CN113406171A - Composite electrode and preparation method and application thereof - Google Patents
Composite electrode and preparation method and application thereof Download PDFInfo
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Abstract
The invention discloses a composite electrode and a preparation method and application thereof, and belongs to the technical field of electrochemical biosensors. A composite electrode, comprising: a conductive base; a polyaniline/graphene composite layer; the polyaniline/graphene composite layer is coated on the surface of the conductive matrix; gold-platinum bimetallic nanoparticles; the gold-platinum bimetallic nanoparticles are deposited on the surface of the polyaniline/graphene composite layer. The composite electrode provided by the invention improves the stability of the composite electrode and the detection sensitivity of hormone through the synergistic effect of all parts, and can simultaneously detect dopamine, 5-hydroxytryptamine and melatonin.
Description
Technical Field
The invention belongs to the technical field of electrochemical biosensors, and particularly relates to a composite electrode and a preparation method and application thereof.
Background
With the social development and the accelerated pace of life, the pressure of people in all aspects is getting larger, and in addition to the rapid development of mobile internet products, the sleep problem of people is getting more serious, and the people are developing towards the direction of youthfulness and generalization.
The level of neurotransmitters and hormones determines to a large extent the quality of sleep, and the neurotransmitters and hormones associated with sleep are mainly dopamine, 5-hydroxytryptamine and melatonin. The sleep quality is poor, and it is likely that the contents of these three hormones are abnormal, specifically:
dopamine (Dopamine), formula C8H11NO2The dopamine neurotransmitter is a catechol neurotransmitter, can regulate and control various physiological functions of a central nervous system, has an excitation function, can cause the problems of fatigue, somnolence, low emotion and the like due to the fact that the dopamine in a human body is excessively secreted, and can cause the symptoms of insomnia, easy emotion excitement and the like due to the fact that the dopamine is excessively secreted.
5-hydroxytryptamine (5-hydroxytryptamine) of formula C10H12N2O, also known as serotonin, is an inhibitory neurotransmitter, and the lack of 5-hydroxytryptamine in the body causes the problems of poor sleep, difficult sleep, easy waking, short sleep time and the like.
Melatonin (Melatonin), formula C13H16N2O2Also known as pineal hormone, is one of the hormones secreted by the pineal gland. Melatonin secretion has obvious circadian rhythm, daytime secretion is inhibited, and night secretion is active. Melatonin can improve sleep, shorten wake time before sleep and fall asleep time, and improve sleep quality.
Sleep is an indispensable life requirement, the quality of sleep is closely related to human health, the immunity is reduced due to long-term poor sleep quality, various diseases are caused, and the health hazard is great, so that a method for simultaneously detecting the three substances is necessary.
There are many methods for detecting hormones, such as high performance liquid chromatography, spectrophotometry, chemiluminescence, mass spectrometry, and near infrared spectroscopy, but these methods generally have the problems of low operation integration level, expensive and heavy instruments, inconvenient field detection, high economic cost of detection, high detection time/labor cost, and the like. Compared with other detection methods, the electrochemical analysis method has the advantages of high sensitivity, high analysis speed, simple instrument and equipment, easy miniaturization and integration, and contribution to realizing field detection and online real-time monitoring.
However, oxidation potentials of dopamine, 5-hydroxytryptamine and melatonin are similar, and the oxidation potentials are difficult to distinguish on a common electrode, that is, the common electrode cannot detect dopamine, 5-hydroxytryptamine and melatonin at the same time.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art described above. Therefore, the composite electrode provided by the invention has the advantages that the stability of the composite electrode is improved and the detection sensitivity to hormone is improved through the synergistic effect among the conductive matrix, the polyaniline/graphene composite layer and the gold-platinum bimetallic nanoparticles, the oxidation peaks of dopamine, 5-hydroxytryptamine and melatonin can be separated, and the separate detection or the simultaneous detection of the dopamine, 5-hydroxytryptamine and melatonin can be realized.
The invention also provides a preparation method of the composite electrode.
The invention also provides an application of the composite electrode in hormone detection.
The invention also provides a detection sensor comprising the composite electrode.
The invention also provides a detection system comprising the detection sensor.
According to an aspect of the present invention, there is provided a composite electrode comprising:
a conductive base;
a polyaniline/graphene composite layer; the polyaniline/graphene composite layer is coated on the surface of the conductive substrate;
gold-platinum bimetallic nanoparticles; the gold-platinum bimetallic nanoparticles are deposited on the surface of the polyaniline/graphene composite layer.
According to a preferred (specific) embodiment of the present invention, at least the following advantageous effects are obtained:
(1) in the polyaniline/graphene composite layer adopted by the invention, graphene and polyaniline both have special electrical properties, and after the polyaniline/graphene composite layer is modified to the surface of a conductive matrix, on one hand, the conductivity of the composite electrode can be increased, and on the other hand, the polyaniline/graphene composite layer can be used as an active substance, so that the detection sensitivity of the composite electrode on hormone is improved.
(2) In the gold-platinum bimetallic nano-particles adopted by the invention, gold and platinum respectively have catalytic activity, and after the gold and the platinum are co-deposited, the catalytic activity of the composite electrode is further improved; meanwhile, compared with the nano particles formed by single metal, the gold-platinum bimetallic nano particles have strong toxicity resistance (small probability of pollution and failure), so that the gold-platinum bimetallic nano particles can be recycled for many times, and the cost is saved.
(3) The gold-platinum bimetallic nanoparticles exist on the surface of the polyaniline/graphene composite layer in a nanoparticle shape, and the particle size is small and the particles are not agglomerated, so that the specific surface area of the composite electrode can be increased.
(4) The detection sensitivity of the composite electrode to the hormone and whether various hormones can be distinguished are related to the conductivity, the specific surface area and the catalytic activity of the composite electrode, wherein the conductivity is high, which indicates that the mass transfer is fast, so that the oxidation peaks of the hormones with various oxidation potentials close to each other can be distinguished; the specific surface area is large, the more sites can be subjected to catalytic reaction, so that the electrochemical signal is strong, and the detection sensitivity is favorably improved; the catalytic activity is strong, which shows that the catalytic rate is high, the corresponding speed of the electrode is high, the electrochemical signal intensity can be improved, and the method is also beneficial to distinguishing the oxidation peaks of various hormones; in addition, the catalysis has specificity, and a specific type of catalyst is required for detecting a specific type of hormone;
in conclusion, the composite electrode supports each part, and not only can be used for independently detecting any one of dopamine, 5-hydroxytryptamine and melatonin, but also can be used for simultaneously detecting and distinguishing the three hormones.
In some embodiments of the present invention, the conductive substrate is made of at least one of gold, copper, nickel and glassy carbon.
In some preferred embodiments of the present invention, the conductive substrate is made of gold.
In some embodiments of the present invention, the gold-platinum bimetallic nanoparticles refer to nanoparticles containing two metal elements, namely gold and platinum, and the two metal elements may be present in the form of an alloy, a mixture of two simple metals, or a secondary mixture of the two metal elements.
In some embodiments of the present invention, the gold-platinum bimetallic nanoparticles have a particle size between 20nm and 200 nm.
In the present inventionIn some embodiments, the composite electrode has a charge transfer resistance of 2.26 Ω cm or less2
In some preferred embodiments of the invention, the composite electrode is coated with 2mM [ Fe (CN) ] in 0.1M KCl as supporting electrolyte6]3-/4-In the solution, the charge transfer resistance was 2.26. omega. cm2。
Said [ Fe (CN)6]3-/4-Solution, means that in solution [ Fe (CN) ]occurs6]4-And [ Fe (CN)6]3-The conversion reaction between them.
The 0.1M KCl is 2mM [ Fe (CN)6 of supporting electrolyte]3-/4-The solution contains KCl with concentration of 0.1M and K with concentration of 2mM3[Fe(CN)6]And 2mM of K4[Fe(CN)6]。
According to still another aspect of the present invention, there is provided a method of manufacturing a composite electrode, comprising the steps of:
s1, arranging the polyaniline/graphene composite layer on the surface of the conductive matrix by adopting an electrodeposition method;
s2, depositing the gold-platinum bimetallic nanoparticles on the surface of the material obtained in the step S1 by adopting an electrodeposition method to obtain the composite electrode.
The preparation method according to a preferred embodiment of the present invention has at least the following advantageous effects:
the preparation method provided by the invention can obtain the composite electrode only by an electrochemical deposition method, and is simple, easy to implement and high-efficiency.
In some embodiments of the present invention, in step S1, the electrodeposition method includes graphene and aniline in the deposition solution.
In some preferred embodiments of the present invention, in step S1, the electrodeposition method further includes an acid in the deposition solution.
In some preferred embodiments of the present invention, in step S1, the electrodeposition method further includes hydrogen chloride (HCl) and sulfuric acid (H)2SO4) At least one of (1).
The acid is used for providing doped protons in the polymerization process of the aniline so that the aniline is polymerized to generate a semi-oxidized state, and further the conductivity of the polyaniline is improved.
In some embodiments of the present invention, in step S1, the electrodeposition method, the preparing step of the deposition solution includes:
D1. firstly, adding the graphene powder into a first dispersing agent, and carrying out ultrasonic treatment for 30min to form graphene dispersion liquid which is uniformly dispersed and has the concentration of 0.5-2 mg/mL;
D2. adding 5-50 mL of HCl solution with the concentration of 0.08M into each 100 mu L of graphene dispersion liquid, and performing ultrasonic treatment for 3h to form uniform suspension;
D3. and D2, adding 50-100 mu L of aniline into 10mL of the suspension obtained in the step D2, and carrying out ultrasonic treatment for 30min to obtain the deposition solution.
In some embodiments of the invention, in step D1, the first dispersant is at least one of deionized water, methanol, absolute ethanol, isopropanol, N-methylformamide, and dimethylformamide.
In some embodiments of the invention, in step S1, the electrodeposition method is at least one of cyclic voltammetry, galvanostatic, and potentiostatic methods.
In some preferred embodiments of the present invention, when the cyclic voltammetry is used in the electrodeposition method in step S1, the scan speed is 25mV/S to 100mV/S, the scan potential is-0.3V to 0.7V, and the number of cycles is 15 to 25.
In some embodiments of the present invention, when the electrodeposition method is the cyclic voltammetry method in step S1, the cyclic voltammetry method is performed in a three-electrode system, specifically, the conductive substrate is used as a working electrode, commercial Ag/AgCl is used as a reference electrode, and a platinum sheet is used as a counter electrode.
In some preferred embodiments of the present invention, when the electrodeposition method employs the constant current method in step S1, the voltage is set between-0.1V and-0.8V, and the deposition time is set between 600S and 2400S.
In some preferred embodiments of the present invention, when step S1, the electrodepositionWhen the constant potential method is adopted, the current density is between-0.01 and-0.1A/cm2The deposition time is 600-2400 s.
The film obtained by adopting the cyclic voltammetry deposition is thinner, and the adhesion between the polyaniline/graphene composite layer obtained by the method and the conductive matrix is stronger, namely the mechanical strength of the obtained composite electrode is higher.
In some embodiments of the present invention, the preparation method further includes, between step S1 and step S2, cleaning the conductive substrate coated with the polyaniline/graphene composite layer, and drying; specifically, the conductive substrate coated with the polyaniline/graphene composite layer is washed by deionized water and then placed in an oven at 40-60 ℃ for drying for 10 hours.
In some embodiments of the present invention, in step S2, the electrodeposition method includes chloroauric acid and chloroplatinic acid in the deposition solution.
In some embodiments of the present invention, in step S2, the electrodeposition method further includes salts, wherein the salts are potassium chloride (KCl), sodium chloride (NaCl) and sodium sulfate (Na)2SO4) At least one of (1).
In step S2, the salt in the deposition solution acts to enhance the conductivity of the deposition solution.
In some embodiments of the present invention, in step S2, the electrodeposition method, the preparing step of the deposition solution includes: adding 0.5 mM-2 mM chloroauric acid solution and 0.5 mM-2 mM chloroplatinic acid solution into 0.1M-0.5M KCl solution, and uniformly stirring; the volume ratio of the KCl solution to the chloroauric acid solution to the chloroplatinic acid solution is (50-200): 1: 1.
In some embodiments of the invention, in step S2, the electrodeposition method is at least one of a galvanostatic method, a potentiostatic method, and a cyclic voltammetry method.
In some preferred embodiments of the present invention, in step S2, when the electrodeposition method employs the constant current method, the deposition potential is-0.2V to-0.5V, and the deposition time is 180S to 360S.
In some preferred embodiments of the invention, the stepsIn step S2, when the electrodeposition method is the potentiostatic method, the current density is-0.02 to 0.1mA/cm2。
In some preferred embodiments of the present invention, in step S2, when the cyclic voltammetry is used as the electrodeposition method, the scanning potential is 0.2 to-0.4V, the scanning speed is 25 to 100mV/S, and the number of turns is 3 to 10.
In some embodiments of the present invention, the chronoamperometry is performed in a three-electrode system, and specifically, the conductive substrate coated with the polyaniline/graphene composite layer obtained in step S1 is used as a working electrode, a commercial Ag/AgCl is used as a reference electrode, and a platinum sheet is used as a counter electrode.
In some embodiments of the present invention, the method further comprises washing the composite electrode with water after depositing the gold-platinum bimetallic nanoparticles.
According to a further aspect of the invention, the use of the composite electrode for detecting hormones is proposed.
The application according to a preferred embodiment of the invention has at least the following advantageous effects:
the method for detecting the hormone by using the composite electrode is easy to operate: the special electrode structure can realize the real-time detection of a sampling site in a complex environment, does not need a complex processing procedure in laboratory detection, and greatly improves the detection efficiency.
In some embodiments of the invention, the hormone is at least one of dopamine, 5-hydroxytryptamine, and melatonin.
In some embodiments of the present invention, the use of the composite electrode in detecting hormone comprises preparing the composite electrode as a portable detection sensing device for detecting hormone(s).
A detection sensor comprising the composite electrode.
In some embodiments of the invention, the detection sensor is a portable detection sensor.
A detection system comprising the detection sensor.
Drawings
The invention is further described with reference to the following figures and examples, in which:
FIG. 1 is a scanning electron microscope image of a composite electrode obtained in example 1 of the present invention;
FIG. 2 is a differential pulse voltammogram of a composite electrode obtained in example 1 of the present invention with respect to dopamine;
FIG. 3 is a graph of differential pulse voltammetry of a composite electrode pair of 5-hydroxytryptamine obtained in example 1 of the present invention;
FIG. 4 is a differential pulse voltammogram of the composite electrode obtained in example 1 of the present invention against melatonin;
FIG. 5 is a differential pulse voltammetry curve of the composite electrode obtained in example 1 of the present invention for simultaneously detecting dopamine, 5-hydroxytryptamine and melatonin;
FIG. 6 is a differential pulse voltammetry curve of the composite electrode obtained in example 1 of the present invention and the comparative example for simultaneously detecting dopamine, 5-hydroxytryptamine and melatonin;
FIG. 7 is an AC impedance spectrum of gold and a composite electrode obtained in example 1 of the present invention.
Detailed Description
The concept and technical effects of the present invention will be clearly and completely described below in conjunction with the embodiments to fully understand the objects, features and effects of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and those skilled in the art can obtain other embodiments without inventive effort based on the embodiments of the present invention, and all embodiments are within the protection scope of the present invention.
Example 1
In this embodiment, a composite electrode is prepared, and the specific process is as follows:
s1, modifying a conductive substrate by using a polyaniline/graphene composite layer:
s1a, preparing a first deposition solution: firstly, adding graphene powder into a methanol solution, and carrying out ultrasonic treatment for 30min to form a graphene dispersion liquid which is uniformly dispersed and has a concentration of 1 mg/mL;
adding 10mL of HCl solution (0.08M) into each 100 mu L of graphene dispersion solution, and performing ultrasonic treatment for 3h to form uniform suspension;
taking 10mL of the suspension, adding 70 mu L of aniline (analytically pure liquid aniline), and carrying out ultrasonic treatment for 30min to obtain a first deposition solution;
s1b, depositing a polyaniline/graphene composite layer: adopting a three-electrode system, taking planar gold (conductive matrix) as a working electrode, commercial Ag/AgCl as a reference electrode and a platinum sheet as a counter electrode, in a first deposition solution, performing cyclic voltammetry at a scanning speed of 50mV/s and a scanning potential of-0.3V-0.7V for 15 circles, cleaning the obtained intermediate electrode with deionized water, and then putting the cleaned intermediate electrode into a 60 ℃ drying oven to dry for 10 hours to obtain the conductive matrix modified by a polyaniline/graphene composite layer;
s2, modifying the electrode obtained in the step S1 by using gold-platinum bimetallic nanoparticles:
s2a, preparing a second deposition solution: adding a 1mM chloroauric acid solution and a 1mM chloroplatinic acid solution into a 0.1M KCl solution, and uniformly stirring to obtain a second deposition solution; the volume ratio of the KCl solution to the chloroauric acid solution to the chloroplatinic acid solution is 100:1: 1;
s2b, depositing gold-platinum bimetallic nanoparticles: depositing gold-platinum bimetallic nanoparticles on the surface of the electrode obtained in the step S1 in a second deposition solution by a timed current method by adopting a three-electrode system and taking the electrode prepared in the step S1 as a working electrode, commercial Ag/AgCl as a reference electrode and a platinum sheet as a counter electrode; the deposition potential is-0.2V, the deposition time is 240s, and the composite electrode is obtained after the electrodeposition is finished and is washed clean by deionized water.
Example 2
In this example, a composite electrode was prepared, which specifically differs from example 1 in that:
(1) in step S1b, 20 cycles are performed.
Example 3
In this example, a composite electrode was prepared, which specifically differs from example 1 in that:
(1) in step S2b, the deposition potential is-0.3V and the deposition time is 180S.
Example 4
In this example, a composite electrode was prepared, which specifically differs from example 4 in that:
(1) in the step S1a, the concentration of the graphene dispersion liquid is 2 mg/mL;
(2) in step S2a, the concentrations of chloroauric acid and chloroplatinic acid were 0.5mM each.
Comparative example 1
This comparative example prepared a composite electrode, differing from example 1 in that:
(1) step S2 is not included, namely, the product obtained in step S1 is directly used as a composite electrode.
Comparative example 2
This comparative example prepared a composite electrode, differing from example 1 in that:
(1) in step S2a, chloroplatinic acid was not added.
Comparative example 3
This comparative example prepared a composite electrode, differing from example 1 in that:
(1) in step S2a, chloroauric acid was not added.
Comparative example 4
This comparative example prepared a composite electrode, differing from example 1 in that:
(1) in step S1a, the aniline solution is not included, i.e., the suspension formed after 3 hours of sonication is directly used as the first deposition solution.
Test examples
This test example tested the performance of the composite electrodes prepared in the examples and comparative examples.
In the first aspect of this test example, the morphology performance of the composite electrode obtained in example 1 was tested by a scanning electron microscope, and the test result is shown in fig. 1.
The results in fig. 1 show that gold-platinum bimetallic nanoparticles are uniformly distributed on the surface of the composite electrode obtained in example 1, and no agglomeration phenomenon occurs; the morphology of the composite electrode obtained in examples 2-4 is similar to that of the composite electrode obtained in example 1.
In a second aspect of this test example, the response performance of the composite electrode obtained in example 1 to a single kind of dopamine, 5-hydroxytryptamine or melatonin was tested, and the test method was differential pulse voltammetry, specifically, the composite electrode obtained in example 1 was used as a working electrode, an Ag/AgCl electrode was used as a reference electrode, a Pt sheet was used as a counter electrode, and a solution of dopamine, 5-hydroxytryptamine or melatonin at an appropriate concentration was added to a 0.1M phosphate buffer solution (pH 7.0), and scanned by differential pulse voltammetry to determine the change curve of the peak current.
FIG. 2 is a differential pulse voltammetry curve of the composite electrode obtained in example 1 of the present invention for detecting dopamine solutions at concentrations of 1. mu.M, 3. mu.M, 5. mu.M, 7. mu.M, 10. mu.M, 15. mu.M, 20. mu.M, 30. mu.M, 50. mu.M, 70. mu.M, 100. mu.M, 150. mu.M, 200. mu.M and 300. mu.M, respectively;
FIG. 3 is a differential pulse voltammetry curve of the composite electrode obtained in example 1 of the present invention for detecting 5-hydroxytryptamine solutions with concentrations of 1. mu.M, 5. mu.M, 15. mu.M, 50. mu.M, 70. mu.M, 100. mu.M, 200. mu.M and 300. mu.M, respectively;
FIG. 4 is a differential pulse voltammetry curve of the composite electrode obtained in example 1 of the present invention for detecting melatonin solutions at concentrations of 1. mu.M, 5. mu.M, 15. mu.M, 30. mu.M, 50. mu.M, 70. mu.M, 100. mu.M, 150. mu.M, 200. mu.M and 300. mu.M, respectively; 2-4, the abscissa E of the differential pulse voltammogram represents voltage in volts (V) based on Ag/AgCl; the ordinate j is the current density.
As can be seen from FIGS. 2 to 4, the peak current density gradually increases with the gradually increasing concentrations of Dopamine (DA), 5-hydroxytryptamine (5-HT) and Melatonin (MEL), which indicates that the composite electrode prepared by the method has excellent response characteristics to trace amounts of dopamine, 5-hydroxytryptamine and melatonin. The performance of the composite electrodes obtained in examples 2-4 is comparable to that of the composite electrodes obtained in the examples.
In the third aspect of this test example, the response performance of the composite electrode pair obtained in example 1 to jointly test dopamine, 5-hydroxytryptamine and melatonin is tested for 7 times of gradient tests, the content of three hormones in the solution to be tested is shown in table 1, and the difference between the specific method and the second aspect of this test example is: the solution contains dopamine, 5-hydroxytryptamine and melatonin simultaneously in a 0.1M phosphoric acid buffer solution (pH 7.0), wherein the specific concentrations of dopamine, 5-hydroxytryptamine and melatonin are shown in Table 1.
TABLE 1 specific concentrations of dopamine, 5-hydroxytryptamine and melatonin in FIG. 5
| Test number | Test No. 1 | Test No. 2 | Test No. 3 | Test No. 4 | Test No. 5 | Test No. 6 | Test No. 7 |
| Dopamine | 1μM | 3μM | 5μM | 7μM | 15μM | 50μM | 100μM |
| 5-hydroxytryptamine | 1μM | 3μM | 5μM | 7μM | 15μM | 50μM | 100μM |
| 5-hydroxytryptamine | 1μM | 3μM | 5μM | 7μM | 15μM | 50μM | 100μM |
The results are shown in FIG. 5, where the abscissa E represents the voltage in volts (V) based on Ag/AgCl; the ordinate j is the current density. As can be seen from the figure:
the peak position of the differential pulse curve is gradually increased along with the increase of the concentrations of dopamine, 5-hydroxytryptamine and melatonin;
the differential pulse curve shows three distinct oxidation peaks which respectively correspond to the oxidation peaks of Dopamine (DA), 5-hydroxytryptamine (5-HT) and Melatonin (MEL), and shows that the three hormones all have good electrochemical responsiveness on the composite electrode obtained in example 1;
the oxidation peak potentials of the dopamine, the 5-hydroxytryptamine and the melatonin are different, and the oxidation peak potentials do not interfere with the measurement, so that the composite electrode prepared by the method can be used for simultaneously detecting the dopamine, the 5-hydroxytryptamine and the melatonin; the performance of the composite electrodes obtained in examples 2-4 is comparable to that of the composite electrodes obtained in the examples.
In conclusion, the invention establishes a novel electrochemical method for simultaneously measuring dopamine, 5-hydroxytryptamine and melatonin.
In the fourth aspect of the present test example, the composite electrodes obtained in example 1 and the comparative example were tested for their effects in detecting three hormones, namely, dopamine, 5-hydroxytryptamine and melatonin, and the difference between the test method and the third aspect of the present test example is that the working electrode employs the composite electrode obtained in the comparative example in addition to the composite electrode obtained in example 1.
The results are shown in FIG. 6, where the abscissa E represents the voltage in volts (V) based on Ag/AgCl; the ordinate j is the current density. It is shown that the composite electrode obtained in example 1 shows an oxidation peak of each hormone in terms of detecting the effects of three hormones, dopamine, 5-hydroxytryptamine and melatonin, and that the response intensity is superior to that of all the composite electrodes obtained in comparative examples; specifically, if the composite electrode does not include gold-platinum bimetallic nanoparticles, the obtained composite electrode does not respond to melatonin; if pure gold nanoparticles or platinum nanoparticles are used for replacing gold-platinum bimetallic nanoparticles, or polyaniline is not included in the composite electrode, the obtained composite electrode has response to the three hormones, but the response strength is low; the composite electrode provided by the invention has the advantages that all parts generate synergistic action, and the response characteristics of the composite electrode to the three hormones are improved together.
In the fifth aspect of this test example, the composite electrode obtained in example 1 was tested, and an EIS (alternating current impedance) spectrum of gold was obtained, as shown in fig. 7, in which the abscissa represents the real-part impedance and the ordinate represents the imaginary-part impedance.
The results in FIG. 7 show that the charge transfer resistance of gold is about 15.94. omega. cm2The charge transfer resistance of the composite electrode obtained in example 1 was much lower than that of gold, about 2.2. omega. cm2。
The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention. Furthermore, the embodiments of the present invention and the features of the embodiments may be combined with each other without conflict.
Claims (10)
1. A composite electrode, comprising:
a conductive base;
a polyaniline/graphene composite layer; the polyaniline/graphene composite layer is coated on the surface of the conductive substrate;
gold-platinum bimetallic nanoparticles; the gold-platinum bimetallic nanoparticles are deposited on the surface of the polyaniline/graphene composite layer.
2. The composite electrode of claim 1, wherein the conductive substrate is at least one of gold, copper, nickel, and glassy carbon.
3. The composite electrode according to claim 1, wherein the gold-platinum bimetallic nanoparticles have a particle size of 20-200 nm.
4. The composite electrode of claim 1, wherein the composite electrode has a charge transfer resistance of 2.26 Ω cm or less2。
5. A method for preparing a composite electrode according to any one of claims 1 to 4, comprising the steps of:
s1, arranging the polyaniline/graphene composite layer on the surface of the conductive matrix by adopting an electrodeposition method;
s2, depositing the gold-platinum bimetallic nanoparticles on the surface of the material obtained in the step S1 by adopting an electrodeposition method to obtain the composite electrode.
6. The method of claim 5, wherein in step S1, the electrodeposition solution comprises graphene and aniline; preferably, the electrodeposition method is at least one of cyclic voltammetry, galvanostatic and potentiostatic methods.
7. The method of claim 5, wherein in step S2, the electrodeposition method includes chloroauric acid and chloroplatinic acid in the deposition solution; preferably, the electrodeposition method is at least one of a galvanostatic method, a potentiostatic method and a cyclic voltammetry method.
8. Use of the composite electrode of any one of claims 1 to 4 for detecting a hormone; preferably, the hormone is at least one of dopamine, 5-hydroxytryptamine and melatonin.
9. A detection sensor comprising the composite electrode according to any one of claims 1 to 4.
10. A detection system comprising the detection sensor of claim 9.
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