CN114910541B - Electrochemical sensor and preparation method and application thereof - Google Patents
Electrochemical sensor and preparation method and application thereof Download PDFInfo
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Abstract
The invention discloses an electrochemical sensor and a preparation method and application thereof. The electrochemical sensor of the present invention comprises: a carbonaceous non-conductive substrate and a three electrode system disposed within the recess of the surface of the carbonaceous non-conductive substrate; the three electrode system consisted of an Ag/AgCl/carbon electrode, a Pt/carbon electrode and a graphite alkyne/copper/carbon electrode. The preparation method of the electrochemical sensor comprises the following steps: etching 3 electrode slots containing a conductive carbon layer on the surface of a carbon-containing non-conductive substrate by using laser, depositing copper nano particles in 1 electrode slot, then growing graphite alkyne in situ, coating Ag/AgCl slurry in 1 electrode slot, and depositing platinum nano particles in 1 electrode slot. The electrochemical sensor is an integral material containing a three-electrode system, has the advantages of convenience in carrying, simplicity in preparation and low cost, and can accurately and efficiently detect the tryptophan content of an unknown solution or a plant.
Description
Technical Field
The invention relates to the technical field of electrochemical sensors, in particular to an electrochemical sensor, a preparation method and application thereof.
Background
The electrochemical sensor has very important practical value in the aspects of environmental monitoring, food inspection, medicine analysis, plant active molecule analysis and the like. Along with the continuous progress of the current electrochemical sensing technology, the requirements on electrochemical sensing are gradually increased, and the development of a novel, simple, sensitive, durable, accurate and reliable electrochemical sensor is particularly important. Compared with the traditional electrode system, the electrochemical chip electrode has the advantages of simple and convenient manufacture, low cost, wide application range, high integration level and the like, and can be used as a portable sensor.
Tryptophan, an important precursor for auxin biosynthesis in plants, has a structure similar to that of indoleacetic acid (IAA) and is ubiquitous in higher plants. In plants, tryptophan is used as a synthesis precursor, decarboxylated to form a tryptamine, then oxidative deaminated to form indoleacetic aldehyde, and finally converted to indoleacetic acid. The auxin regulates a great number of life processes in the growth and development process of plants, so that the development of a method capable of directly monitoring the tryptophan content of the plant body is of great significance. At present, researchers construct a composite film type electrochemical sensor by modifying the surface of an electrode by Au-Ag nano particles and polydimethyl diallyl ammonium chloride modified graphene oxide, but the electrochemical sensor has the technical problems of high cost, large volume, high detection limit for detecting tryptophan, complex use and the like.
Therefore, research and development of an electrochemical sensor capable of accurately and efficiently detecting tryptophan content, which has advantages of convenience in carrying, simplicity in preparation and low cost, is needed.
Disclosure of Invention
In order to overcome the problems of the prior art, an object of the present invention is to provide an electrochemical sensor.
Another object of the present invention is to provide a method for manufacturing the above electrochemical sensor.
It is a further object of the present invention to provide an application of the above electrochemical sensor.
The invention is characterized in that: firstly, carbonizing the surface of a carbon-containing non-conductive substrate material by a laser etching technology to obtain 3 electrode slots containing conductive carbon layers; then loading copper nano-particles (marked as Cu NPs) on the electrode slot positions of 1 conductive carbon layer by an electrodeposition method, and loading graphite alkyne (GDY for short) by an in-situ synthesis method to obtain graphite alkyne/copper nano-particles/carbon electrodes (namely GDY/Cu NPs/carbon electrodes); loading Ag/AgCl composite materials on the electrode slots containing 1 conductive carbon layer by a coating method to obtain Ag/AgCl/carbon electrodes; loading platinum nano-particles (marked as Pt NPs) on the electrode slot positions of 1 conductive carbon layer by using an electrodeposition method to obtain platinum nano-particles/carbon electrodes (namely Pt NPs/carbon electrodes); finally, the electrochemical sensor is obtained. Meanwhile, the electrochemical sensor of the invention has a schematic structure, as shown in FIG. 1, wherein a GDY/Cu NPs/carbon electrode is used as a working electrode, an Ag/AgCl/carbon electrode is used as a reference electrode, and a Pt NPs/carbon electrode is used as a counter electrode. The electrochemical sensor prepared by the method is an integral material and is also a chip electrode. The method can be used as an electrochemical sensor for detecting the tryptophan of an unknown solution and monitoring the tryptophan content of plants in real time, and has the advantages of strong preparation controllability, low cost, small volume, wide application range, high reaction speed, low detection limit and the like.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
in a first aspect, the present invention provides an electrochemical sensor comprising a carbonaceous non-conductive substrate and a three electrode system disposed within a recess in a surface of the carbonaceous non-conductive substrate; the three-electrode system consists of an Ag/AgCl/carbon electrode, a Pt/carbon electrode and a graphite alkyne/copper/carbon electrode; the composition of the Ag/AgCl/carbon electrode comprises a carbon layer and an Ag/AgCl layer; the composition of the Pt/carbon electrode comprises a carbon layer and a platinum nanoparticle layer; the composition of the graphite alkyne/copper/carbon electrode comprises a carbon layer and a copper nanoparticle-graphite alkyne composite layer.
Preferably, the carbon-containing nonconductive substrate is one of a polystyrene substrate, a polyimide substrate, a wood substrate and a polytetrafluoroethylene substrate.
In a second aspect, the present invention provides a method for preparing the above electrochemical sensor, comprising the steps of:
etching 3 electrode slots A, B and C containing conductive carbon layers on the surface of a carbon-containing non-conductive substrate by using laser, depositing copper nano particles in the electrode slot A, then growing graphite alkyne in situ, coating Ag/AgCl slurry in the electrode slot B, and depositing platinum nano particles in the electrode slot C to obtain the electrochemical sensor.
Preferably, the laser etching is performed under the condition that the scanning speed is 30 mV/s-100 mV/s and the current is 12A-25A.
Preferably, the shape of the electrode slot containing the conductive carbon layer is one of square, rectangle, round and oval.
Preferably, the spacing between the electrode slots containing the conductive carbon layer is 3 mm-10 mm.
Preferably, the deposition of the electrode slot A is potentiostatic deposition, the deposition voltage is-1.0V to-0.5V, and the deposition time is 50s to 200s.
Preferably, the electrolyte used in the potentiostatic deposition is a soluble copper salt solution.
Preferably, the concentration of the soluble copper salt solution is 0.1mol/L to 1.0mol/L.
Preferably, the soluble copper salt solution is one or more of copper sulfate, copper nitrate and copper chloride.
Specifically, the constant potential deposition on the electrode slot A is to firstly clean and dry the integral material containing conductive carbon, then immerse the integral material in soluble copper salt solution, take the electrode slot A containing the conductive carbon layer as a working electrode, take the existing Ag/AgCl electrode (which is not an electrode on a sensor) as a reference electrode, take the existing platinum plate electrode as a counter electrode, and set relevant constant potential deposition parameters, thereby realizing the effect of loading nano-particle copper on the electrode slot containing the conductive carbon layer.
Preferably, the specific operation of in-situ growing graphite alkyne is to place the carbonaceous non-conductive substrate after copper nano-particles are deposited in a graphite alkyne precursor solution and treat the substrate for 12 to 72 hours at the temperature of 60 to 100 ℃.
Preferably, the specific operation of growing graphite alkyne in situ is carried out under a protective atmosphere.
Preferably, the protective atmosphere is one or more of nitrogen, helium and argon.
Preferably, the composition of the graphite alkyne precursor solution comprises: hexakis (ethynyl) benzene and an organic solvent.
Preferably, the preparation method of the hexakis (ethynyl) benzene comprises the following steps: and (3) placing the hexakis (trimethylsilylethynyl) benzene solution in a nitrogen atmosphere and stirring at the temperature of 0 ℃ to obtain hexakis (ethynyl) benzene.
Preferably, the concentration of the hexakis (trimethylsilylethynyl) benzene solution is 0.01g/L to 0.5g/L.
Further preferably, the concentration of the hexakis (trimethylsilylethynyl) benzene solution is 0.1g/L.
Preferably, the organic solvent is one or more of acetonitrile, tetrahydrofuran and pyridine.
Further preferably, the solvent in the graphite alkyne precursor solution is acetonitrile, pyridine and tetrahydrofuran, and the volume ratio of the pyridine to the acetonitrile is 6:3-6:7.
Preferably, stirring is not included in the specific operation of the in-situ grown graphite alkyne.
Preferably, the method for preparing the electrochemical sensor further comprises the following steps: washing and drying.
Preferably, the cleaning agent used for cleaning is one or more of water, toluene, acetone and diethyl ether.
Preferably, the drying means is operated as infrared drying or vacuum drying.
Preferably, the mass fraction of Ag in the Ag/AgCl slurry is 60% -90%.
Preferably, the deposition of the electrode slot C is potentiostatic deposition, the deposition voltage is-0.7V to-0.1V, and the deposition time is 50s to 200s.
Specifically, the constant potential deposition on the electrode slot C is performed under the condition that the electrode slot C containing a conductive carbon layer is used as a working electrode, the existing Ag/AgCl electrode (not an electrode on a sensor) is used as a reference electrode, and the existing platinum disk electrode is used as a counter electrode.
In a third aspect, the present invention provides the use of an electrochemical sensor as described above in tryptophan detection.
In a fourth aspect, the present invention provides the use of an electrochemical sensor as described above for monitoring in real time the variation of tryptophan content in a plant.
Preferably, the method for monitoring the tryptophan content change in the plant in real time comprises the following steps:
1) In tryptophan-electrolyte systems with different concentrations, a three-electrode system is formed by taking a graphite alkyne/copper/carbon electrode as a working electrode, a Pt/carbon electrode as a counter electrode and an Ag/AgCl/carbon electrode as a reference electrode, and the tryptophan-phosphoric acid buffer solution systems with different concentrations are detected by utilizing a differential pulse voltammetry method to obtain a standard curve of current response values-concentrations;
2) And measuring the current response value of the sample by a pulse voltammetry, and comparing the current response value with the standard curve to obtain the tryptophan content in the real-time plant body.
Specifically, the current response value in the current response value-concentration standard curve is the maximum current response value measured by differential pulse voltammetry.
Preferably, the test parameters in the differential pulse voltammetry are as follows: the enrichment potential is-0.5V, the enrichment time is 15 s-300 s, the rest time is 10s-15s, and the voltage test interval is 0.2-1.2V.
Preferably, the pH value of the tryptophan-phosphoric acid buffer solution in the step 1) is 5.0-7.0.
Preferably, the sample of step 2) is a tryptophan-containing solution or a fruit of a plant.
The beneficial effects of the invention are as follows: the electrochemical sensor is an integral material with a three-electrode system, has the advantages of convenience in carrying, simplicity in preparation and low cost, and can accurately and efficiently detect the tryptophan content of an unknown solution or a plant. The method comprises the following steps:
(1) The electrochemical sensor is an integral material, and has the characteristics of convenience in carrying and application;
(2) The electrochemical sensor has the advantages of simple and convenient manufacture, low cost, wide application range, high integration level, high response speed, low detection limit (0.039 mu M) and the like;
(3) The working electrode modified by the copper nanoparticle-graphite alkyne composite material is prepared by in-situ synthesis of graphite alkyne, and the electrode is a chip electrode material with good load firmness, large specific surface area, more tryptophan adsorption sites and strong conductivity;
(4) The preparation method of the electrochemical sensor has controllability, can control the content of copper nano particles and graphite alkyne on the working electrode, so as to increase the adsorption tryptophan locus, thereby realizing the technical effects of high sensitivity to tryptophan detection and real-time detection of the tryptophan content change in the plant body, and being further suitable for practical application and popularization.
Drawings
Fig. 1 is a schematic diagram of the electrochemical sensors in examples 1 to 4.
Fig. 2 is an SEM image of a working electrode on the electrochemical sensor in example 2.
FIG. 3 is a graph of current versus voltage measured by differential pulse voltammetry of tryptophan solutions of different concentrations in example 3.
Fig. 4 is a standard graph of current response value versus concentration in example 3.
FIG. 5 is a graph of current versus voltage measured by differential pulse voltammetry in example 4.
FIG. 6 is a schematic diagram of tryptophan detection method for a plant entity in example 4.
Detailed Description
The present invention will be described in further detail with reference to specific examples.
The invention provides an electrochemical sensor, the structure and composition of which are schematically shown in FIG. 1.
As can be seen from fig. 1: firstly, carbonizing the surface of a carbon-containing non-conductive substrate material by a laser etching technology to obtain 3 electrode slots containing conductive carbon layers; then loading copper nano particles on the electrode slot position of the first conductive carbon layer by an electrodeposition method, and loading graphite alkyne by an in-situ synthesis method (GDY); loading Ag/AgCl composite material on the electrode slot position of the second conductive carbon layer by a coating method; and loading platinum nano particles on the electrode slot position of the third conductive carbon layer by using an electrodeposition method to obtain the graphite alkyne modified electrochemical sensor. The graphite alkyne-modified electrochemical sensor takes an electrode slot (namely GDY/Cu NPs/carbon electrode) of a conductive carbon layer loaded with copper nano-particles and graphite alkyne as a working electrode, takes an electrode slot (namely Ag/AgCl/carbon electrode) of a conductive carbon layer loaded with Ag/AgCl composite material as a reference electrode, and takes an electrode slot (namely Pt NPs/carbon electrode) of a conductive carbon layer loaded with platinum nano-particles as a counter electrode.
Example 1
The present embodiment provides an electrochemical sensor, which comprises: a base material and 3 electrode slots containing conductive carbon layers on the surface of the base material; wherein, silver and silver chloride are loaded on the electrode slot position of 1 conductive carbon layer, platinum nano-particles are loaded on the electrode slot position of 1 conductive carbon layer, and graphite alkyne and copper nano-particles are loaded on the electrode slot position of 1 conductive carbon layer.
A method of manufacturing an electrochemical sensor comprising the steps of:
1) In the polystyrene film (polystyrene film has the following dimensions: 4.5×3.5×0.12 cm), etching 3 electrode slots containing conductive carbon layers with laser, setting rectangle with 4cm×5mm electrode slots to be processed, setting the interval between the electrode slots containing conductive carbon layers to be 5mm, and setting the technological parameters of laser etching to be: the sweeping speed is 60mV/s, the current is 18A, and the integral material containing conductive carbon is obtained;
2) Washing the integral material containing conductive carbon in the step 1) by using ultrapure water, drying by using an infrared lamp, immersing in 0.5mol/L copper sulfate solution, setting the deposition voltage to be-0.6V and the constant potential deposition time to be 50s, and depositing copper nano particles on the groove of the working electrode by using a constant potential method to obtain the integral material containing copper and conductive carbon;
3) Mixing 60mL of pyridine with 40mL of acetonitrile, placing the mixture into a round-bottom flask together with an integral material containing copper and conductive carbon, mixing 5mL of hexa (ethynyl) benzene solution with 45mL of tetrahydrofuran to obtain a hexa (ethynyl) benzene-tetrahydrofuran mixed solution, filling the mixed solution into a dropping funnel, assembling the mixed solution with the round-bottom flask, checking air tightness, introducing nitrogen for 20 minutes, opening a dropping valve, controlling the flow rate, dripping the hexa (ethynyl) benzene-tetrahydrofuran mixed solution for 5 hours, heating to 70 ℃, maintaining for 72 hours, and washing with hot toluene, acetone and diethyl ether after naturally cooling to room temperature to obtain the integral material containing graphite alkyne/copper nano particles/carbon electrodes (working electrodes);
4) Coating Ag/AgCl slurry on a reference electrode slot, wherein the mass fraction of Ag in the slurry is 70%, electrodepositing platinum nano particles at a constant potential on a counter electrode slot, setting the deposition voltage to be-0.7V, the deposition time to be 100s, and cleaning and drying to obtain an electrochemical sensor;
in the step 2), the copper nanoparticles are electrodeposited by taking a working electrode slot in a monolithic material containing conductive carbon as a working electrode, taking another Ag/AgCl electrode as a reference electrode and taking another platinum disk electrode as a counter electrode.
The 0.1g/L of the hexakis (ethynyl) benzene solution in this example was obtained by stirring 10mL of 0.1g/L of the hexakis (silylethynyl) benzene solution at 0℃for 20 minutes under a nitrogen atmosphere, and the 0.1g/L of the hexakis (silylethynyl) benzene solution was prepared by using hexakis (silylethynyl) benzene as a solute and tetrahydrofuran as a solvent.
Example 2
A method of manufacturing an electrochemical sensor comprising the steps of:
1) In the polystyrene film (polystyrene film has the following dimensions: 5.6X5.0X0.12 cm) on the substrate, etching 3 electrode slots containing conductive carbon layers by laser, setting rectangle with the electrode slots to be processed being 4.5cm×8mm, setting the spacing between the electrode slots containing conductive carbon layers to be 8mm, and setting the technological parameters of laser etching to be: the sweeping speed is 80mV/s, and the current is 20A, so that the integral material containing conductive carbon is obtained;
2) Washing the integral material containing conductive carbon in the step 1) by using ultrapure water, drying by using an infrared lamp, immersing in 0.5mol/L copper sulfate solution, setting the deposition voltage to be-0.6V, setting the constant potential deposition time to be 100s, and depositing copper nano particles on the groove of the working electrode by using a constant potential method to obtain the integral material containing copper and conductive carbon;
3) Mixing 90mL of pyridine with 75mL of acetonitrile, placing the mixture in a round-bottom flask together with a monolithic material containing copper and conductive carbon, mixing 5mL of a 0.1g/L hexa (ethynyl) benzene solution with 60mL of tetrahydrofuran to obtain a hexa (ethynyl) benzene-tetrahydrofuran mixed solution, filling the mixed solution into a dropping funnel, assembling the mixed solution with the round-bottom flask, checking the air tightness, introducing nitrogen for 20 minutes, opening a dropping valve, controlling the flow rate, dropping the hexa (ethynyl) benzene-tetrahydrofuran mixed solution for 5 hours, heating to 80 ℃, maintaining for 48 hours, and washing with hot toluene, acetone and diethyl ether after naturally cooling to room temperature to obtain the monolithic material containing graphite alkyne/copper nano particles/carbon electrodes (working electrodes);
4) Coating Ag/AgCl slurry on a reference electrode slot, wherein the mass fraction of Ag in the slurry accounts for 85%, electrodepositing platinum nano particles at a constant potential on a counter electrode slot, setting the deposition voltage to be-0.4V, the deposition time to be 100s, and cleaning and drying to obtain an electrochemical sensor;
in the step 2), the copper nanoparticles are electrodeposited by taking a working electrode slot in a monolithic material containing conductive carbon as a working electrode, taking another Ag/AgCl electrode as a reference electrode and taking another platinum disk electrode as a counter electrode.
The 0.1g/L of the hexakis (ethynyl) benzene solution in this example was obtained by stirring 10mL of 0.1g/L of the hexakis (silylethynyl) benzene solution at 0℃for 20 minutes under a nitrogen atmosphere, and the 0.1g/L of the hexakis (silylethynyl) benzene solution was prepared by using hexakis (silylethynyl) benzene as a solute and tetrahydrofuran as a solvent.
SEM image of the working electrode in the electrochemical sensor in example 2, as shown in fig. 2.
As can be seen from fig. 2: graphite alkyne grows on the surface of a working electrode in the electrochemical sensor, so that the roughness of the surface is increased, the specific surface area and conductivity of the working electrode are effectively increased, more adsorption sites are provided for tryptophan, the contact area between the electrode and electrolyte in the electrochemical process is effectively increased, and the electrochemical performance of the working electrode can be improved.
Example 3
A method of manufacturing an electrochemical sensor comprising the steps of:
1) In the polyimide film (the size of the polyimide film is: 5.6X5.0X0.12 cm) on the substrate, etching 3 electrode slots containing conductive carbon layers by laser, setting rectangle with the electrode slots to be processed being 4.5cm×8mm, setting the spacing between the electrode slots containing conductive carbon layers to be 8mm, and setting the technological parameters of laser etching to be: the sweeping speed is 64mV/s, and the current is 16A, so that the integral material containing conductive carbon is obtained;
2) Washing the integral material containing conductive carbon in the step 1) by using ultrapure water, drying by using an infrared lamp, immersing in 0.5mol/L copper sulfate solution, setting the deposition voltage to be-0.6V, setting the constant potential deposition time to be 100s, and depositing copper nano particles on the groove of the working electrode by using a constant potential method to obtain the integral material containing copper and conductive carbon;
3) Mixing 60mL of pyridine with 45mL of tetrahydrofuran, placing the mixture in a round-bottom flask together with an integral material containing copper and conductive carbon, mixing 5mL of a 0.1g/L hexa (ethynyl) benzene solution with 40mL of acetonitrile to obtain a hexa (ethynyl) benzene-acetonitrile mixed solution, filling the mixed solution into a dropping funnel, assembling the mixed solution with the round-bottom flask, checking air tightness, introducing nitrogen for 20min, opening a dropping valve, controlling the flow rate, dropping the hexa (ethynyl) benzene-acetonitrile mixed solution for 5h, heating to 80 ℃, maintaining for 48h, and washing with hot toluene, acetone and diethyl ether after naturally cooling to room temperature to obtain the integral material containing graphite alkyne/copper nano particles/carbon electrodes (working electrodes);
4) Coating Ag/AgCl slurry on a reference electrode slot, wherein the mass fraction of Ag in the slurry accounts for 85%, electrodepositing platinum nano particles at a constant potential on a counter electrode slot, setting the deposition voltage to be-0.2V, the deposition time to be 100s, and cleaning and drying to obtain an electrochemical sensor;
in the step 2), the copper nanoparticles are electrodeposited by taking a working electrode slot in a monolithic material containing conductive carbon as a working electrode, taking another Ag/AgCl electrode as a reference electrode and taking another platinum disk electrode as a counter electrode.
The 0.1g/L of the hexakis (ethynyl) benzene solution in this example was obtained by stirring 10mL of 0.1g/L of the hexakis (silylethynyl) benzene solution at 0℃for 20 minutes under a nitrogen atmosphere, and the 0.1g/L of the hexakis (silylethynyl) benzene solution was prepared by using hexakis (silylethynyl) benzene as a solute and tetrahydrofuran as a solvent.
A method for a standard curve for tryptophan testing, comprising the steps of:
1) The electrochemical sensor was immersed in 10mL tryptophan-phosphate buffer system (ph=6.5) with stirrer concentrations of 10 μΜ, 20 μΜ, 30 μΜ, 40 μΜ, 50 μΜ, 70 μΜ, 90 μΜ, respectively, and the electrochemical workstation differential pulse voltammetry parameters were set: the enrichment potential is +0.2V, the enrichment time is 15s, the rest time is 10s, the voltage interval is 0.55V-1.0V, and differential pulse voltammetry curves which are sequentially measured are adopted;
2) And (3) corresponding the maximum current response value in the measured differential pulse voltammetry curve to tryptophan phosphate buffers with different concentrations, and drawing a standard curve of the current response value-tryptophan concentration by taking the maximum current response value as an ordinate and taking the tryptophan concentration as an abscissa. "μM", that is, "μmol/L", is a unit of concentration of a solution.
The voltage-current profile measured by differential pulse voltammetry for different concentrations of tryptophan solution in example 3 is shown in fig. 3. A standard curve of the current response value-tryptophan concentration was made with a voltage value of about 0.696V on the ordinate and the concentration of tryptophan solution on the abscissa, as shown in fig. 4.
As can be seen from fig. 3 and 4: as the tryptophan concentration increases, the peak current value corresponding to the differential pulse voltammogram also increases. Taking the concentration of tryptophan solution as the abscissa and the peak current of the corresponding differential pulse voltammetry curve as the ordinate, the standard curve for tryptophan test can be obtained, and as shown in fig. 4, the corresponding relation between the peak current value and the concentration is as follows: i=0.05157c+0.5343, r 2 =0.997, where i represents the peak current value of the differential pulse voltammetry curve, C represents the molar concentration of tryptophan in the standard solution, R 2 Representing the correlation coefficient and having a value greater than 0.99, indicating a high degree of confidence in the curve.
By data processing, it can be derived that: the detection limit of the electrochemical sensor composed of the electrochemical sensor was 0.039. Mu.M.
Under the same experimental conditions and electrochemical parameters, 50 mu M tryptophan is added into the solution to be detected, the corresponding peak current increase value is 2.65 mu A, the corresponding tryptophan addition concentration is 51.39 mu M according to the measured curve relationship, and the recovery rate of the tryptophan is 102.77%. This indicates that the standard curve for tryptophan testing measured by this method is highly reliable and can be used to determine the tryptophan concentration or content of an unknown solution.
Based on the detection results, it can be seen that the electrochemical sensor in embodiment 3 or the sensor assembled by the electrochemical sensor can realize rapid detection of tryptophan and has the advantages of small volume, wide application range, high response speed, detection limit and the like.
Example 4
A method of manufacturing an electrochemical sensor comprising the steps of:
1) In the polyimide film (the size of the polyimide film is: 3.5×3.5×0.12 cm), etching 3 electrode slots containing conductive carbon layers with laser, setting rectangle with electrode slots to be processed of 3.0cm×5mm, setting spacing between electrode slots containing conductive carbon layers to be 5mm, and setting technological parameters of laser etching to be: the sweeping speed is 64mV/s, and the current is 16A, so that the integral material containing conductive carbon is obtained;
2) Washing the integral material containing conductive carbon in the step 1) by using ultrapure water, drying by using an infrared lamp, immersing in 0.5mol/L copper sulfate solution, setting the deposition voltage to be 1.0-2.0V, setting the constant potential deposition time to be 100s, and depositing copper nano particles at the groove position of a working electrode by using a constant potential method to obtain the integral material containing copper and conductive carbon;
3) Mixing 60mL of pyridine with 45mL of tetrahydrofuran, placing the mixture in a round-bottom flask together with an integral material containing copper and conductive carbon, mixing 5mL of a 0.1g/L hexa (ethynyl) benzene solution with 40mL of acetonitrile to obtain a hexa (ethynyl) benzene-acetonitrile mixed solution, filling the mixed solution into a dropping funnel, assembling the mixed solution with the round-bottom flask, checking the air tightness, introducing nitrogen for 20min, opening a dropping valve, controlling the flow rate, dropping the hexa (ethynyl) benzene-acetonitrile mixed solution for 5h, heating to 75 ℃, maintaining for 72h, and washing with hot toluene, acetone and diethyl ether after naturally cooling to room temperature to obtain the integral material containing graphite alkyne/copper nano particles/carbon electrodes (working electrodes);
4) Coating Ag/AgCl slurry on a reference electrode slot, wherein the mass fraction of Ag in the slurry accounts for 85%, electrodepositing platinum nano particles at a constant potential on a counter electrode slot, setting the deposition voltage to be-0.2V, the deposition time to be 100s, and cleaning and drying to obtain an electrochemical sensor;
in the step 2), the copper nanoparticles are electrodeposited by taking a working electrode slot in a monolithic material containing conductive carbon as a working electrode, taking another Ag/AgCl electrode as a reference electrode and taking another platinum disk electrode as a counter electrode.
A method for a standard curve for tryptophan testing, comprising the steps of:
1) The electrochemical sensor was immersed in 10mL tryptophan phosphate buffer (ph=6.5) with stirrer concentrations of 10 μΜ, 20 μΜ, 30 μΜ, 40 μΜ, 50 μΜ, 70 μΜ, 90 μΜ, respectively, and the electrochemical workstation differential pulse voltammetry parameters were set: the enrichment potential is +0.2V, the enrichment time is 15s, the rest time is 10s, the voltage interval is 0.55V-1.0V, and differential pulse voltammetry curves which are sequentially measured are adopted;
2) And (3) corresponding the maximum current response value in the measured differential pulse voltammetry curve to tryptophan phosphate buffers with different concentrations, and drawing a standard curve for tryptophan test by taking the maximum current response value as an ordinate and taking the tryptophan concentration as an abscissa.
A tryptophan detection method (see fig. 6) for a plant entity, comprising the steps of:
1) The prepared electrochemical sensor is attached to cucumber fruits subjected to surface treatment, and differential pulse voltammetry parameters of an electrochemical workstation are set: the enrichment potential is +0.2V, the enrichment time is 15s, the rest time is 10s, the voltage interval is 0.45V-1.0V, and the differential pulse voltammetry is adopted to measure the current response value, so that a differential pulse voltammetry curve is obtained;
2) And calculating to obtain the tryptophan concentration in the plant material.
The differential pulse voltammogram obtained from the test in example 4 is shown in fig. 5. A schematic diagram of the tryptophan detection method for the plant material in example 4 is shown in FIG. 6.
As can be seen from fig. 5 and 6: according to the method, as for tryptophan detection in cucumber fruits, a current signal appears in the differential pulse voltammogram at a corresponding peak position, so that the electrochemical sensor prepared by the method can be used for detecting tryptophan in plants, and further real-time change of the tryptophan content of a certain part of the plants can be judged through the peak current value of the differential pulse voltammogram. The electrochemical sensor has the advantages of small volume and the like, can be suitable for in-situ detection of tryptophan content in fruits, stems, leaves and the like in plants, and can monitor the change trend of tryptophan concentration in the parts in real time.
Based on the detection result, the electrochemical sensor prepared by the method can realize the on-site detection of plant tryptophan and has the advantages of small volume, wide application range, high response speed, low detection limit and the like.
The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the equivalent manner, and the embodiments are included in the protection scope of the present invention.
Claims (8)
1. An electrochemical sensor comprising a carbonaceous non-conductive substrate and a three electrode system disposed within a recess in a surface of the carbonaceous non-conductive substrate; the three-electrode system consists of an Ag/AgCl/carbon electrode, a Pt/carbon electrode and a graphite alkyne/copper/carbon electrode; the composition of the Ag/AgCl/carbon electrode comprises a carbon layer and an Ag/AgCl layer; the composition of the Pt/carbon electrode comprises a carbon layer and a platinum nanoparticle layer; the graphite alkyne/copper/carbon electrode comprises a carbon layer and a copper nanoparticle-graphite alkyne composite layer;
the electrochemical sensor is prepared by a preparation method comprising the following steps:
etching 3 electrode slots A, B and C containing conductive carbon layers on the surface of a carbon-containing non-conductive substrate by using laser, depositing copper nano particles in the electrode slot A, then growing graphite alkyne in situ, coating Ag/AgCl slurry in the electrode slot B, and depositing platinum nano particles in the electrode slot C to obtain the electrochemical sensor;
the specific operation of in-situ growth of the graphite alkyne is that a carbonaceous non-conductive substrate after copper nano particles are deposited is placed in a graphite alkyne precursor solution, and is treated for 12 to 72 hours under the condition that the temperature is 60 to 100 ℃; the graphite alkyne precursor solution comprises hexa (ethynyl) benzene and an organic solvent;
the deposition of the electrode slot A is constant potential deposition, the deposition voltage is-1.0V to-0.5V, and the deposition time is 50s to 200s; the electrolyte used in the potentiostatic deposition is a soluble copper salt solution, and the concentration of the soluble copper salt solution is 0.1 mol/L-1.0 mol/L.
2. The electrochemical sensor according to claim 1, wherein: the carbon-containing nonconductive substrate is one of a polystyrene substrate, a polyimide substrate, a wood substrate and a polytetrafluoroethylene substrate.
3. The method for manufacturing an electrochemical sensor according to claim 1 or 2, comprising the steps of:
etching 3 electrode slots A, B and C containing conductive carbon layers on the surface of a carbon-containing non-conductive substrate by using laser, depositing copper nano particles in the electrode slot A, then growing graphite alkyne in situ, coating Ag/AgCl slurry in the electrode slot B, and depositing platinum nano particles in the electrode slot C to obtain the electrochemical sensor;
the specific operation of in-situ growth of the graphite alkyne is that a carbonaceous non-conductive substrate after copper nano particles are deposited is placed in a graphite alkyne precursor solution, and is treated for 12 to 72 hours under the condition that the temperature is 60 to 100 ℃; the graphite alkyne precursor solution comprises hexa (ethynyl) benzene and an organic solvent;
the deposition of the electrode slot A is constant potential deposition, the deposition voltage is-1.0V to-0.5V, and the deposition time is 50s to 200s; the electrolyte used in the potentiostatic deposition is a soluble copper salt solution, and the concentration of the soluble copper salt solution is 0.1 mol/L-1.0 mol/L.
4. A method of manufacturing an electrochemical sensor according to claim 3, characterized in that: the specific operation of growing graphite alkyne in situ is carried out under a protective atmosphere; the protective atmosphere is one or more of nitrogen, helium and argon.
5. A method of manufacturing an electrochemical sensor according to claim 3, characterized in that: the mass fraction of Ag in the Ag/AgCl slurry is 60% -90%.
6. A method of manufacturing an electrochemical sensor according to claim 3, characterized in that: the deposition of the electrode slot C is constant potential deposition, the deposition voltage is-0.7V to-0.1V, and the deposition time is 50s to 200s.
7. Use of an electrochemical sensor according to claim 1 or 2 for tryptophan detection.
8. Use of an electrochemical sensor according to claim 1 or 2 for monitoring in real time the variation of tryptophan content in a plant body.
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