Hybrid graphene electrodes

Abstract

The present invention relates to a hybrid graphene electrode which comprises a graphene composite having a structure in which a plurality of microparticles and multi-layer graphene are mixed, the microparticles are metal or semiconductor particles which are attached to a surface or inside of the multi-layer graphene, some of the microparticles are mutually bonded and solidified, the multi-layer graphene has a three-dimensional structure in which a plurality of layers of graphene are stacked and bent in any direction, and some of the spaces between the microparticles are filled with the multi-layer graphene and interconnected, and electrons flow through the graphene composite.

Description

[Technical Field]

[0001] The present invention relates to a hybrid graphene electrode, and more particularly to a dementia-specific antigen hybrid graphene electrode that has excellent selectivity and specificity for low concentrations of antigens, due to the formation of a three-dimensional structure by cross-linking fine particles and graphene, and high electrical conductivity due to such structural characteristics, and is particularly optimized for use in immunosensors for detecting dementia-specific antigens. [Background technology]

[0002] Graphene not only has very stable and excellent electrical, mechanical, and chemical properties, but is also an excellent conductive material, allowing electrons to move about 100 times faster than silicon and allowing current to flow about 100 times faster than copper. Research into its production and applications is therefore actively underway.

[0003] This can be applied to immunosensors based on antigen-antibody binding, which are widely used in clinical diagnostics to detect disease-related substances such as biomarkers. Due to the specific binding of antibodies to antigens, antibodies are immobilized on the surface of the immunosensor to specifically detect biomarkers.

[0004] For example, prostate-specific antigen (PSA) is widely used as a prostate cancer marker for screening, diagnosis, and treatment of prostate cancer. PSA is an enzyme synthesized and secreted by prostate epithelial cells and is measured at 0-4 ng / ml (milliliter) in the general population, but is measured at higher concentrations in prostate cancer patients. Therefore, an immunosensor with excellent selectivity, specificity, and sensitivity for PSA can be useful for the early diagnosis and prevention of prostate cancer.

[0005] There are two types of immunosensors: sandwich-type immunosensors and label-free immunosensors. In the sandwich-type, a primary antibody capable of binding to an antigen is immobilized on the surface of a substrate, and a labeled antibody capable of binding to prostate-specific antigen is used as the secondary antibody. In the sandwich-type, the use of primary and labeled secondary antibodies allows for improved antigen-antibody binding efficiency, selectivity, sensitivity, and signal amplification. In contrast, label-free immunosensors can immediately measure antigen-antibody binding, offering not only superior convenience, speed, and sensitivity, but also cost savings and economical advantages, making them a noteworthy biomarker detection and analysis tool.

[0006] To develop better label-free immunosensors, graphene-based composites using graphene, which has excellent biocompatibility and electron transfer properties, are attracting attention as electrode materials. As a result, active research is being conducted into applying graphene to biosensors, and graphene is known to be able to effectively contribute to the development of electrochemical biosensors with extremely high sensitivity.

[0007] Korean Patent No. 1400976 discloses a biosensor in which a molecular linker is connected to a reduced graphene oxide layer and a metal nanoparticle layer is added, but since it has a horizontal structure and is not a three-dimensional structure, the molecular linker is limited. Korean Patent No. 1339403 discloses a reduced graphene oxide-metal nanoparticle composite film, but it appears that it only suggests the possibility of using this as a biosensor.

[0008] Therefore, the present inventors have developed a three-dimensional nanoparticle-graphene composite fabricated using photochemical and photothermal irradiation, and an immunosensor based on this composite is characterized by high selectivity, specificity, cost-effectiveness, high sensitivity, and excellent reproducibility. The present invention can be particularly applied to an immunosensor that is highly effective in detecting dementia-specific antigens. Summary of the Invention [Problem to be solved by the invention]

[0009] The object of the present invention is to provide a hybrid graphene electrode for a dementia-specific antigen immunosensor, which has excellent sensitivity and specificity to low concentrations of antigens by utilizing the three-dimensional structure formed by cross-linking fine particles and graphene and the high electrical conductivity resulting from such structural characteristics, and is particularly optimized for use as an immunosensor for detecting dementia-specific antigens. [Means for solving the problem]

[0010] To solve the above problems, the present invention provides a hybrid graphene electrode comprising a graphene composite having a structure in which a plurality of microparticles and multi-layer graphene are mixed, the microparticles being metal or semiconductor particles that are attached to the surface or inside of the multi-layer graphene, some of the microparticles being mutually bonded and solidified, the multi-layer graphene having a three-dimensional structure in which a plurality of graphene layers are stacked and bent in any direction, and some of the vacant spaces between the microparticles are filled with the multi-layer graphene and interconnected, and electrons flow through the graphene composite.

[0011] The present invention also provides a hybrid graphene electrode characterized in that the surfaces of the fine particles are coated with graphene.

[0012] The present invention also provides a hybrid graphene electrode, wherein the graphene composite is produced by a photochemical, photothermal irradiation, or heat treatment process.

[0013] The present invention also provides a hybrid graphene electrode in which external electrons are injected or emitted through the graphene composite.

[0014] In addition, the present invention provides a method for manufacturing a silicon substrate, comprising the steps of: forming a silicon substrate using a silicon carbide (SiC, SiC, or SiCX containing SiC); X The present invention provides a hybrid graphene electrode characterized by a silver (Ag) coating on the surface of a copper (Cu) metal.

[0015] The present invention also provides a hybrid graphene electrode for an electrochemical sensor that detects a specific target substance using an electrochemical reaction in the graphene-metal composite.

[0016] The present invention also provides a hybrid graphene electrode in which lithium (Li) ions are bound to and separated from the graphene composite, thereby allowing charging and discharging to proceed. [Effects of the Invention]

[0017] The hybrid graphene electrode of the present invention, which has a three-dimensional structure formed by cross-linking microparticles and graphene, has excellent sensitivity to low concentrations of antigens due to its high electrical conductivity due to its structural characteristics, and is particularly optimized for use as an immune sensor for detecting dementia-specific antigens. [Brief explanation of the drawings]

[0018] [Figure 1a] 1A to 1C are SEM photographs and conceptual diagrams of the steps of the hybrid graphene electrode of the present invention. [Figure 1b] 1A to 1C are SEM photographs and conceptual diagrams of the steps of the hybrid graphene electrode of the present invention. [Figure 1c] 1A to 1C are SEM photographs and conceptual diagrams of the steps of the hybrid graphene electrode of the present invention. [Figure 1d]1A to 1C are SEM photographs and conceptual diagrams of the steps of the hybrid graphene electrode of the present invention. [Figure 1e] 1A to 1C are SEM photographs and conceptual diagrams of the steps of the hybrid graphene electrode of the present invention. [Figure 2] 1 is a graph comparing the electrical conductivity characteristics of a hybrid graphene electrode (graphene metal composite) according to the present invention, a metal electrode, and a graphene electrode. [Figure 3] 1 is a graph showing the measured current depending on the concentration of an electrochemically measured substance (PAP) for a hybrid graphene electrode according to the present invention, a graphene electrode, and a metal electrode. [Figure 4] 1 is a graph showing the difference in current signals measured for the same concentration of PAP on a graphene metal composite electrode according to the present invention, a graphene electrode, and a metal electrode. [Figure 5] 1 is a diagram showing an interdigitated electrode (IDA) using a hybrid graphene electrode according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following, preferred embodiments of the present invention will be described in detail. First, in describing the present invention, detailed descriptions of related known functions or configurations will be omitted in order to avoid obscuring the gist of the present invention.

[0020] As used herein, terms of degree such as "about," "substantially," and the like are used in the sense of a numerical value or close to a numerical value when the manufacturing and material tolerances inherent in the referred meaning are given, and are used to prevent unscrupulous infringers from unfairly taking advantage of disclosures in which precise or absolute numerical values ​​are referred to in order to aid in the understanding of the present invention.

[0021] The present invention relates to a hybrid graphene electrode that comprises a graphene composite having a structure in which microparticles and a graphene composite layer are mixed, and in which electrons flow through the graphene-metal composite.

[0022] 1a to 1e are SEM photographs and conceptual diagrams showing the steps of the hybrid graphene electrode of the present invention. (a) is a photograph showing silver (Ag) microparticles, an example of the present invention, with a spherical particle diameter of approximately 5 μm. (b) is a photograph showing silver (Ag) microparticles whose surfaces are melted and bonded to adjacent microparticles through a photochemical, photothermal irradiation, or heat treatment process. Some microparticles are not connected, forming open spaces. (c) is a photograph of graphene after the photochemical and photothermal reaction (multilayer graphene bent into a three-dimensional structure).

[0023] Graphene is a carbon allotrope, a structure in which carbon atoms are assembled into a two-dimensional plane. Each carbon atom forms a hexagonal lattice, with carbon atoms located at the vertices of the hexagon. At the nanoscale, the two-dimensional graphene is stacked or bent, resulting in an irregular shape.

[0024] The fine particles may be gold (Au), silicon (Si), silicon carbide (SiC, SiC or SiC), or X ), silicon oxide (SiO or SiO containing SiO X ), silver (Ag), copper metal surface coated with silver (Ag).

[0025] Semiconductor particles are particles that fall under the category of semiconductor materials, and include all materials whose electrical conductivity at room temperature is intermediate between that of a conductor like copper and a non-conductor (insulator) like glass, and whose conductivity changes when voltage, heat, or light wavelengths are applied to the semiconductor. This primarily refers to silicon (Si) particles, which are intrinsic semiconductors. They also include mixtures of non-intrinsic semiconductors such as phosphorus (P), arsenic (As), antimony (Sb), bismuth (Bi), boron (B), aluminum (Al), indium (In), and gallium (Ga).

[0026] When the graphene composite layer is formed of graphene and silicon particles, which are semiconductors, it can be used as a battery cathode material in which charging and discharging occur as lithium ions are bound to and separated from the graphene and silicon particles.

[0027] FIG. 1(d) is an SEM photograph of the hybrid graphene electrode of the present invention, showing a fixed structure in which fine particles can be attached to the surface or inside of the graphene composite layer by photochemical or photothermal irradiation, and some of the fine particles can be coagulated and bonded to each other.

[0028] (e) is a conceptual diagram showing a structure in which graphene produced by the photochemical or photothermal reaction of (d) is positioned and fixed in the vacant spaces (b) of silver (Ag) nanoparticles. The silver (Ag) nanoparticles may be attached inside or outside the graphene composite layer, and although not shown in the conceptual diagram, some nanoparticles may be interconnected and solidified due to the irregular positions of the silver (Ag) nanoparticles.

[0029] In addition, the silver (Ag) nanoparticles can have a graphene coating on their surfaces through a photochemical or photothermal reaction. Figure 1(e) shows a graphene coating structure on the particle surface.

[0030] Conventional graphene requires complicated processes, including high-temperature processes, but photothermal or photochemically synthesized graphene can be synthesized relatively easily in a single step.

[0031] Figure 2 is a graph comparing the electrical conductivity characteristics of the hybrid graphene electrode (graphene-metal composite) of the present invention, a metal electrode, and a graphene electrode. Compared to an electrode made of a gold (Au) thin film, the graphene electrode produced a larger measured current signal.

[0032] This is because the porous structure of the electrode provides a large surface area, allowing for excellent electron inflow and outflow through graphene, resulting in a larger flow of electrons generated during the electrochemical reaction.

[0033] The graphene-metal composite electrode has all the advantages of the graphene electrode, and the metal particles improve the conductivity, resulting in a very low electrode resistance.

[0034] Therefore, when measuring electrochemical signals using three types of electrodes, the graphene metal composite electrode generates the largest current signal.

[0035] In this case, the sensitivity is higher as the absolute value of the measured current signal is larger. Therefore, the graphene-metal composite electrode of the present invention has a very large signal-to-noise ratio (SNR) of the generated signal, which can detect even low concentrations of target substances, by utilizing the advantages of graphene's large surface area, its ability to more efficiently generate electrochemical reactions through the absorption and emission of electrons, and the low resistance of metal particles.

[0036] This technique allows for the production of 3D porous graphene through photochemical and photothermal reactions, and has the advantage of being able to fabricate and pattern 3D graphene in a single step without any wet chemical steps.

[0037] In addition, the silver (Ag) fine particles of the present invention can be used by coating the surface of copper metal with silver (Ag). Although silver particles have excellent conductivity, this may be a preferable structure considering the cost, etc., since the particle surface contributes greatly to conductivity even when used as a coating.

[0038] 3 is a graph showing the measured current as a function of the concentration of an electrochemical analyte (PAP) for a hybrid graphene electrode, a graphene electrode, and a metal electrode according to the present invention. For each electrode, the magnitude of the current signal increases with the PAP concentration. It can also be seen that for the same concentration of PAP, the signal from the graphene electrode, which has advantages over the metal electrode in terms of surface area and electron inflow and outflow, is larger, while the signal from the graphene-metal composite electrode, which has lower resistance than the graphene electrode, is larger.

[0039] The hybrid graphene electrode of the present invention can be used to fabricate an interdigitated electrode (IDA) using a graphene-metal composite material, which can be used as an electrochemical sensor to detect specific target substances using electrochemical reactions in the graphene-metal composite.

[0040] The interdigitated electrode (IDA) is characterized by the electrochemical reaction between the two finger-shaped electrodes, which transfers electrons and generates a current. Using the interdigitated electrode (IDA) for electrochemical enzyme-linked immunosorbent assay (ELISA) measurement allows for the first highly sensitive electrochemical detection of Alzheimer's disease.

[0041] The National Institute of Aging and Alzheimer's Association (NIA-AA) has proposed that amyloid beta (Aβ), Aβ-40, and Aβ-42 in the brain and cerebrospinal fluid (CSF) are Alzheimer's biomarkers, as are total tau protein (t-tau) and phosphorylated tau protein (p-tau) in CSF, which reflect neuronal damage. To electrochemically measure Aβ-42 and Aβ-40, t-tau, and p-tau, alkaline phosphatase (AP) is commonly used as an enzyme label for ELISA. The AP is attached to a secondary antibody, and the more the Alzheimer's biomarker, the more AP enzyme is immobilized, generating a larger electrochemical signal. The electroactive enzyme-substrate p-aminophenylphosphate (PAPP) reacts with the enzyme product to generate the electroactive product p-aminophenol (PAP). PAP is oxidized by p-quinoneimine (PQI) on the surface of an MHG interdigitated electrode (IDA), and then PQI is reduced by PAP, resulting in a redox cycle of PAP. As the concentration of Alzheimer's biomarker increases, more AP enzymes are immobilized in the reaction chamber, increasing the electrochemical signal.

[0042] Based on the above principle, measurement of the electroactive product p-aminophenol (PAP) is important in early Alzheimer's diagnosis, and the hybrid graphene electrode of the present invention can be applied as an electrode capable of distinguishing very small amounts.

[0043] Therefore, the shape of the microparticles in the hybrid graphene electrode affects the sensitivity of measuring the electroactive product p-aminophenol (PAP), and it can be seen that the spherical shape of silver (Ag) microparticles provides the best sensitivity.

[0044] Also, as the concentration of PAP molecules increases, the redox cycle of the PAP molecules also increases, resulting in a linear increase in the current measured by the MHG interdigitated electrode (IDA).

[0045] 4 is a graph showing the difference in current signals measured for the same concentration of PAP using a graphene metal composite electrode of the present invention, a graphene electrode, and a metal electrode. The graphene metal composite electrode of the present invention generates a larger current signal than the reference electrode, and the signal-to-noise ratio (SNR) is larger than that of the reference electrode.

[0046] FIG. 5 is a diagram showing an interdigitated electrode (IDA) using a hybrid graphene electrode according to the present invention.

[0047] The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and it will be apparent to those skilled in the art to which the present invention pertains that various substitutions, modifications and changes can be made without departing from the technical spirit of the present invention.

Claims

1. A graphene metal composite is formed having a structure in which a plurality of microparticles and a multilayer graphene in which a plurality of planar graphenes are stacked are mixed, the microparticles are particles of metal, metal oxide, or semiconductor, and are bonded to the surface or between layers of the multilayer graphene, and some of the microparticles are mutually bonded and solidified; The multilayer graphene has a three-dimensional structure in which multiple layers of graphene are stacked and bent in any direction, A part of the vacant space between the microparticles is filled with the multi-layer graphene and interconnected, a flow of electrons occurs through the graphene-metal composite; The surface of the fine particles is coated with graphene, The graphene metal composite is produced by a photochemical, photothermal irradiation, or heat treatment process; Inflow or emission of external electrons occurs through the graphene metal composite; Lithium (Li) ions are bound to and separated from the graphene metal composite, thereby allowing charging and discharging to proceed. Hybrid graphene electrodes.

2. The fine particles are made of gold (Au), silicon (Si), silicon carbide (Si ２ C, SiC or SiC ２ SiC containing Ｘ ), silicon oxide (SiO or SiO ２ SiO containing Ｘ ), silver (Ag), copper metal surface is coated with silver (Ag), the hybrid graphene electrode of claim 1 characterized by the above-mentioned.

Images