Biosensor based on organic electrochemical transistor

Abstract

The invention relates to the technical field of sensor preparation and parameter optimization, and discloses a biosensor based on an organic electrochemical transistor, the biosensor comprises a biological sensitive grid, a drain electrode 1, a source electrode 2, an organic semiconductor channel 3, a substrate 4 and an electrolyte solution 5, the organic semiconductor channel 3 is arranged between the drain electrode 1 and the source electrode 2, and is connected with the drain electrode 1 and the source electrode 2; and the biological sensitive grid is arranged on the top layer and is connected with a device below through the electrolyte solution 5. The application can effectively reduce the influence of other dielectric media on the concentration detection of target fungi.

Description

Technical Field

[0001] The invention relates to the technical field of sensor preparation and parameter optimization, and discloses a biosensor based on an organic electrochemical transistor. Background Art

[0002] As the global food supply chain becomes increasingly complex and expanded, people are increasingly concerned about food safety. Among the many factors that may endanger public health, mycotoxins have attracted widespread attention. Mycotoxin contamination is widely found in food. As a major grain importer and exporter, my country has become more and more frequent in grain imports and exports driven by economic development, which has led to the continuous strengthening of supervision and spot checks on various animals, plants, grains and oils. However, during the storage, transportation and processing of grain, due to factors such as unsuitable environment and improper operation, it is very easy to cause mold growth and toxin production.

[0003] After years of research, a variety of technologies have been developed for the detection and analysis of mycotoxins, mainly including enzyme-linked immunosorbent assay and thin-layer chromatography. Although these methods have advantages such as high sensitivity and high accuracy, they still have obvious disadvantages. These methods require the experimenter to have skilled operating skills, expensive equipment and materials, and complex sample pretreatment processes. In addition to the above methods, emerging technologies such as electrochemistry, fluorescence, chemiluminescence, optical fiber and surface plasmon resonance have emerged in recent years for the detection of mycotoxin concentrations. These emerging technologies provide a solution with great potential for the detection of mycotoxins with their high sensitivity, low cost, simplicity and ease of use. However, they also face problems such as high detection limits, difficulty in integration, and sensitivity to environmental interference.

[0004] For example, the existing Chinese patent with the authorization publication number CN113203785A discloses that the present invention discloses an Aβ oligomer biosensor based on an organic photoelectrochemical transistor and its preparation method and application, wherein the Aβ oligomer biosensor includes a gate electrode with one end inserted into an electrolyte solution, a photoelectric active layer is arranged on the gate electrode, a nucleic acid aptamer Apt1 specifically binding to the Aβ oligomer in the sample to be tested is arranged on the photoelectric active layer, and also includes a spare enzyme-labeled aptamer specifically binding to the Aβ oligomer in the sample to be tested, the enzyme-labeled aptamer is composed of a nucleic acid aptamer Apt2, micro-nanoparticles and an enzyme combined together; and a spare catalytic substrate that reacts with the enzyme to generate a colored precipitate. The present invention uses a nucleic acid aptamer that is highly specific to the Aβ oligomer to construct a sandwich immune structure, and under the catalysis of the enzyme, a colored precipitate can be generated at the same time, and at the same time, the low-cost, simple instrument, high sensitivity and good selectivity detection of the Aβ oligomer is realized through the organic photoelectrochemical transistor.

[0005] However, the above patents have the following problems: the biosensor has low biosensitive gate selectivity, the measurement signal is easily affected by external interference, it is difficult to stably and continuously map the concentration changes of the target detection substance, and the detection environment changes lead to low stability, large errors in the measurement results, and it is impossible to follow up the temperature parameter changes in real time. Finally, due to structural limitations, the detection application range and sensitivity of the biosensor are restricted. Summary of the invention

[0006] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0007] In order to solve the above technical problems, the main purpose of the present invention is to provide a biosensor based on an organic electrochemical transistor, comprising:

[0008] A biosensitive grid comprises a grid (7), a biosensitive layer (9) and an electrode modification layer (8) which are arranged opposite to each other, wherein the surface of the biosensitive layer (9) is modified with an immune response structure;

[0009] an electrolyte solution (5), comprising a charged medium and a test fungus;

[0010] An electrode layer, the electrode layer comprising a drain electrode (1), a source electrode (2), an organic semiconductor channel (3) and a substrate (4);

[0011] The biosensitive grid is connected to the electrode layer via an electrolyte solution (5).

[0012] Optionally, the structure of the organic electrochemical transistor is a planar structure, and the drain electrode (1) is located on one side of the semiconductor channel (3).

[0013] Optionally, the structure of the organic electrochemical transistor is a vertical structure, and the drain electrode (1) is located at the top of the semiconductor channel (3).

[0014] Optionally, the biosensitive gate material of the biosensor includes noble metals and alloys, transition metal oxides and carbon-based materials;

[0015] The material of the electrode of the biosensor biosensitive layer (9) includes a cationic functional group or a functional group having a specific affinity with a specific enzyme.

[0016] Optionally, the biosensitive gate material includes noble metals and oxides;

[0017] The material of the biosensor electrode modification layer (8) includes transition metal oxide;

[0018] The material of the electrode of the biosensor biosensitive layer (9) includes a cationic functional group or a functional group having a specific affinity with a specific enzyme.

[0019] Optionally, the biosensor is provided with a microfluidic channel, and the microfluidic channel is a Y-shaped structure or a T-shaped structure;

[0020] A microcolumn array is arranged in the microfluidic channel.

[0021] The present application also provides a method for preparing a biosensor based on an organic electrochemical transistor as described above, comprising the following steps:

[0022] S1. preparing chitosan-graphene nanocomposite materials;

[0023] S2, preparing a biosensitive gate;

[0024] S3. Preparation of organic electrochemical transistors;

[0025] S4. Use the prepared biosensitive gate as a gate to connect the organic electrochemical transistor and immerse it in the electrolyte solution (5).

[0026] Optionally, the steps of preparing the chitosan-graphene nanocomposite material include:

[0027] The chitosan solution is prepared by dissolving chitosan in acetic acid;

[0028] The graphene dispersion is obtained by ultrasonically dispersing graphene nanosheet powder in anhydrous ethanol and centrifuging to obtain a supernatant;

[0029] The chitosan-graphene nanocomposite solution was prepared by mixing the graphene dispersion with the chitosan solution.

[0030] Optionally, the step of preparing the biosensitive gate includes:

[0031] S201, placing the gate electrode (7) in ethanol and ultrapure water for ultrasonic cleaning, and performing cyclic voltammetry scanning activation in a sulfuric acid solution;

[0032] S202, performing carboxyl treatment on the surface of the gate electrode (7) in a p-aminobenzoic acid solution by cyclic voltammetry;

[0033] S203, taking the prepared chitosan-graphene nanocomposite dispersion droplets and applying them on the surface of the gate electrode (7), after drying, adding EDC and NHS solutions, incubating to activate the carboxyl groups, washing the treated electrode with PBS solution, adding fungal toxin antibodies, incubating, and then adding BSA solution to block the surface active sites, and the electrode modification layer 8 and the biosensitive layer (9) are prepared;

[0034] S204, obtaining a biosensitive gate.

[0035] Optionally, the step of preparing an organic electrochemical transistor comprises:

[0036] S301, preparing a treated base (4) by ultrasonic cleaning with isopropyl alcohol and cleaning with UV light.

[0037] S302, using the processed substrate (4) as an operating platform, obtaining a source electrode (2) and a drain electrode (1) by evaporation;

[0038] S303, spin coating a semiconductor solution between the prepared source electrode (3) and the drain electrode (2) to prepare an organic semiconductor channel (4);

[0039] S304, spin-coating photoresist, aligning the mask photoresist plate with the substrate (4), and irradiating with ultraviolet light to obtain an encapsulation layer 6, thereby obtaining the organic electrochemical transistor.

[0040] Beneficial effects of the present invention:

[0041] The mycotoxin biosensor based on organic electrochemical transistors prepared by the present invention is a planar or vertical structure, and exhibits good detection limit and sensitivity. The prepared mycotoxin biosensor based on organic electrochemical transistors shows excellent stability in a short time regardless of whether it uses a glassy carbon electrode or a gold electrode as a working electrode, and its measurement signal is not easily affected by external interference, and can continuously and stably reflect the concentration change of the target substance. The prepared mycotoxin biosensor based on organic electrochemical transistors has a biologically sensitive gate with high selectivity, and can quickly and accurately detect the concentration of mycotoxins at low concentrations. The cross-point sensitive inhibition of the present invention can effectively reduce the cross sensitivity of the mycotoxin biosensor based on OECTs, and improve its detection specificity and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0043] Figure 1 This is a system composition diagram of a biosensor based on an organic electrochemical transistor according to the present invention;

[0044] Figure 2 The present invention provides a method for preparing a fungal toxin biosensor based on an organic electrochemical transistor; Figure 3 A microfluidic channel with a Y-shaped inlet of a biosensor based on an organic electrochemical transistor according to the present invention;

[0045] Figure numbers: 1. drain electrode; 2. source electrode; 3. organic semiconductor channel; 4. substrate; 5. electrolyte solution; 6. encapsulation layer; 7. gate electrode; 8. electrode modification layer; 9. biosensitive layer; 10. fungal solution flow channel; 11. microfluidic channel; 12. microcolumn. DETAILED DESCRIPTION

[0046] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0047] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0048] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0049] Embodiment 1:

[0050] like Figure 1 As shown, the embodiment of the present application provides a biosensor based on an organic electrochemical transistor, comprising:

[0051] A biosensitive layer 9, a drain electrode 1, a source electrode 2, an organic semiconductor channel 3, a substrate 4, an electrolyte solution 5, and an encapsulation layer 6; a biosensitive gate, comprising a gate 7, a biosensitive layer 9, and an electrode modification layer (8) arranged relatively to each other, wherein the surface of the biosensitive layer 9 is modified with an immune response structure; an electrolyte solution 5, comprising a charged dielectric and a detected fungus; and an electrode layer comprising a drain electrode 1, a source electrode 2, an organic semiconductor channel 3, and a substrate 4.

[0052] The surface of the biosensitive layer 9 is modified with an immune response structure. When the sample containing fungi enters the electrolyte solution 5, the fungi, as the detected fungi, will specifically bind to the immune response structure on the biosensitive layer 9. This causes the electrical properties of the biosensitive layer 9 to change, and the fungal concentration can be detected by detecting the change in electrical properties.

[0053] When used specifically, the drain electrode 1 and the source electrode 2 are connected via the organic semiconductor channel 3. Under normal circumstances, when a voltage is applied between the gate 7 and the source electrode 2 (or the drain electrode 1), the charged dielectric in the electrolyte solution 5 will gather near the organic semiconductor channel 3 under the action of the electric field, thereby adjusting the conductive properties of the channel.

[0054] When the fungus combines with the biosensitive layer 9, the electric field or charge distribution near the biosensitive layer 9 will be changed, affecting the aggregation of charged dielectrics in the electrolyte solution 5 near the organic semiconductor channel 3. For example, if the combination of the fungus causes the surface potential of the biosensitive layer 9 to increase, it will make it more difficult for the cations in the electrolyte solution 5 to aggregate near the organic semiconductor channel 3, thereby causing the conductivity of the channel to decrease. The change in conductivity can then be reflected by detecting the change in the current between the drain electrode 1 and the source electrode 2.

[0055] Specifically, the drain electrode 1 and the source electrode 2 are connected by a detection circuit, and the current signal is converted into a voltage signal for detection and amplification. Since the fungal concentration is proportional to the number of fungi bound to the biosensitive layer 9, and the number of bound fungi is related to the degree of change in the electrical properties of the biosensitive layer 9, and ultimately related to the current change between the drain-source electrode. A series of standard samples with known fungal concentrations can be used for calibration in advance to establish a standard curve between the fungal concentration and the detected current (or voltage) signal change. In this way, when actually measuring a sample with an unknown fungal concentration, the fungal concentration can be calculated based on the detected signal change and the standard curve.

[0056] Specifically, the organic semiconductor channel 3 is placed between the drain electrode 1 and the source electrode 2, connecting the drain electrode 1 and the source electrode 2, the biosensitive layer 9 is placed on the top layer and connected to the device below through the electrolyte solution 5, and the encapsulation layer 6 surrounds the electrolyte solution 5; the encapsulation layer 6 is used to cover unnecessary areas on the biosensor of the organic electrochemical transistor, leaking the channel and the source and drain electrodes to prevent contact with liquid to affect performance. In the embodiment of the present application, the encapsulation layer 6 can be selected from the photoresist SU-8.

[0057] Furthermore, in the embodiment of the present application, the material of the substrate 4 can be rigid or flexible, such as one or more of silicon wafer, glass, PI, PEN, etc.

[0058] Furthermore, in the embodiment of the present application, the material of the organic semiconductor channel 3 can be one of the n-type or p-type, such as Homo-gDPP, BBL, etc.

[0059] Furthermore, in the embodiment of the present application, the material of the source electrode 2 and the drain electrode 1 can be gold, silver, platinum, etc., or one of the conductive polymers.

[0060] Furthermore, in the embodiment of the present application, the biosensitive gate comprises a gate electrode 7, an electrode modification layer 8 and a biosensitive layer 9. The gate 7 is located at the top of the biosensor of the organic electrochemical transistor and is connected to the electrode modification layer 8; the electrode modification layer 8 is located between the gate electrode 7 and the biosensitive layer 9, and the electrode modification layer 8 is connected to the biosensitive layer 9.

[0061] The structure of the organic electrochemical transistor is a planar structure or a vertical structure, which is not limited in the present application. Specifically, if the structure of the organic electrochemical transistor is a planar structure, the drain electrode (1) is located on one side of the semiconductor channel (3); if the structure of the organic electrochemical transistor is a vertical structure, the drain electrode (1) is located on the top of the semiconductor channel (3).

[0062] The further inventive concepts of the present application are described in detail below.

[0063] In the embodiment of the present application, the fungus in the embodiment of the present application may be vomitoxin (deoxynivalenol), the chemical structure of which contains polar groups such as hydroxyl groups, and exhibits weak acidity. In a solution with a specific pH value higher than its isoelectric point, it will dissociate hydrogen ions and carry a negative charge. In addition, the fungus in the embodiment of the present application may also be ochratoxin A, and in an alkaline environment, groups such as carboxyl groups in the molecular structure of ochratoxin A may also dissociate, thereby carrying a negative charge.

[0064] Based on this, the present application further inserts functional groups matching the target fungi into the biosensor biosensitive layer by modification, thereby forming synergy with the macroscopic structure of the present application.

[0065] Specifically, the biosensitive gate material of the biosensor includes precious metals and alloys, transition metal oxides and carbon-based materials. In the embodiment of the present application, precious metals (gold, silver, platinum) and their alloys are selected as basic electrode materials, which have good electrical conductivity and chemical stability, and are convenient for subsequent modification and application. In addition, the crystal structure and surface properties of transition metal oxides (titanium dioxide, zinc oxide, etc.) can provide more modification sites. At the same time, carbon-based materials (graphene, carbon nanotubes) have high specific surface area and excellent electronic conductivity, which can effectively promote electrochemical reactions. In this way, cationic functional groups or functional groups with specific affinity for specific enzymes can be inserted into the material of the electrode of the biosensor biosensitive layer (9) by modification.

[0066] Specifically, in the embodiments of the present application, cationic functional groups or functional groups having specific affinity with specific enzymes can be selected according to the characteristics of the fungi. For example, for fungi with more negative charges, the use of modified cationic functional groups can increase the charge attraction, thereby more accurately and quickly detecting the fungal content. The interference source cannot be stably adsorbed to the electrode of the biosensitive layer (9) during competitive electrosorption due to its less negative charge, thereby improving accuracy and speed.

[0067] Furthermore, the present application may also perform functional group modification on the biosensitive layer, and the present application does not limit this. Specifically, as a parallel solution, the biosensitive gate material includes noble metals and oxides;

[0068] The material of the biosensor electrode modification layer (8) includes transition metal oxide;

[0069] The material of the electrode of the biosensor biosensitive layer (9) includes a cationic functional group or a functional group having a specific affinity with a specific enzyme.

[0070] Furthermore, in the embodiments of the present application, the electrode surface can be modified by quaternary ammonium salt functional groups.

[0071] In this way, the target fungi with more negative charges are attracted through electrostatic attraction, while negatively charged interferents are repelled.

[0072] Furthermore, in the embodiments of the present application, a silane coupling agent can be used to covalently bond the quaternary ammonium salt group to the surface of the titanium dioxide electrode. The silane coupling agent (such as 3-aminopropyltriethoxysilane) is first reacted with the quaternary ammonium salt to generate a silane derivative with a quaternary ammonium salt functional group, which is then reacted with the titanium dioxide electrode under certain conditions to achieve stable modification.

[0073] For target fungi that secrete specific enzymes, functional groups with specific affinity to the enzyme are modified. For example, the boric acid group can specifically bind to sugar substances. If the target fungi secrete sugar-labeled enzymes, the boric acid is modified onto the surface of the gold electrode. In this way, the present application can attract the target fungi to the electrode, enhance the detection signal, and reduce the interference of other irrelevant enzymes.

[0074] Furthermore, the thiol compound containing the boric acid group can be adsorbed on the surface of the gold electrode by the self-assembled monolayer technology to form a regular and stable functional group modification layer, which will not be elaborated in this application.

[0075] In an embodiment of the present application, a biosensor can be provided with a microfluidic channel, and the microfluidic channel has a Y-shaped structure or a T-shaped structure; a microcolumn array is provided in the microfluidic channel, and the microcolumn array is provided in the microfluidic channel to disrupt the fluid dynamics of the fungal solution and prolong the contact time between the fungal solution and each layer of the biosensor.

[0076] Specifically, a fine fungal solution flow channel 10 is constructed through microfluidic chip technology, and a Y-shaped or T-shaped inlet is designed so that the fungal solution and the buffer solution are mixed in a certain proportion before entering the sensor body. This can dilute the concentration of interfering substances in the fungal solution, while adjusting the solution's ionic strength, pH value and other parameters to optimize the detection environment of the target fungi.

[0077] like Figure 3 As shown, it is a microfluidic channel with a Y-shaped inlet. The fungal solution flow channel 10 adopts a Y-shaped structure as a whole. The fungal solution enters through the fungal solution flow channel 10, and the fungal solution flows through the cylindrical microfluidic channel 11.

[0078] A microcolumn array is arranged in the microfluidic channel 11, and the microcolumns 12 are spaced at intervals of 100-500 nanometers, which further disrupts the fluid dynamics and prolongs the contact time between the fungal solution and each layer of the sensor, allowing the target fungi more opportunities to penetrate into the sensitive layer, while the interferents are effectively blocked. The target fungi and interferents are fluorescently labeled, and their flow paths and distribution in the microfluidic channel 11 are observed under a microscope to verify the effectiveness of the structural design, and the parameters such as the position, height and spacing of the microcolumns are fine-tuned according to the observation results.

[0079] Through the above embodiments, the present application modifies the functional groups on the electrode, and combined with the microfluidic channel configuration, a synergistic effect can be achieved, that is, the microfluidic channel forms a certain disturbance in the detection area, which increases the residence time of the charged medium in contact with the electrode surface, and provides more time and a more stable residence environment for the coupling of fungi and functional groups, which is more conducive to the detection of fungal concentration. In addition, since the functional groups are targeted, the coupling and binding force with the target fungi is enhanced, so that the electrode preferentially forms functional group coordination with the target fungi, and combined with the microfluidic channel, the residence time of the target fungi is greatly extended. The combination of the two allows the target fungi to be quickly adsorbed by the electrode, and will not affect the charged media of other non-target fungi. Therefore, even if the charged media of other non-target fungi are constantly disturbed in the microfluidic channel to extend the residence time, they will not be combined with the electrode, thereby reducing the impact of other charged media on the detection of target fungi concentration.

[0080] Embodiment 2:

[0081] like Figure 2 Shown: A method for preparing a fungal toxin biosensor based on an organic electrochemical transistor;

[0082] S1. preparing chitosan-graphene nanocomposite materials;

[0083] A chitosan-graphene nanocomposite material is prepared by mixing a graphene dispersion with a chitosan solution;

[0084] The chitosan solution is prepared by dissolving chitosan in acetic acid;

[0085] The graphene dispersion is obtained by ultrasonically dispersing graphene nanosheet powder in anhydrous ethanol and centrifuging to obtain a supernatant;

[0086] Specifically, 5 mg of chitosan powder was weighed and dissolved in 5 mL of 1.0% (V / V) acetic acid, magnetically stirred for 1 h, and stored at 4°C for later use. 5 mg of nanographene nanosheet powder was weighed and ultrasonicated in 5 mL of anhydrous ethanol for 10 h. After dispersion, the supernatant was taken after centrifugation at 9000 r / min for 15 min in a centrifuge, 5 ml of DMF was added, and ultrasonicated for more than 2 h until completely dispersed. 5 mL of the prepared graphene dispersion was mixed with 5 mL of the prepared chitosan solution, and ultrasonicated for 2 h to obtain a uniform CS-GNs nanocomposite material;

[0087] S2, preparing a biosensitive gate;

[0088] The biosensitive gate comprises a gate electrode 7, an electrode modification layer 8 and a biosensitive gate 9;

[0089] The method for preparing the biosensitive gate comprises:

[0090] S201, placing the gate electrode 7 in ethanol and ultrapure water for ultrasonic cleaning, and performing cyclic voltammetry scanning activation in a sulfuric acid solution;

[0091] S202, performing carboxyl treatment on the surface of the gate electrode 7 in a p-aminobenzoic acid solution by cyclic voltammetry;

[0092] S203, drop the prepared chitosan-graphene nanocomposite dispersion on the surface of the gate electrode 7, add EDC and NHS solution after drying, incubate to activate the carboxyl group, wash the treated electrode with PBS solution, add fungal toxin antibody, incubate, and then add BSA solution to block the surface active sites, and the electrode modification layer 8 and the biosensitive layer 9 are prepared;

[0093] S204, obtaining a biosensitive gate;

[0094] Specifically, the gold foil was placed in a 0.5M sulfuric acid (H2SO4) solution and subjected to cyclic voltammetry (CV, -0.3~1.5V, 50mV / s) scanning for 15 cycles for cleaning and activation. After activation, it was ultrasonically cleaned in ultrapure water for 10min and rinsed with a large amount of ultrapure water. CV (-1.5~1.0V, 50mV / s) was scanned for 15 cycles in a 5mM p-aminobenzoic acid solution to electropolymerize carboxyl groups on the surface of the gold foil. 10μL of the prepared CS-GNs nanocomposite dispersion was drop-coated on the surface of the pretreated gold foil, dried at room temperature, and 10μL of a freshly prepared EDC and NHS (0.4M:0.1M) solution was added, and incubated at 37℃ for 1h to activate the carboxyl groups. The electrode was thoroughly washed with PBS, and 10μL of 150μg / mL AFB1 antibody was added to the electrode surface and incubated at 37℃ for 50min, and then the electrode surface was rinsed with PBS to remove the physically adsorbed antibody. Then, 10 μL of 3% BSA solution was added to the obtained electrode and incubated at 37°C for 1 h to block the excess active sites on the electrode. The preparation of the biosensitive gate was completed.

[0095] S3. Preparation of organic electrochemical transistors;

[0096] S301, preparing a treated base 4 by ultrasonic cleaning with isopropyl alcohol and UV light cleaning of the base 4;

[0097] S302, using the processed substrate 4 as an operating platform, obtaining a source electrode 2 and a drain electrode 1 by evaporation;

[0098] S303, spin coating a semiconductor solution between the prepared source electrode 3 and the drain electrode 2 to prepare an organic semiconductor channel 4;

[0099] S304, spin-coating photoresist, aligning the mask photoresist plate with the substrate 4 and irradiating with ultraviolet light to obtain the encapsulation layer 6;

[0100] S305, the organic electrochemical transistor is prepared;

[0101] Since the structure of the organic electrochemical transistor is a planar structure or a vertical structure, the specific operation takes the preparation of a vertical organic electrochemical transistor as an example:

[0102] Use a silicon wafer cutter to cut the SiO2 wafer into 2cm×2cm size, ultrasonically treat it in isopropanol for 15 minutes, blow dry the surface solution with nitrogen, and clean it in a UV light cleaner for 15 minutes to ensure that the SiO2 substrate is clean and dry. Place the shadow mask of the source electrode on the cleaned and dried SiO2 substrate, and use a vacuum coating machine to evaporate 150nm of Au on the substrate at a speed of about 0.5~2.0A / s to serve as the source electrode of the vertical organic electrochemical transistor. Clean the evaporated source electrode in a UV light cleaner for 10 minutes to remove organic dirt on the surface. Spin-coat the prepared semiconductor mixed solution evenly on the prepared source electrode at a speed of 3000rpm for 30 seconds to obtain an organic semiconductor channel. Place the prepared drain electrode shadow mask on the SiO2 substrate, and evaporate 150nm of Au on the SiO2 substrate in the same way at a speed of about 0.5~2.0A / s to serve as the drain electrode of the vertical organic electrochemical transistor. Take SU8 photoresist as the encapsulation insulating layer solution and spin-coat it evenly at a speed of 3000 rpm for 30 seconds. Align the prepared photolithography mask with the SiO2 substrate and irradiate it with ultraviolet light with a wavelength of 360nm for 1-2 minutes to perform mask photolithography. After photolithography, place it in a developer and use a nitrogen spray gun to blow off the surface dirt to achieve vertical organic electrochemical transistor device packaging;

[0103] S4, using the prepared biosensitive gate as a gate to connect the organic electrochemical transistor and immerse it in the electrolyte solution 5.

[0104] The biosensitive gate prepared by S2 was connected to the vertical organic electrochemical transistor prepared by S3 as a gate electrode, and the two were immersed in PBS solution together. Thus, a vertical organic electrochemical transistor fungal toxin biosensor with gold foil as the gate electrode was successfully constructed.

[0105] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A biosensor based on an organic electrochemical transistor, comprising: A biosensitive grid comprises a grid (7), a biosensitive layer (9) and an electrode modification layer (8) which are arranged opposite to each other, wherein the surface of the biosensitive layer (9) is modified with an immune response structure; an electrolyte solution (5), comprising a charged medium and a test fungus; An electrode layer, the electrode layer comprising a drain electrode (1), a source electrode (2), an organic semiconductor channel (3) and a substrate (4); The biosensitive grid is connected to the electrode layer via an electrolyte solution (5).

2. The biosensor based on an organic electrochemical transistor according to claim 1, characterized in that: The structure of the organic electrochemical transistor is a planar structure, and the drain electrode (1) is located on one side of the semiconductor channel (3).

3. The biosensor based on an organic electrochemical transistor according to claim 1, characterized in that: The structure of the organic electrochemical transistor is a vertical structure, and the drain electrode (1) is located at the top of the semiconductor channel (3).

4. The biosensor based on an organic electrochemical transistor according to claim 3, characterized in that: The biosensitive gate material of the biosensor includes noble metals and alloys, transition metal oxides and carbon-based materials; The material of the electrode of the biosensor biosensitive layer (9) includes a cationic functional group or a functional group having a specific affinity with a specific enzyme.

5. The biosensor based on an organic electrochemical transistor according to claim 4, characterized in that: The biosensitive gate material includes noble metals and oxides; The material of the biosensor electrode modification layer (8) includes transition metal oxide; The material of the electrode of the biosensor biosensitive layer (9) includes a cationic functional group or a functional group having a specific affinity with a specific enzyme.

6. The biosensor based on an organic electrochemical transistor according to claim 5, characterized in that: The biosensor is provided with a microfluidic channel, and the microfluidic channel is a Y-shaped structure or a T-shaped structure; A microcolumn array is arranged in the microfluidic channel.

7. A method for preparing a biosensor based on an organic electrochemical transistor as claimed in claim 1, characterized in that: The steps include: S1. preparing chitosan-graphene nanocomposite materials; S2, preparing a biosensitive gate; S3. Preparation of organic electrochemical transistors; S4. Use the prepared biosensitive gate as a gate to connect the organic electrochemical transistor and immerse it in the electrolyte solution (5).

8. The method for preparing a mycotoxin biosensor based on an organic electrochemical transistor according to claim 7, characterized in that: The steps of preparing chitosan-graphene nanocomposite materials include: The chitosan solution is prepared by dissolving chitosan in acetic acid; The graphene dispersion is obtained by ultrasonically dispersing graphene nanosheet powder in anhydrous ethanol and centrifuging to obtain a supernatant; The chitosan-graphene nanocomposite solution was prepared by mixing the graphene dispersion with the chitosan solution.

9. The method for preparing a mycotoxin biosensor based on an organic electrochemical transistor according to claim 8, characterized in that: The steps of preparing the biosensitive gate include: S201, placing the gate electrode (7) in ethanol and ultrapure water for ultrasonic cleaning, and performing cyclic voltammetry scanning activation in a sulfuric acid solution; S202, performing carboxyl treatment on the surface of the gate electrode (7) in a p-aminobenzoic acid solution by cyclic voltammetry; S203, taking the prepared chitosan-graphene nanocomposite dispersion droplets and applying them on the surface of the gate electrode (7), after drying, adding EDC and NHS solutions, incubating to activate the carboxyl groups, washing the treated electrode with PBS solution, adding fungal toxin antibodies, incubating, and then adding BSA solution to block the surface active sites, and the electrode modification layer 8 and the biosensitive layer (9) are prepared; S204, obtaining a biosensitive gate.

10. The method for preparing a mycotoxin biosensor based on an organic electrochemical transistor according to claim 9, characterized in that: The steps for preparing an organic electrochemical transistor include: S301, preparing a treated base (4) by ultrasonic cleaning with isopropyl alcohol and cleaning with UV light. S302, using the processed substrate (4) as an operating platform, obtaining a source electrode (2) and a drain electrode (1) by evaporation; S303, spin coating a semiconductor solution between the prepared source electrode (3) and the drain electrode (2) to prepare an organic semiconductor channel (4); S304, spin-coating photoresist, aligning the mask photoresist plate with the substrate (4), and irradiating with ultraviolet light to obtain an encapsulation layer 6, thereby obtaining the organic electrochemical transistor.

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