CN108982612B - Integrated electrochemical electrode system based on nanochannel array surface gold spraying - Google Patents

Abstract

The invention discloses a novel integrated electrochemical electrode system based on nano-channel array surface gold spraying. Taking an anode alumina nano-channel array as a carrier, and spraying gold layers on two sides of the carrier by an ion sputtering method; and then the electrode system is connected to an electrochemical workstation system through a lead, the gold layer on one side of the AAO is used as a working electrode, and the gold layer on the other side of the AAO is used as a reference electrode and a counter electrode, so that the electrode system is constructed. The electrode system integrates the nano-channel and the electrode, has the functions of a conventional electrochemical system, is simple and convenient to manufacture, small in size, convenient to carry and convenient to operate, and has innovativeness and application prospects in the aspects of micro-nano analysis and detection.

Description

Integrated electrochemical electrode system based on nanochannel array surface sputtering gold

technical field

The invention belongs to the field of nano-channel-based electrochemistry, and in particular relates to an integrated electrochemical electrode system based on nano-channel array surface sputtering gold.

Background technique

Nanochannels have an ordered structure, stable and good physical and chemical properties and have been commercialized. These characteristics make them have great potential in the field of ultrasensitive single-molecule analysis and detection, and detection technologies based on nanochannels are also increasing. At present, detection methods using nanochannels can be mainly divided into electrochemical detection methods and optical detection methods. Among them, the electrochemical detection method is easy to operate and has high sensitivity, which is favored by many researchers. The detection of transmembrane electrical signals of nanochannels by electrochemical testing is a commonly used analytical method.

Electrodes are an essential part of electrochemical testing. When using an electrochemical workstation for transmembrane electrical signal testing of nanochannels, there are usually three testing systems: a two-electrode testing system, a three-electrode testing system, and a four-electrode testing system. Conventional three-electrode and four-electrode test systems often contain traditional reference electrodes and counter electrodes. In order to make these electrodes fully contact with the electrolyte, the electrolytic cell cannot be omitted; while the conventional two-electrode test system requires two electrodes to be placed separately. into the electrolytic cells at both ends of the nanochannel for electrical signal detection. In short, in the conventional two-electrode, three-electrode and four-electrode test systems, the electrodes are separated from the nanochannels and contain electrolytic cells; these two characteristics make the overall test environment of the conventional electrode test system bulky, which is not conducive to low concentrations. Detection of analytes. Therefore, the search for electrode systems that can be integrated with nanochannels has significant innovation and application prospects.

SUMMARY OF THE INVENTION

The purpose of the present invention is to fully integrate the nano-channel and the electrode, reduce the volume of the entire electrode system, develop a new electrochemical system that can be used for micro-nano analysis, and improve the electrochemical analysis and detection. simplicity and sensitivity.

For achieving the above object, the technical scheme adopted in the present invention is as follows:

The integrated electrochemical electrode system is a three-electrode test system or a two-electrode test system of a working electrode, a reference electrode and a counter electrode. At least the working electrode is an AAO-Au electrode sheet, and the AAO-Au electrode sheet is composed of an anode. Alumina nanochannel array (AAO) (sheet material) is composed of a gold layer sputtered on the surface of the anodized aluminum nanochannel array.

The AAO-Au electrode sheet is encapsulated by an insulating layer and connected to an electrochemical workstation via a wire.

The AAO-Au electrode sheet produced by the invention can be combined with an electrochemical workstation for electrochemical analysis and detection.

A gold layer is sprayed on both surfaces of the sheet layer of the anodized aluminum nanochannel array, and the gold layer completely covers the surface. A sandwich structure in which an anodic aluminum oxide nanochannel array sheet is sandwiched between two gold layers is formed.

The AAO-Au electrode sheet adopts the ion sputtering method, and the anodized aluminum nanochannel array (AAO) is placed in the ion sputtering chamber at a certain angle, and the sputtering current and time are adjusted, respectively. (AAO) Gold layers are sprayed on both sides to obtain AAO-Au electrode sheets.

The AAO-Au electrode sheet thus prepared in the present invention is found to have a nano-enhancing effect in the experiment of an integrated electrochemical electrode, thereby improving the sensitivity of electrochemical analysis and testing.

During ion sputtering, the angle between the plane where the anodic aluminum nanochannel array (AAO) is located and the base plane of the ion sputtering chamber is in the range of 5° to 80°, the charge and discharge current is not less than 3 μA, and the sputtering time is not less than 3 μA. less than 10s.

The anodized aluminum nanochannel array is a double-pass type and contains any pore size.

Two wires are used to connect the gold layers on both sides of the AAO-Au electrode sheet respectively, and a viscous and waterproof film-like material is used as the insulating layer. The insulating layer has a hollow structure, and the insulating layer covers the wires immersed in the electrolyte solution. The connection and contact part of the part, the wire and the AAO-Au electrode sheet and the two sides of the AAO-Au electrode sheet except the hollow structure. The AAO-Au electrode sheet is only in contact with the electrolyte solution at the hollow structure. The side surfaces are all provided with insulating layers, so that the part of the wire below the liquid level of the electrolyte solution and the connection and contact part between the wire and the AAO-Au electrode sheet are not exposed to the electrolyte solution.

The two sides of the AAO-Au electrode sheet are used as the working electrode at the hollow structure, or one side of the AAO-Au electrode sheet is at the hollow structure as the working electrode, and the other side surface is at the hollow structure as the reference electrode and the counter electrode.

The wires include but are not limited to gold wire, copper wire, platinum wire and aluminum foil.

The adhesive and waterproof film-like materials include, but are not limited to, polydimethylsiloxane (PDMS) films and tapes.

The electrochemical analysis and testing methods involved in the present invention include, but are not limited to, cyclic voltammetry, chronoamperometry, electrochemical impedance spectroscopy, and the like.

In the specific implementation of the present invention, the AAO-Au electrode sheet is immersed in a conventional electrolyte solution to construct a two-electrode system, which can perform conventional electrochemical tests (such as cyclic voltammetry, chronoamperometry, electrochemical impedance spectroscopy, etc.).

The size of the implemented AAO-Au electrode sheet is limited to the nanometer scale.

In the electrode system of the present invention, the gold layer on one side of the AAO serves as the working electrode, and the gold layer on the other side serves as the reference electrode and the counter electrode, thereby constructing a dual-electrode system. The electrode system is suitable for conventional electrolyte solutions and can be used for conventional electrochemical tests (such as cyclic voltammetry, electrochemical impedance method, chronoamperometry, etc.).

The beneficial technical effects of the present invention are:

1 Compared with the conventional electrode system, the electrode system has a small amount of metal used, simple preparation and small volume, and has significant advantages in cost and use.

2. The electrode system of the present invention is suitable for conventional electrochemical analysis and testing technology, combined with the advantages of nano-channels, compared with conventional large-volume electrode systems, it has a nano-enhancing effect, which is conducive to improving the sensitivity of electrochemical analysis and testing, and even achieves a single Molecular analysis and detection.

3. The electrode system of the present invention is expected to be further developed into a micro-nano detection system.

In general, the electrode system of the present invention integrates nano-channels and electrodes, has the functions of a conventional electrochemical system, is simple to manufacture, small in size, portable, and easy to operate, and has innovation and application prospects in micro-nano analysis and detection.

Description of drawings

FIG. 1 shows the component diagram of the novel integrated electrochemical electrode system based on the nanochannel array surface sputtering gold in the present invention.

FIG. 2 is a diagram showing the use method of the novel integrated electrochemical electrode system based on the nanochannel array surface sputtering gold in the present invention.

FIG. 3 is a scanning electron microscope image of the surface of the AAO-Au electrode sheet in the present invention before and after double-sided gold spraying.

FIG. 4 is a scanning electron microscope image of the longitudinal section of the AAO-Au electrode sheet in the present invention before and after double-sided gold spraying.

FIG. 5 shows the cyclic voltammetry (CV) curve measured in potassium ferricyanide solution when the novel integrated electrochemical electrode system of the present invention is used as a working electrode in a three-electrode test system on one side.

Figure 6 shows the electrochemical curves obtained from the test of the novel integrated electrochemical electrode system and the rod-shaped commercial gold electrode in 0.1M phosphate buffer solution to construct a two-electrode system respectively, wherein Figure A is the CV curve , Figure B is an electrochemical impedance spectroscopy (EIS) curve, and Figure C is a chronoampere (i-t) curve. The dotted curve in the figure is the test result of the AAO-Au electrode system, and the solid line curve is the test result of the commercial gold electrode.

Figure 7 shows that the novel integrated electrochemical electrode system and the commercial rod-shaped gold electrode in Example 2 were constructed in a solution containing one inorganic redox couple (1 mM potassium ferrocyanide/potassium ferricyanide solution), respectively. The electrochemical curves obtained by the two-electrode system test, in which Figure A is the CV curve, Figure B is the EIS curve, and Figure C is the i-t curve. The dotted curve in the figure is the test result of the AAO-Au electrode system, and the solid line curve is the test result of the commercial gold electrode.

Figure 8 shows the electrochemical curves obtained from the test of constructing a two-electrode system in an organic solution (5mM p-benzoquinone solution) for the novel integrated electrochemical electrode system and the commercial rod-shaped gold electrode in Example 3, wherein Fig. A is the CV curve, Figure B is the EIS curve, and Figure C is the i-t curve. The dotted curve in the figure is the test result of the AAO-Au electrode system, and the solid line curve is the test result of the commercial gold electrode.

Figure 9 shows the electrochemical curves obtained from the test of constructing a two-electrode system in a 1 mM potassium ferrocyanide/potassium ferricyanide solution before and after the new integrated electrochemical electrode system in Example 4 was blocked with BSA, wherein Figure A For the CV curve, Figure B is the EIS curve, Figure C is the i-t curve. The solid curve in the figure is the electrode test curve before BSA treatment, and the dotted curve is the electrode test curve after BSA treatment.

Figure 10 shows the electrochemical curves obtained by constructing a two-electrode system test in 1 mM potassium ferrocyanide/potassium ferricyanide solution before and after the BSA blocking of the commercial rod-shaped gold electrode in Example 4, wherein Figure A is the CV Curves, Figure B is the EIS curve, Figure C is the i-t curve. The solid curve in the figure is the electrode test curve before BSA treatment, and the dotted curve is the electrode test curve after BSA treatment.

In the figure: 1 represents the anodized aluminum nanochannel array, 2 represents the gold layer, 3 represents the wire, and 4 represents the insulating layer.

Detailed ways

The embodiments of the present invention will be described below through specific specific examples in conjunction with the accompanying drawings, but it should be pointed out that the implementation of the present invention is not limited to the following embodiments.

Embodiments of the present invention are as follows:

(1) Fabrication of integrated electrochemical electrode system:

As shown in FIG. 1 , AAO-Au electrode sheets are formed by sputtering gold layers 2 on both sides of the sheet material of the anodic aluminum nanochannel array (AAO) 1 , and the two ends of the AAO-Au electrode sheets are encapsulated by insulating layers 4 and connected to wires 3 Connection, wire 3 is connected to the electrochemical workstation. Two wires 3 are respectively connected to both ends of the AAO-Au electrode sheet, and the insulating layer is a viscous and waterproof film-like material. In the embodiment, gold wire is used as the wire, and tape is used as the insulating layer.

The following takes examples as an example to describe in detail the fabrication method and characterization results of the novel integrated electrochemical electrode system based on the nanochannel array surface sputtering gold sputtering in the present invention.

First, the AAO with a pore size of 80-100 nm was fixed on a glass sheet and placed in the cavity of the ion sputtering instrument. The glass sheet and the base plane were at an angle of 20°. The charge-discharge current during the spraying process was 15 μA, and the spraying time was 400 s. After the two sides of the AAO were sprayed with gold layers with the same parameters, the AAO-Au electrode sheet with the gold layers sprayed on both sides was removed.

The AAO before sputtering and the AAO-Au electrode sheet after sputtering gold layer were characterized by scanning electron microscope and element distribution. As can be seen in Figure 3, comparing the scanning electron microscope images of the surface of the AAO-Au electrode sheet before and after double-sided gold spraying, it can be found that the AAO-Au electrode sheet after gold spraying has a gold layer on the surface compared with the AAO surface; Figure 4 It can be seen that by comparing the scanning electron microscope images of the longitudinal section of the AAO-Au electrode sheet before and after double-sided gold spraying, it can be found that the AAO-Au electrode sheet after gold spraying has no significant difference compared with the longitudinal section of AAO. According to the results of element distribution characterization in the table, it can be found that the conductivity of the AAO-Au electrode sheet after gold spraying increases compared with that of AAO, and the surface gold content increases from 0% to 6.71%.

Next, two gold wires are used to connect the two sides of the AAO-Au electrode sheet respectively, and the lower end of the gold wire and the contact part between the gold wire and the electrode sheet are covered with adhesive tape. At the same time, the gold-plated layers at the circular holes on both sides of the AAO-Au electrode sheet were exposed as electrodes. The tape is sticky and seals the gold wire so that it does not come into contact with the solution.

The two sides of the AAO are sputtered with gold layers respectively, that is, two gold electrodes are integrated on both sides of the AAO, and the AAO and Au together form an AAO-Au electrode sheet. The packaging of the integrated AAO-Au electrode sheet with gold wire and tape effectively reduces the volume of the entire electrode system. This new integrated electrochemical electrode system based on nanochannel array surface sputtering gold meets the requirements of integration and portability. , with innovation and application prospects.

The gold layer on one side of the AAO-Au electrode sheet was used as the working electrode, the standard calomel electrode was used as the reference electrode, and the carbon rod was used as the counter electrode. , the electrolyte solution is a phosphate buffer solution containing potassium ferricyanide, and the characterization results are shown in Figure 5. It can be seen from Figure 5 that the measured CV curve can completely show a pair of redox characteristic peaks of potassium ferricyanide, and the peak voltage difference is less than 400mV, indicating that the AAO-Au electrode sheet has good conductivity and can be used as a routine work. electrodes are used.

(2) The use of the integrated electrochemical electrode system:

As shown in Figure 2, the contents of the beaker represent conventional electrolyte solutions. The AAO-Au electrode sheet in the electrode system is immersed in the electrolyte solution, the gold layer on one side of the AAO-Au electrode sheet is used as the working electrode, and the gold layer on the other side is used as the reference electrode and the counter electrode to form a two-electrode system. AAO-Au electrode sheet, wire, electrolyte solution and electrochemical workstation form a pathway during electrochemical testing to measure transmembrane electrical signals. The testing methods include but are not limited to cyclic voltammetry (CV) method, electrochemical impedance spectroscopy (EIS) ) method, chronoampere (i-t) method.

Example 1:

In this example, the conventional electrolyte solution used was 0.1 M phosphate buffered solution. The AAO-Au electrode sheet in the new electrode system is immersed in the electrolyte solution, and the working electrode of the electrochemical workstation is connected to a wire on the electrode, and the reference electrode and the counter electrode are connected to another wire on the electrode to form a two-electrode system. Electrochemical test, the test results are shown in the dotted curve in Figure 6.

Immerse the two purchased rod-shaped commercial gold electrodes in the electrolyte solution. The rod-shaped commercial gold electrodes are from Tianjin Yingke United Technology Co., Ltd., one is connected to the working electrode of the electrochemical workstation, and the other is connected to the reference of the electrochemical workstation. The electrode and the counter electrode constitute a two-electrode system, and the same electrochemical test as the AAO-Au electrode is carried out. The test results are shown as the solid curve in Figure 6.

Figure 6A represents the CV curve, the specific measurement parameters: the scanning voltage is -0.4V ~ 0.4V, the scanning rate is 0.1V/s; Figure 6B represents the EIS curve, the specific measurement parameters: the frequency range is 1 ~ 10^5Hz , the initial voltage is 0V, and the amplitude is 0.01V; Figure 6C represents the i-t curve, specific measurement parameters: the initial voltage is -0.2V, and the test time is 600s.

It can be seen from Figure 6A and B that the CV and EIS curves have the same trend, indicating that the two electrodes have similar charge transfer capabilities in this solution. As can be seen in Figure 6C, the two curves have the same trend. The test results of the two electrodes are very similar, indicating that the AAO-Au electrode system can successfully measure the electrochemical signal as a two-electrode system in 0.1M phosphate buffer solution, and has properties such as charge transfer ability similar to the rod-shaped commercial gold electrode. , indicating that the electrochemical system of the present invention is suitable for the electrochemical system using conventional buffer solution.

Example 2:

In this example, the conventional electrolyte solution used was a 1 mM potassium ferrocyanide/potassium ferricyanide (an inorganic redox couple) solution. The electrochemical signal measurement method is as in Example 1, and the electrochemical test results are shown in Figure 7. The dotted curve in the figure is the test result of the AAO-Au electrode system, and the solid line curve is the test result of a commercial gold electrode.

FIG. 7A represents the CV curve, FIG. 7B represents the EIS curve, and FIG. 7C represents the i-t curve, and the specific measurement parameters are the same as those in Example 1. As can be seen from Figure 7A, both the AAO-Au electrode system and the commercial gold electrode can successfully characterize the characteristic peak of this redox pair, and the peak potential corresponding to the characteristic peak does not exceed 5mV, indicating that both electrodes can successfully Characterization of inorganic redox couples.

It can be seen from Figure 7B and Figure 7C that the curves of the two electrodes mostly overlap or have the same trend, which further illustrates the similarity of the two electrodes and the practicability of the AAO-Au electrode system, and also shows that the electrochemical system of the present invention is applicable for electrochemical systems employing inorganic redox compounds.

Example 3:

In this example, the conventional electrolyte solution used was a 5 mM solution of p-benzoquinone (classical redox organic). The electrochemical signal measurement method is as in Example 1, and the electrochemical test results are shown in FIG. 8 .

The dotted curve in the figure is the test result of the AAO-Au electrode system, and the solid line curve is the test result of the commercial gold electrode. Figure 8A represents the CV curve, with specific measurement parameters: the scan voltage is -1.5V to 1.5V, and the scan rate is 0.1V/s; Figure 8B represents the EIS curve, and the specific measurement parameters are the same as in Example 1; Figure 8C represents the The i-t curve is the specific measurement parameters: the initial voltage is -0.8V, and the test time is 600s. As can be seen from Figure 8A, both the AAO-Au electrode system and the rod-shaped commercial gold electrode have successfully characterized the characteristic peaks of p-benzoquinone. Although there are differences in the peak voltages corresponding to the characteristic peaks, the characteristic The number of peaks is consistent and the peak shape is complete. The radians of the EIS curves of the two electrodes are similar in Fig. 8B, indicating that the surface conditions of the two electrodes are similar; and the i-t curves of the two electrodes in Fig. 8C have the same trend, which further proves the similarity of the two electrodes.

From the comparison in Figure 8, it can be seen that the AAO-Au electrode system and the rod-shaped commercial gold electrode can successfully measure the electrical signal and characterize the electrode surface in the p-benzoquinone solution, indicating that the electrochemical system of the present invention is suitable for the use of organic redox. The electrochemical system of matter.

Example 4:

The AAO-Au electrode sheet and two rod-shaped commercial gold electrodes in the new electrode system were soaked in 4% BSA solution for one hour, respectively, and washed three times with ultrapure water after taking them out, and then the surface of the electrodes was dried. The treated AAO-Au electrode sheet and two commercial gold electrodes were respectively measured in a 1 mM potassium ferrocyanide/potassium ferricyanide solution, and the measurement method and specific measurement parameters were as in Example 2.

The electrical signal comparison diagram of the AAO-Au electrode system before and after BSA treatment is shown in Figure 9, and the electrical signal comparison diagram of the commercial gold electrode before and after BSA treatment is shown in Figure 10. The solid line curves in Figures 9 and 10 represent The electrode test curve before BSA treatment, the dotted curve represents the electrode test curve after BSA treatment.

It can be seen from the two CV diagrams in Figures 9A and 10A that, compared with before treatment, the characteristic peak current values of the two electrodes after BSA treatment decreased, and the peak voltage difference slightly increased, indicating that the charge transfer of the electrodes Decrease in ability. It can be seen from the two EIS diagrams in Figures 9B and 10B that the charge transfer steric hindrance of the two electrodes after BSA treatment is significantly increased compared with that before treatment, indicating that the charge transfer ability of the electrode surface is reduced, which is consistent with the results of the CV diagram. It can be seen from the two i-t graphs in Figures 9C and 10C that the i-t curves of the two electrodes before and after BSA treatment also changed.

From the comparison of Fig. 9 and Fig. 10, it can be seen that the change trend of the AAO-Au electrode system and the rod-shaped commercial gold electrode after BSA treatment is the same, indicating that the electrode surface of the electrochemical system of the present invention has similar resistance to proteins as the commercial gold electrode. Adsorption capacity, suitable for electrochemical systems that require surface modification.

The above results show that a novel integrated electrochemical electrode system based on nanochannel array surface sputtering gold can be used in conventional electrolyte solutions to measure electrochemical signals, and the electrochemical performance is comparable to that of common ones. Rod-shaped commercial gold electrodes.

Claims (5)

1. an integrated electrochemical electrode system based on nano-channel array surface sputtering gold, described integrated electrochemical electrode system is a two-electrode test system, it is characterized in that: working electrode is AAO-Au electrode sheet, AAO-Au The electrode sheet is composed of an anodized aluminum nanochannel array AAO (1) and a gold layer (2) sprayed on the surface of the anodized aluminum nanochannel array (1); The integrated electrochemical electrode system is used for electrochemical analysis and detection; The AAO-Au electrode sheet is encapsulated by an insulating layer (4) and connected to an electrochemical workstation via a wire (3); A gold layer (2) is spray-coated on both surfaces of the sheet layer of the anodic aluminum oxide nanochannel array (1), and the gold layer (2) completely covers the surface; Two wires (3) are used to connect the gold layers on both sides of the AAO-Au electrode sheet respectively, and a viscous and waterproof film-like material is used as the insulating layer. The part of the wire, the connection and contact part of the wire and the AAO-Au electrode sheet, and the two sides of the AAO-Au electrode sheet except the hollow structure, the AAO-Au electrode sheet is only connected and contacted with the electrolyte solution at the hollow structure; Both sides of the AAO-Au electrode sheet are used as working electrodes at the hollow structure, or one side of the AAO-Au electrode sheet is at the hollow structure as a working electrode, and the other side surface is at the hollow structure as a counter electrode. 2. A kind of integrated electrochemical electrode system based on nano-channel array surface sputtering gold according to claim 1, it is characterized in that: described AAO-Au electrode sheet adopts ion sputtering method, and anodized aluminum oxide nano-channel array is AAO is placed in an ion sputtering chamber at a certain angle, and by adjusting the sputtering current and time, gold layers are sprayed on both surfaces of the anodic aluminum nanochannel array to obtain AAO-Au electrode sheets. 3. A kind of integrated electrochemical electrode system based on nano-channel array surface sputtering gold according to claim 2, it is characterized in that: during ion sputtering, the plane where the anodic aluminum nano-channel array AAO is located and the ion sputtering chamber The angle between the base planes of the body ranges from 5° to 80°, the charge and discharge current is not less than 3 μA, and the sputtering time is not less than 10 s. 4. An integrated electrochemical electrode system based on nanochannel array surface sputtering gold according to claim 1, characterized in that: the wire (3) comprises gold wire, copper wire, platinum wire or aluminum foil. 5. An integrated electrochemical electrode system based on nanochannel array surface sputtering gold according to claim 1, characterized in that: the viscous and waterproof membrane material comprises polydimethylsiloxane (PDMS) film or tape.

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