Blood glucose detection electrode, nucleic acid detection electrode and preparation method
By growing upright graphene on the substrate surface and combining it with nanoparticles and a polymer coating membrane, the problem of unstable fixation of planar graphene conjugates was solved, enabling reusable blood glucose detection and highly sensitive nucleic acid detection, suitable for industrial production and distributed detection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHENZHEN YICK XIN TECH DEV CO LTD
- Filing Date
- 2023-02-21
- Publication Date
- 2026-06-09
AI Technical Summary
When existing planar graphene is used as a biosensor electrode carrier, the binding material is unstable, leading to detection failure. Furthermore, traditional blood glucose detection electrodes are costly, and nucleic acid detection is complex and expensive, making it difficult to achieve rapid and accurate multi-indicator joint detection.
Vertical graphene is grown on the substrate surface using the PECVD method, active sites are formed through plasma treatment, and Au or Pt nanoparticles are grown on it. Enzymes or nucleic acid aptamers are immobilized by polymer coating membranes to form reusable blood glucose and nucleic acid detection electrodes.
This invention enables the reusability of blood glucose detection electrodes, reducing costs, while nucleic acid detection electrodes offer high sensitivity and speed, making them suitable for distributed detection. It also solves the problems of fixing traditional electrodes and the complexity of nucleic acid detection.
Smart Images
Figure CN116337970B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of biosensor technology, and in particular to a blood glucose detection electrode, a nucleic acid detection electrode, and a method for their preparation. Background Technology
[0002] Planar graphene is a material with excellent electrical conductivity and has applications in various fields. In the field of biosensor technology, planar graphene is widely studied as an electrode carrier for biosensors. However, planar graphene as an electrode carrier requires immobilization with conjugates (such as glucose oxidase and nucleic acids) to allow the conjugates to bind with the analyte, generating an electrical signal for detection. If the conjugates are not immobilized on the planar graphene, they will be lost during detection, leading to detection failure. To ensure good immobilization of planar graphene with conjugates, a common practice is to perform plasma treatment on the surface of the planar graphene to obtain active sites, i.e., grafting various light water groups onto the surface of the planar graphene. However, this operation will destroy the structure of the planar graphene, resulting in a decrease in its conductivity, which seriously affects the application of planar graphene as an electrode carrier for biosensors. This is why many studies on planar graphene as a biosensor electrode carrier have not yet achieved actual industrial application.
[0003] Currently, most portable blood glucose meters use sensors based on the reaction of glucose oxidase (GODx) catalyzing the oxidation of glucose substrates to produce hydrogen peroxide. The glucose level in the blood is indirectly determined by detecting the decrease in oxygen or the amount of hydrogen peroxide produced. This method of detecting hydrogen peroxide is widely used due to its high sensitivity. However, existing blood glucose sensor electrodes are disposable and cannot be cleaned and reused, resulting in high costs.
[0004] Currently, nucleic acid testing is a crucial basis for diagnosing many diseases. However, the technology is currently demanding in its operation, time-consuming, and requires expensive equipment and specially trained personnel, placing enormous pressure on frontline medical testing resources. Therefore, developing rapid, accurate, multi-indicator, distributed (POCT) and economical pathogen detection technologies is of great significance for efficient disease control.
[0005] Therefore, existing technologies have shortcomings and need to be improved. Summary of the Invention
[0006] The technical problem to be solved by the present invention is to provide a substrate material, a blood glucose detection electrode, a nucleic acid detection electrode and a preparation method thereon, so as to solve the technical problems mentioned in the background art.
[0007] The technical solution of the present invention is as follows: a method for preparing a blood glucose detection electrode is provided, comprising the following steps.
[0008] S1: Vertical graphene with a three-dimensional petal-like structure is grown on the surface of a substrate using the PECVD method. The substrate is selected from insulating materials such as ceramics, silicon dioxide, and quartz.
[0009] S2: The upright graphene is treated with plasma to obtain active sites, wherein the active sites are at least one of carboxyl, amino, aldehyde, and hydroxyl groups.
[0010] S3: Using the PEPVD method, Au or Pt nanoparticles with adjustable size are grown on upright graphene, wherein the size of the Au or Pt nanoparticles is 1-100 nm, thus obtaining the substrate material.
[0011] S4: Prepare enzyme solution: 10-100 mg / ml glucose oxidase + 10-100 mg / ml bovine serum albumin + 1%-10% glutaraldehyde, using sterile PBS buffer with pH 7.4±0.2 and 0.1±0.01 mol / L as the solvent.
[0012] S5: Apply enzyme to the substrate material in an amount of 0.1-1 μL, seal and place in an environment of -10°C to +10°C for 4-24 hours. The enzyme will then adhere to the surface of the upright graphene. The area where the enzyme is applied is the working electrode area.
[0013] S6: Coating with a polymer coating membrane, wherein the polymer coating membrane is a glucose semi-permeable membrane, and the porosity of the polymer coating membrane is 20% to 30%.
[0014] The polymer-coated membrane comprises: a porous support layer with a pore size of 100-400 nm, a microfiltration layer with a pore size of 10-30 nm, and an ultrafiltration skin layer with a pore size of 0.1-6.0 nm; the porous support layer is attached to the surface of the upright graphene, and the microfiltration layer is sandwiched between the porous support layer and the ultrafiltration skin layer.
[0015] The pore size of the ultrafiltration skin layer is 0.8-1.0 nm.
[0016] The present invention also provides a blood glucose detection electrode, which is made using the aforementioned method for preparing a blood glucose detection electrode.
[0017] After plasma treatment, vertical graphene develops hydrophilic groups on its surface. Glucose oxidase is then immobilized on the electrode surface through physical adsorption (due to the porous nature of graphene) and chemical bonding (between the hydrophilic groups and the enzyme). Finally, a polymer coating further immobilizes the enzyme, reducing enzyme loss during use and enabling repetitive blood glucose monitoring. Blood glucose passes through the polymer membrane and, under platinum catalysis, reacts with glucose oxidase to generate hydrogen peroxide. This electrochemical reaction produces a current signal, which is amplified and simulated by an electrochemical workstation to convert into the corresponding blood glucose concentration. Commonly used enzymes include glucose oxidase and glucose dehydrogenase.
[0018] The blood glucose detection electrode of the present invention is a reusable upright graphene blood glucose detection electrode used for electrochemical detection of blood glucose. The enzyme on the electrode surface is fixed by a polymer membrane and can be reused after cleaning under certain conditions, reducing the cost of electrode use. It is different from traditional planar enzyme electrodes and is better than traditional electrodes.
[0019] The present invention also provides a method for preparing a nucleic acid detection electrode, comprising the following steps.
[0020] A1: Vertical graphene with a three-dimensional petal-like structure is grown on the surface of a substrate using the PECVD method. The substrate is selected from insulating materials such as ceramics, silicon dioxide, and quartz.
[0021] A2: Vertical graphene is treated with plasma to obtain active sites, which are at least one of carboxyl, amino, aldehyde, and hydroxyl groups. Various non-hexacyclic large pi-bonded carbon atom point defect clusters (i.e., active sites) are formed through plasma ion bombardment and in-situ chemical synthesis of large π carbon atoms, including but not limited to hydroxyl, carboxyl, and amino groups.
[0022] A3: A polymer coupled with carboxyl functionalization to carboxylate upright graphene; the polymer concentration is 0.1-10 mM, the self-assembly time is 1-72 h, and the temperature is 10-50℃.
[0023] A4: The carboxyl group is activated by using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) and N-hydroxysuccinimide (NHS) as activating agents. The ratio of EDC to NHS is 2:1 to 1:5, and the activation time is 1-300 min.
[0024] A5: Using the PEPVD method, Au or Pt nanoparticles with adjustable size are grown on upright graphene, wherein the size of the Au or Pt nanoparticles is 1-100 nm, thus obtaining the substrate material.
[0025] A6: Prepare the nucleic acid aptamer solution by dissolving the nucleic acid in Tris-HCl or PBS buffer at pH 7.2-8.0. The molar concentration of the nucleic acid aptamer should be 1-10 μM.
[0026] A7: Nucleic acid aptamers are immobilized on the substrate material, and the area where the nucleic acid aptamers are immobilized is the working electrode area; the immobilization method is any one of the following: chemical covalent coupling, self-assembly, avidin & biotin method, and physical adsorption method.
[0027] The chemical covalent coupling method involves selecting an amino group to modify one end of the nucleic acid chain, and using the amino group to covalently couple with the activated carboxyl group on the vertical graphene to form an amide bond, thereby fixing the nucleic acid aptamer onto the vertical graphene; fixing temperature: 10-50℃, time: 1-76h.
[0028] The self-assembly method involves selecting one end of a thiol-modified nucleic acid chain and using the Au-S bond between the thiol group and gold nanoparticles on the upright graphene to fix the nucleic acid aptamer onto AuNPs and upright graphene. The fixation temperature is 10-50℃ and the time is 1-76h.
[0029] The avidin & biotin method: nucleic acid aptamers are immobilized by a high affinity reaction between avidin-modified upright graphene and biotin-modified nucleic acids. The immobilization temperature is 10-50℃ and the time is 1-76h.
[0030] The physical adsorption method utilizes the electrostatic interaction between positively charged upright graphene and the negatively charged phosphate backbone of DNA to immobilize nucleic acid aptamers; immobilization temperature: 10-50℃, time: 1-76h.
[0031] The carboxyl-functionalized polymers include, but are not limited to, at least one of HS-PEG-COOH, COOH-PEG-COOH, NH2-PEG-COOH, PS-DVB-COOH, carboxylated polyimide, maleic anhydride-acrylic acid, succinic anhydride, polyvinyl alcohol, and carboxylated polypropylene.
[0032] The nucleic acid aptamer is a single-stranded oligonucleotide, which is ssDNA and / or ssRNA; the nucleic acid aptamer modification group includes, but is not limited to, at least one of thiol, amino, carboxyl, aldehyde, methylation, and biotin; the nucleic acid aptamer labeling material includes, but is not limited to, at least one of methylene blue, ferrocene, rhodamine, and enzyme-catalyzed labeling.
[0033] The present invention also provides a nucleic acid detection electrode, which is prepared using the aforementioned method for preparing a nucleic acid detection electrode.
[0034] This invention utilizes upright graphene film composite nanomaterials to replace traditional precious metals as the sensitive material for biosensors. Upright graphene possesses excellent properties such as large specific surface area, good conductivity, abundant reactive sites, and good biocompatibility. Furthermore, nucleic acid aptamers, as single-stranded DNA or RNA molecules with a certain three-dimensional structure, can be chemically synthesized and offer numerous advantages over other probe molecules such as antibodies, including low cost, ease of modification with functional groups, and stable properties. By combining upright graphene with nucleic acid biomolecules, upright graphene nucleic acid nanobioelectrodes are fabricated. Electrochemical detection methods are employed, and this detection technology offers advantages such as high sensitivity, speed, low pollution, low cost, and ease of distributed detection (POCT), making it suitable for the high-throughput and rapid detection requirements of pathogenic microorganisms.
[0035] Using the above-described scheme, this invention provides a blood glucose detection electrode, a nucleic acid detection electrode, and a preparation method thereof. The upright graphene grown by PECVD has a three-dimensional petal-like structure. This structure of upright graphene is more robust than planar graphene and can be used for plasma-mediated grafting of chemical groups such as carboxyl, amino, aldehyde, and hydroxyl groups. Introducing these groups in this way not only does not damage the structure and conductivity of the upright graphene, but also facilitates the occupation of active sites by nucleic acids and antibodies, allowing for the loading of more nucleic acids and antibodies and improving the electrochemical detection signal. Furthermore, the blocking step can be omitted, avoiding interference. This method can be industrialized. Attached Figure Description
[0036] Figure 1 This is a flowchart of the method for preparing the blood glucose detection electrode of the present invention;
[0037] Figure 2 This is a flowchart of the method for preparing the nucleic acid detection electrode of the present invention. Detailed Implementation
[0038] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.
[0039] Example 1
[0040] Please see Figure 1 This embodiment provides a method for preparing a blood glucose detection electrode, including the following steps.
[0041] S1: Vertical graphene with a three-dimensional petal-like structure is grown on the surface of a substrate using the PECVD method. The substrate is selected from insulating materials such as ceramics, silicon dioxide, and quartz.
[0042] S2: The upright graphene is treated with plasma to obtain active sites, wherein the active sites are at least one of carboxyl, amino, aldehyde, and hydroxyl groups.
[0043] S3: Using the PEPVD method, Au or Pt nanoparticles with adjustable size are grown on upright graphene, wherein the size of the Au or Pt nanoparticles is 1-100 nm, thus obtaining the substrate material.
[0044] S4: Prepare enzyme solution: 10-100 mg / ml glucose oxidase + 10-100 mg / ml bovine serum albumin + 1%-10% glutaraldehyde, using sterile PBS buffer with pH 7.4±0.2 and 0.1±0.01 mol / L as the solvent.
[0045] S5: Apply enzyme to the substrate material in an amount of 0.1-1 μL. Seal and place in an environment of -10°C to +10°C for 4-24 hours. This can be done by placing the substrate directly in a refrigerator. The enzyme will then adhere to the surface of the upright graphene. The area where the enzyme is applied is the working electrode area.
[0046] S6: Coating with a polymer-coated membrane, wherein the polymer-coated membrane is a glucose semi-permeable membrane with a porosity of 20%–30%. The polymer-coated membrane comprises: a porous support layer with a pore size of 100–400 nm, a microfiltration layer with a pore size of 10–30 nm, and an ultrafiltration skin layer with a pore size of 0.1–6.0 nm; the porous support layer is attached to the surface of upright graphene, and the microfiltration layer is sandwiched between the porous support layer and the ultrafiltration skin layer.
[0047] Preferably, the pore size of the ultrafiltration skin layer is 0.8-1.0 nm.
[0048] Once the polymer coating membrane is complete, it can be used to test blood glucose signals. After use, it can be washed with 0.01 PBS and reused.
[0049] This embodiment also provides a blood glucose detection electrode, which is manufactured using the aforementioned method for preparing a blood glucose detection electrode.
[0050] After plasma treatment, vertical graphene develops hydrophilic groups on its surface. Glucose oxidase is then immobilized on the electrode surface through physical adsorption (due to the porous nature of graphene) and chemical bonding (between the hydrophilic groups and the enzyme). Finally, a polymer coating further immobilizes the enzyme, reducing enzyme loss during use and enabling repetitive blood glucose monitoring. Blood glucose passes through the polymer membrane and, under platinum catalysis, reacts with glucose oxidase to generate hydrogen peroxide. This electrochemical reaction produces a current signal, which is amplified and simulated by an electrochemical workstation to convert into the corresponding blood glucose concentration. Commonly used enzymes include glucose oxidase and glucose dehydrogenase.
[0051] The blood glucose detection electrode of the present invention is a reusable upright graphene blood glucose detection electrode used for electrochemical detection of blood glucose. The enzyme on the electrode surface is fixed by a polymer membrane and can be reused after cleaning under certain conditions, reducing the cost of electrode use. It is different from traditional planar enzyme electrodes and is better than traditional electrodes.
[0052] Example 2
[0053] Please see Figure 2 This embodiment provides a method for preparing a nucleic acid detection electrode, including the following steps.
[0054] A1: Vertical graphene with a three-dimensional petal-like structure is grown on the surface of a substrate using the PECVD method. The substrate is selected from insulating materials such as ceramics, silicon dioxide, and quartz.
[0055] A2: Vertical graphene is treated with plasma to obtain active sites, which are at least one of carboxyl, amino, aldehyde, and hydroxyl groups. Various non-hexacyclic large pi-bonded carbon atom point defect clusters (i.e., active sites) are formed through plasma ion bombardment and in-situ chemical synthesis of large π carbon atoms, including but not limited to hydroxyl, carboxyl, and amino groups.
[0056] A3: A polymer with carboxyl functionalization via coupling, which carboxylates the upright graphene; the polymer concentration is 0.1-10 mM, the self-assembly time is 1-72 h, and the temperature is 10-50℃.
[0057] A4: The carboxyl group is activated by using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) and N-hydroxysuccinimide (NHS) as activating agents. The ratio of EDC to NHS is 2:1 to 1:5, and the activation time is 1-300 min.
[0058] A5: Using the PEPVD method, Au or Pt nanoparticles with adjustable size are grown on upright graphene, wherein the size of the Au or Pt nanoparticles is 1-100 nm, thus obtaining the substrate material.
[0059] A6: Prepare the nucleic acid aptamer solution by dissolving the nucleic acid in Tris-HCl or PBS buffer at pH 7.2-8.0. The molar concentration of the nucleic acid aptamer should be 1-10 μM.
[0060] A7: Nucleic acid aptamers are immobilized on the substrate material, and the area where the nucleic acid aptamers are immobilized is the working electrode area; the immobilization method is any one of the following: chemical covalent coupling, self-assembly, avidin & biotin method, and physical adsorption method.
[0061] In application, the electrode modification process was characterized using EIS electrochemical impedance spectroscopy, and electrochemical detection was performed in 1-10 mM potassium ferricyanide / potassium ferrocyanide solutions. Electrodes modified with the signal DNA probe were reacted with different concentrations of target DNA at 10-40 °C for 10-120 min. After incubation, the electrodes were rinsed with 0.01 M PBS buffer, and then detected in a three-electrode system using square wave voltammetry in 0.1 M PBS buffer. The detection voltage range was 0-0.6 V, and the scan frequency was 10-200 Hz. The changes in peak current before and after hybridization between the DNA sensor and the target DNA were compared.
[0062] The chemical covalent coupling method involves selecting an amino group to modify one end of the nucleic acid chain, and using the amino group to covalently couple with the activated carboxyl group on the vertical graphene to form an amide bond, thereby fixing the nucleic acid aptamer onto the vertical graphene; fixing temperature: 10-50℃, time: 1-76h.
[0063] The self-assembly method involves selecting one end of a thiol-modified nucleic acid chain and using the Au-S bond between the thiol group and gold nanoparticles on the upright graphene to fix the nucleic acid aptamer onto AuNPs and upright graphene. The fixation temperature is 10-50℃ and the time is 1-76h.
[0064] The avidin & biotin method: nucleic acid aptamers are immobilized by a high affinity reaction between avidin-modified upright graphene and biotin-modified nucleic acids. The immobilization temperature is 10-50℃ and the time is 1-76h.
[0065] The physical adsorption method utilizes the electrostatic interaction between positively charged upright graphene and the negatively charged phosphate backbone of DNA to immobilize nucleic acid aptamers; immobilization temperature: 10-50℃, time: 1-76h.
[0066] The carboxyl-functionalized polymers include, but are not limited to, at least one of HS-PEG-COOH, COOH-PEG-COOH, NH2-PEG-COOH, PS-DVB-COOH, carboxylated polyimide, maleic anhydride-acrylic acid, succinic anhydride, polyvinyl alcohol, and carboxylated polypropylene.
[0067] The nucleic acid aptamer is a single-stranded oligonucleotide, which is ssDNA and / or ssRNA; the nucleic acid aptamer modification groups include, but are not limited to, thiol, amino, carboxyl, aldehyde, methylation, and biotin; the nucleic acid aptamer labeling materials include, but are not limited to, methylene blue, ferrocene, rhodamine, and enzyme-catalyzed labels.
[0068] This embodiment also provides a nucleic acid detection electrode, which is prepared using the aforementioned method for preparing nucleic acid detection electrodes.
[0069] This invention utilizes upright graphene film composite nanomaterials to replace traditional precious metals as the sensitive material for biosensors. Upright graphene possesses excellent properties such as large specific surface area, good conductivity, abundant reactive sites, and good biocompatibility. Furthermore, nucleic acid aptamers, as single-stranded DNA or RNA molecules with a certain three-dimensional structure, can be chemically synthesized and offer numerous advantages over other probe molecules such as antibodies, including low cost, ease of modification with functional groups, and stable properties. By combining upright graphene with nucleic acid biomolecules, upright graphene nucleic acid nanobioelectrodes are fabricated. Electrochemical detection methods are employed, and this detection technology offers advantages such as high sensitivity, speed, low pollution, low cost, and ease of distributed detection (POCT), making it suitable for the high-throughput and rapid detection requirements of pathogenic microorganisms.
[0070] In summary, this invention provides a blood glucose detection electrode, a nucleic acid detection electrode, and a preparation method thereof. The upright graphene grown by PECVD has a three-dimensional petal-like structure. This structure of upright graphene is more robust than planar graphene and can be used for plasma-mediated grafting of chemical groups such as carboxyl, amino, aldehyde, and hydroxyl groups. Introducing these groups in this way not only preserves the structure and conductivity of the upright graphene but also facilitates the occupation of active sites by nucleic acids and antibodies, allowing for the loading of more nucleic acids and antibodies and improving the electrochemical detection signal. Furthermore, the blocking step can be omitted, avoiding interference. This method is suitable for industrial production.
[0071] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing a blood glucose detection electrode, characterized in that, Includes the following steps: S1: Vertical graphene is grown on the surface of a substrate using the PECVD method, and the vertical graphene has a three-dimensional petal-like structure; S2: The upright graphene is treated with plasma to obtain active sites, wherein the active sites are at least one of carboxyl, amino, aldehyde, and hydroxyl groups; S3: Using the PEPVD method, Au or Pt nanoparticles with adjustable size are grown on upright graphene, wherein the size of the Au or Pt nanoparticles is 1-100 nm, thus obtaining the substrate material. S4: Prepare enzyme solution: 10-100 mg / ml glucose oxidase + 10-100 mg / ml bovine serum albumin + 1%-10% glutaraldehyde, using sterile PBS buffer at pH 7.4±0.2 and 0.1±0.01 mol / L as the solvent; S5: Apply enzyme to the substrate material in an amount of 0.1-1 μL, seal and place in an environment of -10°C to +10°C for 4-24 hours. The enzyme will then adhere to the surface of the upright graphene. The area where the enzyme is applied is the working electrode area. S6: Coating with a polymer coating membrane, wherein the polymer coating membrane is a glucose semi-permeable membrane, and the porosity of the polymer coating membrane is 20%~30%; The polymer-coated membrane comprises: a porous support layer with a pore size of 100-400 nm, a microfiltration layer with a pore size of 10-30 nm, and an ultrafiltration skin layer with a pore size of 0.1-6.0 nm; the porous support layer is attached to the surface of the upright graphene, and the microfiltration layer is sandwiched between the porous support layer and the ultrafiltration skin layer.
2. The method for preparing a blood glucose detection electrode according to claim 1, characterized in that, The pore size of the ultrafiltration skin layer is 0.8-1.0 nm.
3. A blood glucose detection electrode, characterized in that, It is prepared using the method described in any one of claims 1-2 for preparing a blood glucose detection electrode.
4. A method for preparing a nucleic acid detection electrode, characterized in that, Includes the following steps: A1: Vertical graphene is grown on the surface of a substrate by PECVD, and the vertical graphene has a three-dimensional petal-like structure; A2: Plasma is used to treat upright graphene to obtain active sites, wherein the active sites are at least one of carboxyl, amino, aldehyde, and hydroxyl groups; A3: A polymer coupled with carboxyl functionalization to carboxylate upright graphene; the polymer concentration is 0.1-10 mM, the self-assembly time is 1-72 h, and the temperature is 10-50℃. A4: The carboxyl group is activated by using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide and N-hydroxysuccinimide as activating agents. The feed ratio of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide to N-hydroxysuccinimide is 2:1-1:5, and the activation time is 1-300 min. A5: Using the PEPVD method, Au or Pt nanoparticles with adjustable size are grown on upright graphene, wherein the size of the Au or Pt nanoparticles is 1-100 nm, thus obtaining the substrate material. A6: Prepare the nucleic acid aptamer solution by dissolving the nucleic acid in Tris-HCl or PBS buffer at pH 7.2-8.
0. The molar concentration of the nucleic acid aptamer should be 0.1-10 μM. A7: Nucleic acid aptamers are immobilized on the substrate material, and the area where the nucleic acid aptamers are immobilized is the working electrode area; the immobilization method is any one of the following: chemical covalent coupling, self-assembly, avidin & biotin method, and physical adsorption method. The carboxyl-functionalized polymers include, but are not limited to, at least one of HS-PEG-COOH, COOH-PEG-COOH, NH2-PEG-COOH, PS-DVB-COOH, carboxylated polyimide, maleic anhydride-acrylic acid, succinic anhydride, polyvinyl alcohol, and carboxylated polypropylene.
5. The method for preparing a nucleic acid detection electrode according to claim 4, characterized in that, The chemical covalent coupling method involves selecting an amino group to modify one end of a nucleic acid chain, and using the amino group to covalently couple with an activated carboxyl group on vertical graphene to form an amide bond, thereby fixing the nucleic acid aptamer onto the vertical graphene; fixing temperature: 10-50℃, time: 1-76h. The self-assembly method involves selecting one end of a thiol-modified nucleic acid chain and using the Au-S bond between the thiol and gold nanoparticles on the upright graphene to fix the nucleic acid aptamer onto AuNPs and upright graphene. The fixation temperature is 10-50℃ and the time is 1-76h. The avidin & biotin method: uses the high affinity reaction between avidin-modified upright graphene and biotin-modified nucleic acid to immobilize nucleic acid aptamers, with an immobilization temperature of 10-50℃ and a time of 1-76h. The physical adsorption method utilizes the electrostatic interaction between positively charged upright graphene and the negatively charged phosphate backbone of DNA to immobilize nucleic acid aptamers; immobilization temperature: 10-50℃, time: 1-76h.
6. The method for preparing a nucleic acid detection electrode according to claim 4, characterized in that, The nucleic acid aptamer is a single-stranded oligonucleotide, which is ssDNA and / or ssRNA.
7. A method for preparing a nucleic acid detection electrode according to any one of claims 4-6, characterized in that, The modifying groups of the nucleic acid aptamers include, but are not limited to, at least one of thiol, amino, carboxyl, aldehyde, methylation, and biotin; the labeling materials of the nucleic acid aptamers include, but are not limited to, at least one of methylene blue, ferrocene, rhodamine, and enzyme-catalyzed labeling.
8. A nucleic acid detection electrode, characterized in that, It is prepared using the method described in claim 7 for the preparation of nucleic acid detection electrodes.