Oxygen molecule sensor based on graphene / metalloporphyrin and preparation method thereof

Abstract

The invention relates to an oxygen molecule sensor based on graphene / metalloporphyrin and a preparation method thereof. The oxygen molecule sensor comprises a substrate layer, a graphene layer, an epoxy resin layer, a metal electrode and recognition probe molecules, the graphene layer is made of single-layer graphene; the identification probe molecule comprises the following components: heme, FeTPPCl, CuTPP, NiTPP, and CoTPP. The graphene / metalloporphyrin oxygen molecule sensor prepared by the invention is high in sensitivity, and can also be used for detecting gas-phase and liquid-phase oxygen molecules at the same time.

Description

Technical Field

[0001] The invention relates to the technical field of oxygen sensors, and in particular to a graphene / metalloporphyrin-based oxygen molecule sensor and a preparation method thereof. Background Art

[0002] As we all know, oxygen is an essential substance for maintaining human life activities. All aspects of human life and production are inseparable from oxygen. An adult metabolizes about 200g of oxygen every day and can survive for a month without food, but can only survive for 2 weeks without water. Without oxygen for more than 10 minutes, they will suffocate to death. However, high oxygen will cause bacteria to grow on the lung membrane, causing pneumonia, leading to damage to human health or even death. Therefore, oxygen monitoring is particularly important.

[0003] There are mature oxygen detection methods at home and abroad, such as Winkler titration, electrochemical analysis and optical methods; the Winkler method is very accurate, but cannot achieve continuous measurement; the electrochemical analysis method is suitable for small volume oxygen detection, usually operated at a relatively high oxidation potential (>0.6V), while consuming the analyte and being interfered by gases such as chlorine and ozone; the optical method has attracted much attention due to its accuracy, reversibility, imaging and easy miniaturization, but it requires expensive instruments, time-consuming and labor-intensive operation and analysis, and is not easy to translate into practical applications.

[0004] Porphyrin is a class of large π-structured compounds with biomimetic properties of many important enzyme active sites, and can be used as an electron mediator with good electrocatalytic performance. Porphyrin chelates with metal ions to form stable metal coordination compounds, which can be widely used as efficient catalysts for oxygen reduction reactions. However, metalloporphyrin-catalyzed oxygen reduction reactions are usually carried out in acidic solutions, which limits their application in biological systems.

[0005] In recent years, the composite materials of porphyrin and graphene have attracted extensive attention. The two can be combined through covalent bonds and non-covalent bonds. Compared with covalent bonds, the combination of non-covalent bonds (such as π-π stacking, electrostatic attraction and hydrogen bonds, etc.) can not only maintain the excellent electrocatalytic performance of porphyrin macromolecules, but also will not destroy the unique electronic properties and structural characteristics of graphene. However, the sensitivity of combining porphyrin and graphene to measure oxygen is not high enough at present, and there is no oxygen sensor that works both in solution environment and in gas environment. Summary of the invention

[0006] In order to solve the above problems, the present invention intends to provide a graphene / metalloporphyrin composite material, which can be used in oxygen sensors to achieve ultra-sensitive and highly specific real-time detection of oxygen molecules, and the sensor can work both in a solution environment and in a gaseous environment.

[0007] The present invention provides a graphene / metalloporphyrin-based oxygen molecule sensor, comprising a substrate layer, a graphene layer, an epoxy resin layer, a metal electrode and a recognition probe molecule;

[0008] The graphene layer is a single-layer graphene;

[0009] The recognition probe molecules include: heme, FeTPPCl, CuTPP, NiTPP, and CoTPP.

[0010] Graphene is a two-dimensional carbon nanomaterial separated from graphite, which is composed of carbon atoms in a hexagonal honeycomb lattice with sp2 hybrid orbitals. It is called graphene in English and is a two-dimensional crystal composed of a layer of carbon atoms. Graphene can be divided into single-layer graphene, double-layer graphene, few-layer graphene and multi-layer graphene according to the number of layers. In the prior art, multi-layer graphene is mostly used, while the present invention uses single-layer graphene in order to retain its inherent physical and chemical properties (excellent conductivity, good chemical inertness).

[0011] In the present invention, the preparation methods of single-layer graphene include but are not limited to: (1) "top-down": starting from the raw material of graphite block, a single layer or a few layers of graphene with a thickness of atoms are peeled off from the graphite block, such as "liquid phase peeling method" and "mechanical peeling method"; (2) "bottom-up": starting from the molecular structure of carbon atoms or carbon compounds, such as CH4, C 2 H 2 Etc., using crystal growth to rearrange graphene, such as "chemical vapor deposition", "small molecule chemical synthesis", "epitaxial growth", etc.

[0012] In some specific embodiments of the present invention, a single-layer graphene is prepared by a vapor deposition method.

[0013] In the present invention, the liquid phase oxygen molecule detection concentration of the oxygen molecule sensor is 100 pMol-100 uMol.

[0014] In the present invention, the gas phase oxygen molecule detection concentration of the oxygen molecule sensor is 200ppm-23000ppm.

[0015] In some specific embodiments of the present invention, the substrate layer includes at least one of silicon, polyethylene terephthalate, polyimide, polydimethylsiloxane, and glass materials.

[0016] The present invention provides a method for preparing the above-mentioned oxygen molecule sensor, comprising the following steps:

[0017] S1, transferring the single-layer graphene to the substrate layer to form a graphene layer / substrate layer;

[0018] S2, lead out metal electrodes on the graphene layer;

[0019] S3, sealing with epoxy resin to obtain the device to be modified;

[0020] S4, modifying the recognition probe molecules on the surface of the device to be modified to obtain the oxygen molecule sensor.

[0021] In some specific embodiments of the present invention, in S1, the transfer comprises the following steps: dropping PMMA onto the surface of the single-layer graphene, heating to 80° C. to 120° C., etching with a 0.1% APS solution, and completing the transfer.

[0022] In some specific embodiments of the present invention, the metal electrode includes an input electrode and an output electrode, both ends of the input electrode and the output electrode are electrically connected by silver dots, and the input electrode and the output electrode are connected by graphene.

[0023] In some specific embodiments of the present invention, the size of the oxygen molecule sensor is 1×1 cm 2 .

[0024] In some embodiments of the present invention, the probe exposure area is 1×1 mm 2 .

[0025] The graphene / metalloporphyrin oxygen molecule sensor prepared under the same conditions of the present invention detects oxygen molecules in liquid and gas phases. The detection of gas phase oxygen molecules is carried out in a closed system (the concentration of oxygen molecules is controllable), while the detection of liquid phase oxygen molecules is carried out in a microfluidic system (to estimate the solubility of oxygen in a buffer solution).

[0026] The present invention also provides an oxygen molecule detection method, which uses the above oxygen molecule sensor for detection.

[0027] The beneficial effects of the present invention are:

[0028] (1) The present invention non-covalently combines two-dimensional monolayer graphene with heme, FeTPPCl, CuTPP, NiTPP, and CoTPP as raw materials to design a composite system, develop components that work both in solution and gas environments, and give the ability to sense extremely small concentrations of oxygen molecules in the environment;

[0029] (2) Oxygen molecules exist naturally in the environment, so during the component preparation process, the components are easily contaminated by oxygen molecules in the external environment; the present invention utilizes the science and technology of a pure nitrogen environment and a microfluidic system in the process of component preparation and sensor detection to overcome the difficulties caused by the environment in achieving ultra-sensitive detection.

[0030] (3) The materials and reagents used in the present invention have low toxicity and can meet the needs of accurate and rapid detection of oxygen molecule concentration in aerospace and biological detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 For wet transfer of graphene and surface modification process through MTPP;

[0032] Figure 2 Schematic diagram of gas-phase oxygen molecule biochemical sensor ((a) circuit diagram of liquid-gate MTPP-modified electrical (resistance-type) device; (b) schematic diagram of oxygen molecule detection response of gas-phase MTPP-modified electrical (resistance-type) device); Figure 3 Schematic diagram of biochemical sensing of oxygen molecules based on graphene / metalloporphyrin composite materials;

[0033] Figure 4 Schematic diagram of liquid-phase oxygen molecule biochemical sensor ((a) circuit diagram of liquid-gate MTPP-modified GFET device; (b) schematic diagram of oxygen molecule detection response of liquid-gate MTPP-modified GFET);

[0034] Figure 5 Schematic diagram of biochemical sensing of dissolved oxygen molecules based on graphene / metalloporphyrin composite materials. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Example 1 Preparation of graphene / metal porphyrin composite material

[0037] The CVD graphene / copper sheet was immersed in acetone overnight to remove organic contaminants and amorphous carbon remaining on the graphene surface during growth and storage. Then a PMMA (polymethyl methacrylate) solution was dropped onto the graphene surface, spin-coated at 3000 rpm for 30 seconds, and then heated on a hot plate at 100°C for about 5 minutes. Subsequently, the PMMA / graphene / copper foil was etched with a 0.1% APS solution for about 2 hours, and the copper foil was removed and rinsed with deionized water three times. After etching, the sample was transferred to a p-doped Si substrate (with a 300nm thick SiO 2layer). After the sample was air-dried, it was placed in an acetone bath for 2.5 hours, an isopropanol bath for 0.3 hours, and then washed with methanol. The source (input electrode) and the drain (output electrode) were electrically connected with silver dots and then sealed with epoxy to enable it to work in an electrolyte environment. The GFET was incubated in a 1 μM metalloporphyrin (heme, FeTPPCl, CuTPP, NiTPP, CoTPP, J&K) chloroform solution at room temperature for 5 minutes. It was then rinsed three times with isopropanol and ethanol respectively to remove non-π-stacking metalloporphyrins on the surface of the GFET, such as Figure 1 shown.

[0038] Example 2 Preparation of Device and Biochemical Detection of Oxygen Molecules (Gas Phase Environment)

[0039] Graphene / metalloporphyrin complex composite (G / MTPP) material oxygen molecule sensor (1×1cm 2 ) The channel area is about 1×1mm 2 The source and drain electrodes at both ends of the device were connected by silver wires and then encapsulated with epoxy resin. The G / MTPP device was installed in a self-made sealed chamber (4×4cm 2 ) is configured with target gases (synthetic air) of different concentrations through the GL-III humidity control gas-liquid distribution system, and a constant bias voltage V is applied to both ends of the device through a large series resistor of 1MΩ≤ sd , using the Zurich lock-in amplifier (MFLI) to detect (constant source-drain current I sd ) The change of current over time can obtain the change curve of device resistance over time, and the resistance can be calculated as: R sd =I sd / V sd .

[0040] The oxygen molecule sensor prepared by the present invention has a gas phase oxygen molecule detection concentration of 200ppm-23000ppm in the graphene / FeTPPCl detector at room temperature, and a signal-to-noise ratio of 5.25. Moreover, the sensitivity completely recovers to the baseline when heated to 100°C.

[0041] Example 3 Biochemical Detection of Oxygen Molecules (Liquid Phase Environment)

[0042] For biochemical sensing of dissolved oxygen molecules, human blood isotonic phosphate buffered saline (PBS) is used as a solvent to pass pure nitrogen and target gas into the saturated solution of the target molecule. The amount of phosphate saturated solution is regulated by the microfluidic system to obtain a series of concentrations of target molecules. A Zurich lock-in amplifier (MFLI) with a size of about 1×1cm is used. 2 , the probe exposure area is about 1×1mm 2G / MTPP device with silver wire connecting the source and drain (sealed with epoxy resin).

[0043] By applying a bias voltage V across a series resistor of 1MΩ≤ ref (much larger than the graphene channel resistance <5kΩ), obtaining a constant source-drain current I sd , the resistance can be calculated as R = I sd / V sd During the test, PBS buffer solutions of different concentrations were injected into the liquid chamber. After the sample was added, it was allowed to stabilize (for about 5 minutes) before recording the data.

[0044] Note: All measurements were performed at room temperature. sd The changes over time provide information on the concentration of target molecules, response time, and sensitivity. During the test, the liquid gate of the GFET is connected to a microfluidic system, and the liquid is then delivered to the device surface in a closed state to prevent contamination.

[0045] The oxygen molecule sensor prepared by the present invention has a detection concentration of 100 pMol-100 uMol of oxygen molecules in the liquid phase state in the graphene / FeTPPCl detector at room temperature, and a signal-to-noise ratio of 4.7.

[0046] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An oxygen molecule sensor based on graphene / metalloporphyrin, characterized in that: It includes a substrate layer, a graphene layer, an epoxy resin layer, a metal electrode and a recognition probe molecule; The graphene layer is a single-layer graphene; The recognition probe molecules include: heme, FeTPPCl, CuTPP, NiTPP, and CoTPP.

2. The oxygen molecule sensor according to claim 1, characterized in that: The liquid phase oxygen molecule detection concentration of the oxygen molecule sensor is 100 pMol-100 uMol.

3. The oxygen molecule sensor according to claim 1, characterized in that: The gas phase oxygen molecule detection concentration of the oxygen molecule sensor is 200ppm-23000ppm.

4. The oxygen molecule sensor according to claim 1, characterized in that: The substrate layer includes at least one of silicon, polyethylene terephthalate, polyimide, polydimethylsiloxane, and glass materials.

5. The method for preparing the oxygen molecule sensor according to claim 1, characterized in that: The steps include: S1, transferring the single-layer graphene to the substrate layer to form a graphene layer / substrate layer; S2, lead out metal electrodes on the graphene layer; S3, sealing with epoxy resin to obtain the device to be modified; S4, modifying the recognition probe molecules on the surface of the device to be modified to obtain the oxygen molecule sensor.

6. The preparation method according to claim 5, characterized in that: In S1, the transfer includes the following steps: dropping PMMA onto the surface of the single-layer graphene, heating to 80° C. to 120° C., etching with a 0.1% APS solution, and completing the transfer.

7. The preparation method according to claim 5, characterized in that: The metal electrode comprises an input electrode and an output electrode, and both ends of the input electrode and the output electrode are electrically connected by silver dots; and the input electrode and the output electrode are connected by graphene.

8. The preparation method according to claim 5, characterized in that: The size of the oxygen molecule sensor is 1×1 cm 2 .

9. The preparation method according to claim 1, characterized in that: The probe exposure area is 1×1 mm 2 .

10. A method for detecting oxygen molecules, characterized in that: The oxygen molecule sensor according to claim 1 is used for detection.

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