Laser-induced cobalt-based enzyme-free glucose sensor as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of glucose sensors, and particularly relates to a laser-induced cobalt-based enzyme-free glucose sensor as well as a preparation method and application thereof. The preparation method comprises the following steps: S1, preparing a polyimide film; S2, carrying out CO2 laser induction treatment; s3, dispensing a cobalt nitrate ethanol solution on a working electrode area of the laser-induced graphene, drying, and then carrying out CO2 laser-induced treatment to form a Co-coated LIG / CoO sensing material; s4, printing the Ag / AgCl slurry to a reference electrode area in the three electrodes, and curing at 4 DEG C to form a reference electrode; and S5, sputtering gold nanoparticles in a working area except the three electrodes, and packaging by using an insulating tape to obtain the cobalt-based enzyme-free glucose sensor. According to the method, the cobalt nitrate precursor solution is dropwise added to the surface of the laser-induced graphene subjected to primary laser, and the cobalt metal and carbon material composite material can be rapidly and simply prepared through secondary laser after drying.

Description

Technical Field

[0001] The present invention belongs to the technical field of glucose sensors, and particularly relates to a laser-induced cobalt-based enzyme-free glucose sensor, a preparation method thereof, and an application thereof. Background Art

[0002] Diabetes is caused by insufficient insulin production induced by pancreatic β-cell destruction (type I or juvenile diabetes), or due to insulin resistance / insulin deficiency in target cells (type 2 or adult diabetes). In order to maintain the blood glucose level of diabetic patients within the normal range (<100 mg / dL when fasting; 2 hours after eating) and have proper metabolic functions, type 1 diabetic patients should measure their blood glucose level 5 times a day, and type 2 diabetic patients should measure their blood glucose level several times a week.

[0003] Enzyme and enzyme-free glucose sensors have been widely used for glucose measurement. Glucose oxidase (GOx), as a representative enzymatic oxidant, rapidly degrades during several days of use, and the current commercially available enzymatic sensors generally have a service life of about 14 (or 15) days, with a relatively short service life, mostly due to the contamination of the sensing material and the poor stability of the enzyme itself.

[0004] In contrast, non-enzyme glucose sensors based on metals or metal oxides exhibit excellent stability, longer working time, and extremely poor environmental tolerance, and the measurement results are independent of temperature and humidity.

[0005] However, since the oxidation of glucose by the enzyme-free glucose sensor is not a specific reaction, it will also oxidize substances such as uric acid and ascorbic acid, and the oxidation current magnitudes of different substances are not the same. The selectivity of the enzyme-free glucose sensor is mainly measured from the current response value.

[0006] There are various existing enzyme-free glucose sensors, mainly including noble metal materials such as gold and platinum, and metal-organic framework materials. Although the noble metal materials have relatively excellent sensing performance, their cost is high, and the noble metal materials are prone to adsorb chloride ions present in the solution during the reaction process, which contaminates the surface of their electrode materials, thereby making it difficult to maintain an ideal state during their catalytic process. Although the metal-organic framework materials have good sensing performance, since most of the action systems of the enzyme-free sensors are still limited to alkaline electrolytes, the metal ions in the metal-organic framework are in an unsaturated state, and they will preferentially coordinate with the hydroxide ions in the alkaline electrolyte, thereby causing the collapse of the original framework structure and making it difficult to exist stably.

[0007] Therefore, there is an urgent need to develop a laser-induced cobalt-based enzyme-free glucose sensor, a preparation method thereof, and an application thereof. Summary of the Invention

[0008] To overcome the defects in the above-mentioned prior art, the present invention provides a laser-induced cobalt-based enzyme-free glucose sensor, its preparation method and application. In the present invention, a cobalt nitrate precursor solution is dropped onto the surface of laser-induced graphene after the first laser, and after drying, the second laser can quickly and simply prepare a composite material of cobalt metal and carbon materials.

[0009] To achieve one of the above purposes, the present invention adopts the following technical solutions:

[0010] A preparation method of a laser-induced cobalt-based enzyme-free glucose sensor, comprising the following steps:

[0011] S1. Prepare a polyimide film: Coat a polyimide precursor solution on a glass slide to form a coating with a thickness of 70-90 μm, and obtain a polyimide film after heat preservation and cooling; the polyimide precursor solution is a polyamic acid solution;

[0012] S2. CO2 laser-induced treatment: Import a pre-designed three-electrode pattern into a CO2 laser, and perform CO2 laser-induced treatment on the obtained polyimide film to obtain laser-induced graphene, that is, LIG;

[0013] S3. Drop and coat a cobalt nitrate ethanol solution with a concentration of 0.05-1.2 M / L on the working electrode area of the laser-induced graphene, and perform CO2 laser-induced treatment again after drying to form a Co@LIG / CoO sensing material, that is, a working electrode is formed on the laser-induced graphene;

[0014] S4. Coat and print an Ag / AgCl paste onto the reference electrode area of the three electrodes by screen printing, and cure it at 4 °C to form a reference electrode;

[0015] S5. Sputter gold nanoparticles on the working area outside the three electrodes and encapsulate them with insulating tape to obtain a cobalt-based enzyme-free glucose sensor.

[0016] Preferably, the preparation method steps of the cobalt nitrate ethanol solution are as follows: Take 10 ml of ethanol solution, add cobalt nitrate hexahydrate powder to it, and prepare a cobalt nitrate ethanol solution with a concentration gradient of 0.05-1.2 M / L, ultrasonically mix for 10 min, and store it in a 4 °C refrigerator when not in use.

[0017] Preferably, the parameters of the CO2 laser are as follows: laser wavelength 10.6 μm, scanning speed 200-400 mm / s, laser power 3W-5W, and scanning pitch 0.05-0.1 mm.

[0018] Preferably, in step S1, the size of the glass slide is 76 mm × 25 mm, which is pre-treated with anhydrous ethanol by ultrasonic treatment for 10 min and then dried at room temperature.

[0019] Preferably, in step S1, the thickness of the coating is 80 um, the heat preservation temperature is 180 °C, and the heat preservation time is 1 h.

[0020] Preferably, in step S5, the sputtering current is 30 mA - 50 mA, and the sputtering time is 5 - 10 min.

[0021] Preferably, in step S2, the working parameters of the CO2 laser are: the laser wavelength is 10.6 um, the scanning speed is 3400 mm / s, the laser power is 5 W, and the scanning pitch is 0.08 mm.

[0022] Preferably, in step S3, the working parameters of the CO2 laser are: the laser wavelength is 10.6 um, the scanning speed is 300 mm / s, the laser power is 3.6 W, and the scanning pitch is 0.08 mm.

[0023] To achieve the second above-mentioned object, the present invention provides a sensor prepared by a method for preparing a laser-induced cobalt-based enzyme-free glucose sensor. This sensor is prepared by the above-mentioned preparation method.

[0024] To achieve the third above-mentioned object, the present invention provides an application of a laser-induced cobalt-based enzyme-free glucose sensor in the detection of diabetes blood glucose.

[0025] The advantages of the present invention are as follows:

[0026] (1) The Co@LIG / CoO enzyme-free glucose sensor of the present invention can be used for the detection of glucose in diabetic patients, has excellent glucose sensing performance, fast response, high sensitivity, low detection limit, and good anti-interference performance, and can effectively avoid the problems existing in the conventional enzyme-based glucose sensors, such as the enzyme being easily inactivated, resulting in the easy failure of the sensor, and further limiting the use of the enzyme-based glucose sensors; and the laser direct writing technology is used to prepare 3D porous laser-induced graphene, which has obvious advantages such as simple preparation, low cost, good conductivity, and high environmental stability. Moreover, the wrinkles caused by laser etching on the surface of graphene can further increase the specific surface area of the composite material and improve the electron transfer efficiency, thereby significantly enhancing the electrochemical catalytic performance; the cobalt metal composite material has excellent electrocatalytic activity, and has a significant synergistic effect after being combined with laser-induced graphene, which can enhance charge transfer, increase the transient current, and thus improve the glucose sensing performance.

[0027] (2) In the present invention, the cobalt metal itself has a slow charge transfer rate, while graphene has strong conductivity. After laser treatment, the cobalt metal and the induced graphene material are tightly combined, enhancing the charge transfer rate of the cobalt metal. At the same time, the induced graphene can provide a large number of positions as catalytic active sites for the cobalt metal.

[0028] (3) In the present invention, a polyimide film is made from a polyimide precursor solution, and then a cobalt nitrate ethanol solution is dropped. The use of an ethanol solution in the cobalt nitrate ethanol solution can accelerate drying. After being irradiated by a laser once, the surface wettability of the LIG is better, and the solution dropped on it can easily wet the surface, making the dispersion more uniform, and finally forming a structure with a metal-coated carbon material. In the present invention, insulating tape encapsulation can prevent the reaction between gold nanoparticles and glucose from affecting the test accuracy when the sensor is used. Description of the Drawings

[0029] Figure 1 It is the X-ray diffraction image (XRD) of Example 2 of the present invention.

[0030] Figure 2 It is the scanning electron microscope image (SEM) of Example 2 of the present invention.

[0031] Figure 3 It is the high-resolution transmission electron microscope image (TEM) and its particle size distribution diagram of Example 2 of the present invention.

[0032] Figure 4 It is the Raman spectrum image (Raman) of Example 2 of the present invention.

[0033] Figure 5 It is the linear relationship between different glucose concentrations detected by the Co@LIG / CoO enzyme-free glucose sensor prepared by the present invention and the detection current density.

[0034] Figure 6 The detection current of the present invention shows a linear relationship with the glucose concentration in the range of 10 - 1100 μM. Detailed Embodiments

[0035] In order to make the objectives, technical solutions and advantages of the present invention clearer, the following further describes the present invention in detail with reference to the drawings and embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0036] A laser-induced cobalt-based enzyme-free glucose sensor, which includes a semi-circular graphene counter electrode, an unclosed annular working electrode, and an arc-shaped reference electrode connected to the counter electrode. The counter electrode and the reference electrode are arranged outside the working electrode.

[0037] A preparation method of a laser-induced cobalt-based enzyme-free glucose sensor, the specific steps are as follows:

[0038] S1. Preparation of cobalt nitrate ethanol solution: Cobalt nitrate hexahydrate powder was added to 10 ml of ethanol solution to prepare a cobalt nitrate ethanol solution with a concentration gradient of 0.05 - 1.2 M / L. After ultrasonic mixing for 10 min, it was stored in a 4°C refrigerator for later use.

[0039] S2. Preparation of polyimide film: A glass slide with dimensions of 76 mm × 25 mm was selected and ultrasonically treated with absolute ethanol for 10 min in advance to make its surface clean, flat, and free of debris, facilitating uniform film coating. Then it was dried at room temperature. Next, the polyimide precursor solution was dropped at one end of the glass slide, and a coating with a thickness of approximately 80 μm was formed on the glass slide using a film applicator. Then it was placed in a muffle furnace and kept at 180°C for 1 h. After cooling, it was taken out to obtain the polyimide film.

[0040] S3. CO2 laser-induced treatment:

[0041] (1). Three electrodes that match the interface of the commercial electrode adapter were pre-drawn in AUTOCAD software and imported into the CO2 laser.

[0042] (2). CO2 laser parameter settings: The wavelength was 10.6 μm, the scanning speed was 200 - 400 mm / s, the laser power was 3 - 5 W, and the scanning spacing was 0.05 - 0.1 mm.

[0043] (3). Laser operation was performed using the laser parameters in step (2) to obtain laser-induced graphene, and the specific morphology was three electrodes.

[0044] S4. Fabrication of the working electrode: Different concentrations of cobalt nitrate ethanol solution were dropped in the working electrode area of the three electrodes. After drying, laser operation was performed again to obtain Co@LIG / CoO sensing materials with different Co concentrations, that is, a working electrode was formed on the laser-induced graphene.

[0045] S5. Fabrication of the reference electrode: Commercial Ag / AgCl paste was printed onto the reference electrode area of the three electrodes by screen printing and cured at 4°C to form the reference electrode.

[0046] S6. Ion sputtering of gold nanoparticles: Gold nanoparticles were sputtered onto the working area outside the three electrodes, and the specific parameters were a current of 30 - 50 mA and a time of 5 - 10 min.

[0047] S7. Encapsulation with insulating tape: The cut insulating tape was pasted onto the corresponding area to cover the working area outside the three electrodes, and the final cobalt-based enzyme-free glucose sensor was prepared.

[0048] Example 1

[0049] 1. Coat a polyimide coating on a glass slide cleaned with absolute ethanol using a film applicator, and place it in a muffle furnace at 180 °C for 1 h to obtain a polyimide film.

[0050] 2. Perform laser operation on the film obtained in step 1 using a CO2 laser. The parameters are set as follows: laser wavelength 10.6 μm, scanning speed 300 mm / s, laser power 5 W, scanning pitch 0.08 mm, to obtain laser-induced graphene.

[0051] 3. Drop 4 μL of

[0052] 0.2 M / L cobalt nitrate ethanol solution on the surface of the working electrode area of the laser-induced graphene obtained in step 2, dry it at room temperature for 5 min, and perform laser operation again. The scanning speed is 300 mm / s, the laser power is 3.6 W, and the scanning pitch is 0.08 mm to obtain Co@LIG / CoO.

[0053] 4. Print commercial Ag / AgCl paste onto the reference electrode area of the three-electrode system by screen printing, and cure it in a refrigerated environment at 4 °C for 24 h.

[0054] 5. Sputter gold nanoparticles on the working area other than the three electrodes. The specific parameters are current 30 mA and time 5 min.

[0055] 6. Use insulating tape for simple encapsulation to cover the non-working area of the electrodes, and fabricate cobalt-based enzyme-free glucose sensor 1.

[0056] Example 2

[0057] The difference between this example and Example 1 is that the concentration of cobalt nitrate ethanol solution is 0.6 M / L, and cobalt-based enzyme-free glucose sensor 2.

[0058] The XRD image of cobalt-based enzyme-free glucose sensor 2 is as Figure 1 shown, the SEM image is as Figure 2 shown, and the TEM image is as Figure 3 shown.

[0059] It can be clearly seen from Figure 1 the (002) peak of graphene. In addition, the three strongest peaks of Co / CoO can be seen more clearly;

[0060] It can be seen from Figures 2-3 that uniformly distributed nanoparticles can be clearly seen on the surface of the graphene after laser treatment. The particle size distribution diagram of its transmission image shows that the average particle size is 14.56 nm. And Figure 3From the high-resolution transmission image, it can be seen that the Co nanoparticles are surrounded by laser-induced carbon materials (LIG), and this core-shell structure greatly enhances the chemical stability of the Co nanoparticles. In addition, the lattice spacing of CoO can also be clearly observed, indicating the successful preparation of the Co@LIG / CoO active material.

[0061] The Raman of the cobalt-based enzyme-free glucose sensor 2 is as Figure 4 shown. Figure 4 Figure shows the comparison of the Raman images of Co@LIG / CoO in Example 2 and pure LIG. By comparison, it can be seen that Co@LIG / CoO shows the characteristic peaks of graphene as well as LIG, namely the D peak near 1350 cm -1 , the G peak near 1580 cm -1 , and the 2D peak near 2750 cm -1 . Moreover, Co@LIG / CoO shows the characteristic peaks of CoO in the range of 100 - 1000 cm -1 , confirming the existence of CoO.

[0062] The three-electrode microdevice prepared from the cobalt-based enzyme-free glucose sensor 2 prepared in Example 2 was used to detect glucose in a 0.1 M potassium hydroxide solution using an electrochemical workstation. Select the chronoamperometry curve in the technical menu of the settings, set the starting potential to the detection potential +0.7 V in the parameter settings, and set the time to 4000 s. Different concentrations of glucose solution were added dropwise every 50 s starting from 200 s, and finally the relationship between the detected current and the glucose concentration is as Figure 5 shown. The detected current and the glucose concentration show a linear relationship in the range of 10 - 1100 μM, as Figure 6 shown.

[0063] Comparative Example 1

[0064] The difference between this comparative example and Example 1 is that 4 μl of 0.2 M / L cobalt nitrate aqueous solution was added dropwise in step 3.

[0065] It was experimentally found that the drying time of using cobalt nitrate aqueous solution is 30 - 40 min, which is much longer than the drying time of cobalt nitrate ethanol solution (5 min), and is not conducive to the rapid preparation of electrode materials.

[0066] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a laser-induced cobalt-based enzyme-free glucose sensor, characterized in that: The steps include: S1. Preparation of polyimide film: coating a polyimide precursor solution on a glass slide to form a coating with a thickness of 70-90 μm, and obtaining a polyimide film after cooling under heat preservation; S2, CO2 laser induced treatment: the three-electrode pattern is introduced into a CO2 laser, and the obtained polyimide film is subjected to CO2 laser induced treatment to obtain laser induced graphene, i.e., LIG; S3, drop-coating a 0.05-1.2M / L cobalt nitrate ethanol solution on the working electrode area of ​​the laser-induced graphene, and after drying, performing CO2 laser induction treatment again to form a Co@LIG / CoO sensing material; S4, printing the Ag / AgCl slurry onto the reference electrode region of the three electrodes, and curing at 4° C. to form a reference electrode; S5. Gold nanoparticles were sputtered on the working area outside the three electrodes and encapsulated with insulating tape to obtain a cobalt-based enzyme-free glucose sensor.

2. A method for preparing a laser-induced cobalt-based enzyme-free glucose sensor according to claim 1, characterized in that: The preparation method of the cobalt nitrate ethanol solution comprises the following steps: taking 10 ml of the ethanol solution, adding cobalt nitrate hexahydrate powder thereto, preparing a cobalt nitrate ethanol solution with a concentration gradient of 0.05-1.2 M / L, and ultrasonically mixing for 10 minutes.

3. A method for preparing a laser-induced cobalt-based enzyme-free glucose sensor according to claim 1, characterized in that: The parameters of the CO2 laser are: laser wavelength is 10.6um, scanning speed is 200-400mm / s, laser power is 3W-5W, and scanning spacing is 0.05-0.1mm.

4. A method for preparing a laser-induced cobalt-based enzyme-free glucose sensor according to claim 1, characterized in that: In step S1, the size of the glass slide is 76 mm×25 mm, and it is pre-ultrasonicated with anhydrous ethanol for 10 min and then dried at room temperature.

5. A method for preparing a laser-induced cobalt-based enzyme-free glucose sensor according to claim 1, characterized in that: In step S1, the thickness of the coating is 80 um, the insulation temperature is 180° C., and the insulation time is 1 hour.

6. A method for preparing a laser-induced cobalt-based enzyme-free glucose sensor according to claim 1, characterized in that: In step S5, the sputtering current is 30mA-50mA, and the sputtering time is 5-10min.

7. A method for preparing a laser-induced cobalt-based enzyme-free glucose sensor according to claim 1, characterized in that: In step S2, the operating parameters of the CO2 laser are: laser wavelength is 10.6um, scanning speed is 3400mm / s, laser power is 5W, and scanning interval is 0.08mm.

8. A method for preparing a laser-induced cobalt-based enzyme-free glucose sensor according to claim 1, characterized in that: In step S3, the operating parameters of the CO2 laser are: laser wavelength is 10.6um, scanning speed is 300mm / s, laser power is 3.6W, and scanning interval is 0.08mm.

9. A sensor prepared by the laser-induced cobalt-based enzyme-free glucose sensor preparation method according to any one of claims 1 to 8, characterized in that: The sensor is prepared by the above preparation method.

10. Use of the laser-induced cobalt-based enzyme-free glucose sensor according to claim 9 in diabetic blood glucose detection.

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