CN114019000B - Multi-signal response thin film electrode, preparation method and application thereof - Google Patents

Multi-signal response thin film electrode, preparation method and application thereof Download PDF

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CN114019000B
CN114019000B CN202111294161.2A CN202111294161A CN114019000B CN 114019000 B CN114019000 B CN 114019000B CN 202111294161 A CN202111294161 A CN 202111294161A CN 114019000 B CN114019000 B CN 114019000B
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pani
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刘红云
肖睿琦
姚惠琴
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Beijing Normal University
Ningxia Medical University
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Ningxia Medical University
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Abstract

The invention discloses a multi-signal response film electrode, which comprises a light-transmitting electrode with conductivity and a multi-signal response film covering the surface of the light-transmitting electrode, wherein the multi-signal response film comprises: polyaniline, molybdenum disulfide quantum dots, polymer hydrogel and glucose oxidase. According to the multi-signal response thin film electrode provided by the invention, the thin film containing polyaniline, molybdenum disulfide quantum dots, polymer hydrogel and glucose oxidase is deposited on the surface of the light-transmitting electrode with conductivity, so that the multi-signal response thin film electrode has reversible electrochromic performance, electrochromism performance, pH-dependent biocatalysis and electrocatalytic performance, and can respond to various signals. Based on the characteristics, the thin film electrode provided by the invention can be used for detecting peroxide substances (such as hydrogen peroxide) and glucose in a solution; and on the other hand can be used for an analog D-type flip-flop.

Description

Multi-signal response film electrode, preparation method and application thereof
Technical Field
The invention relates to the technical field of thin film electrode preparation, in particular to a multi-signal response thin film electrode, a preparation method and application thereof.
Background
Molybdenum Disulfide Quantum Dots (Molybdenum nanoparticles, moS) 2 QDs), as a new nano material, has both Photoluminescence (PL) characteristics and catalytic properties of peroxidase-like enzymes, and has the advantages of being easily available, easy to prepare in large scale, and the like. MoS 2 As a bifunctional material, QDs has been proven to have very good peroxidase-like catalytic properties, and is widely applied to the fields of biological imaging, metal ion detection and the like due to PL properties.
Polyaniline (PANI) is a classic electrochromic material, has good biocompatibility and can promote electron transfer. Can be obtained by solution polymerization or electrochemical polymerization of aniline monomer. Polyaniline is composed of an oxidation unit and a reduction unit, the redox state of the polyaniline can be reversibly switched by applying a voltage in a certain range in an acid environment, and an obvious change from almost colorless to bluish purple is observed. The electrochromic property of the polyaniline can be easily adjusted by adjusting the voltage and the pH value of the solution.
In recent years, some multi-signal response materials for substance detection have been reported, but the use of a combination of molybdenum disulfide quantum dots, polyaniline and a biological enzyme for preparing a multi-signal response material has not been reported.
Disclosure of Invention
The invention aims to combine molybdenum disulfide quantum dots, polyaniline and biological enzyme to provide a multi-signal response thin film electrode. The invention also provides a preparation method and application of the multi-signal response thin film electrode.
In order to achieve the above object, a first aspect of the present invention provides a multiple-signal-response thin-film electrode, including a light-transmissive electrode having conductivity and a multiple-signal-response thin film covering a surface of the light-transmissive electrode, wherein the multiple-signal-response thin film includes: polyaniline, molybdenum disulfide quantum dots, polymer hydrogel and glucose oxidase.
In some embodiments, the polyaniline is covered on the surface of the light-transmitting electrode, and the molybdenum disulfide quantum dots, the polymer hydrogel and the glucose oxidase are covered on the surface of the polyaniline.
In some embodiments, the polymer hydrogel is selected from at least one of chitosan (Chit), poly N, N-dimethylaminoethyl methacrylate (PDMEM), and polyallylamine hydrochloride (PAH).
In some embodiments, the light-transmitting electrode having conductivity is an indium tin oxide electrode or an indium fluoride oxide electrode.
The invention provides a preparation method of the multi-signal response thin film electrode, which comprises the following steps:
forming a polyaniline layer on the surface of the light-transmitting electrode with conductivity by electrochemical polymerization,
and coating a mixed solution containing molybdenum disulfide quantum dots, polymer hydrogel and glucose oxidase on the surface of the polyaniline layer, and drying to obtain the multi-signal response thin film electrode.
In some embodiments, the step of forming a polyaniline layer by electrochemical polymerization comprises:
under nitrogen atmosphere, in a solution containing 0.5M H 2 SO 4 And 0.01mM aniline monomer, and synthesizing the polyaniline layer in a three-electrode system by using the conductive light-transmitting electrode as a working electrode through cyclic voltammetry.
In some embodiments, the mass ratio of the molybdenum disulfide quantum dots, the polymer hydrogel and the glucose oxidase in the mixed solution is 1 (40-60) to (15-30), preferably 1.
In a third aspect, the invention provides the use of a multiple signal responsive membrane electrode as described above in the detection of peroxide and/or glucose.
A fourth aspect of the invention provides the use of a multiple signal responsive thin film electrode as described above in an analogue D-type flip-flop.
In a fifth aspect, the invention provides a molecular analogue trigger comprising a multi-signal responsive thin film electrode as described above.
According to the multi-signal response thin film electrode provided by the invention, the thin film containing polyaniline, molybdenum disulfide quantum dots, polymer hydrogel and glucose oxidase is deposited on the surface of the light-transmitting electrode with conductivity, so that the multi-signal response thin film electrode has reversible electrochromic performance, electrochromism performance, pH-dependent biocatalysis and electrocatalytic performance, and can respond to various signals. Based on the characteristics, the thin film electrode provided by the invention can be used for detecting peroxide substances (such as hydrogen peroxide) and glucose in a solution; and on the other hand can be used for analog D-type flip-flops.
Drawings
Fig. 1A is a transmission electron microscope image of the molybdenum disulfide quantum dot dispersion prepared in the present invention, the upper right inset in fig. 1A is an image accompanied by a clear lattice fringe after enlarging the size, and the lower left inset in fig. 1A is a particle size distribution frequency diagram of nanoparticles.
Fig. 1B is a fluorescence spectrum of a molybdenum disulfide quantum dot dispersion prepared according to the present invention and a molybdenum disulfide nanosheet aqueous dispersion for comparison, in which a curve a is a fluorescence spectrum curve of the molybdenum disulfide nanosheet aqueous dispersion, B is a fluorescence spectrum curve of the molybdenum disulfide quantum dot dispersion, an inset in fig. 1B is a photograph of the dispersion under an ultraviolet lamp, a is the molybdenum disulfide nanosheet aqueous dispersion, and B is the molybdenum disulfide quantum dot dispersion.
FIG. 2 shows a bare ITO electrode (a), a PANI thin film electrode (b) and a Chit-MoS prepared in example 1 2 GOD/PANI thin film electrodes (c) in the presence of 0.5mM Fc (COOH) 2 The CV curve in the pH 5.0BR buffer at a sweep rate of 0.05 vs -1 。
FIG. 3A is a Chit-MoS 2 -GOD/PANI Red Thin film electrode (a), chip-MoS 2 /PANI Red Thin film electrodes (b), PANI Red Thin film electrode (c) and MoS 2 -GOD/PANI Red The fluorescence spectrogram curve of the thin film electrode (d), in FIG. 3A, the inset shows the Chit-MoS 2 -GOD/PANI Red The thin film electrode emits blue fluorescence under an ultraviolet lamp.
FIG. 3B shows a Chit-MoS 2 -GOD/PANI Red Fluorescence stability of the thin film electrode in buffer solutions at pH 9.0 (a) and 5.0 (b).
FIG. 4A shows Chit-MoS prepared in example 1 in a buffer solution at pH 5.0 2 UV-visible extinction spectroscopy after application of a constant voltage of-0.5V (a) and 0.5V (b) for 25s by GOD/PANI thin film electrodes.
FIG. 4B is a Chit-MoS diagram 2 UV switching diagram of GOD/PANI thin film electrodes in a buffer solution at pH 5.0, applied voltage of 0.5V and-0.5V.
FIG. 5 shows a Chit-MoS 2 GOD thin film electrodes (a), PANI Red Thin film electrode (b) and PANI Ox Ultraviolet visible extinction spectrum of the thin film electrode (c) in a buffer solution with pH 5.0, and fluorescence emission spectrum curve (d) of the molybdenum disulfide quantum dot dispersion.
FIG. 6 shows Chit-MoS prepared in example 1 in a buffer solution at pH 9.0 2 UV-visible extinction after application of-0.5V (a) and 0.5V (b) constant voltage 25s to GOD/PANI thin film electrodesSpectrum, with inset of chip-MoS 2 UV switching diagram of-GOD/PANI thin film electrode in buffer solution of pH 9.0 under applied voltage of 0.5V and-0.5V.
FIG. 7A is a Chit-MoS prepared in example 1 in a buffer solution at pH 5.0 2 Fluorescence spectra of thin film electrodes after application of-0.5V (a) and 0.5V (b) constant voltage 25s for GOD/PANI thin film electrodes.
FIG. 7B is a Chit-MoS 2 Fluorescent switching characteristics of GOD/PANI thin film electrodes in a buffer solution at pH 5.0 under the applied voltages of 0.5V and-0.5V.
FIG. 8 shows Chit-MoS at-0.5V applied in buffer pH 9.0 (a) and 5.0 (b) saturated with nitrogen 2 Continuous addition of 0.1mM H to the-GOD/PANI thin film electrode pairs 2 O 2 The ampere response of.
FIG. 9 shows Chit-MoS at-0.5V applied in oxygen-saturated pH 9.0 (a) and 5.0 (b) buffers 2 Ampere response of GOD/PANI thin film electrode to continuous addition of 0.5mM glucose, chit-MoS prepared in example 1 is shown by the inset in FIG. 9 2 -amperometric response of GOD/PANI thin film electrodes to pH 9.0 buffer solutions containing 0mM and 3mM glucose under-0.5V test conditions.
FIG. 10 shows a Chit-MoS 2 E for various input combinations when GOD/PANI thin film electrodes simulate D-type flip-flops 600 Outputs results (A) and PL 450 And outputting the result (B).
FIG. 11 (A) shows a truth table for a thin film electrode versus D-type flip-flop and (B) shows a circuit schematic for a D-type flip-flop; (C) Showing a Chit-MoS as a D flip-flop at random input clock and data sequence 2 -GOD/PANI thin film electrode output signal (E) 600 ) The switching period of (2).
Detailed Description
In order to clearly understand the technical solution, the purpose and the effect of the present invention, a detailed description of the present invention will be described with reference to the accompanying drawings.
In the following examples, those not indicated with specific conditions were performed according to conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are conventional products which are not indicated by manufacturers and are commercially available.
First, the procedure for preparing the raw material solution used in the following examples will be described.
1. Preparation of Chitosan solution
Dissolving chitosan (Chit) in acetic acid water solution with the mass fraction of 1%, and performing ultrasonic assisted dissolution to obtain chitosan solution with the concentration of 20 mg/mL.
2. Preparation of molybdenum disulfide quantum dot dispersion stock solution
Firstly, micron-sized molybdenum disulfide powder is dispersed in N, N-Dimethylformamide (DMF). And (3) centrifuging the dispersion liquid at the speed of 6000 rpm after ultrasonic treatment for 8 hours, and taking supernatant liquid to obtain the molybdenum disulfide nanosheet dispersion liquid. And refluxing the supernatant for 6 hours under the condition of vigorous stirring at 140 ℃, re-dispersing the obtained DMF dispersion system of the molybdenum disulfide quantum dots in water with the same volume after removing the solvent through rotary evaporation, and ultrafiltering to obtain the aqueous dispersion stock solution of the molybdenum disulfide quantum dots with uniform size, wherein the concentration is about 0.05mg/mL.
The aqueous dispersion of the molybdenum disulfide nanosheets for comparison is obtained by removing a solvent from a DMF dispersion of the molybdenum disulfide nanosheets obtained after ultrasonic centrifugation and then re-dispersing the dispersion in water of the same volume.
The prepared molybdenum disulfide quantum dot water dispersion liquid is characterized by adopting a transmission electron microscope, and the result is shown in figure 1A. As can be seen from FIG. 1A, the prepared molybdenum disulfide quantum dots are uniformly distributed in the dispersion liquid, the size range is 0.6-2.3 nm, and the average particle size is 1.3nm. At a spacing of
Figure BDA0003335876870000051
Corresponding to MoS 2 Has confirmed MoS by (103) plane 2 Crystal structure of quantum dots (inset in fig. 1A).
In addition, fluorescence spectrum analysis is performed on the prepared molybdenum disulfide quantum dot water dispersion liquid and the water dispersion liquid of the molybdenum disulfide nanosheet, and the result is shown in fig. 1B, and as can be seen from fig. 1B, the molybdenum disulfide quantum dot water dispersion liquid shows an obvious emission peak (curve B in fig. 1B) at about 465nm, which indicates that the molybdenum disulfide quantum dot is successfully prepared.
3. Preparation of glucose oxidase solution
Glucose Oxidase (GOD) was dissolved in water to obtain a glucose oxidase solution with a concentration of 10 mg/mL.
EXAMPLE 1 preparation of a Multi-responsive thin film electrode
Step 1, electrodepositing a Polyaniline (PANI) film on the surface of an ITO (indium tin oxide) electrode: under nitrogen atmosphere, in a solution containing 0.5M H 2 SO 4 And 0.01mM aniline monomer, in a 10mL solution, with an ITO electrode as the working electrode, cyclic Voltammetric (CV) scans were performed at a scan rate of 50mV/s in a three-electrode system (saturated calomel electrode (SCE) used as the reference electrode and a platinum sheet electrode used as the counter electrode) in the range of-0.2 to 1.2V (vs SCE). After 2 cycles of CV scanning, aniline free radical cations are generated in the solution, and then a constant potential of 50s of 1.2V is applied to successfully synthesize a dark green polyaniline layer on the surface of the ITO working electrode. After thoroughly cleaning with ultrapure water to remove unreacted chemical substances, the polyaniline membrane electrode is directly used for subsequent experiments.
Step 2, mixing 80 mu L of molybdenum disulfide quantum dot water dispersion stock solution, 10 mu L of chitosan solution and 10 mu L of glucose oxidase solution to obtain 100 mu L of mixed solution; then, the mixed solution is coated on the surface of polyaniline, and is dried for 2 hours at room temperature, so that a thin film layer (also called Chit-MoS) containing molybdenum disulfide quantum dots, chitosan and glucose oxidase is formed on the surface of the polyaniline 2 A GOD layer) to obtain a multi-responsive thin film electrode (herein, also referred to as a Chit-MoS) 2 GOD/PANI thin film electrodes).
As can be seen from the example 1, the preparation method of the multi-response thin film electrode is simple and easy to realize.
Example 2
Example 2 differs from example 1 in that in step 2, 80 μ L of a stock solution of an aqueous dispersion of molybdenum disulfide quantum dots, 8 μ L of a chitosan solution, and 6 μ L of a glucose oxidase solution were mixed to obtain 96 μ L of a mixed solution, wherein the mass ratio of the molybdenum disulfide quantum dots, the polymer hydrogel, and the glucose oxidase was 1.
Example 3
Example 3 differs from example 1 in that in step 2, 80 μ L of an aqueous dispersion of molybdenum disulfide quantum dots, 12 μ L of chitosan solution and 12 μ L of glucose oxidase solution were mixed to give 104 μ L of mixed liquor, wherein the mass ratio of molybdenum disulfide quantum dots, polymer hydrogel and glucose oxidase was about 1.
Comparative example 1 preparation of chitosan-free thin film electrode
Step 1 is the same as in example 1.
Step 2, mixing 80 mu L of molybdenum disulfide quantum dot water dispersion stock solution, 10 mu L of 1% acetic acid aqueous solution (without chitosan) and 10 mu L of glucose oxidase solution to obtain 100 mu L of mixed solution; the mixed solution was then applied to the surface of polyaniline and dried at room temperature for 2 hours to obtain a chitosan-free thin film electrode (hereinafter referred to as MoS) 2 -GOD/PANI thin film electrodes).
Comparative example 2 preparation of a glucose oxidase free membrane electrode
Step 1 is the same as in example 1.
Step 2, mixing 80 mu L of molybdenum disulfide quantum dot water dispersion stock solution, 10 mu L of chitosan solution and 10 mu L of water (without glucose oxidase) to obtain 100 mu L of mixed solution; the mixed solution was then applied to the surface of polyaniline, and dried at room temperature for 2 hours to obtain a glucose oxidase-free thin film electrode (hereinafter referred to as "Chit-MoS") 2 /PANI thin film electrode).
Comparative example 3 preparation of a thin film electrode without molybdenum disulfide Quantum dots
Step 1 is the same as in example 1.
Step 2, mixing 80 mu L of water (without molybdenum disulfide), 10 mu L of chitosan solution and 10 mu L of glucose oxidase solution to obtain 100 mu L of mixed solution; the mixed solution was then coated on the polyaniline surface and dried at room temperature for 2 hours to obtain a thin film electrode without molybdenum disulfide quantum dots (hereinafter referred to as a "chip-GOD/PANI thin film electrode").
Comparative example 4 preparation of polyaniline membrane electrode
A polyaniline film was electrodeposited on the surface of the ITO electrode according to step 1 of example 1 to obtain a polyaniline film electrode (hereinafter referred to as PANI film electrode).
Characterization of a Multi-responsive thin film electrode
1. Cyclic Voltammetry (CV) analysis
Successful preparation of the multi-signal responsive thin film electrode was further demonstrated by Cyclic Voltammetry (CV) experiments using an electrochemical workstation model CHI 660A from CH Instruments. The tests were all performed in a typical three-electrode system, in which the Chit-MoS prepared in example 1 was used 2 The GOD/PANI thin film electrode, the bare ITO electrode and the PANI thin film electrode were used as working electrodes, the Saturated Calomel Electrode (SCE) was used as a reference electrode and the platinum sheet electrode was used as a counter electrode, respectively.
Using an electroactive probe Fc (COOH) 2 To characterize the Chit-MoS 2 Successful fixing of GOD/PANI on the surface of the ITO thin film electrode. In Britton-Robinson (BR) buffer solution at pH 5.0, a pair of reversible CV peaks (curve a in FIG. 2) was found around 0.4V for bare ITO electrodes, which is Fc/Fc + Redox electrochemical reaction. However, after electrodeposition of a layer of polyaniline, no CV peak of ferrocene was observed, but the redox current of polyaniline appeared around 0.2V and 0.7V, respectively (curve b in fig. 2). Further, the surface of polyaniline was covered with Chit-MoS by step 2 of example 1 2 GOD layer, the redox peak of the probe disappears, but the peak of polyaniline is not significantly affected (curve c in FIG. 2). These results indicate that the ITO electrode surface is continuously deposited with the PANI layer and the Chit-MoS 2 The GOD layer hinders to some extent the diffusion of the probe towards the electrode surface.
In coating Chit-MoS 2 After GOD layer, chit-MoS prepared in example 1 2 The GOD/PANI thin film electrode still presents dark green color, and the color of the PANI film electrodeposited under the acidic condition is the same. Furthermore, when Chit-MoS 2 GOD/PANI thin film electrodes were immersed in Britton-Robinson (BR) buffer solution at pH 5.0 and the color of the film changed to nearly transparent or bluish purple, respectively, with application of-0.5 or 0.5V. Not only indicates the successful preparation of PANI on ITO, but also indicates the coverage of Chit-MoS 2 The GOD layer does not affect the electrochromic properties of the polyaniline.
when-0.5V voltage is applied to the multi-signal response film electrode, so that the color of the multi-signal response film on the electrode is changed to be nearly transparent, the polyaniline is in a reduction state, and the electrode can be called Chit-MoS 2 -GOD/PANI Red And a thin film electrode. When 0.5V voltage is applied to the multi-signal response film electrode to change the color of the multi-signal response film on the electrode into bluish purple, the polyaniline is in an oxidation state, and the electrode can be called as Chit-MoS 2 -GOD/PANI Ox And a thin film electrode.
It is noted that, when referring to voltages or potentials of "-0.5V" and "0.5V" herein, both are relative to a reference electrode in a three-electrode system, such as a Saturated Calomel Electrode (SCE).
2. Fluorescence spectroscopy
To characterize the presence of the molybdenum disulfide quantum dot component, a nearly transparent Chit-MoS was used 2 -GOD/PANI Red The thin film electrode was used to observe the fluorescence characteristics, and the results are shown in FIG. 3A. As can be seen in FIG. 3A, under 365nm ultraviolet light, the Chit-MoS 2 -GOD/PANI Red The thin film electrode (inset in figure 3A) fluoresces blue, similar to that emitted by the aqueous dispersion of molybdenum disulfide quantum dots. In addition, the Chit-MoS is excited by 385nm ultraviolet light 2 -GOD/PANI Red The thin film electrode showed an emission Peak (PL) at 450nm 450 ) (curve a in FIG. 3A), which is substantially the same as the emission peak position of the aqueous dispersion of molybdenum disulfide quantum dots represented by curve B in FIG. 1B, indicates that the molybdenum disulfide quantum dots are successfully immobilized in the film and retain their fluorescent properties.
For comparison, a Chit-MoS containing molybdenum disulfide quantum dots but no glucose oxidase was used 2 /PANI Red Thin film electrode and chitosan-free MoS 2 -GOD/PANI Red The thin film electrode was subjected to the same fluorescence spectrum analysis. Chit-MoS here 2 /PANI Red Thin film electrode and MoS 2 -GOD/PANI Red Thin film electrode and the foregoing Chit-MoS 2 -GOD/PANI Red The thin film electrodes are similar and are all divided intoOriented Chit-MoS 2 /PANI thin film electrode and MoS 2 The color of the film formed after-0.5V voltage is applied to GOD/PANI thin film electrodes becomes nearly transparent thin film electrodes, and likewise, polyaniline is in a reduced state in these electrodes.
As shown in FIG. 3A, the Chit-MoS is excited by 385nm ultraviolet light 2 /PANI Red The thin film electrode shows the same effect with Chit-MoS at 450nm 2 -GOD/PANI Red Thin film electrodes have similar fluorescence emission peaks (curve b in FIG. 3A), but the intensity is much lower than that of Chit-MoS 2 -GOD/PANI Red Thin film electrodes, even less so than chip-MoS 2 -GOD/PANI Red 1/2 of the fluorescence intensity of the thin film electrode. Therefore, the glucose oxidase is added to generate a positive synergistic effect on the fluorescence emission of the molybdenum disulfide quantum dots, and the fluorescence emission intensity of the molybdenum disulfide quantum dots can be obviously enhanced.
As can be seen from the curve c in fig. 3A, polyaniline itself does not emit light.
Comparing curves a and d in FIG. 3A, it can be seen that for MoS without chitosan 2 -GOD/PANI Red The thin-film electrode (curve d in fig. 3A) was not able to detect fluorescence emission, and it was estimated that the molybdenum disulfide quantum dots were aggregated on the PANI layer surface, and the fluorescence characteristics of the quantum dots were lost. Therefore, the chitosan is very important for stabilizing the molybdenum disulfide quantum dots. According to the experimental results, without being limited to any theoretical analysis, this is probably due to the fact that the polymer hydrogel is less than pK at pH a Has a net positive charge on the surface in aqueous solution. The surface of the molybdenum disulfide quantum dot is generally negatively charged due to more crystal defects and sulfur vacancies on the surface. Therefore, based on electrostatic interaction, the negatively charged molybdenum disulfide quantum dots can be immobilized in the three-dimensional network structure of the positively charged polymer hydrogel under certain pH conditions. To verify this conclusion, the present inventors discovered that these polymer hydrogels can also function similarly to chitosan, after replacing chitosan with other positively chargeable polymer hydrogels such as poly-N, N-dimethylaminoethyl methacrylate and polyallylamine hydrochloride.
Furthermore, chit-MoS 2 -GOD/PANI Red The membrane electrodes were immersed in Britton-Robinson (BR) buffer solutions at pH 5.0 and pH 9.0, respectively, and tested for Chit-MoS at 0, 20, 40, 60, 80, 100, and 120 minutes, respectively 2 -GOD/PANI Red The fluorescence intensity of the thin film electrode was normalized, and the result is shown in fig. 3B.
As can be seen from FIG. 3B, the Chit-MoS 2 -GOD/PANI Red The thin film electrode keeps good fluorescence stability under both acidic and alkaline conditions, and the fluorescence of the molybdenum disulfide quantum dots in the thin film can keep stable for a long time under test.
Chit-MoS 2 Multiple response characteristics of GOD/PANI thin film electrodes
1、Chit-MoS 2 GOD/PANI thin film electrode potential sensitive ultraviolet-visible (UV-vis) characteristics
Characterization of Chit-MoS by ultraviolet-visible (UV-vis) spectroscopy 2 PANI at different potentials in-GOD/PANI thin film electrodes Red (reduced polyaniline) and PANI Ox (oxidized polyaniline). The test was still performed under the three-electrode system described above. In Chit-MoS 2 The voltage of-0.5V is applied to the GOD/PANI thin film electrode for 25s, the thin film changes from blue-green to nearly colorless, and no obvious UV-visible absorption peak is observed (curve a in FIG. 4A), indicating that the thin film is reduced to Chit-MoS 2 -GOD/PANI Red . When a voltage of 0.5V was applied for 25s, the film on the electrode changed from nearly colorless to bluish violet, and a significant degree of UV-visible extinction (E) was observed at 600nm 600 ) (Curve b in FIG. 4A), indicating that the thin film was oxidized to Chit-MoS 2 -GOD/PANI Ox . If the Chit-MoS is applied with the voltage of 0.5V 2 -GOD/PANI Ox E of the thin-film electrode 600 Defined as on, will be applied with-0.5V voltage after the Chit-MoS 2 -GOD/PANI Red E of the thin-film electrode 600 By alternately applying a voltage of 0.5 and-0.5V to the electrodes, defined as off, the uv-visible switching behavior of the electrodes can be reversibly repeated (fig. 4B).
Further experiments show that the Chit-MoS 2 -GOD/PANI filmThe potential sensitive uv-vis absorption spectral properties of the electrodes are attributed to the PANI component in the thin film. In the comparison experiment, chit-MoS 2 GOD thin-film electrode (obtained according to example 1 by directly proceeding to step 2 without electrodepositing polyaniline) shows no UV-vis absorption peak before and after voltage application (curve a in FIG. 5), whereas PANI thin-film electrode can be observed in comparison with Chit-MoS 2 Similar properties of GOD/PANI thin film electrodes (curves b and c in FIG. 5), demonstrating the above-described Chit-MoS 2 The potential sensitive uv-vis absorption spectral properties of the GOD/PANI thin film electrodes are attributed to the PANI component in the thin film.
2、Chit-MoS 2 pH sensitive UV-vis characteristics of GOD/PANI thin film electrodes
Characterization of Chit-MoS by UV-vis Spectroscopy 2 UV-visible extinction of GOD/PANI films at different pH values. Chit-MoS in buffer at pH 5.0 2 -GOD/PANI thin film electrode applying 0.5V and-0.5V voltage, chit-MoS 2 The GOD/PANI thin film electrodes can be switched between blue-violet and nearly colorless (FIG. 4A). On the other hand, in the buffer solution of pH 9.0, the membrane electrode was in an environment of insufficient protons, and therefore, the membrane could not be switched from a bluish-purple color to a colorless state even when a voltage of-0.5V was applied (FIG. 6).
3、Chit-MoS 2 -GOD/PANI thin film electrode potential sensitive fluorescence spectrum property
Under 365nm excitation light (lambda) 365 )，Chit-MoS 2 Emission Peak (PL) with maximum emission wavelength of 450nm detected by GOD/PANI thin film electrode 450 ) A potential sensitive response is also exhibited. In Chit-MoS 2 When a voltage of-0.5V was applied to the GOD/PANI thin film electrode for 25s, the film became nearly colorless and a distinct fluorescence emission peak was observed at 450nm (curve a in FIG. 7A). When a voltage of 0.5V was applied for 25s, the film turned bluish-purple, and the fluorescence emission intensity at 450nm was greatly reduced (curve b in FIG. 7A). The PANI thin-film electrode showed no fluorescence peak before and after voltage application (curve c in FIG. 3A), which demonstrates the above-mentioned Chit-MoS 2 The potential-sensitive fluorescence spectroscopy properties of GOD/PANI thin film electrodes are attributed to MoS in the thin film 2 FRET (fluorescence resonance energy) of component and PANIMetastasis), PANI Ox There are a large number of overlapping bands between the uv extinction spectrum of (figure 5) and the fluorescence emission spectrum of the molybdenum disulfide quantum dots, energy transfer readily occurs at close donor-acceptor distances while quenching fluorescence (curve b in figure 7A). If the Chit-MoS is applied after-0.5V voltage is applied 2 -GOD/PANI Red PL of thin film electrode 450 Defined as on, will be Chit-MoS after applying 0.5V voltage 2 -GOD/PANI Ox PL of thin film electrode 450 Defined as off, the switching behavior of the fluorescence can be reversibly repeated by alternately applying a voltage of-0.5 and 0.5V to the electrodes (fig. 7B).
4. pH sensitive Chit-MoS 2 H of GOD/PANI thin film electrode 2 O 2 Response property
Because the molybdenum disulfide quantum dots have good peroxidase-like properties, the molybdenum disulfide quantum dots can catalyze H 2 O 2 Electrochemical decomposition of (2). Gradually adding H to the buffer solution 2 O 2 When a reducing voltage of-0.5V was applied, a gradual increase in current was detected at pH 9.0, whereas the current did not rise significantly at pH 5.0 (FIG. 8).
Without being bound to any theory, the inventors believe that the above phenomena are due to surface defects and free radical mechanisms of the molybdenum disulfide quantum dots, and the corresponding reaction principles are as follows:
under an acidic condition:
H 2 O 2 +e - →·OH+OH - (1)
·OH+H + +e - →H 2 O (2)
OH - +H + →H 2 O (3)
MoS 2 +·OH→MoS 2 ·OH ads (4)
under alkaline conditions:
H 2 O 2 +OH - →H 2 O+OOH - (5-1)
H 2 O 2 +OOH - →·OOH+·OH+OH - (5-2)
MoS 2 ·OH ads +·OOH→H 2 O+O 2 +MoS 2 (6)
first, under acidic conditions, H 2 O 2 The electrochemical decomposition itself causes hydroxyl radical (. OH) to exist in the solution, and the reaction is difficult to proceed because the voltage for reduction of. OH on the electrode is too high (2.59V vs. NHE). Inherent defects exist on the surface of the molybdenum disulfide quantum dot, and generated OH is preferentially adsorbed on the catalytic sites of the molybdenum disulfide quantum dot to form MoS 2 ·OH ads 。H 2 O 2 The reaction with the molybdenum disulfide quantum dots follows a free radical mechanism, and the final products of the reaction are water and oxygen by calculating the surface binding energy. Because the surface of the quantum dot has certain negative electricity when being stable, the quantum dot is rich in H + In the conditions (2), it is difficult for OH to compete with these sites, and OH is produced - Fast sum H + The reaction produces water. Under alkaline conditions, negatively charged ions such as OH are present in large amounts in solution - And hydrogen peroxide (OOH) - ) The negatively charged quantum dot surfaces tend to repel these anions, OH and hydroperoxyl radicals (. OOH) dominate the reaction sites, OH attacks further surface defects, and OOH and adsorption onto MoS 2 The surface OH reaction produces water and oxygen, accelerating the forward direction of electrocatalytic decomposition.
5. PH-sensitive Chit-MoS 2 Glucose response Properties of GOD/PANI thin film electrodes
Glucose oxidase fixed on the electrode can biologically catalyze glucose to be oxidized into H under the action of oxygen 2 O 2 And the molybdenum disulfide quantum dots can also be used for electrocatalysis of H 2 O 2 Decomposition, which is a pH dependent process. By such a cascade reaction, a controlled pH sensitive glucose response signal can be obtained (fig. 9).
Figure BDA0003335876870000111
In conclusion, the chip-MoS provided by the invention 2 -GOD/PANI thin film electrodes having reversible electrochromic properties, electrochromic properties andbiocatalysis and electrocatalysis. Has electrochemical response to glucose and hydrogen peroxide in solution and can be used for detecting the glucose and the hydrogen peroxide based on the electrochemical response.
6、Chit-MoS 2 -GOD/PANI thin film electrode simulation D type trigger
A flip-flop is a sequential circuit, i.e. a logic circuit that depends on both the combination of inputs and the internal state of the device. Such sequential circuits are thus memorised, i.e. memory-capable, can mimic the basic principle of Random Access Memory (RAM), and are potential candidates for solving the "memory capacity problem". The flip-flop has a finite number of states and, in response to an input signal, generates an output signal, i.e. a switch state, according to a predefined logic condition. Among the various flip-flops, the simulation for a D-type flip-flop is more complex because the D-type flip-flop contains four integrated NAND gates (NAND gates), requiring more complexity to integrate the operations into one single component. The operation of a chemical analog D-type flip-flop contains logic as two inputs and two outputs. The output signals being complementary outputs (Q and)
Figure BDA0003335876870000121
) And can generally be detected directly, e.g., absorbance or fluorescence intensity; the inputs are required not to interfere with each other. The D flip-flop consists of a Data (Data) input and a Clock (Clock) input. The Clock input is equivalent to an enable signal, and only when the input Clock is high (1) will subsequent operations be triggered, and the output will follow the input Data. If Clock =1 and Data =1, then Q =1. On the other hand, when Clock =1 and Data =0, Q =0. However, when Clock is low (0), the output Q holds the previous state, independent of the input D.
As mentioned above, the Chit-MoS provided by the invention 2 The GOD/PANI thin film electrode has ultraviolet and fluorescence signals which can be adjusted under specific conditions, so that a D-type trigger can be simulated to realize the function of storage and memory.
Specifically, chit-MoS 2 The GOD-PANI thin film electrode changes the oxidation-reduction state of PANI in the electrode through voltage when the voltage is inWhen the voltage is switched between 0.5V and-0.5V, the oxidation-reduction state of PANI is changed, so that the ultraviolet absorption signal of the electrode is changed, and the electrode is in a nearly colorless reduction state (PANI) Red ) And bluish violet oxidation state (PANI) Ox ) Can be reversibly switched, and can further change the fluorescence signal of the electrode through Fluorescence Resonance Energy Transfer (FRET). The switch can be realized only under a slightly acidic condition, while the film can keep a high extinction degree under an alkaline condition, and the state of the film cannot be changed even if voltage is applied (figure 6), so that the effect of controlling the output of the film electrode under different enabling signals is realized. The used pH value can expand and enrich clock signals, and output signals are diversified due to the complementation of ultraviolet and fluorescent signals. Thus, a D-type flip-flop can be simulated.
In some embodiments of the invention, a Chit-MoS is utilized 2 The GOD/PANI thin film electrode simulates the function of a D-type trigger. The thin film electrode was immersed in a buffer solution having a pH of 5.0 or an input operation (high level) defined as "1" by applying a voltage of 0.5V to the electrode, and was immersed in a buffer solution having a pH of 9.0 or an input operation (low level) defined as "0" by applying a voltage of-0.5V to the electrode. The output signal Q of the D flip-flop takes the extinction value (E) of the electrode at 600nm 600 ) Output the signal
Figure BDA0003335876870000132
Is the complementary state of the output Q, which may be the output value of the fluorescence signal here. The definition of the input signal and the threshold value of the output signal are shown in table 1. According to the definition in Table 1, by Chit-MoS 2 The original state of a D-type trigger (hereinafter referred to as a trigger) is simulated to be a '1' state by the-GOD/PANI thin film electrode, and E 600 Above the threshold value 0.3, the output signal Q is "1".
TABLE 1 definition of input signals and threshold values of output signals
Figure BDA0003335876870000131
According to the foregoing Chit-MoS 2 -GOD/PANI thin film electrode multi-response characteristic experimental result, corresponding toThe output of the various input combinations is shown in fig. 10.
The original state of the flip-flop is the "1" state (high level), E, according to the definition in Table 1 600 Above the threshold value 0.3, the output signal Q is "1". The characteristic table of the clock and data input operation is shown in (a) in fig. 11. The sequential operation of the D flip-flops is as follows: for the first input sequence "00" and the second sequence "01", the electrodes are immersed in a pH 9.0 buffer, with the Clock input (Clock) in the "0" state by definition. In a buffer with pH of 9.0, no matter what the pH value is applied to the Chit-MoS 2 The extinction remains high, depending on the voltage on the GOD/PANI thin film electrodes. The Next state (Next state) and output Q will retain the Current state (Current state), resulting in the system writing and maintaining the Current original state (Next state = Current state). For the "10" combination of sequences 3 and 4, when the Clock input (Clock) is in the "1" state (in pH 5.0 buffer), the enable signal is applied, dipping the membrane electrode into pH 5.0 buffer, applying-0.5V, resulting in the membrane being in the reduced state, with a lower E 600 The output signal Q is at "0". Regardless of the current state, the next state will be a "0". When the Data input (Data) is at "1", i.e. the (11) sequences of 5 th and 6 th, the 0.5V potential switches the electrodes to high extinction, resulting in the next state being at "1", and the output Q being "1" regardless of the current state. E of the flip-flop when the random clock and data input sequence of the thin film electrode and the various transition results from the current state to the next state 600 The response is shown in fig. 11 (C). Reversibility makes it possible to establish any state at a random point in the operating cycle to some extent. Thus, the function of a D-type trigger is simply simulated on a thin film electrode containing biomolecules and nanocomposites that can integrate other functional alternatives.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (7)

1. A multi-signal response film electrode, which is characterized by comprising a light-transmitting electrode with conductivity and a multi-signal response film covering the surface of the light-transmitting electrode, wherein the multi-signal response film comprises: polyaniline, molybdenum disulfide quantum dots, polymer hydrogel and glucose oxidase; the polyaniline covers the surface of the light-transmitting electrode, and the molybdenum disulfide quantum dots, the polymer hydrogel and the glucose oxidase cover the surface of the polyaniline;
the multi-signal response thin film electrode is prepared by the following method:
forming a polyaniline layer on the surface of the light-transmitting electrode with conductivity by electrochemical polymerization,
coating a mixed solution containing molybdenum disulfide quantum dots, polymer hydrogel and glucose oxidase on the surface of the polyaniline layer, and drying to obtain the multi-signal response thin film electrode;
the polymer hydrogel is selected from at least one of chitosan, poly N, N-dimethylaminoethyl methacrylate and polyacrylamide hydrochloride;
in the mixed solution, the mass ratio of the molybdenum disulfide quantum dots to the polymer hydrogel to the glucose oxidase is 1 (40-60) to 15-30.
2. The multi-signal-responsive thin film electrode of claim 1, wherein the light-transmissive electrode having conductivity is an indium tin oxide electrode or an indium fluoride oxide electrode.
3. The multi-signal-responsive thin film electrode according to claim 1, wherein the step of forming a polyaniline layer by electrochemical polymerization in the method of manufacturing the multi-signal-responsive thin film electrode comprises:
under nitrogen atmosphere, in a solution containing 0.5M H 2 SO 4 And 0.01mM aniline monomer, using the light-transmitting electrode with conductivity as a working electrode, and adopting a circulating voltage in a three-electrode systemThe polyaniline layer was synthesized by the Ann method.
4. The multi-signal response thin film electrode according to claim 1, wherein the mass ratio of the molybdenum disulfide quantum dots to the polymer hydrogel to the glucose oxidase in the mixed solution is 1.
5. Use of a multiple signal responsive membrane electrode according to any one of claims 1 to 4 in peroxide and/or glucose detection.
6. Use of a multi-signal responsive thin film electrode according to any one of claims 1 to 4 in an analogue D-type trigger.
7. A trigger for molecular simulation comprising a multiple signal-responsive thin film electrode according to any one of claims 1 to 4.
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