CN103454325B - Photocatalysed glucose microelectrode sensor and preparation method thereof - Google Patents

Abstract

The invention relates to the field of electrochemical detection, in particular to a photocatalytic glucose microelectrode sensor and a preparation method thereof. The invention provides a photocatalytic glucose microelectrode sensor, comprising a base material, a working electrode, a counter electrode and a reference electrode are arranged on the base material, and a semiconductor quantum dot modification layer and a semiconductor quantum dot modification layer are arranged on the working area of the working electrode. Glucose oxidase modification layer, the substrate is provided with micro-fibers, the light transmitted by the micro-fibers passes through the working electrode vertically, and the semiconductor quantum dots are CdSeCdS semiconductor quantum dots. The photocatalytic glucose microelectrode sensor provided by the invention is a photocatalytic glucose microelectrode sensor that does not need oxygen and can detect blood sugar at a lower potential.

Description

A kind of photocatalytic glucose microelectrode sensor and preparation method thereof

technical field

The invention relates to the field of electrochemical detection, in particular to a photocatalytic glucose microelectrode sensor and a preparation method thereof.

Background technique

The traditional glucose microelectrode sensor uses glucose oxidase to modify the electrode. When the glucose microelectrode sensor detects blood sugar, it has a certain dependence on oxygen, and the detection must be carried out at a high potential, so the coexisting electroactive substances may cause a series of side effects.

In recent years, the field of nanoscience has become the frontier of science in the new century, which will change human production and life style. At the same time, nanotechnology poses many new challenges to people in basic science and promotes the development of basic science. Semiconductor quantum dots are a typical structure of semiconductor nanomaterials, which have played an important role in the field of information technology. Due to the quantum size effect and surface effect, semiconductor quantum dots have become a research hotspot. Efforts to prepare quantum dots and study their properties have been going on for more than two decades, and great progress has been made. Quantum dots are nanoparticles composed of II-VI and III elements, which have size-dependent electrical and optical properties and are widely used in light-emitting diodes, non-linear optics, solar cells, and life sciences. The currently produced semiconductor quantum dot materials mainly include the following categories: (1) Group IV quantum dot materials, such as Si, Ge; (2) III-V group quantum dot materials, such as InAs, GaSb, GaN, etc. Quantum dots; (3) Group II-VI quantum dot materials, such as: CdSe, ZnSe, CdTe and other quantum dots.

Due to the unique photoelectric properties of semiconductor nano-quantum dots, wide light absorption spectrum, narrow and adjustable emission spectrum, high photoelectric stability, etc., and high surface activity, they are easy to analyze the reaction of substances and generate corresponding signals. Therefore, the application range of semiconductor nanometer quantum dots in the field of biosensors is increasing.

Contents of the invention

In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a photocatalytic glucose microelectrode sensor and its preparation method, which are used to solve the problems in the prior art.

In order to achieve the above purpose and other related purposes, the present invention uses semiconductor quantum dots to have the maximum light absorption at a specific wavelength, electrons undergo transitions to generate photocurrent, and the quantum dots are fixed on the enzyme electrodes as photosensitive elements, thereby preparing photocatalytic glucose microbes. electrode sensor.

The first aspect of the present invention provides a photocatalytic glucose microelectrode sensor, including a substrate, a working electrode, a counter electrode and a reference electrode are arranged on the substrate, and semiconductor quantum dots are arranged on the working area of the working electrode As for the modification layer and the glucose oxidase modification layer, micro-fibers are arranged in the base material, the light transmitted by the micro-fibers passes through the working electrode vertically, and the semiconductor quantum dots are CdSeCdS semiconductor quantum dots.

Preferably, each of the working electrode, the counter electrode and the reference electrode is provided with a corresponding pin, and each pin is located on the top of the microelectrode sensor.

Preferably, the electrodes (working electrode, counter electrode and reference electrode) are insulated from each other, and are arranged sequentially from the end to the top of the microelectrode sensor in the order of the working electrode, counter electrode and reference electrode.

Preferably, a biocompatible protective layer is provided on the surface of the microelectrode sensor. Specifically, it means that the entire surface of the microelectrode sensor (including the surface of each electrode) is provided with a layer of biocompatible protective layer.

More preferably, the biocompatible protective layer is made of organic silicone.

Further preferably, the biocompatible protective layer is organosilicone, such as dimethylsiloxane and its hydrophilic modification.

The biocompatible protective layer can regulate the penetration of glucose; it can protect the modified layer from falling off; it can make the sensor have good biocompatibility and reduce the immune rejection reaction of the human body.

Preferably, the working electrode is an indium tin oxide (ITO, Indium tin oxide) conductive glass electrode.

In the present invention, there is no special requirement on the ratio of SnO ₂ :In ₂ O ₃ in indium tin oxide.

Preferably, the ratio of SnO ₂ :In ₂ O ₃ in indium tin oxide is the usual mass ratio, that is, the mass ratio of SnO ₂ :In ₂ O ₃ is 1:9.

Preferably, the counter electrode is a platinum electrode.

Preferably, the reference electrode is an Ag/AgCl electrode.

Preferably, the wavelength range of the light transmitted by the micro-fiber is 350-1250nm. Preferably it is 580nm-680nm.

Preferably, the particle size range of the semiconductor quantum dots is 4-10 nm.

Preferably, a carbon nanotube modification layer is also provided on the working area of the working electrode.

More preferably, on the working area of the working electrode, the order of the modification layers is as follows: first modify a layer of carbon nanotubes, then modify a layer of semiconductor quantum dots, and then modify a layer of glucose oxidase.

Preferably, the thickness of the microelectrode sensor is 0.05-1 mm, the working area of the working electrode is 2-10 mm ² , the working area of the counter electrode is 2-15 mm ² , and the working area of the reference electrode is 1-10 mm ² .

The preparation process of the photocatalytic glucose microelectrode sensor provided by the present invention is the same as that of the conventional photocatalytic microelectrode sensor except for the working electrode. The preparation of connecting wires, counter electrodes and reference electrodes is to use ultrasonic spraying method to directly spray the corresponding counter electrode patterns, reference electrode patterns and connecting wires on the electrode substrate. The sprayed materials can use nano-platinum or nano-silver ; The method of inkjet micro-printing can also be used to directly print the corresponding counter electrode graphics, reference electrode graphics and connecting wires on the electrode substrate. The printed materials can use nano-platinum or nano-silver; photolithography technology can also be used Prepare corresponding patterns and masks on the substrate, then sputter precious metal gold by sputtering technology to form connecting wires, then sputter platinum on the counter electrode position to form the counter electrode, and sputter silver/silver on the reference electrode position. Silver chloride forms the reference electrode. The preparation of the working electrode is to use photolithography, electroforming and injection molding technology to make MEMS (Micro-Electro-Mechanic System) molds, use thermal molding technology to micro-cast the micro-fiber array, and then spray indium tin on the working electrode oxide.

The second aspect of the present invention provides a method for preparing the working electrode of the photocatalytic glucose microelectrode sensor, which adopts a layer-by-layer self-assembly method, comprising the following steps:

a) The indium tin oxide conductive glass electrode used as the working electrode is pretreated to make its surface negatively charged; the obtained working electrode is immersed in polyallylamine hydrochloride (PAH) and o-phenanthroline cobalt ([Co(Phen ) ₃ ] ^2+/3+ ) mixed aqueous solution, after taking it out, rinse it with deionized water and dry it with nitrogen;

b) Immerse the obtained working electrode in the carbon nanotube aqueous solution, after taking it out, rinse it with deionized water and dry it with nitrogen;

c) Immerse the resulting working electrode in a mixed aqueous solution of polyallylamine hydrochloride (PAH) and o-phenanthroline cobalt ([Co(Phen) ₃ ] ^2+/3+ ), take it out, rinse it with deionized water and clean it with Blow dry with nitrogen;

d) Immerse the obtained working electrode in the semiconductor quantum dot aqueous solution, after taking it out, rinse it with deionized water and dry it with nitrogen;

e) Immerse the resulting working electrode in a mixed aqueous solution of polyallylamine hydrochloride (PAH) and o-phenanthroline cobalt ([Co(Phen) ₃ ] ^2+/3+ ), take it out, rinse it with deionized water and clean it with Blow dry with nitrogen;

f) Finally, immerse the obtained working electrode in the prepared glucose oxidase aqueous solution, take it out, rinse it with deionized water and dry it with nitrogen.

Preferably, in the step a), the specific steps of pretreating the indium tin oxide conductive glass electrode as the working electrode to make its surface negatively charged are: preparing concentrated sulfuric acid/hydrogen peroxide treatment solution, and then The working electrode area of the electrode is placed in concentrated sulfuric acid/hydrogen peroxide treatment solution, treated in a constant temperature water bath at 70-80°C for 1-2 hours, taken out from the treatment solution and fully cleaned with deionized water. Then put the working electrode area of the microelectrode into the hydrogen peroxide/ammonia water treatment solution, treat it in a constant temperature water bath at 60-70°C for 1-2 hours, and finally rinse it with deionized water.

More preferably, the concentrated sulfuric acid/hydrogen peroxide treatment solution is prepared from concentrated sulfuric acid aqueous solution and hydrogen peroxide aqueous solution in a ratio of 7:3 (volume ratio).

Further preferably, the concentrated sulfuric acid aqueous solution has a concentration of 95-98wt%.

Further preferably, the aqueous hydrogen peroxide solution is commercially available with a concentration of about 30wt%.

More preferably, the hydrogen peroxide/ammonia water treatment solution is prepared from aqueous hydrogen peroxide solution and ammonia water in a ratio of 1:1 (volume ratio).

Further preferably, the concentration of the ammonia water is 25-28wt%.

Further preferably, the aqueous hydrogen peroxide solution is commercially available with a concentration of about 30wt%.

Preferably, in the steps a), c), and e), the mixed aqueous solution of polyallylamine hydrochloride (PAH) and o-phenanthroline cobalt ([Co(Phen) ₃ ] ^2+/3+ ) The time is 5-10min.

Preferably, in the steps a), c), and e), in the mixed aqueous solution of polyallylamine hydrochloride (PAH) and o-phenanthroline cobalt ([Co(Phen) ₃ ] ^2+/3+ ), The concentration of polyallylamine hydrochloride (PAH) is 1-2mg/mL, and the concentration of o-phenanthroline cobalt ([Co(Phen) ₃ ] ^2+/3+ ) is 1-2mg/mL.

The cobalt o-phenanthroline is prepared by grinding cobalt chloride hydrate (CoCl ₂ ·2H ₂ O) and o-phenanthroline (C ₁₂ H ₈ N ₂ ·H ₂ O) in a certain ratio by a solid-phase chemical reaction method .

Preferably, in the step b), the working electrode is immersed in the carbon nanotube solution for 5-10 minutes.

Preferably, in the step b), the concentration of the carbon nanotube aqueous solution is 10-20 mg/mL.

The specific method for acidifying the carbon nanotubes is: adding the carbon nanotubes to the mixed acid of excess concentrated sulfuric acid and concentrated nitric acid, ultrasonic treatment for 4-6h, centrifuging, and washing the obtained carbon nanotubes to neutrality; After centrifugation and drying, add appropriate amount of deionized water to the obtained carbon nanotubes, and sonicate for 1-2 hours (the purpose of sonication is to redisperse, that is, to disperse the carbon nanotubes in water).

The carbon nanotubes are subjected to acidification treatment, and the treated carbon nanotubes form negatively charged carboxyl groups on the surface.

Preferably, in the step d), the working electrode is immersed in the semiconductor quantum dot aqueous solution for 5-10 minutes.

Preferably, in the step d), the aqueous solution of semiconductor quantum dots is an aqueous solution of CdSeCdS semiconductor quantum dots, with a concentration of 1×10 ^-6 -5×10 ^-6 mol/L.

The preparation method of the semiconductor quantum dot aqueous solution is: cadmium perchlorate hexahydrate (Cd(ClO ₄ ) ₂ 6H ₂ O) and sodium citrate dihydrate (Na ₃ C ₆ H ₅ O ₇ 2H ₂ O) Dissolve in deionized water, blow nitrogen to remove oxygen, and adjust the pH of the mixed solution to 9.0 with sodium hydroxide. Next, selenourea (C ₃ H ₈ N ₂ Se) was added, and nitrogen gas was passed to remove oxygen. Finally, microwave heating was carried out under high heat for 0.5-2 minutes. After heating, the mixed solution was taken out and left to cool at room temperature. Add thioacetamide (CH ₃ CSNH ₂ ) to the above mixture, shake and mix evenly, then heat the reaction system for reflux reaction, the reaction condition is 60-70°C, and nitrogen is kept flowing during the reaction to protect, and you can get Quantum dots needed for experiments.

Those skilled in the art can obtain CdSeCdS semiconductor quanta with different particle sizes by adjusting the reaction time based on experience.

The molar feeding ratio of cadmium perchlorate hexahydrate, sodium citrate dihydrate, selenourea and thioacetamide is: 8:17-25:2-3:2-3.

Preferably, in the step f), the working electrode is immersed in the glucose oxidase aqueous solution for 5-10 minutes.

Preferably, in the step f), the concentration of the glucose oxidase aqueous solution is 20-100 mg/mL.

Preferably, a biocompatible protective layer is also prepared on the surface of the obtained microelectrodes.

The preparation method of the biocompatible protective layer is: modifying the organic silicone on the surface of the electrode by dip coating, spray coating or spin coating.

The third aspect of the present invention provides the application of the photocatalytic glucose microelectrode sensor in the field of glucose detection.

As mentioned above, the photocatalytic glucose microelectrode sensor provided by the present invention is a photocatalytic glucose microelectrode sensor that does not require oxygen and can detect blood sugar at a lower potential.

In the glucose oxidase layer of this glucose microelectrode sensor, o-phenanthroline cobalt ([Co(Phen)3]2+/3+) and glucose oxidase are mixed together, and o-phenanthroline cobalt is used as an electron mediator It can conduct electrons by changing between the oxidation state ([Co(Phen) ₃ ] ³⁺ ) and the reduction state ([Co(Phen) ₃ ] ²⁺ ). When glucose oxidase catalyzes glucose into gluconic acid, glucose oxidase obtains electrons and changes from an oxidized state to a reduced state, and the oxidized state of o-phenanthroline cobalt ([Co(Phen) ₃ ] ³⁺ ) can oxidize the reduced state Glucose oxidase gets electrons to transform into reduced cobalt o-phenanthroline ([Co(Phen) ₃ ] ²⁺ ), which does not require the participation of oxygen. At the same time, under light conditions, semiconductor quantum dots are excited by light, and their valence band electrons transition to the conduction band and then transfer to the surface of the working electrode; the valence band of semiconductor quantum dots produces oxidative holes due to the loss of electrons, and the holes can be oxidized Reduced state ([Co(Phen) ₃ ] ²⁺ ), thus forming a continuous electronic circuit and generating a stable photocurrent. (The specific mechanism is shown in Figure 4A and 4B)

Description of drawings

Fig. 1 is a top view of the photocatalytic glucose microelectrode sensor of the present invention.

Fig. 2 is a longitudinal sectional view of a photocatalytic glucose microelectrode sensor.

Fig. 3 is a flow chart of modifying the working electrode by the layer-by-layer self-assembly method.

4A and 4B are detection principle diagrams of the photocatalytic glucose microelectrode sensor of the present invention.

Figure 5 is the ultraviolet-visible absorption spectrum and fluorescence spectrum of CdSeCdS quantum dots diluted 20 times.

Figure 6 measures the infrared spectrum of o-phenanthroline cobalt compound (Co(Phen) ₃ Cl ₂ ) in the range of 1800-400 cm ^-1 .

Component designation description

1 Substrate

2 pins

3 conductor

4 Reference electrode

5 counter electrode

6 Working electrode

7 Micro fiber

Detailed ways

Embodiments of the present invention are described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation modes, and various modifications or changes can be made to the details in this specification based on different viewpoints and applications without departing from the spirit of the present invention.

It should be noted that the process equipment or devices not specifically indicated in the following examples all adopt conventional equipment or devices in the art; all pressure values and ranges refer to absolute pressures.

In addition, it should be understood that one or more method steps mentioned in the present invention do not exclude that there may be other method steps before and after the combined steps or other method steps may be inserted between these explicitly mentioned steps, unless otherwise There are descriptions; it should also be understood that the combined connection relationship between one or more devices/devices mentioned in the present invention does not exclude that there may be other devices/devices before and after the combined devices/devices or those explicitly mentioned Other devices/apparatus can also be interposed between the two devices/apparatus, unless otherwise stated. Moreover, unless otherwise stated, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the sequence of each method step or limit the scope of the present invention. The change or adjustment of its relative relationship is in In the case of no substantive change in the technical content, it shall also be regarded as the applicable scope of the present invention.

A kind of photocatalytic glucose microelectrode sensor as shown in Figure 1 and Figure 2, comprises substrate 1, is provided with working electrode 6, counter electrode and reference electrode on described substrate 1, the working area of described working electrode 6 It is decorated with a carbon nanotube layer, a CdSeCdS semiconductor quantum dot layer, a glucose oxidase layer, and a biocompatible protective layer in sequence from the inside to the outside. The substrate 1 is provided with a micro-optical fiber 7, and the micro-fiber 7 transmits The light passes through the working electrode 6 vertically. Each of the working electrode 6 , the counter electrode 5 and the reference electrode 4 is provided with a corresponding pin 2 , and each pin 2 is located at the top of the microelectrode sensor, and is connected to the corresponding electrode through a conductor 3 . The working electrode 6, the counter electrode 5, and the reference electrode 4 are insulated from each other, and are arranged sequentially from the end to the top of the microelectrode sensor in the order of the working electrode 6, the counter electrode 5, and the reference electrode 4.

Example 1

Preparation of CdSeCdS semiconductor quantum dots

Weigh 0.0336g cadmium perchlorate hexahydrate (Cd(ClO ₄ ) ₂ 6H ₂ O) and 0.05g sodium citrate dihydrate (Na ₃ C ₆ H ₅ O ₇ 2H ₂ O) and dissolve them into 45ml deionized In the water, nitrogen gas was used to remove oxygen for 10 minutes, and the pH value of the mixed solution was adjusted to 9.0 with 2 moles of sodium hydroxide (NaOH). Immediately after adding 0.003g selenourea (C ₃ H ₈ N ₂ Se), and then blowing nitrogen gas to remove oxygen for 1min, finally put it into a microwave oven and heat it in microwave for 1min to make the color of the mixed solution change from colorless to red, take out and mix The solution was left to cool at room temperature.

Finally, add 0.0015g of thioacetamide (CH ₃ CSNH ₂ ) to the above mixture, shake and mix evenly, inject the mixture into a cleaned three-necked bottle, and heat the reaction system in an oil bath for reflux reaction. The temperature of the bath is 70° C., the reaction time is 24 hours, and nitrogen is always passed through for protection during the reaction. The CdSeCdS quantum dots needed for the experiment can be obtained.

Figure 5 shows the ultraviolet-visible absorption spectrum and fluorescence spectrum of CdSeCdS quantum dots diluted 20 times. The position of the first absorption peak of the ultraviolet absorption spectrum is 560nm, and the emission peak position of the fluorescence spectrum is 586nm. According to calculation, the particle size of the CdSe quantum dots is 3.3nm, and the concentration of the CdSeCdS quantum dot solution is 1.59×10 ^-6 molL ^-1 .

Example 2

Preparation of o-phenanthroline cobalt ([Co(Phen) ₃ ] ^2+/3+ ) by solid-state chemical reaction

Weigh cobalt chloride hydrate (CoCl ₂ ·2H ₂ O) and o-phenanthroline (Phen, C ₁₂ H ₈ N ₂ ·H ₂ O) in a grinding machine at a molar ratio of 1:3, Mix and grind, the color of the mixture first turns light pink, continue to grind, the color of the mixture gradually turns green, and grind until the color of the mixture gradually changes from green to orange.

The solid phase reaction of CoCl ₂ 6H ₂ O with o-phenanthroline is a two-step reaction process through a green intermediate, which is expressed by the equation:

The synthesized o-phenanthroline cobalt compound (Co(Phen) ₃ Cl ₂ ) was characterized by Fourier transform infrared spectroscopy. The infrared spectrum of Co(Phen) ₃ Cl ₂ was measured in the range of 1800-400cm ^-1 , as shown in Figure 6, the main absorption peak positions are: 1623cm ^-1 , 1516cm ^-1 , 1421cm ^-1 , 1103cm ^-1 , 852cm ^-1 , 773cm ^-1 , 723cm ^-1 . The embedded picture is the enlarged infrared spectrum in the range of 600-400cm ^-1 , and the absorption peak positions are: 507cm ^-1 , 472cm ^-1 , 441cm ^-1 , 420cm ^-1 . The infrared spectrum of o-phenanthroline cobalt (Co(Phen) ₃ Cl ₂ ) prepared by solid state reaction method is consistent with the results reported in the literature.

Example 3

Preparation of glucose microelectrode sensor (s1-s5):

Glucose microelectrode sensor (thickness 0.1mm, working electrode area 6mm ² , counter electrode area 9mm ² , reference electrode area 6mm ² ), using photolithography, electroforming and injection molding technology to make MEMS (Micro-Electro-Mechanical System, Micro-Electro-MechanicSystem ) mould, using thermal molding technology to micro-cast the micro-fiber array to form the working electrode, and directly spray the corresponding counter electrode pattern, reference electrode pattern, working electrode pattern and connecting wires on the electrode substrate. The sprayed materials can be used Nano platinum, nano silver or indium tin oxide.

The preparation process of the functional layer of the sensor is shown in Figure 3, using a layer-by-layer self-assembly method, including the following steps:

a) The indium tin oxide conductive glass electrode used as the working electrode is pretreated to make its surface negatively charged; the resulting working electrode is immersed in polyallylamine hydrochloride (1.5 mg/mL, PAH) and o-phenanthroline cobalt (1.5mg/mL, [Co(Phen) ₃ ] ^2+/3+ ) mixed aqueous solution for 8 minutes, after taking it out, rinse it with deionized water and dry it with nitrogen;

b) Immerse the obtained working electrode in an aqueous solution of carbon nanotubes (15 mg/mL) for 8 minutes, take it out, rinse it with deionized water and dry it with nitrogen;

c) Immerse the obtained working electrode in the mixed aqueous solution of polyallylamine hydrochloride and o-phenanthroline cobalt for 8 minutes, after taking it out, rinse it with deionized water and dry it with nitrogen;

d) Immerse the obtained working electrode in an aqueous solution of semiconductor quantum dots (1.59×10 ^-6 mol/L, particle size 7nm, corresponding to light wavelength 641nm) for 8 minutes, after taking it out, rinse it with deionized water and dry it with nitrogen;

e) Immerse the obtained working electrode in the mixed aqueous solution of polyallylamine hydrochloride and o-phenanthroline cobalt for 8 minutes, after taking it out, rinse it with deionized water and dry it with nitrogen;

f) Finally, immerse the obtained working electrode in the prepared glucose oxidase aqueous solution (60mg/mL) for 8min, take it out, rinse it with deionized water and dry it with nitrogen.

The obtained microelectrodes s1-s5 were tested for accuracy and repeatability (the counter electrode is a platinum electrode, and the reference electrode is an Ag/AgCl electrode), and the results are shown in Example 8.

Example 4

Preparation of glucose microelectrode sensor:

Glucose microelectrode sensor (thickness 0.1mm, working electrode area 6mm ² , counter electrode area 9mm ² , reference electrode area 6mm ² ), using photolithography, electroforming and injection molding technology to make MEMS (Micro-Electro-Mechanical System, Micro-Electro-MechanicSystem ) mould, using thermal molding technology to micro-cast the micro-fiber array to form the working electrode, and directly spray the corresponding counter electrode pattern, reference electrode pattern, working electrode pattern and connecting wires on the electrode substrate. The sprayed materials can be used Nano platinum, nano silver or indium tin oxide.

The preparation process of the functional layer of the sensor is shown in Figure 3, using a layer-by-layer self-assembly method, including the following steps:

a) The indium tin oxide conductive glass electrode used as the working electrode is pretreated to make its surface negatively charged; the resulting working electrode is immersed in polyallylamine hydrochloride (1.5 mg/mL, PAH) and o-phenanthroline cobalt (1.5mg/mL, [Co(Phen) ₃ ] ^2+/3+ ) mixed aqueous solution for 8 minutes, after taking it out, rinse it with deionized water and dry it with nitrogen;

b) Immerse the obtained working electrode in an aqueous solution of carbon nanotubes (15 mg/mL) for 8 minutes, take it out, rinse it with deionized water and dry it with nitrogen;

c) Immerse the obtained working electrode in the mixed aqueous solution of polyallylamine hydrochloride and o-phenanthroline cobalt for 8 minutes, after taking it out, rinse it with deionized water and dry it with nitrogen;

d) Immerse the obtained working electrode in an aqueous solution of semiconductor quantum dots (1×10 ^-6 mol/L, particle size 10nm, corresponding to light wavelength 673nm) for 8 minutes, after taking it out, rinse it with deionized water and dry it with nitrogen;

e) Immerse the obtained working electrode in the mixed aqueous solution of polyallylamine hydrochloride and o-phenanthroline cobalt for 8 minutes, after taking it out, rinse it with deionized water and dry it with nitrogen;

f) Finally, immerse the obtained working electrode in the prepared glucose oxidase aqueous solution (60mg/mL) for 8min, take it out, rinse it with deionized water and dry it with nitrogen.

The obtained microelectrode tested the blood sugar content (about 10mM), which had high accuracy and repeatability, which was similar to Example 3 (the counter electrode was a platinum electrode, and the reference electrode was an Ag/AgCl electrode).

Example 5

Preparation of glucose microelectrode sensor:

Glucose microelectrode sensor (thickness 0.05mm, working electrode area 10mm ² , counter electrode area 15mm ² , reference electrode area 10mm ² ), using photolithography, electroforming and injection molding techniques to make MEMS (Micro-Electro-Mechanical Systems, Micro-Electro-Mechanic System) mould, using thermal molding technology to micro-cast the micro-fiber array to form the working electrode, and directly spray the corresponding counter electrode pattern, reference electrode pattern, working electrode pattern and connecting wires on the electrode substrate. The sprayed materials can be Use nano platinum, nano silver or indium tin oxide.

The preparation process of the functional layer of the sensor is shown in Figure 3, using a layer-by-layer self-assembly method, including the following steps:

a) The indium tin oxide conductive glass electrode used as the working electrode is pretreated to make its surface negatively charged; the resulting working electrode is immersed in polyallylamine hydrochloride (1 mg/mL, PAH) and o-phenanthroline cobalt ( 1mg/mL, [Co(Phen) ₃ ] ^2+/3+ ) mixed aqueous solution for 10min, after taking it out, rinse it with deionized water and dry it with nitrogen;

b) Immerse the obtained working electrode in carbon nanotube aqueous solution (10mg/mL) for 10min, take it out, rinse it with deionized water and dry it with nitrogen;

c) Immerse the obtained working electrode in the mixed aqueous solution of polyallylamine hydrochloride and o-phenanthroline cobalt for 10 minutes, after taking it out, rinse it with deionized water and dry it with nitrogen;

d) Immerse the obtained working electrode in an aqueous solution of semiconductor quantum dots (5×10 ^-6 mol/L, particle size 7nm, corresponding to light wavelength 641nm) for 10 minutes, after taking it out, rinse it with deionized water and dry it with nitrogen;

e) Immerse the obtained working electrode in the mixed aqueous solution of polyallylamine hydrochloride and o-phenanthroline cobalt for 10 minutes, after taking it out, rinse it with deionized water and dry it with nitrogen;

f) Finally, immerse the obtained working electrode in the prepared glucose oxidase aqueous solution (20 mg/mL) for 10 min, take it out, rinse it with deionized water and dry it with nitrogen.

The obtained microelectrode tested the blood sugar content (about 10mM), which had high accuracy and repeatability, which was similar to Example 3 (the counter electrode was a platinum electrode, and the reference electrode was an Ag/AgCl electrode).

Example 6

Preparation of glucose microelectrode sensor:

Glucose microelectrode sensor (thickness 1mm, working electrode area 2mm ² , counter electrode area 2mm ² , reference electrode area 1mm ² ), using photolithography, electroforming and injection molding technology to make MEMS (Micro-Electro-Mechanical System, Micro-Electro-MechanicSystem) Mold, using thermal molding technology to micro-cast the micro-fiber array to form the working electrode, directly spray the corresponding counter electrode pattern, reference electrode pattern, working electrode pattern and connecting wire on the electrode substrate, the sprayed material can use nanometer Platinum, Nanosilver or Indium Tin Oxide.

The preparation process of the functional layer of the sensor is shown in Figure 3, using a layer-by-layer self-assembly method, including the following steps:

a) The indium tin oxide conductive glass electrode used as the working electrode is pretreated to make its surface negatively charged; the resulting working electrode is immersed in polyallylamine hydrochloride (2 mg/mL, PAH) and o-phenanthroline cobalt ( 2mg/mL, [Co(Phen) ₃ ] ^2+/3+ ) mixed aqueous solution for 5min, after taking it out, rinse it with deionized water and dry it with nitrogen;

b) Immerse the obtained working electrode in an aqueous solution of carbon nanotubes (20mg/mL) for 5min, take it out, rinse it with deionized water and dry it with nitrogen;

c) Immerse the obtained working electrode in the mixed aqueous solution of polyallylamine hydrochloride and o-phenanthroline cobalt for 5 minutes, after taking it out, rinse it with deionized water and dry it with nitrogen;

d) Immerse the obtained working electrode in an aqueous solution of semiconductor quantum dots (5×10 ^-6 mol/L, particle size 4nm, corresponding to light wavelength 586nm) for 5 minutes, after taking it out, rinse it with deionized water and dry it with nitrogen;

e) Immerse the obtained working electrode in the mixed aqueous solution of polyallylamine hydrochloride and o-phenanthroline cobalt for 5 minutes, after taking it out, rinse it with deionized water and dry it with nitrogen;

f) Finally, immerse the obtained working electrode in the prepared glucose oxidase aqueous solution (100 mg/mL) for 5 min, take it out, rinse it with deionized water and dry it with nitrogen.

The obtained microelectrode tested the blood sugar content (about 10mM), which had high accuracy and repeatability, which was similar to Example 3 (the counter electrode was a platinum electrode, and the reference electrode was an Ag/AgCl electrode).

Example 7

Preparation of glucose microelectrode sensor:

Glucose microelectrode sensor (thickness 0.15mm, working electrode area 4mm ² , counter electrode area 7mm ² , reference electrode area 4mm ² ), using photolithography, electroforming and injection molding technology to make MEMS (Micro-Electro-Mechanical System, Micro-Electro-MechanicSystem ) mould, using thermal molding technology to micro-cast the micro-fiber array to form the working electrode, and directly spray the corresponding counter electrode pattern, reference electrode pattern, working electrode pattern and connecting wires on the electrode substrate. The sprayed materials can be used Nano platinum, nano silver or indium tin oxide.

The preparation process of the functional layer of the sensor is shown in Figure 3, using a layer-by-layer self-assembly method, including the following steps:

a) The indium tin oxide conductive glass electrode used as the working electrode is pretreated to make its surface negatively charged; the resulting working electrode is immersed in polyallylamine hydrochloride (1.5 mg/mL, PAH) and o-phenanthroline cobalt (1.5mg/mL, [Co(Phen) ₃ ] ^2+/3+ ) mixed aqueous solution for 8 minutes, after taking it out, rinse it with deionized water and dry it with nitrogen;

b) Immerse the obtained working electrode in an aqueous solution of carbon nanotubes (15 mg/mL) for 8 minutes, take it out, rinse it with deionized water and dry it with nitrogen;

c) Immerse the obtained working electrode in the mixed aqueous solution of polyallylamine hydrochloride and o-phenanthroline cobalt for 8 minutes, after taking it out, rinse it with deionized water and dry it with nitrogen;

d) Immerse the obtained working electrode in an aqueous solution of semiconductor quantum dots (3×10 ^-6 mol/L, particle size 7nm corresponding to light wavelength 641nm) for 8 minutes, after taking it out, rinse it with deionized water and dry it with nitrogen;

e) Immerse the obtained working electrode in the mixed aqueous solution of polyallylamine hydrochloride and o-phenanthroline cobalt for 8 minutes, after taking it out, rinse it with deionized water and dry it with nitrogen;

f) Finally, immerse the obtained working electrode in the prepared glucose oxidase aqueous solution (60mg/mL) for 8min, take it out, rinse it with deionized water and dry it with nitrogen.

The obtained microelectrode tested the blood sugar content (about 10mM), which had high accuracy and repeatability, which was similar to Example 3 (the counter electrode was a platinum electrode, and the reference electrode was an Ag/AgCl electrode).

Example 8

Adopt the microelectrode prepared by embodiment 3 to carry out glucose test;

Take 5 microelectrodes (s1-s5) to test the blood sugar content in a certain blood sample (about 10mM), and correct it according to the measured current value; among them, the blood sugar content in the blood sample, tested by YSI, is 9.83mM; Therefore, the sensitivity of these 5 microelectrodes is:

Use these 5 microelectrodes to test three blood samples with different concentrations of blood sugar, and the blood sugar content in the blood samples is measured by YSI:

s1 s2 s3 s4 s5 aver(s1-s5) YSI blood sample 1 3.92 3.83 3.54 3.56 3.44 3.66 3.59 blood sample 2 13.8 14.6 14.3 14.5 13.7 14.18 14.2 blood sample 3 33.9 35.2 32.9 34.2 35.3 34.30 34.6

It can be seen that the microelectrode of the present invention tests the blood sugar content with high accuracy and repeatability.

To sum up, the present invention effectively overcomes various shortcomings in the prior art and has high industrial application value.

The above-mentioned embodiments only illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Anyone skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical ideas disclosed in the present invention should still be covered by the claims of the present invention.

Claims (12)

1. A photocatalytic glucose microelectrode sensor, comprising a substrate, the substrate is provided with a working electrode, a counter electrode and a reference electrode, and the working area of the working electrode is provided with a semiconductor quantum dot modification layer and glucose Oxidase modified layer, the base material is provided with a micro-fiber, the light transmitted by the micro-fiber passes through the working electrode vertically, the semiconductor quantum dot is a CdSeCdS semiconductor quantum dot; the photocatalytic glucose micro The preparation method of the working electrode of the electrode sensor adopts the method of self-assembly layer by layer, including the following steps: a) The indium tin oxide conductive glass electrode as the working electrode is pretreated to make its surface negatively charged; the resulting working electrode is immersed in a mixed aqueous solution of polyallylamine hydrochloride and o-phenanthroline cobalt, and after taking it out, use Rinse it with deionized water and dry it with nitrogen; in the step a), the indium tin oxide conductive glass electrode as the working electrode is pretreated to make its surface negatively charged. The specific steps are: prepare concentrated sulfuric acid/peroxide Hydrogen treatment solution, then put the working electrode area of the microelectrode into the concentrated sulfuric acid/hydrogen peroxide treatment solution, treat it in a constant temperature water bath at 70-80°C for 1-2 hours, take it out from the treatment solution and fully clean it with deionized water; then put The working electrode area of the microelectrode is placed in the hydrogen peroxide/ammonia water treatment solution, treated in a constant temperature water bath at 60-70°C for 1-2 hours, and finally rinsed with deionized water; b) immerse the obtained working electrode in the carbon nanotube aqueous solution, after taking it out, rinse it with deionized water and dry it with nitrogen; c) Dip the obtained working electrode into a mixed aqueous solution of polyallylamine hydrochloride and o-phenanthroline cobalt, after taking it out, rinse it with deionized water and dry it with nitrogen; d) immerse the obtained working electrode in the semiconductor quantum dot aqueous solution, after taking it out, rinse it with deionized water and dry it with nitrogen; e) Dip the obtained working electrode into the mixed aqueous solution of polyallylamine hydrochloride and o-phenanthroline cobalt, after taking it out, rinse it with deionized water and dry it with nitrogen; f) Finally, immerse the obtained working electrode in the prepared aqueous solution of glucose oxidase, take it out, rinse it with deionized water and dry it with nitrogen. 2. A kind of photocatalytic glucose microelectrode sensor as claimed in claim 1, is characterized in that, the surface of described microelectrode sensor is also provided with one deck biocompatibility protection layer. 3. A photocatalytic glucose microelectrode sensor as claimed in claim 1, wherein the working electrode is an indium tin oxide conductive glass electrode. 4. A kind of photocatalytic glucose microelectrode sensor as claimed in claim 1, is characterized in that, described counter electrode is platinum electrode. 5. A kind of photocatalytic glucose microelectrode sensor as claimed in claim 1, is characterized in that, described reference electrode is Ag/AgCl electrode. 6. the preparation method of the working electrode of the photocatalytic glucose microelectrode sensor as claimed in any one of claims 1-5, adopt the method for self-assembly layer by layer, comprising the steps: a) The indium tin oxide conductive glass electrode as the working electrode is pretreated to make its surface negatively charged; the resulting working electrode is immersed in a mixed aqueous solution of polyallylamine hydrochloride and o-phenanthroline cobalt, and after taking it out, use Rinse it with deionized water and dry it with nitrogen; in the step a), the indium tin oxide conductive glass electrode as the working electrode is pretreated to make its surface negatively charged. The specific steps are: prepare concentrated sulfuric acid/peroxide Hydrogen treatment solution, then put the working electrode area of the microelectrode into the concentrated sulfuric acid/hydrogen peroxide treatment solution, treat it in a constant temperature water bath at 70-80°C for 1-2 hours, take it out from the treatment solution and fully clean it with deionized water; then put The working electrode area of the microelectrode is placed in the hydrogen peroxide/ammonia water treatment solution, treated in a constant temperature water bath at 60-70°C for 1-2 hours, and finally rinsed with deionized water; b) immerse the obtained working electrode in the carbon nanotube aqueous solution, after taking it out, rinse it with deionized water and dry it with nitrogen; c) Dip the obtained working electrode into a mixed aqueous solution of polyallylamine hydrochloride and o-phenanthroline cobalt, after taking it out, rinse it with deionized water and dry it with nitrogen; d) immerse the obtained working electrode in the semiconductor quantum dot aqueous solution, after taking it out, rinse it with deionized water and dry it with nitrogen; e) Dip the obtained working electrode into the mixed aqueous solution of polyallylamine hydrochloride and o-phenanthroline cobalt, after taking it out, rinse it with deionized water and dry it with nitrogen; f) Finally, immerse the obtained working electrode in the prepared aqueous solution of glucose oxidase, take it out, rinse it with deionized water and dry it with nitrogen. 7. the preparation method of the working electrode of photocatalytic glucose microelectrode sensor as claimed in claim 6, is characterized in that, in described step a), c), e), polyallylamine hydrochloride and o-phenanthroxine In the mixed aqueous solution of phenanthroline cobalt, the concentration of polyallylamine hydrochloride is 1-2 mg/mL, and the concentration of o-phenanthroline cobalt is 1-2 mg/mL. 8. The preparation method of the working electrode of photocatalytic glucose microelectrode sensor as claimed in claim 6, is characterized in that, in described step b), the concentration of carbon nanotube aqueous solution is 10-20mg/mL. 9. the preparation method of the working electrode of photocatalytic glucose microelectrode sensor as claimed in claim 6, is characterized in that, in described step d), the concentration of semiconductor quantum dot aqueous solution is 1 * 10 ^-6 -5 * 10 ^-6 mol/L. 10. The preparation method of the working electrode of photocatalytic glucose microelectrode sensor as claimed in claim 6, is characterized in that, in described step f), the concentration of glucose oxidase aqueous solution is 10-20mg/mL. 11. the preparation method of the working electrode of photocatalytic glucose microelectrode sensor as claimed in claim 6, is characterized in that, after described step f), also prepare one deck biocompatibility protection layer on gained working electrode surface . 12. Application of the photocatalytic glucose microelectrode sensor according to any one of claims 1-5 in the field of glucose detection.