Biosensor of organic electrochemical transistor and preparation method of biosensor

Abstract

According to the biosensor of the organic electrochemical transistor and the preparation method of the biosensor, due to the capillary force of a conical micropore and the difference between the hydrophilic and hydrophobic properties of the upper surface and the lower surface of a device, sweat can be spontaneously sucked and transferred to the side of a biological functional modified vertical gold nanowire from the side of a substrate, and automatic extraction and detection of the sweat are achieved; the vertical gold nanowire has a relatively high specific surface area, has relatively high loading capacity on oxidase and a catalyst, and can realize low-richness biomarker detection; a mutual separation and permeation network structure of the stretchable active layer material and the gold nanowires can relieve strain damage of the device, and excellent device performance can still be kept under strain; separation of a grid sensing function and a signal amplification function is realized, signal crosstalk generated by pollutants is reduced, and detection sensitivity and selectivity of the device are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of flexible microelectronic devices, and in particular relates to a biosensor of an organic electrochemical transistor and a preparation method thereof. Background Art

[0002] Wearable biosensors have attracted widespread attention, especially in on-site healthcare applications. Compared with traditional blood samples, non-invasive sweat can provide real-time and accurate metabolic information, becoming a research hotspot in the field of wearable biosensors. However, the films used in most wearable sweat sensors are impermeable, and biological enzymes cannot react with analytes in sweat, and are ineffective for ultra-low concentration analytes. In order to achieve directional transmission of sweat and optimize sensor performance, researchers have realized that film surface modification is crucial. However, high-performance sweat self-absorption biosensors are still scarce because of their very demanding requirements in terms of film surface modification, sensor integration, and performance optimization.

[0003] Organic electrochemical transistors (OECTs) have attracted much attention in the fields of biosensors, bioelectronics, and nanomedicine due to their unique advantages, such as low-temperature processing, good water-electrolyte interface, and "soft" mechanical properties. Compared with inorganic semiconductor (such as silicon)-based transistors, OECTs use organic semiconductor materials, show advantages in signal amplification, and operate stably in low-voltage (<1 V) aqueous solutions. OECT biosensors have been successfully used to detect biomolecules such as glucose, dopamine, DNA, antigens, and mammalian cells.

[0004] However, the current wearable sweat sensors based on OECTs are still underdeveloped in terms of sweat self-collection and intrinsic stretchability. Controlling the directional transport of sweat from the skin surface to the sensing area and maintaining the stability of sensor performance after deformation are the key to promoting the development of wearable sweat sensors, and are also a major challenge.

[0005] Therefore, it is necessary to develop a biosensor of an organic electrochemical transistor and a preparation method thereof to solve the above problems. Summary of the invention

[0006] The purpose of the present invention is to design an organic electrochemical transistor biosensor and a preparation method thereof in order to solve the above problems.

[0007] The present invention achieves the above-mentioned purpose through the following technical solutions: A biosensor of an organic electrochemical transistor, comprising: Flexible substrates; The first gate is placed above the flexible substrate; the first gate is a porous vertical gold nanowire gate, a plurality of micrometer-scale conical micropores are arranged on the surface of the first gate, and the large opening ends of the micrometer-scale conical micropores penetrate downward through the flexible substrate, and biological oxidase and biological catalyst are deposited on the first gate; the first gate has a Janus structure, the top surface is hydrophilic, and the bottom surface of the flexible substrate is hydrophobic; A second gate; the second gate is disposed above the flexible substrate; the second gate is connected to the first gate; Stretchable source; A stretchable drain electrode; a stretchable source electrode and a stretchable drain electrode are arranged side by side and spaced apart on the flexible substrate; A stretchable active layer; the stretchable active layer is disposed above the stretchable source electrode and the stretchable drain electrode; An electrolyte layer; the electrolyte layer is disposed above the stretchable active layer and the second grid; Flexible packaging layer; the flexible packaging layer covers the second gate, the stretchable source, the stretchable drain, the electrolyte, and the stretchable active layer.

[0008] A method for preparing a biosensor of an organic electrochemical transistor, comprising: S1, cleaning the substrate with deionized water, isopropanol, and acetone solution, drying with nitrogen, and then spin coating PDMS on the surface of the substrate for annealing; S2, spin-coating a positive photoresist on the surface of the PDMS film, performing thermal annealing, and exposing and developing the positive photoresist; S3, after the surface of the substrate is subjected to oxygen plasma surface treatment, it is immersed in an anhydrous ethanol solution containing 3-aminopropyltriethoxysilane, after being cleaned with anhydrous ethanol and nitrogen, it is immersed in a gold seed solution, after being cleaned with deionized water and nitrogen, it is immersed in a gold nanowire growth solution, after being cleaned with anhydrous ethanol and nitrogen, the PDMS is peeled off from the surface of the substrate to obtain a patterned flexible stretchable vertical gold nanowire thin film electrode; S4, using a laser cutter to etch the surface of the patterned flexible stretchable vertical gold nanowire film electrode to obtain a first gate of a conical micropore, and dripping glucose oxidase and an aqueous solution of ferrocyanide (III) on the first gate, and standing to dry; S5, spin coating the active layer material on the surface of the OTS-treated silicon wafer and transferring it onto the stretchable source and drain electrodes; S6. Attach the patterned flexible material onto the second gate and the electrolyte layer to achieve packaging and obtain a biosensor.

[0009] The advantages of the present invention are: 1. Due to the capillary force of the conical micropores and the difference in hydrophilicity and hydrophobicity between the upper and lower surfaces of the device, sweat will be spontaneously absorbed and transferred from the base side to the biofunctionalized vertical gold nanowire side, realizing the automated extraction and detection of sweat.

[0010] 2. Vertical gold nanowires have a high specific surface area and a high loading capacity for oxidases and catalysts, enabling the detection of low-abundance biomarkers.

[0011] 3. The mutually separated and permeated network structure of the stretchable active layer material and gold nanowires can alleviate the strain damage of the device and still maintain excellent device performance under strain.

[0012] 4. The separation of gate sensing function and signal amplification function is realized, which reduces the signal crosstalk caused by pollutants and improves the detection sensitivity and selectivity of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a top view of the present invention; Figure 2 is a cross-sectional view (front view) of the present invention; Figure 3 is an electron microscope photograph of the flexible and stretchable vertical gold nanowire electrode grown on the PDMS surface in step (3) of Example 1; The reference numerals in the figure are: 1. flexible substrate, 2. first gate, 3. flexible encapsulation layer, 4. second gate, 5. stretchable source, 6. stretchable drain, 7. electrolyte, 8. stretchable active layer. DETAILED DESCRIPTION

[0014] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0015] like Figure 1 As shown, an organic electrochemical transistor biosensor comprises: Flexible substrates; The first gate is placed above the flexible substrate; the first gate is a porous vertical gold nanowire gate, a plurality of micrometer-scale conical micropores are arranged on the surface of the first gate, and the large opening ends of the micrometer-scale conical micropores penetrate downward through the flexible substrate, and biological oxidase and biological catalyst are deposited on the first gate; the first gate has a Janus structure, the top surface is hydrophilic, and the bottom surface of the flexible substrate is hydrophobic; A second gate; the second gate is disposed above the flexible substrate; the second gate is connected to the first gate; Stretchable source; A stretchable drain electrode; a stretchable source electrode and a stretchable drain electrode are arranged side by side and spaced apart on the flexible substrate; A stretchable active layer; the stretchable active layer is disposed above the stretchable source electrode and the stretchable drain electrode; An electrolyte layer; the electrolyte layer is disposed above the stretchable active layer and the second grid; Flexible packaging layer; the flexible packaging layer covers the second gate, the stretchable source, the stretchable drain, the electrolyte, and the stretchable active layer.

[0016] In some embodiments, the flexible substrate is made of any one of polydimethylsiloxane, hydrogenated styrene-butadiene block copolymer, and water-soluble polyurethane, and the thickness of the flexible substrate is 0.1-5 mm.

[0017] In some embodiments, the biological oxidase comprises any one of glucose oxidase, lactate oxidase, urate oxidase, and ascorbate oxidase.

[0018] In some embodiments, the biocatalyst is platinum nanoparticles or iron (III) ferrocyanide.

[0019] In some embodiments, the diameter of the upper cone of the conical micropore is 100-800 μm, and the ratio of the diameter of the upper cone to the lower cone is 1:3-1:5. The stretchable active layer is any one of Pg2t-T, P3HT, and PEDOT:PSS.

[0020] In some embodiments, the electrolyte layer is a PBS solution or a solid ion gel.

[0021] The porous vertical gold nanowire has a Janus structure, with a hydrophilic head and a hydrophobic tail. The flexible substrate surface at the bottom is hydrophobic. Due to the capillary force of the conical micropores and the difference in hydrophilicity and hydrophobicity between the upper and lower surfaces, sweat will spontaneously be absorbed and transferred from the substrate side to the biofunctionalized vertical gold nanowire side, and then react specifically with the corresponding target oxidase to produce H2O2. Under the action of the catalyst, H2O2 is decomposed into H2O and e - , changing the double electric layer of the gate / electrolyte interface, resulting in a change in the effective gate voltage, which in turn causes a change in the drain current. In addition, the vertical gold nanowires have a high specific surface area and a high loading capacity for oxidases and catalysts, enabling low-abundance biomarker detection. The mutually separated permeable network structure of the stretchable active layer and the gold nanowires during the stretching process can alleviate the strain damage of the device, and ultimately maintain excellent device performance under strain. This biosensor based on sweat self-absorption stretchable organic electrochemical transistors can automatically realize sweat absorption and biomarker recognition, and has excellent device stretchability, detection selectivity, and low-abundance marker detection capabilities.

[0022] A method for preparing a biosensor of an organic electrochemical transistor, comprising: S1, cleaning the substrate with deionized water, isopropanol, and acetone solution, drying with nitrogen, and then spin coating PDMS on the surface of the substrate for annealing; S2, spin-coating a positive photoresist on the surface of the PDMS film, performing thermal annealing, and exposing and developing the positive photoresist; S3, after the surface of the substrate is subjected to oxygen plasma surface treatment, it is immersed in an anhydrous ethanol solution containing 3-aminopropyltriethoxysilane, after being cleaned with anhydrous ethanol and nitrogen, it is immersed in a gold seed solution, after being cleaned with deionized water and nitrogen, it is immersed in a gold nanowire growth solution, after being cleaned with anhydrous ethanol and nitrogen, the PDMS is peeled off from the surface of the substrate to obtain a patterned flexible stretchable vertical gold nanowire thin film electrode; S4, using a laser cutter to etch the surface of the patterned flexible stretchable vertical gold nanowire film electrode to obtain a first gate of a conical micropore, and dripping glucose oxidase and an aqueous solution of ferrocyanide (III) on the first gate, and standing to dry; S5, spin coating the active layer material on the surface of the OTS-treated silicon wafer and transferring it onto the stretchable source and drain electrodes; S6. Attach the patterned flexible material onto the second gate and the electrolyte layer to achieve packaging and obtain a biosensor.

[0023] In some embodiments, in step S2, the positive photoresist is any one of AZ5214E ​​and AZ1500 series, the thermal annealing temperature ranges from 90 to 110° C., and the time ranges from 2 to 10 min.

[0024] In some embodiments, in step S3, the concentration of 3-aminopropyltriethoxysilane (APTMS) is 5-50 mM, and the immersion time is 2-4 hours; the concentration of chloroauric acid in the gold seed solution is 0.25 mM, the concentration of sodium citrate is 0.25 mM, the concentration of sodium borohydride is 6 mM, and the immersion time is 2-4 hours; the concentration of chloroauric acid in the gold nanowire growth solution is 12 mM, the concentration of 4-mercaptobenzoic acid is 1.1 mM, the concentration of L-ascorbic acid is 30 mM, and the immersion time is 5-10 min.

[0025] In some embodiments, in step S1, the thermal annealing temperature ranges from 60 to 80°C, and the time ranges from 1 to 3 hours.

[0026] In some embodiments, in step S4, the concentration of the glucose oxidase aqueous solution is 5-20 mg / ml, and the concentration of the iron (III) ferrocyanide aqueous solution is 5-10 mM.

[0027] In some embodiments, the thermal annealing method adopts one or more of constant temperature hot plate heating, oven heating, far infrared heating, and hot air heating.

[0028] Embodiment 1:

[0029] A method for preparing a biosensor of an organic electrochemical transistor, comprising: (1) The Si / SiO2 wafer was cleaned with deionized water, isopropanol, and acetone solution, dried with nitrogen, coated with PDMS, and annealed at 80°C for 10 minutes; (2) Spin-coat the positive photoresist AZ5214E ​​on the surface of the PDMS film at 3000 rpm / s, thermally anneal at 90°C for 1 minute, expose with a 365 nm UV lamp for 1 minute, develop with MIF 300 developer for 50 seconds, soak in deionized water for 50 seconds, and then blow dry with nitrogen; (3) After the substrate surface was treated with oxygen plasma for 5 minutes, it was immersed in an anhydrous ethanol solution containing 5 mM 3-aminopropyltriethoxysilane (APTMS) for 2 hours. After being cleaned with anhydrous ethanol and nitrogen, it was immersed in a gold seed solution with a chloroauric acid concentration of 0.25 mM, a sodium citrate concentration of 0.25 mM, and a sodium borohydride concentration of 6 mM for 2 hours, and then rinsed with deionized water and nitrogen. After being cleaned with deionized water and nitrogen, it was immersed in a gold nanowire growth solution with a chloroauric acid concentration of 12 mM, a 4-mercaptobenzoic acid concentration of 1.1 mM, and a L-ascorbic acid concentration of 30 mM for 5 minutes, and then rinsed with anhydrous ethanol and nitrogen to obtain a patterned flexible and stretchable vertical gold nanowire thin film electrode; (4) Use a 45W carbon dioxide laser cutter to etch the electrode surface to obtain a porous vertical gold nanowire gate, and then drop a glucose oxidase aqueous solution (5 mg / ml) and an iron (III) ferrocyanide (5 mM) aqueous solution on the gate and let it stand for 24 hours to dry; (5) Spin-coat 10 mg / ml Pg2t-t on the surface of the OTS-treated Si wafer and transfer it to the channel area; (6) Use 1X PBS as the electrolyte; (7) The patterned PDMS was treated with plasma for 45 seconds and then attached to the device surface for encapsulation, thereby obtaining a sweat self-absorption stretchable organic electrochemical transistor biosensor.

[0030] Embodiment 2: The difference from Example 1 is that in step (2), positive photoresist PMMA (950K A5) is spin-coated on the surface of the PDMS film at 3000 rpm / s, thermally annealed at 150° C. for 3 minutes, exposed using UV-ozone surface treatment for 3 minutes, developed using IPA / deionized water = 2:1 developer for 50 seconds, soaked in deionized water for 50 seconds for cleaning, and then blown dry with nitrogen;

[0031] Embodiment 3: The difference from Example 1 is that in step (4), a urate oxidase aqueous solution (5 mg / ml) and an iron (III) ferrocyanide (5 mM) aqueous solution are drop-coated on the gate and left to stand for 24 hours to dry;

[0032] Embodiment 4: The difference from Example 1 is that in step (4), a lactate oxidase aqueous solution (5 mg / ml) and an iron (III) ferrocyanide (5 mM) aqueous solution are drop-coated on the gate and left to stand for 24 hours to dry;

[0033] Embodiment 5: The difference from Example 1 is that in step (4), a mixed solution of HPtCl4 (10 mM) and L-AA (25 mM) is dripped on the gate, and then washed with deionized water after standing for 5 minutes. A carbon dioxide laser cutter with a power of 45W is used to etch the electrode surface to obtain a porous vertical gold nanowire gate, and an ascorbic acid oxidase aqueous solution (5 mg / ml) is dripped on the gate and left to dry for 24 hours; The present invention has been described by the above embodiments, but it should be understood that the above embodiments are only for the purpose of example and description, and are not intended to limit the present invention to the scope of the described embodiments. In addition, it can be understood by those skilled in the art that the present invention is not limited to the above embodiments, and more variations and modifications can be made according to the teachings of the present invention, and these variations and modifications all fall within the scope of the protection claimed by the present invention. The protection scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A biosensor of an organic electrochemical transistor, characterized in that: include: Flexible substrates; a first gate; A first gate is disposed above the flexible substrate; The first gate is a porous vertical gold nanowire gate, and a plurality of micrometer-scale conical micropores are arranged on the surface of the first gate. The large opening ends of the micrometer-scale conical micropores penetrate downward through the flexible substrate. The biological oxidase and the biological catalyst are deposited on the top of the first gate. The first gate has a Janus structure, the top surface is hydrophilic, and the bottom surface of the flexible substrate is hydrophobic. A second gate; the second gate is disposed above the flexible substrate; the second gate is connected to the first gate; Stretchable source; A stretchable drain electrode; a stretchable source electrode and a stretchable drain electrode are arranged side by side and spaced apart on the flexible substrate; A stretchable active layer; The stretchable active layer is disposed above the stretchable source electrode and the stretchable drain electrode; Electrolyte layer; The electrolyte layer is disposed above the stretchable active layer and the second gate; Flexible packaging layer; The flexible encapsulation layer covers the second gate, the stretchable source, the stretchable drain, the electrolyte, and the stretchable active layer.

2. The organic electrochemical transistor biosensor according to claim 1, characterized in that: The preparation material of the flexible substrate is any one of polydimethylsiloxane, hydrogenated styrene-butadiene block copolymer and water-soluble polyurethane, and the thickness of the flexible substrate is 0.1-5 mm.

3. The organic electrochemical transistor biosensor according to claim 1, characterized in that: The biological oxidase includes any one of glucose oxidase, lactate oxidase, urate oxidase, and ascorbate oxidase.

4. The organic electrochemical transistor biosensor according to claim 1, characterized in that: The biocatalysts are platinum nanoparticles or iron(III) ferrocyanide.

5. The organic electrochemical transistor biosensor according to claim 1, characterized in that: The diameter of the upper cone surface of the conical micropore is 100-800 μm, and the diameter ratio of the upper cone surface to the lower cone surface is 1:3-1:

5.

6. The organic electrochemical transistor biosensor according to claim 1, characterized in that: The stretchable active layer is any one of Pg2t-T, P3HT, and PEDOT:PSS.

7. The organic electrochemical transistor biosensor according to claim 1, characterized in that: The electrolyte layer is PBS solution or solid ion gel.

8. The method for preparing an organic electrochemical transistor biosensor according to any one of claims 1 to 7, characterized in that: include: S1, cleaning the substrate with deionized water, isopropanol, and acetone solution, drying with nitrogen, and then spin coating PDMS on the surface of the substrate for annealing; S2, spin-coating a positive photoresist on the surface of the PDMS film, performing thermal annealing, and exposing and developing the positive photoresist; S3, after the surface of the substrate is subjected to oxygen plasma surface treatment, it is immersed in an anhydrous ethanol solution containing 3-aminopropyltriethoxysilane, after being cleaned with anhydrous ethanol and nitrogen, it is immersed in a gold seed solution, after being cleaned with deionized water and nitrogen, it is immersed in a gold nanowire growth solution, after being cleaned with anhydrous ethanol and nitrogen, the PDMS is peeled off from the surface of the substrate to obtain a patterned flexible stretchable vertical gold nanowire thin film electrode; S4, using a laser cutter to etch the surface of the patterned flexible stretchable vertical gold nanowire film electrode to obtain a first gate of a conical micropore, and dripping glucose oxidase and an aqueous solution of ferrocyanide (III) on the first gate, and standing to dry; S5, spin coating the active layer material on the surface of the OTS-treated silicon wafer and transferring it onto the stretchable source and drain electrodes; S6. Attach the patterned flexible material onto the second gate and the electrolyte layer to achieve packaging and obtain a biosensor.

9. The method for preparing an organic electrochemical transistor biosensor according to claim 8, characterized in that: In step S2, the positive photoresist is any one of AZ5214E ​​and AZ1500 series, the thermal annealing temperature ranges from 90 to 110°C, and the time ranges from 2 to 10 min.

10. The method for preparing an organic electrochemical transistor biosensor according to claim 8, characterized in that: In step S3, the concentration of 3-aminopropyltriethoxysilane is 5-50 mM, and the immersion time is 2-4 hours; the concentration of chloroauric acid in the gold seed solution is 0.25 mM, the concentration of sodium citrate is 0.25 mM, the concentration of sodium borohydride is 6 mM, and the immersion time is 2-4 hours; the concentration of chloroauric acid in the gold nanowire growth solution is 12 mM, the concentration of 4-mercaptobenzoic acid is 1.1 mM, the concentration of L-ascorbic acid is 30 mM, and the immersion time is 5-10 min.

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