon-based gate was placed in a PBS solution containing protein antibodies (0.1 mg / mL) to bind the antibodies to the self-assembled layer. The activated carboxyl groups that were not bound to antibodies were blocked with a PBS solution containing 1 M ethanolamine for 1 h. Finally, a PBS solution containing bovine serum albumin (BSA, 0.1 mg / mL) was added to fill any remaining vacancies and minimize nonspecific binding.

[0060] Furthermore, in step (5), different concentrations of target protein detection solutions are dropped into the electrolyte and incubated for 5-20 minutes for testing.

[0061] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the materials and reagents used are commercially available.

[0062] Example 1

[0063] This embodiment presents a schematic diagram of the organic electrochemical transistor for detecting immunoglobulins, including, from bottom to top, a substrate, source and drain electrodes (source and drain electrodes), a channel layer, an electrolyte, and a porous carbon-based gate; the source and drain electrodes are arranged in parallel and form a channel. The specific fabrication method of the above organic electrochemical transistor is as follows:

[0064] (1) Fabrication of source and drain electrodes: A silicon wafer containing 300 nm thermally oxidized silicon was selected as the substrate, and the source and drain electrodes were fabricated using photolithography. The silicon wafer was spin-coated with photoresist to form a uniform thin film, and then soft-baked at 105 °C for 180 s. An interdigitated electrode pattern mask was aligned with the silicon wafer, exposed for 2.5 s, and developed for 5 s to obtain the photoresist mask layer pattern. The electrode pattern used interdigitated electrodes with an electrode channel length of 10 μm, a width of 1340 μm, and an electrode width-to-length ratio of 134:1.

[0065] Then, electrode material is deposited on the photolithographically treated sample using vacuum sublimation, with the vacuum level maintained at 10 during the deposition process. -4 ~10 -5 Pa, with a deposition rate of 0.25 nm / min, deposited 3 nm Cr and 40 nm Au sequentially; then immersed in acetone solution, sonicated for 2 min and dried, and subjected to photoresist stripping to complete the fabrication of patterned source and drain electrodes.

[0066] (2) Preparation of the channel layer: Subsequently, under N2 atmosphere, the organic semiconductor material poly[3,3′-bis{2-[2-(2-methoxyethoxy)ethoxy]ethoxy}-2,2′:5′,2′′-trithiophene-5,5′′-diyl] (Pg2T-T) (purchased from Shenzhen Ruixun) with a concentration of 6 mg / mL was deposited onto the source and drain electrode surface by solution spin coating (2000 rpm / 30 s) to complete the preparation of the device channel layer. The spin coating thickness was 60 nm, the spin coating rate was 2000 rpm, and the spin coating time was 30 s.

[0067] (3) Preparation of electrolyte: 0.1 M PBS solution electrolyte was dropped into patterned polydimethylsiloxane (PDMS) (purchased from Hangzhou Microsonic) membrane wells (in direct contact with the channel layer).

[0068] (4) Preparation of porous carbon-based gate: Reduced graphene oxide (rGO) and multi-walled carbon nanotubes (CNTs) were mixed at a mass ratio of 1:2 to prepare a printing paste. The paste was then printed into 500 μm cylindrical carbon materials using extrusion 3D printing technology. After cryogenic liquid nitrogen freeze-drying (-60 ℃, 12 h) and sintering (200 ℃, N2, 0.5 h), a porous carbon-based gate was obtained. Its SEM morphology is shown in the figure. Figure 2 As shown, the pore size distribution is in the hundreds of nanometers.

[0069] (5) Biofunctionalization modification: In order to achieve biological specific recognition, the porous carbon-based gate needs to be biofunctionalized.

[0070] Under light-protected and N2 atmosphere, a porous carbon-based gate was immersed in an ethanol solution of 11-mercaptoundecanoic acid / 3-mercaptopropionic acid (11MUA / 3MPA, concentration ratio 1:4.8 mg / mL) for 18 hours to form a self-assembled layer. The porous carbon-based gate was then activated for 2 hours in an aqueous solution of 1-ethyl-(3-dimethylaminopropyl)carbodiimide / N-hydroxysuccinimide (EDC / NHS, molar ratio 20:50). Next, the porous carbon-based gate was immersed in a PBS solution containing immunoglobulin antibody IgG (Sigma, I9010) (0.1 mg / mL) to bind the antibody to the self-assembled layer. The activated carboxyl groups that were not bound to the antibody were blocked with a PBS solution containing 1 M ethanolamine for 1 hour. Finally, a PBS solution containing bovine serum albumin (BSA, 0.1 mg / mL) was added to fill any remaining vacancies and minimize nonspecific binding. After the above self-assembly, group activation, antibody binding, and surface blocking, a functionalized porous carbon-based gate with IgG recognition function was obtained.

[0071] (6) The obtained functionalized porous carbon-based gate and device body are assembled to obtain an organic electrochemical transistor.

[0072] The organic electrochemical transistor prepared above was placed on a probe station, and its electrical performance was tested using a semiconductor parameter analyzer.

[0073] Figure 3 The electrochemical characterization data of the porous carbon-based gate obtained in Example 1 of this invention were obtained by testing a three-electrode system on an electrochemical workstation (the counter electrode was a platinum wire, the reference electrode was silver / silver chloride, and the electrolyte was a 5 mM potassium ferrocyanide / potassium ferrocyanide solution diluted with 10 mM PBS). Figure 3 As shown in (a), as the oxidation peak of the CV curve shifts to the right and the corresponding current decreases, it indicates that corresponding modification layers are formed on the gate surface, thereby reducing the charge transfer of the electrode.

[0074] Different concentrations of immunoglobulin detection solutions were dropped onto the electrode surface and incubated at room temperature for 10 min before electrochemical testing. The functionalized porous carbon-based gate obtained in Example 1 was immersed in IgG solutions of different concentrations (10... -15 mol / L, 10 -14 mol / L, 10 -13 mol / L, 10 -12 After incubation in (mol / L) for 5 minutes, electrochemical impedance spectroscopy was performed. The results are shown in […]. Figure 3 (b) shows that the impedance increases with increasing IgG concentration, proving that the antibody bound to the carbon-based gate electrode surface has a sensing concentration response to IgG and can realize the conversion of biological signals into electrical signals.

[0075] Figure 4 (a) is a schematic diagram of the device structure during the test in Example 1, wherein the semiconductor layer material (channel layer) is P(g2T-T). Figure 4 In the figure, (c)-(d) are the electrical performance curves of the prepared OECT; (c) is the OECT transfer characteristic curve; and (d) is the OECT output characteristic curve. The results show that the porous carbon-based gate OECT based on biofunctionalization still has mA-level current values ​​and good gate control effect, and has high signal amplification capability.

[0076] Example 2

[0077] This embodiment provides a method for preparing an organic electrochemical transistor for detecting immunoglobulins, similar to Example 1, except that in step (4), rGO and CNTs are mixed in a mass ratio of 1:4; and printed as a cylinder with a diameter of 500 μm using a 3D printer. The remaining steps are consistent with those in Example 1.

[0078] Comparative Example 1

[0079] This comparative example provides a method for preparing an organic electrochemical transistor, which is similar to Example 2, except that step (5) is missing and no biofunctionalization modification is performed. The remaining steps are consistent with those in Example 2.

[0080] Figure 5 The biosensing performance of Example 2 and Comparative Example 1 of the present invention was compared by adding different concentrations of IgG solution to 0.1 M PBS electrolyte. Figure 5 (a) and (b) in the figure represent the IgG concentration response test performance using the device obtained in Example 2, with a concentration range of 10. -15 M to 10 -8M, as the IgG concentration increases, the device output current gradually decreases. This is because the binding of the antibody-functionalized gate to the antigen reduces the resistance and potential of the gate interface, thereby reducing the channel current signal. Figure 5 In the figures (c)-(d), the sensing performance of the OECT based on a non-biofunctionalized carbon-based gate in Comparative Example 1 is shown, with a concentration range of 10. -15 M to 10 -8 M has a sensitivity performance that is two orders of magnitude lower than that of the biofunctionalized gate-modified device of the present invention.

[0081] Example 3

[0082] This embodiment provides a method for preparing an organic electrochemical transistor for detecting amyloid protein, similar to Example 1, except that: in step (5), an amyloid protein antibody Aβ is introduced. 1-42 (Sigma, A9810) was used as a receptor for grafting, eliminating the need for the ethanolamine blocking step, and a specific modified gate for amyloid protein was obtained.

[0083] Comparative Example 2

[0084] This comparative example provides a method for fabricating an organic electrochemical transistor based on a gold-modified gate, similar to Example 3, except that a commonly used gold gate (50 nm gold deposited on a silicon substrate) is used, followed by self-assembly and antibody antigen modification steps similar to those in Example 3.

[0085] The sensing performance was then tested for different concentrations of amyloid protein. Figure 6 (a) and (b) in the figure are the test results of the device obtained in Example 3, with a concentration range of 10. -16 M to 10 -8 M can achieve a detection limit of 0.1 fM. Figure 6 (c)-(d) in the figure represent the OECT sensing performance comparison of Comparative Example 2 using a biofunctionalized gold gate, with a concentration range of 10. -15 M to 10 -8 M, the sensing performance using the method of the present invention is nearly 40 times better than that of typical gold gate processes.

[0086] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An organic electrochemical transistor for detecting protein-like substances, characterized in that, It includes a substrate, a source electrode, a drain electrode, a channel layer, an electrolyte, and a functionalized porous carbon-based gate: the source electrode and the drain electrode are disposed parallel to each other on the substrate and form a channel; The functionalized porous carbon-based gate comprises a porous carbon-based gate, a self-assembled layer, and a protein-specific recognition layer stacked sequentially. The self-assembled layer is formed on the surface of the porous carbon-based substrate through the self-assembly of a carboxyl-containing thiol compound. The protein-specific recognition layer is covalently bonded to the surface of the self-assembled layer via amide bonds. The functionalized porous carbon-based gate achieves specific recognition of target protein substances through the protein-specific recognition layer. The porous carbon-based gate electrode is prepared by the following method: A porous carbon-based gate electrode was obtained by mixing reduced graphene oxide with multi-walled carbon nanotubes, 3D printing, freeze-drying, and sintering.

2. The organic electrochemical transistor according to claim 1, characterized in that, The substrate is one or more of silicon, silicon oxide, glass, polyimide (PI), polyethylene naphthalate (PEN), and polyethylene terephthalate (PET).

3. The organic electrochemical transistor according to claim 1, characterized in that, The source electrode and drain electrode are each independently Au and Cr.

4. The organic electrochemical transistor according to claim 1, characterized in that, The organic semiconductor material of the channel layer is P(g2T-T), P3HT, Pg2T-TT, or PrC. 60 One or more of MA and BBL.

5. The organic electrochemical transistor according to claim 1, characterized in that, The electrolyte is prepared from phosphate buffer solution (PBS), potassium chloride solution, sodium chloride solution, physiological saline or human serum solution.

6. The organic electrochemical transistor according to claim 1, characterized in that, The mass ratio of the reduced graphene oxide to the multi-walled carbon nanotubes is 1:2-1:5; And / or, the porous carbon-based gate is a cylindrical carbon material with a diameter of 500 μm-2000 μm; And / or, the parameters of the 3D printing are: nozzle diameter of 100 μm-800 μm and printing speed of 30 mm / s-60 mm / s.

7. The organic electrochemical transistor according to claim 1, characterized in that, The functionalized porous carbon-based gate electrode is prepared by the following method: A porous carbon-based gate is placed in an alcohol solution containing 11-mercaptoundecanoic acid and 3-mercaptopropionic acid to form a self-assembled layer; the resulting self-assembled layer is activated in an aqueous solution containing 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide; the activated self-assembled layer is placed in a buffer solution containing protein-specific receptors, so that the protein-specific receptors bind to the self-assembled layer to form a protein-specific recognition layer, thus obtaining a functionalized porous carbon-based gate.

8. The organic electrochemical transistor according to claim 1, characterized in that, The protein is one or more of immunoglobulin A, immunoglobulin G, immunoglobulin M, amyloid protein, C-reactive protein, and troponin.

9. The method for preparing the organic electrochemical transistor according to any one of claims 1-8, characterized in that, Includes the following steps: (1) Deposit metallic materials on the substrate as source and drain electrodes; (2) A uniform organic semiconductor material thin film is deposited using a solution method as the channel layer; (3) Cover the channel layer with electrolyte; (4) A functionalized porous carbon-based gate is coated on the electrolyte to construct an organic electrochemical transistor for detecting protein substances.

10. The application of the organic electrochemical transistor according to any one of claims 1-8 in the detection of protein-like substances, wherein the application does not relate to the diagnosis and treatment of diseases.

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