Flexible glucose sensor based on carbonized polypyrrole as well as construction method and application of flexible glucose sensor

Abstract

The invention provides a flexible glucose sensor based on carbonized polypyrrole and a construction method and application thereof.The construction method comprises the steps that a silk-screen printing-carbon cloth electrode with nanogold electrically deposited on the surface serves as a material loading platform, carbonized polypyrrole is dispensed on the surface of the material loading platform, and an electrode platform loaded with carbonized polypyrrole is obtained; and dispensing a glucose oxidase solution and a chitosan solution on the surface of the electrode platform loaded with the carbonized polypyrrole to obtain the flexible glucose sensor electrode. The flexible glucose sensor is prepared from the electron transfer mediator and the carbonized conductive polymer with the catalytic effect, efficient and accurate detection of the glucose concentration is achieved, the detection range is 2.0 mM to 35.0 mM, a current response signal to glucose can still keep 85% or above of an initial signal after the glucose sensor is stored at 4 DEG C for 8 days, and the glucose sensor has very high stability.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochemical sensors, and more particularly to a flexible glucose sensor based on carbonized polypyrrole and a construction method and application thereof. Background Art

[0002] Diabetes is a chronic disease characterized by high blood sugar caused by absolute or relative insulin deficiency and utilization disorder. With the aging of my country's population and changes in lifestyle, diabetes has changed from a rare disease to an epidemic. Timely and accurate monitoring of blood sugar is an important guarantee for diabetic patients to control blood sugar fluctuations. Accurate and timely monitoring of blood sugar fluctuations and strengthening of blood sugar control can reduce the risk of recurrence of cardiovascular events and death in diabetic patients.

[0003] Enzyme sensor is a sensor that uses enzyme catalytic reaction to detect substances. Its basic principle is to combine the target substance with a specific enzyme, and under the catalysis of the enzyme, the charge transfer on the electrode surface changes, thereby changing the current or potential. Compared with traditional sensors, enzyme sensors have the advantages of fast response speed, high sensitivity, good stability, long life and good anti-interference performance.

[0004] As a conductive polymer, polypyrrole (PPy) has attracted extensive attention in the research and development and preparation of electrochemical sensors in recent years due to its simple synthesis, stable structure, high conductivity, and good biocompatibility. It has been widely used in the preparation of sensors related to glucose oxidase (GOx). Most traditional polypyrrole-based glucose sensors use electrochemical polymerization to generate PPy films, and this form of PPy can only load a limited amount of enzyme biomass. Summary of the invention

[0005] The present invention provides a flexible glucose sensor based on carbonized polypyrrole and a construction method and application thereof. The flexible glucose sensor prepared by the present invention is free from the traditional glassy carbon electrode, can quantitatively detect glucose, and has high stability.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] The present invention provides a method for constructing a flexible glucose sensor based on carbonized polypyrrole, comprising:

[0008] A screen-printed carbon cloth electrode with gold nanoparticles deposited on its surface is used as a material loading platform, and carbonized polypyrrole is drop-coated on the surface of the material loading platform to obtain an electrode platform loaded with carbonized polypyrrole; glucose oxidase solution and chitosan solution are then drop-coated on the surface of the electrode platform loaded with carbonized polypyrrole to obtain a flexible glucose sensor electrode.

[0009] Preferably, the material loading platform is prepared by the following method: first, a conductive circuit is made on a flexible plastic film by screen printing, and then the carbon cloth is immersed in a H2SO4 solution containing 5.0 mM NaAuCl4, followed by electrodeposition at a potential of -1.0 V to -0.2 V for 200s to 400s, and the treated carbon cloth and the screen-printed circuit are combined as a material loading platform.

[0010] Preferably, the carbonized polypyrrole is prepared by a soft template method: first, a FeCl3·6H2O solution is added to a methyl orange solution, and the reaction product is used as an initiator; then, a pyrrole monomer is added under stirring, and polypyrrole is grown using the initiator as a template, followed by filtering, washing, and drying; and then the dried polypyrrole product is calcined in a tubular furnace at 800°C to 1200°C under nitrogen protection to obtain carbonized polypyrrole.

[0011] More preferably, the concentration of the FeCl3·6H2O solution is 40.0 mM to 120.0 mM, the concentration of the methyl orange solution is 4.0 mM to 8.0 mM, the volume ratio of the FeCl3·6H2O solution to the methyl orange solution is 1:1 to 1:10; and the concentration of the pyrrole monomer is 0.02 mM to 0.1 mM.

[0012] Preferably, the carbonized polypyrrole drop-coated on the surface of the material loading platform is a 5.0 mg / ml to 15.0 mg / ml suspension; the concentration of the glucose oxidase solution is 2.0 mg / ml to 8.0 mg / ml; and the concentration of the chitosan solution is 0.1% to 1.0%.

[0013] Preferably, the method further comprises drop-coating 0.05M to 0.15M ferrocene solution as an electron mediator on the surface of the electrode platform loaded with carbonized polypyrrole before drop-coating the glucose oxidase solution.

[0014] Preferably, the construction method further comprises: using the obtained flexible glucose sensor electrode directly as a working electrode and connecting it to an electrochemical workstation, and then using a platinum sheet electrode and Ag / AgCl as a counter electrode and a reference electrode, respectively, to prepare an electrochemical glucose sensor.

[0015] The present invention also provides a flexible glucose sensor based on carbonized polypyrrole, which is obtained by any of the above construction methods.

[0016] The present invention also provides application of the above-mentioned flexible glucose sensor based on carbonized polypyrrole in flexible wearable electronic products.

[0017] Preferably, glucose concentration is detected using chronoamperometry.

[0018] The beneficial effects of the present invention are:

[0019] (i) First, PPy tubes were synthesized by the soft template method, which increased the specific surface area of ​​PPy and allowed it to load more enzymes, further increasing the adsorption sites of glucose oxidase on the surface of the PPy working electrode.

[0020] (ii) After PPy is carbonized, its conductivity and mechanical strength are improved. Multiple layers of PPy film can be covered on the electrode working area to form a three-dimensional layer, thereby loading more glucose oxidase (GOx). It can respond quickly to the glucose sample to be tested, with high detection sensitivity, good selectivity and wide range.

[0021] (III) The present invention prepares a flexible glucose sensor using an electron transfer intermediary and a carbonized conductive polymer with catalytic activity, thereby achieving efficient and accurate detection of glucose concentration within a detection range of 2.0 mM to 35.0 mM. After being stored at 4°C for 8 days, the current response signal to glucose can still maintain more than 85% of the initial signal, and has high stability.

[0022] (iv) The screen-printed carbon cloth electrode prepared by the present invention is used as a material loading platform. After loading the PPy layer and the enzyme layer, it can be directly used as a working electrode, which is different from traditional glassy carbon electrodes, gold electrodes, etc., and is easy to manufacture and has lower cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0024] Figure 1 This is a schematic diagram of the structure of a flexible glucose sensor based on carbonized polypyrrole provided by the present invention, in which: 1. copper tabs, 2. electrode holes, 3. flexible covering film, 4. screen-printed circuit, 5. PPy / enzyme layer, 6. carbon cloth layer;

[0025] Figure 2 This is a scanning electron microscope (SEM) image of the PPy / GOx / chitosan electrode prepared in the present invention;

[0026] Figure 3 Cyclic voltammetry (CV) curves of the PPy / GOx / chitosan electrode prepared in the present invention and the control electrode;

[0027] Figure 4The it response diagram of the carbonized polypyrrole flexible glucose sensor of the present invention; (a) the it response diagram of the carbonized polypyrrole flexible glucose sensor to different concentrations of glucose; (b) the linear calibration curve of the sensor current and the glucose concentration;

[0028] Figure 5 The long-term stability experimental results of the carbonized polypyrrole flexible glucose sensor of the present invention are shown in FIG. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] The present invention provides a method for preparing a flexible glucose sensor based on carbonized polypyrrole, which mainly comprises:

[0031] Rectangular polypyrrole (PPy) was prepared, and functionalized nano hollow carbon materials were obtained after calcination and grinding. The material was dripped onto a screen-printed electrode with a carbon cloth with a layer of nanogold deposited on the surface as a current collector. A certain concentration of glucose oxidase (GOx) solution was further dripped on the surface of the electrode to preliminarily construct an enzyme electrode. In order to enhance the efficiency of electron transfer, a layer of ferrocene solution was further dripped on the surface of the above electrode material, and then naturally dried at room temperature to form a stable electron transfer layer. Finally, chitosan solution was dripped on the surface of the electrode and dried naturally at room temperature, which improved the biocompatibility, flexibility and durability of the sensor, and obtained a flexible sensor electrode that can be used to detect glucose concentration.

[0032] Example

[0033] The method for constructing a flexible glucose sensor based on a carbonized polypyrrole layer comprises the following steps:

[0034] 1. Preparation of Carbonized PPy Tubes

[0035] Polypyrrole (PPy) was synthesized by the soft template method. First, 80.0 mM FeCl3·6H2O and 5.0 mM methyl orange solution were prepared. The FeCl3·6H2O solution was slowly added to the methyl orange solution at a volume ratio of 1:2 under stirring to generate red flocs and then allowed to stand for 1 hour. Then, 0.05 M pyrrole monomer was slowly added under stirring and reacted at room temperature for 24 hours. The product after the reaction was then collected by filtration, washed with pure water and ethanol until colorless, and dried in an oven at 60°C for 24 hours. The dried PPy product was calcined in a tubular furnace at 800°C for 3 hours under nitrogen protection to obtain carbonized PPy, which was in the shape of a hollow, wrinkled tube with a length of 1.0 to 10.0 μm and a diameter of 50.0 to 300.0 nm.

[0036] 2. Preparation of Flexible Electrode Detection Platform

[0037] First, a conductive circuit was made on a flexible plastic film by screen printing, and then the carbon cloth was immersed in a H2SO4 solution containing 5.0mM NaAuCl4 (0.5mol / L), followed by electrodeposition at a potential of -0.4V for 200s to 400s to increase the conductivity of the carbon cloth. The treated carbon cloth was cut into a circle with a diameter of 0.5mm and combined with the screen-printed circuit as a current collector and material loading platform, such as Figure 1 shown.

[0038] 3. Carbonized PPy for flexible glucose sensor

[0039] The carbonized PPy was prepared into a 10.0 mg / ml suspension, and 20 μl of the carbonized PPy suspension was loaded on the surface of the carbon cloth electrode by drop coating. It was naturally air-dried at room temperature, and then 5 μl of 0.1 M ferrocene solution was drop coated as an electron mediator, and then 10 μl of 5.0 mg / ml glucose oxidase (GOx) solution was drop coated. Finally, 5 μl of 0.5% chitosan solution was drop coated on the outermost layer of the electrode surface to prevent the material from falling off. The surface microstructure is shown in the figure. Figure 2 shown.

[0040] The electrochemical performance of the prepared glucose sensor was characterized by a three-electrode system on a CHI660E electrochemical workstation (Shanghai Chenhua). The sensor performance of the sensor for glucose detection was characterized by an IT curve test. In this work, the working electrode was a carbon cloth electrode loaded with carbonized PPy and GOx, the counter electrode was a platinum sheet, and the Ag / AgCl electrode was the reference electrode.

[0041] The ampere current (it) curve is used for detection as follows:

[0042] The it curve was carried out in phosphate buffer (PBS, 0.1M, pH=7.0), and all tests were carried out at room temperature. In order to prevent oxygen (O2) from interfering with the test results during the test process, nitrogen (N2) was passed throughout the test environment to isolate oxygen.

[0043] The present invention evaluates the electrochemical performance of the prepared glucose sensor by detecting the IT curve. Glucose plays an important role in the field of biology. It is the energy source and metabolic intermediate of living cells and the main energy supply of organisms. The content of glucose in the blood is an important indicator for evaluating the normality of sugar metabolism. Therefore, it is of great significance to quickly and conveniently detect the glucose content. In this experiment, a glucose oxidase (GOx) modified electrode with carbonized PPy as the loading material was prepared, and the oxidation of glucose was tested by IT at a potential of 0.2V.

[0044] Catalytic potential is one of the important parameters for investigating sensor performance. The present invention performs CV scanning on the sensor and finds that the current response reaches the highest at 0.3 V and then decreases with the increase of voltage. Therefore, 0.3 V is selected as the optimal catalytic potential for detecting the electrochemical performance of the glucose sensor electrode ( Figure 3 ).

[0045] Using the it method, under the condition of catalytic potential of 0.3V, 2.0mL of PBS solution containing 0.1M glucose was continuously added to PBS (0.1M, pH=7.0) every 200s, and 2mL of the reaction solution was taken out after the curve stabilized to ensure that the volume of the detection system remained unchanged during the entire detection process, and the corresponding current value generated under the catalytic potential (0.3V) was tested. Figure 4 As shown in the figure, when different concentrations of glucose solutions are added continuously, the sensor can quickly generate a current response to glucose and reach a stable current value within 10s ( Figure 4 a). The constructed carbonized PPy-based sensor has a typical linear relationship between the corresponding current and glucose concentration ( Figure 4 b), the linear equation is y=0.3395x-0.6226, the detection range is 2.0mM to 35.0mM, and the minimum detection limit of glucose is 2.0mM.

[0046] The stability of the constructed glucose sensor is also an important parameter that needs to be tested. In order to measure the stability of the sensor, the prepared electrode was stored in a 4°C refrigerator, and the current response signal was tested every day. The results showed that after 8 days of storage, the current response signal of the electrode to glucose can still maintain more than 85.0% of the initial current response signal ( Figure 5 ). It can be seen that the glucose sensor constructed based on carbonized polypyrrole of the present invention has high stability.

[0047] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0048] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the principles or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for constructing a flexible glucose sensor based on carbonized polypyrrole, comprising: A screen-printed carbon cloth electrode with gold nanoparticles deposited on its surface is used as a material loading platform, and carbonized polypyrrole is drop-coated on the surface of the material loading platform to obtain an electrode platform loaded with carbonized polypyrrole; glucose oxidase solution and chitosan solution are then drop-coated on the surface of the electrode platform loaded with carbonized polypyrrole to obtain a flexible glucose sensor electrode.

2. The construction method according to claim 1, characterized in that: The material loading platform is prepared by the following method: first, a conductive circuit is made on a flexible plastic film by screen printing, and then the carbon cloth is immersed in a H2SO4 solution containing 5.0mM NaAuCl4, followed by electrodeposition at a potential of -1.0V to -0.2V for 200s to 400s, and the treated carbon cloth and the screen-printed circuit are combined as a material loading platform.

3. The construction method according to claim 1, characterized in that: The carbonized polypyrrole is prepared by a soft template method: first, a FeCl3·6H2O solution is added to a methyl orange solution, and the reaction product is used as an initiator; then, a pyrrole monomer is added under stirring, and polypyrrole is grown using the initiator as a template, followed by filtering, washing, and drying; and then the dried polypyrrole product is calcined in a tubular furnace at 800°C to 1200°C under nitrogen protection to obtain the carbonized polypyrrole.

4. The construction method according to claim 3, characterized in that: The concentration of the FeCl3·6H2O solution is 40.0 mM to 120.0 mM, the concentration of the methyl orange solution is 4.0 mM to 8.0 mM, the volume ratio of the FeCl3·6H2O solution to the methyl orange solution is 1:1 to 1:10; and the concentration of the pyrrole monomer is 0.02 mM to 0.1 mM.

5. The construction method according to claim 1, characterized in that: The carbonized polypyrrole drop-coated on the surface of the material loading platform is a suspension of 5.0mg / ml to 15.0mg / ml; the concentration of the glucose oxidase solution is 2.0mg / ml to 8.0mg / ml; and the concentration of the chitosan solution is 0.1% to 1.0%.

6. The construction method according to claim 1, characterized in that: The method also includes drop-coating a 0.05M to 0.15M ferrocene solution as an electron mediator on the surface of the electrode platform loaded with carbonized polypyrrole before drop-coating the glucose oxidase solution.

7. The construction method according to claim 1, characterized in that: Also includes: The obtained flexible glucose sensor electrode was directly used as a working electrode and connected to an electrochemical workstation. Then, a platinum sheet electrode and Ag / AgCl were used as a counter electrode and a reference electrode, respectively, to make an electrochemical glucose sensor.

8. A flexible glucose sensor based on carbonized polypyrrole, obtained by the construction method according to any one of claims 1 to 7.

9. Application of the carbonized polypyrrole-based flexible glucose sensor according to claim 8 in flexible wearable electronic products.

10. The use according to claim 9, characterized in that: Glucose concentration was measured using chronoamperometry.

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