A nickel-cobalt bimetallic enzyme-free glucose sensor material, a preparation method thereof and a sensor

Abstract

The application discloses a kind of nickel-cobalt bimetallic enzyme-free glucose sensor materials and preparation method thereof, sensor;The nickel-cobalt bimetallic enzyme-free glucose sensor material is the composite material that nickel-cobalt bimetallic organic framework material is modified by nano silver particle;Wherein, the mole ratio of nickel-cobalt bimetallic organic framework material and nano silver particle substance in the composite material is 0.1-1.0:1;The sensor material is the composite material that nano silver particle is modified to nickel-cobalt bimetallic organic framework material, it not only has the advantage that bimetallic organic framework material specific surface area is big, more under the modification of silver particle, make nickel-cobalt bimetallic organic framework material have more excellent conductivity, so as to be used as enzyme-free glucose sensor material, sensor has higher sensitivity and reaction speed, so as to be more conducive to the large-scale application of enzyme-free glucose sensor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of glucose detection, and particularly relates to a nickel-cobalt bimetallic enzyme-free glucose sensor material, a preparation method thereof and a sensor. BACKGROUND

[0002] Yellow water is the main by-product of solid-state fermentation of Chinese liquor, and its quality evaluation is crucial for improving fermentation technology and product control. During the alcoholic fermentation process, starch is converted into glucose through microbial metabolism and saccharification. Glucose flows out with the water produced during fermentation and precipitates at the bottom of the pit to form yellow water. The glucose concentration affects the development of yeast, thereby determining the concentration of ethanol after fermentation. Therefore, the glucose concentration in yellow water plays an important role in fermentation status and product quality control. Real-time and rapid detection of glucose concentration in yellow water is of great significance for monitoring the fermentation process of Chinese liquor and controlling the quality of the product. However, traditional detection methods (such as fluorescence spectroscopy, high-performance liquid chromatography, gas chromatography, and colorimetry) have the disadvantages of expensive detection equipment, large space occupation, long detection time, and complex operation, which are not suitable for detecting the glucose concentration in yellow water. Electrochemical sensors are a new type of glucose concentration detection equipment, which have the advantages of short response time, high sensitivity, and suitability for on-site detection, and are very suitable for rapid detection of glucose concentration in yellow water.

[0003] Enzyme-based glucose electrochemical sensors are a relatively mature and widely used type of electrochemical sensors. They have high specificity and sensitivity and are very suitable for detecting glucose concentration in most environments. However, it has been found through practical application that the enzyme components on the sensor are easily affected by temperature and pH, which can cause the enzyme to lose activity and affect the stability and reproducibility of the detection results, thereby limiting their application in high-temperature, acidic, or alkaline environments. To overcome the above-mentioned defects, researchers have developed enzyme-free glucose electrochemical sensors. Since these sensors do not contain enzyme components, they are not affected by temperature or pH during the detection process, thereby ensuring the accuracy of the detection results and expanding their application range. For example, Chinese Patent Publication No. CN104237340A discloses an enzyme-free electrochemical sensor based on a graphene / nano-gold modified electrode (Gr-Au / GC) and used for detecting glucose content. The invention uses chloroauric acid (HAuCl4) and graphene (Gr) to prepare a modified electrode. The electrode has very high activity for the oxidation of glucose, and the highly dispersed nanoparticles provide a large surface area for electrocatalytic reactions, thereby improving the detection sensitivity, accelerating the electron transfer rate, and enhancing the analysis performance for glucose. However, the use of noble metal gold to prepare the electrochemical sensor increases the production cost, which is not conducive to commercialization and large-scale application.

[0004] In order to reduce the production cost of the sensor, researchers have proposed a kind of enzyme-free electrochemical sensor based on metal organic framework material (MOF). Research has found that metal organic framework material is widely used in catalysis, gas adsorption and separation, drug delivery and other fields due to its large specific surface area, ordered crystal structure and adjustable pore size. Therefore, metal organic framework material has the potential to be used as electrode material of glucose sensor in the field of glucose detection. And there have been reports of using metal organic framework material to make enzyme-free electrochemical sensor for glucose content detection. For example, Chinese patent CN111537589A discloses a method for detecting glucose based on cobalt-based metal organic framework enzyme-free glucose sensor. The method first prepares cobalt-based metal organic framework material, then uses the material to make electrode, and further makes enzyme-free glucose sensor, and uses the sensor to detect glucose content. Although the enzyme-free glucose sensor has the advantages of low production cost, no influence of temperature and pH, and wide detection range, its sensitivity and reaction speed can still be further improved due to the poor conductivity of metal organic framework material itself, and the metal organic framework material in the patent is not modified to enhance the conductivity. SUMMARY

[0005] The purpose of the present application is to further improve the sensitivity and reaction speed of the metal organic framework enzyme-free glucose sensor. A nickel-cobalt bimetallic enzyme-free glucose sensor material and its preparation method and sensor are proposed.

[0006] To achieve the above-mentioned purpose of the application, a nickel-cobalt bimetallic enzyme-free glucose sensor material is proposed. The nickel-cobalt bimetallic enzyme-free glucose sensor material is a composite material modified by nickel-cobalt bimetallic organic framework material and nano silver particles. The molar ratio of nickel-cobalt bimetallic organic framework material to nano silver particles in the composite material is 0.1-1.0:1.

[0007] The nickel-cobalt bimetallic enzyme-free glucose sensor material is a composite material modified by nano silver particles on nickel-cobalt bimetallic organic framework material. It not only has the advantage of large specific surface area of bimetallic organic framework material, but also has more excellent conductivity under the modification of silver particles. Therefore, when it is used as the material of enzyme-free glucose sensor, the sensor has higher sensitivity and reaction speed, which is more conducive to the large-scale application of enzyme-free glucose sensor.

[0008] Preferably, the molar ratio of nickel-cobalt bimetallic organic framework material to nano silver particles in the composite material is 0.2-0.5:1. The preferred molar ratio makes the performance of the composite material better, the cost lower, and the composite material more suitable for commercialization and application.

[0009] The sensing principle of the composite material is:

[0010] (1) (II) (II) ;

[0011] (2) (IV) + glucose (II) (II) + gluconolactone.

[0012] Further, in order to achieve the above-mentioned purposes, the application further provides a preparation method of the nickel-cobalt bimetallic enzyme-free glucose sensor material, comprising the following steps:

[0013] (1) Synthesis of nickel-cobalt bimetallic organic framework material: a cobalt source, a nickel source and 1,4-benzenedicarboxylic acid are mixed and dissolved in a solvent, and reacted at a temperature of 130-150 DEG C for 10-14 h, and then filtered, washed and dried to obtain a nickel-cobalt bimetallic organic framework material; wherein the molar ratio of cobalt ions in the cobalt source to nickel ions in the nickel source is 1-3:1; the molar ratio of cobalt ions in the cobalt source to 1,4-benzenedicarboxylic acid is 1:1; and the solvent is N,N-dimethylformamide and ethanol in a volume ratio of 4-6:1;

[0014] (2) Modification treatment: the nickel-cobalt bimetallic organic framework material obtained in step (1) is uniformly dispersed in water, then a silver ion solution is added, and then stirred uniformly, and then a sodium borohydride solution is added, and then stirred and reacted, and then filtered, washed and dried to obtain a composite material.

[0015] Preferably, in step (1), the molar ratio of cobalt ions in the cobalt source to nickel ions in the nickel source is 2:1; and preferably, the molar ratio makes the structure of the obtained nickel-cobalt bimetallic organic framework material more stable and the specific surface area larger.

[0016] Preferably, in step (1), the volume ratio of N,N-dimethylformamide to ethanol in the solvent is 5:1; and preferably, the volume ratio makes the solubility and dispersibility of the solvent better, which is conducive to improving the specific surface area and stability of the nickel-cobalt bimetallic organic framework material.

[0017] Preferably, in step (1), the cobalt source is Co(NO3)2.6H2O; the nickel source is Ni(NO3)2.6H2O; preferably, the cobalt source and the nickel source have a fast reaction speed, better controllability, and the obtained nickel-cobalt bimetallic organic framework material has better comprehensive performance.

[0018] Preferably, in step (1), the reaction temperature is 140℃, and the reaction time is 12h; preferably, the reaction condition has a faster reaction speed, better controllability, and more thorough reaction.

[0019] Preferably, in step (1), N,N-dimethylformamide and ethanol are used for multiple washing; the drying temperature is 50-70℃, and the drying time is 3-6h; preferably, the washing agent and the drying temperature have better washing effect, fast drying speed, low energy consumption, higher purity of the nickel-cobalt bimetallic organic framework material, and less impurities.

[0020] Preferably, in step (2), the concentration of the nickel-cobalt bimetallic organic framework material in water is 0.4-0.6wt%; most preferably, the concentration of the nickel-cobalt bimetallic organic framework material in water is 0.5wt%; preferably, the concentration has better dispersibility, more uniform dispersion of the nano-silver particles, and better performance of the obtained composite material.

[0021] Preferably, in step (2), the silver ion solution is a silver nitrate hexahydrate solution with a concentration of 0.08-0.12mol / L; most preferably, the concentration of the silver nitrate hexahydrate solution is 0.1mol / L; preferably, the concentration has smaller particle size of the formed nano-silver particles, better dispersion effect, and better modification effect on the nickel-cobalt bimetallic organic framework material.

[0022] Preferably, in step (2), the concentration of the sodium borohydride solution is 0.08-0.12mol / L; most preferably, the concentration of the sodium borohydride solution is 0.1mol / L.

[0023] Preferably, in step (2), water is used for multiple washing; the drying temperature is 50-70℃, and the drying time is 3-6h.

[0024] Further, in order to achieve the above-mentioned purposes, the application further provides a nickel-cobalt bimetallic enzyme-free glucose sensor, wherein the working electrode of the sensor contains the above-mentioned composite material.

[0025] Preferably, the enzyme-free glucose sensor further comprises a reference electrode, a counter electrode, and an electrolyte; the counter electrode is a platinum electrode; the reference electrode is an Ag / AgCl electrode; and the electrolyte is a sodium hydroxide solution.

[0026] Preferably, the preparation method of the working electrode comprises: dispersing the composite material in deionized water to obtain a solution; then dropping the solution on a prepared screen printed carbon electrode (SPE) and drying at room temperature to obtain an enzyme-free glucose sensor working electrode.

[0027] Preferably, the content of the composite material in the working electrode is 0.1-0.5wt%; too much will increase the cost significantly while the performance is not significantly improved.

[0028] Further, in order to achieve the above-mentioned purposes, the application further provides an application method of the nickel-cobalt bimetallic enzyme-free glucose sensor, comprising the following steps:

[0029] (1) connecting the nickel-cobalt bimetallic enzyme-free glucose sensor with an electrochemical workstation;

[0030] (2) testing the current response value of the nickel-cobalt bimetallic enzyme-free glucose sensor to a known concentration of glucose solution under a specified application potential, drawing a chronoamperometric curve according to the current response value corresponding to the glucose concentration, and fitting and drawing a calibration curve according to the current response value corresponding to the glucose concentration;

[0031] (3) placing the detection end of the working electrode in a to-be-tested solution, detecting the size of the current of the to-be-tested solution through the electrochemical workstation, and determining the content of glucose in the to-be-tested solution according to the calibration curve of the glucose concentration and the current response value.

[0032] Compared with the prior art, the application has the following beneficial effects:

[0033] 1. The nickel-cobalt bimetallic enzyme-free glucose sensor material has the advantages of a large specific surface area of the bimetallic organic framework material, and under the modification of silver particles, the nickel-cobalt bimetallic organic framework material has more excellent conductivity, so that when the material is used as an enzyme-free glucose sensor, the sensor has higher sensitivity and reaction speed, thereby being more conducive to the large-scale application of the enzyme-free glucose sensor.

[0034] 2. The preparation method of the nickel-cobalt bimetallic enzyme-free glucose sensor material is simple, reliable, stable, easy to industrialize, and conducive to the large-scale and industrialized production of the enzyme-free glucose sensor.

[0035] 3. The nickel-cobalt bimetallic enzyme-free glucose sensor is not affected by temperature, has fast detection speed (4s to reach steady-state current), wide detection range (low detection limit (2.3 μM), wide linear range (5-5235 μM)), and sensitivity up to 1191.84 A•mM-1•cm-2. BRIEF DESCRIPTION OF DRAWINGS:

[0036] Figure 1 FESEM and TEM images of the nickel-cobalt bimetallic organic framework material (NiCo-MOF) and the composite material (AgNPs@NiCo-MOF) in Example 1 of the present application; wherein, (a) FESEM image of NiCo-MOF; (b) FESEM image of AgNPs@NiCo-MOF; (c) TEM image of NiCo-MOF; (d) TEM image of AgNPs@NiCo-MOF.

[0037] Figure 2 XPS spectrum of the composite material (AgNPs@NiCo-MOF) in Example 1 of the present application, wherein, (a) XPS spectrum of AgNPs@NiCo-MOF; (b) high-resolution spectrum of C 1s; (c) high-resolution spectrum of O 1s; (d, e) high-resolution spectrum of Ni 2p and Co 2p; (f) high-resolution spectrum of Ag 3d.

[0038] Figure 3 Performance chart of the nickel-cobalt bimetallic enzyme-free glucose sensor in Example 1 of the present application; wherein, (a) current response of AgNPs@NiCo-MOF under 0.55 V voltage with continuous addition of glucose; (b) magnified view of low glucose concentration; (c) corresponding linear calibration curve of a; (d) response time of AgNPs@NiCo-MOF / SPE.

[0039] Figure 4 Current response chart of the nickel-cobalt bimetallic enzyme-free glucose sensor under different conditions (0.1M NaOH with 500 μM glucose, 50 μM NaCl, 50 μM AA, 50 μM ethanol, and 50 μM Fru) in Example 1 of the present application.

[0040] Figure 5 Performance chart of the nickel-cobalt bimetallic enzyme-free glucose sensor in Example 1 of the present application; wherein, (a) current response of different AgNPs@NiCo-MOF / SPE electrodes to 500 μM glucose; (b) change of current response of AgNPs@NiCo-MOF / SPE to 500 μM glucose with storage time. DETAILED DESCRIPTION

[0041] The present application will be further described in conjunction with test examples and specific embodiments. However, this should not be understood as limiting the scope of the above-mentioned subject matter of the present application to the following examples only, and any technology realized based on the content of the present application falls within the scope of the present application.

[0042] Example 1:

[0043] A nickel-cobalt bimetallic enzyme-free glucose sensor, the specific preparation method is as follows:

[0044] (1) Synthesis of NiCo-MOF: Co(NO3)2•6H2O (2 mmol), Ni(NO3)2•6H2O (1 mmol) and 1,4-benzenedicarboxylic acid (2 mmol) were dissolved in a mixed solution of N,N-dimethylformamide and ethanol (DMF, 50 mL; ethanol, 10 mL) in a 100 mL Teflon-lined autoclave. The autoclave was heated at 140°C for 12 h. The obtained product was washed with DMF and ethanol several times, and then dried at 60°C for 12 hours, and NiCo-MOF was collected (Yield: 1.2 g, 97.5%). Figure 1 a, c) in the specification;

[0045] (2) Synthesis of AgNPs@NiCo-MOF: 50 mg of NiCo-MOF obtained in step (1) was dispersed in 10 mL of deionized water, and then 1 mL of 0.1 mol / L silver nitrate (Ag(NO3)2•6H2O) solution was added dropwise under stirring. Then the mixture was stirred for 30 minutes, and then 1 mL of 0.1 mol / L sodium borohydride (BH4Na) solution was added under stirring. The mixture was stirred for another 30 minutes, and the obtained product was washed with deionized water several times and dried at 60°C for 12 hours, and AgNPs@NiCo-MOF was collected (Yield: 1.2 g, 97.5%). Figure 1 b, d) in the specification.

[0046] (3) Sensor preparation: 6.0 mg of AgNPs@NiCo-MOF composite material prepared in step (2) was weighed and dispersed in 1 mL of deionized water in an ultrasonic instrument to obtain a uniformly dispersed AgNPs@NiCo-MOF solution. 6 μL of the mixed solution was added dropwise on a prepared clean screen printed carbon electrode (SPE), and dried at room temperature to obtain AgNPs@NiCo-MOF / SPE.

[0047] The AgNPs@NiCo-MOF prepared above was detected by X-ray photoelectron spectroscopy, and the results are shown in Figure 2 .

[0048] The AgNPs@NiCo-MOF / SPE prepared above was made into a sensor, and the related performance detection results are as follows Figure 3 , 4 , 5;

[0049] The specific detection method is as follows:

[0050] (1) The AgNPs@NiCo-MOF / SPE is used as the working electrode, the Ag / AgCl electrode is used as the reference electrode, the platinum electrode is used as the counter electrode, a three-electrode system is established, a NaOH solution is used as the electrolyte, and the three-electrode system is connected with an electrochemical workstation;

[0051] (2) The current response value of the AgNPs@NiCo-MOF / SPE to a known concentration of glucose solution is tested under an applied potential of 0.55 V, a chronoamperometric curve is drawn according to the current response value corresponding to the glucose concentration, and a calibration curve is fitted and drawn according to the current response value corresponding to the glucose concentration;

[0052] (3) The detection end of the working electrode is placed in the to-be-tested solution, the size of the current of the to-be-tested solution is detected through the electrochemical workstation, and the content of glucose in the to-be-tested solution is determined according to the calibration curve of the glucose concentration and the current response value.

Claims

1. A nickel-cobalt bimetallic enzyme-free glucose sensor, characterized in that, The working electrode of the sensor contains a nickel-cobalt bimetallic enzyme-free glucose sensor material. The nickel-cobalt bimetallic enzyme-free glucose sensor material is a composite material made of nickel-cobalt bimetallic organic framework material modified with silver nanoparticles; wherein the molar ratio of nickel-cobalt bimetallic organic framework material to silver nanoparticles in the composite material is 0.1-1.0:

1. The preparation method of the nickel-cobalt bimetallic enzyme-free glucose sensor material includes the following steps: (1) Synthesis of nickel-cobalt bimetallic organic framework material: Cobalt source, nickel source and 1,4-phthalic acid are mixed and dissolved in a solvent, reacted at 130-150℃ for 10-14h, filtered, washed and dried to obtain nickel-cobalt bimetallic organic framework material; wherein, the molar ratio of cobalt ions in the cobalt source to nickel ions in the nickel source is 1-3:1; the molar ratio of cobalt ions in the cobalt source to 1,4-phthalic acid is 1:1; the solvent is N,N-dimethylformamide and ethanol in a volume ratio of 4-6:1; (2) Modification treatment: After the nickel-cobalt bimetallic organic framework material obtained in step (1) is evenly dispersed in water, silver ion solution is added, and after mixing and stirring evenly, sodium borohydride solution with a concentration of 0.08-0.12 mol / L is added. After stirring and reacting, the composite material is obtained by filtration, washing and drying. The concentration of nickel-cobalt bimetallic organic framework material in water is 0.4-0.6 wt%.

2. The nickel-cobalt bimetallic enzyme-free glucose sensor according to claim 1, characterized in that, The ratio of nickel-cobalt bimetallic organic framework material to silver nanoparticles in the composite material is 0.2-0.5:

1.

3. The nickel-cobalt bimetallic enzyme-free glucose sensor according to claim 1, characterized in that, The volume ratio of N,N-dimethylformamide to ethanol in the solvent described in step (1) is 5:

1.

4. The nickel-cobalt bimetallic enzyme-free glucose sensor according to claim 1, characterized in that, The cobalt source mentioned in step (1) is Co(NO3)2•6H2O; the nickel source is Ni(NO3)2•6H2O.

5. The nickel-cobalt bimetallic enzyme-free glucose sensor according to claim 1, characterized in that, In step (2), the silver ion solution is a silver nitrate hexahydrate solution with a concentration of 0.08-0.12 mol / L.

6. The nickel-cobalt bimetallic enzyme-free glucose sensor according to any one of claims 1-5, characterized in that, The content of the nickel-cobalt bimetallic enzyme-free glucose sensor material in the working electrode is 0.1-0.5%wt.

Images