Application of monoclinic lanthanum vanadate as a mimetic enzyme in the determination of hydrogen peroxide and glucose

Abstract

The present invention proposes a monoclinic lanthanum vanadate as a simulated enzyme in the determination of hydrogen peroxide and glucose application. The monoclinic lanthanum vanadate of the present invention is a cubic structure, the particle size of the monoclinic lanthanum vanadate is 400-500nm, the monoclinic lanthanum vanadate is used as a simulated enzyme to directly determine the concentration of hydrogen peroxide, and the monoclinic lanthanum vanadate is used as a simulated enzyme to indirectly determine the concentration of glucose. The monoclinic lanthanum vanadate of the present invention is a cubic structure, highly crystalline, large specific surface area, high active site, with good catalytic performance of simulated peroxidase, used as a simulated enzyme to determine the concentration of hydrogen peroxide and glucose, hydrogen peroxide can be rapidly detected, and a kind of indirect, rapid and accurate determination method is provided for glucose detection, this detection method has good selectivity, strong anti-interference, stable measurement results, good repeatability, has been successfully used in the determination of glucose in human serum, and has potential application prospects in the fields of biomedicine and environmental detection.

Description

Technical Field

[0001] The invention relates to the technical field of enzyme simulation, in particular to the application of monoclinic lanthanum vanadate as enzyme simulation in the determination of hydrogen peroxide and glucose. Background Art

[0002] Natural enzymes play an important role in most catalytic reactions in living systems due to their advantages of high efficiency and specificity. However, natural enzymes have inherent disadvantages that are difficult to overcome, such as complex purification, easy inactivation, poor stability under extreme conditions, etc., which limit the practical application of natural enzymes. Therefore, in order to overcome these shortcomings of natural enzymes, researchers have been committed to developing a variety of artificial enzymes with different materials to simulate the structure, properties and functions of natural enzymes. Among them, nanomaterials are a very promising candidate material. Due to their unique advantages such as large specific surface area, adjustable catalytic performance and excellent catalytic activity, they have attracted widespread attention and have broad application prospects in biosensor development, in situ ecological restoration, medical imaging, etc.

[0003] Vanadate nanomaterials are considered to be promising natural enzyme substitutes due to their special structure and flexibility. The vanadate nanomaterials used as enzyme mimics in the prior art mainly include cerium vanadate and silver vanadate. However, cerium vanadate has low utilization rate of sunlight and poor adsorption performance for degradation substrates, which hinders its practical application as an enzyme mimic. Silver vanadate has poor stability and is easily oxidized by air when exposed to air. In addition, the recombination rate of electron-hole pairs is high, which limits its catalytic activity. Summary of the invention

[0004] The purpose of the present invention is to provide a monoclinic lanthanum vanadate for use as a mimetic enzyme in the determination of hydrogen peroxide and glucose, aiming to solve the problems in the prior art that the cerium vanadate nanomaterial used as a mimetic enzyme has low utilization rate of sunlight and poor adsorption performance for degradation substrates, thereby hindering its practical application as a mimetic enzyme, and the silver vanadate nanomaterial has poor stability, is easy to oxidize, and has a high recombination rate of electron-hole pairs, which limits its catalytic activity.

[0005] In order to solve the above technical problems, the technical solution of the present invention is achieved as follows:

[0006] The present invention discloses an application of a monoclinic lanthanum vanadate as a simulated enzyme in the determination of hydrogen peroxide and glucose. The monoclinic lanthanum vanadate has a cubic structure and a particle size of 400-500 nm. The monoclinic lanthanum vanadate is used as a simulated enzyme to directly determine the concentration of hydrogen peroxide, and the monoclinic lanthanum vanadate is used as a simulated enzyme to indirectly determine the concentration of glucose.

[0007] The monoclinic lanthanum vanadate (m-LaVO 4 ) space group is P21 / n(14), lattice parameters Each V atom is at the center of a tetrahedron formed by four O atoms, and the La atom is at the center of the tetrahedron formed by four O atoms. 4 The O atoms on the tetrahedron are connected. In addition, due to La 3+ The ionic radius of LaVO is too large to 4 The stable phase is the monoclinic phase, which is superior to the tetragonal lanthanum vanadate (t-LaVO) in catalytic and luminescent properties. 4 ) is poor. However, the monoclinic lanthanum vanadate of the present invention is a cubic structure, highly crystalline, large specific surface area, high active sites, and has good catalytic performance of simulating peroxidase. It is used as a simulated enzyme to measure the concentration of hydrogen peroxide and glucose, and can quickly detect hydrogen peroxide; because glucose can be catalyzed by glucose oxidase to generate gluconic acid and hydrogen peroxide, the monoclinic lanthanum vanadate of the present invention also provides an indirect, rapid and accurate determination method for glucose detection. This detection method has good selectivity, strong anti-interference ability, stable measurement results and good repeatability. It has been successfully used for the determination of glucose in human serum and has potential application prospects in the fields of biomedicine and environmental testing.

[0008] As a preferred embodiment, the method comprises the following steps: sequentially adding phosphate buffer, a test solution, 3,3',5,5'-tetramethylbenzidine ethanol solution and a monoclinic lanthanum vanadate dispersion into a reaction container, observing the color change of the solution after reacting for 7 minutes, and recording the ultraviolet visible absorption spectrum at 400-800nm, wherein the test solution is a hydrogen peroxide solution or a glucose solution. When the monoclinic lanthanum vanadate of the present invention is used as a mimetic enzyme to measure the concentration of hydrogen peroxide and glucose, the detection method is convenient, the selectivity is good, the anti-interference ability is strong, the measurement result is stable, and the repeatability is good.

[0009] As a preferred embodiment, the pH value of the phosphate buffer is 4, the molar concentration of the phosphate buffer is 50 mmol / L, and the molar ratio of the phosphate buffer to the test solution is 28-32:1; the molar concentration of the 3,3',5,5'-tetramethylbenzidine ethanol solution is 8 mmol / L, and the molar ratio of 3,3',5,5'-tetramethylbenzidine to the test solution is 0.7-0.9:1; the mass concentration of the monoclinic lanthanum vanadate dispersion is 100 μg / mL, and the molar ratio of the monoclinic lanthanum vanadate to the test solution is 0.03-0.05:1. The phosphate buffer provided by the invention has good performance, is easy to prepare, has a fast dissolution speed, high solubility and good use effect; when the monoclinic lanthanum vanadate is used as a simulated enzyme to measure the concentrations of hydrogen peroxide and glucose, the substances to be measured (hydrogen peroxide and glucose) and the color developer are called substrates, 3,3',5,5'-tetramethylbenzidine is the color developer, and the reaction system changes from colorless to blue, the color change is obvious, and it is convenient to observe; when the monoclinic lanthanum vanadate is used as a simulated enzyme to measure the concentrations of hydrogen peroxide and glucose, the dosage is small, the cost is low and the utilization value is high.

[0010] As a preferred embodiment, the detection limit of the monoclinic lanthanum vanadate as a simulated enzyme for determining the concentration of hydrogen peroxide is 0.067 μM, and the detection limit of the monoclinic lanthanum vanadate as a simulated enzyme for determining the concentration of glucose is 0.834 μM. The monoclinic lanthanum vanadate of the present invention has a very low detection limit and ultra-high sensitivity when used as a simulated enzyme to determine the concentration of hydrogen peroxide and glucose. Therefore, the monoclinic lanthanum vanadate of the present invention has high catalytic activity and strong catalytic ability.

[0011] As a preferred embodiment, the linear equation when the monoclinic lanthanum vanadate is used as a simulated enzyme to measure the concentration of hydrogen peroxide is A652 nm=1.8117C+0.0069, and the linear equation when the monoclinic lanthanum vanadate is used as a simulated enzyme to measure the concentration of glucose is A652nm=2.5136C+0.0023, and the unit of C is mM. The linear equations of the present invention are obtained through experimental fitting, and the two linear equations have good fitting and wide versatility; when the monoclinic lanthanum vanadate is used as a simulated enzyme to measure the concentration of hydrogen peroxide or glucose, it is only necessary to measure its absorbance at 652nm, and the corresponding concentration can be calculated by the above equation, which is convenient for calculation and the results are accurate and reliable.

[0012] As a preferred embodiment, the preparation method of the monoclinic lanthanum vanadate is as follows: 1) taking lanthanum nitrate, adding ultrapure water, stirring, and obtaining a lanthanum nitrate solution, wherein the molar concentration of the lanthanum nitrate solution is 0.03-0.04 mmol / mL; 2) taking ammonium metavanadate, adding ultrapure water, stirring, and obtaining an ammonium metavanadate solution, wherein the molar concentration of the ammonium metavanadate solution is 0.03-0.04 mmol / mL; 3) mixing the lanthanum nitrate solution obtained in step 1) with the ammonium metavanadate solution obtained in step 2), wherein the molar ratio of lanthanum nitrate to metavanadic acid is 1:1, and stirring uniformly to obtain a mixed solution; 4) adjusting the pH value of the mixed solution obtained in step 3) to 3.5-4.5, placing the mixed solution in a reactor, performing a hydrothermal reaction at 180° C. for 20-30 hours, taking it out, and cooling it; 5) centrifuging, washing, and drying to obtain the monoclinic lanthanum vanadate.

[0013] The monoclinic lanthanum vanadate of the present invention is obtained by a one-step hydrothermal reaction. The preparation method has a short process flow, simple operation, mild reaction conditions, easy control, low reaction temperature, low energy consumption, short reaction time, high production efficiency, low cost, and has potential application prospects in the fields of biomedicine and environmental testing.

[0014] As a preferred embodiment, in step 5), the washing is carried out by washing with ultrapure water and ethanol in sequence, and the washing times are 3-5 times. The present invention uses ultrapure water and ethanol to wash the hydrothermal reaction product, centrifugally separates after each washing, and washes 3-5 times to make it thoroughly washed.

[0015] As a preferred embodiment, in step 5), the speed of centrifugation is 5000-6000 r / min, and the centrifugation time is 4-6 min. The hydrothermal reaction product of the present invention is separated by centrifugation, and the speed and time of centrifugation are controlled to achieve effective separation and convenient operation.

[0016] As a preferred embodiment, in step 5), the drying is oven drying, the drying temperature is 50-70°C, and the drying time is 10-14h. The hydrothermal reaction product of the present invention is dried in an oven after washing, and the water and solvents such as ethanol contained therein are removed through low-temperature drying; this drying method is convenient and easy to control.

[0017] As a preferred embodiment, the molar ratio of lanthanum, vanadium and oxygen in the monoclinic lanthanum vanadate is 1:1:4. The molecular formula of the monoclinic lanthanum vanadate obtained in the present invention is m-LaVO 4 , molecular weight is 253, each V atom is at the center of a tetrahedron formed by four O atoms, and the La atom is in contact with nine VO atoms. 4 The O atoms on the tetrahedron are connected.

[0018] Compared with the prior art, the present invention has the following beneficial effects: the monoclinic lanthanum vanadate of the present invention has a cubic structure, is highly crystalline, has a large specific surface area, has a high active site, has good catalytic performance of simulating peroxidase, is used as a simulated enzyme to measure the concentration of hydrogen peroxide and glucose, and can quickly detect hydrogen peroxide; because glucose can be catalyzed by glucose oxidase to generate gluconic acid and hydrogen peroxide, the monoclinic lanthanum vanadate of the present invention also provides an indirect, rapid and accurate determination method for glucose detection, and the detection method has good selectivity, strong anti-interference ability, stable measurement results and good repeatability, has been successfully used for the determination of glucose in human serum, and has potential application prospects in the fields of biomedicine and environmental detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the XRD pattern of the monoclinic lanthanum vanadate obtained in Example 1 of the present invention;

[0020] Figure 2 This is a TEM image of the monoclinic lanthanum vanadate obtained in Example 1 of the present invention;

[0021] Figure 3 The wavelength and absorbance curve of the reaction system obtained in Example 2 of the present invention;

[0022] Figure 4 The reaction kinetics curve of the reaction system obtained in Example 3 of the present invention;

[0023] Figure 5 The concentration and absorbance curve of the reaction system obtained in Example 3 of the present invention;

[0024] Figure 6 The reaction kinetics curve of the reaction system obtained in Example 4 of the present invention;

[0025] Figure 7 The concentration and absorbance curve of the reaction system obtained in Example 4 of the present invention is shown;

[0026] Figure 8 This is a stability bar graph of the reaction system obtained in Example 5 of the present invention;

[0027] Fig. 9 This is a stability curve diagram of the reaction system obtained in Example 5 of the present invention;

[0028] Fig.10 This is a selectivity diagram of the hydrogen peroxide series reaction system obtained in Example 6 of the present invention;

[0029] Fig.11 This is a selectivity diagram of the glucose series reaction system obtained in Example 6 of the present invention. DETAILED DESCRIPTION

[0030] The technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0031] The present invention discloses an application of a monoclinic lanthanum vanadate as a simulated enzyme in the determination of hydrogen peroxide and glucose. The monoclinic lanthanum vanadate has a cubic structure and a particle size of 400-500 nm. The monoclinic lanthanum vanadate is used as a simulated enzyme to directly determine the concentration of hydrogen peroxide, and the monoclinic lanthanum vanadate is used as a simulated enzyme to indirectly determine the concentration of glucose.

[0032] Preferably, the method comprises the following steps: sequentially adding a phosphate buffer solution, a test solution, a 3,3',5,5'-tetramethylbenzidine ethanol solution and a monoclinic lanthanum vanadate dispersion into a reaction container, observing the color change of the solution after reacting for 7 minutes, and recording the ultraviolet-visible absorption spectrum at 400-800 nm, wherein the test solution is a hydrogen peroxide solution or a glucose solution.

[0033] Furthermore, the pH value of the phosphate buffer is 4, the molar concentration of the phosphate buffer is 50 mmol / L, and the molar ratio of the phosphate buffer to the solution to be tested is 28-32:1; the molar concentration of the 3,3',5,5'-tetramethylbenzidine ethanol solution is 8 mmol / L, and the molar ratio of 3,3',5,5'-tetramethylbenzidine to the solution to be tested is 0.7-0.9:1; the mass concentration of the monoclinic lanthanum vanadate dispersion is 100 μg / mL, and the molar ratio of the monoclinic lanthanum vanadate to the solution to be tested is 0.03-0.05:1.

[0034] Preferably, the detection limit of the monoclinic lanthanum vanadate when used as a simulated enzyme to measure the concentration of hydrogen peroxide is 0.067 μM, and the detection limit of the monoclinic lanthanum vanadate when used as a simulated enzyme to measure the concentration of glucose is 0.834 μM.

[0035] Preferably, when the monoclinic lanthanum vanadate is used as a simulated enzyme to measure the concentration of hydrogen peroxide, the linear equation is A652 nm=1.8117C+0.0069; when the monoclinic lanthanum vanadate is used as a simulated enzyme to measure the concentration of glucose, the linear equation is A652 nm=2.5136C+0.0023, and the unit of C is mM.

[0036] Preferably, the preparation method of the monoclinic lanthanum vanadate is as follows: 1) taking lanthanum nitrate, adding ultrapure water, stirring, and obtaining a lanthanum nitrate solution, wherein the molar concentration of the lanthanum nitrate solution is 0.03-0.04 mmol / mL; 2) taking ammonium metavanadate, adding ultrapure water, stirring, and obtaining an ammonium metavanadate solution, wherein the molar concentration of the ammonium metavanadate solution is 0.03-0.04 mmol / mL; 3) mixing the lanthanum nitrate solution obtained in step 1) with the ammonium metavanadate solution obtained in step 2), wherein the molar ratio of lanthanum nitrate to metavanadic acid is 1:1, and stirring evenly to obtain a mixed solution; 4) adjusting the pH value of the mixed solution obtained in step 3) to 3.5-4.5, placing the mixed solution in a reactor, performing a hydrothermal reaction at 180° C. for 20-30 hours, removing the mixed solution, and cooling the mixed solution; 5) centrifuging, washing, and drying to obtain the monoclinic lanthanum vanadate.

[0037] Furthermore, in step 5), washing is performed sequentially with ultrapure water and ethanol, and the number of washing times is 3-5 times.

[0038] Furthermore, in the step 5), the rotation speed during centrifugation is 5000-6000 r / min, and the centrifugation time is 4-6 min.

[0039] Furthermore, in step 5), the drying is oven drying, the drying temperature is 50-70° C., and the drying time is 10-14 hours.

[0040] Preferably, in the monoclinic lanthanum vanadate, the molar ratio of lanthanum, vanadium and oxygen is 1:1:4.

[0041] Embodiment 1

[0042] Preparation of Monoclinic Lanthanum Vanadate Enzyme Mimicking Material

[0043] 1) Take lanthanum nitrate hexahydrate (La(NO 3 ) 3 6H 2 O) 433 mg, add 30 mL of ultrapure water, stir, dissolve, and obtain lanthanum nitrate solution;

[0044] 2) Take ammonium metavanadate (NH 4 VO 3 ) 117 mg, add 30 mL of ultrapure water, stir and dissolve to obtain ammonium metavanadate solution;

[0045] 3) mixing the lanthanum nitrate solution obtained in step 1) with the ammonium metavanadate solution obtained in step 2), wherein the molar ratio of lanthanum nitrate to metavanadic acid is 1:1, and stirring evenly to obtain a mixed solution;

[0046] 4) adjusting the pH value of the mixed solution obtained in step 3) to 4.0, placing it in a 100 mL polytetrafluoroethylene reactor, hydrothermally reacting it in an oven at 180° C. for 24 hours, taking it out, and cooling it;

[0047] 5) Centrifuge at 5000 r / min for 5 min, wash three times with methanol, and dry in an oven at 60° C. for 12 h to obtain monoclinic lanthanum vanadate.

[0048] The monoclinic lanthanum vanadate obtained above was placed on a Rigaku Ultima IV X-ray diffractometer produced by Japan Rigaku Co., Ltd. for measurement. Figure 1 It can be seen that the positions of most of the diffraction peaks of the monoclinic lanthanum vanadate obtained in the present invention are similar to those of the standard monoclinic lanthanum vanadate m-LaVO 4 (JCPDS NO50-0367) and no impurity phase is present; therefore, the sample obtained in the present invention is a pure monoclinic lanthanum vanadate structure. Figure 1 It can also be seen that the diffraction peak intensity of the sample obtained in the present invention is relatively large and the diffraction peak is relatively sharp, which indicates that the monoclinic lanthanum vanadate mimetic enzyme material obtained in the present invention has good crystallinity.

[0049] The monoclinic lanthanum vanadate obtained above was placed on a JEOL JEM-2100 transmission electron microscope produced by Japan Electron Technology Co., Ltd. for measurement. Figure 2 It can be seen that the monoclinic lanthanum vanadate m-LaVO obtained in the present invention 4 The overall appearance is a cubic structure with an average size of about 453nm. This cubic structure has a large specific surface area and can provide more catalytic active sites for the reaction, thereby increasing the reaction rate.

[0050] Embodiment 2

[0051] Validation of monoclinic lanthanum vanadate as a mimetic enzyme for the determination of hydrogen peroxide

[0052] 1) Take phosphate buffer saline (PBS) with a pH value of 4.0 and a concentration of 50 mmol / L, 3,3',5,5'-tetramethylbenzidine ethanol solution (TMB ethanol solution) with a concentration of 8 mmol / L, and H 2 O 2 Solution, set aside;

[0053] 2) adding water to the monoclinic lanthanum vanadate obtained in Example 1 to prepare a monoclinic lanthanum vanadate dispersion with a concentration of 100 μg / mL for later use;

[0054] 3) Take 4 centrifuge tubes with a volume of 1.5 mL and label them as a, b, c and d. In the centrifuge tube a, add 600 μL of the above phosphate buffer, 200 μL of the above H 2 O 2solution and 100 μL of the monoclinic lanthanum vanadate dispersion; in centrifuge tube b, add 600 μL of the phosphate buffer, 100 μL of the TMB ethanol solution and 100 μL of the monoclinic lanthanum vanadate dispersion; in centrifuge tube c, add 600 μL of the phosphate buffer, 100 μL of the TMB ethanol solution and 200 μL of the H 2 O 2 Solution; in the centrifuge tube No. d, add 600 μL of the above phosphate buffer, 100 μL of the above TMB ethanol solution, 200 μL of the above H 2 O 2 solution and 100 μL of the above monoclinic lanthanum vanadate dispersion; each centrifuge tube was reacted for 7 min, the solution changes were observed, and the solution was placed on a U-3900H UV-visible absorption spectrometer produced by Hitachi High-Tech Corporation to measure the absorbance at 400-800 nm.

[0055] By the attached Figure 3 It can be seen that the wavelength of 652nm is the characteristic absorption peak of oxidized TMB; a(H 2 O 2 +m-LaVO 4 )、b(TMB+m-LaVO 4 ) and c(TMB+H 2 O 2 ) centrifuge tube had almost no absorption peak, however, d(TMB+H 2 O 2 +m-LaVO 4 ) centrifuge tube has an obvious absorption peak at 652nm, and the peak shape is better.

[0056] In addition, experimental observations show that a(H 2 O 2 +m-LaVO 4 )、b(TMB+m-LaVO 4 ) and c(TMB+H 2 O 2 The color of the solution in the centrifuge tube was colorless and transparent, without obvious change; however, d(TMB+H 2 O 2 +m-LaVO 4 ) showed a distinct blue color, which indicated that m-LaVO 4 In H 2 O 2 In the presence of , TMB was catalytically oxidized to generate blue oxide. 4 The enzyme-mimicking material has good catalytic activity of simulated peroxidase and is a peroxidase-mimicking material. 2 O2 In the presence of , TMB can be catalyzed to generate blue oxides. This color reaction can be used to quickly detect H 2 O 2 .

[0057] Embodiment 3

[0058] A monoclinic lanthanum vanadate is used as a simulated enzyme in the determination of hydrogen peroxide, comprising the following steps:

[0059] 1) Take phosphate buffer saline (PBS) with a pH value of 4.0 and a concentration of 50 mmol / L, 3,3',5,5'-tetramethylbenzidine ethanol solution (TMB ethanol solution) with a concentration of 8 mmol / L, and H 2 O 2 Solution, set aside;

[0060] 2) adding water to the monoclinic lanthanum vanadate obtained in Example 1 to prepare a monoclinic lanthanum vanadate dispersion with a concentration of 100 μg / mL for later use;

[0061] 3) Take hydrogen peroxide (H 2 O 2 ), adding water to prepare hydrogen peroxide solutions with concentrations of 0, 0.002, 0.005, 0.010, 0.020, 0.030, 0.100, 0.200, 0.300, and 0.500 mmol / L, respectively;

[0062] 4) Take 10 centrifuge tubes with a volume of 1.5 mL, mark them as ①, ②, ③, ④, ⑤, ⑥, ⑦, ⑧, ⑨, and ⑩, add 700 μL of the above-mentioned phosphate buffered saline (PBS), 100 μL of the above-mentioned TMB ethanol solution, 100 μL of the above-mentioned monoclinic phase lanthanum vanadate dispersion and 100 μL of the above-mentioned hydrogen peroxide solution of different concentrations, respectively, place them on a U-3900H UV-visible absorption spectrometer produced by Hitachi High-Tech Corporation, and measure the absorbance-time curve at 652 nm.

[0063] By the attached Figure 4 and attached Figure 5 It can be seen that under the optimal conditions, the absorbance of oxidized TMB depends on the hydrogen peroxide concentration between 0-50 μM. In the linear range of 2-30 μM, the hydrogen peroxide concentration is positively correlated with the absorbance, and the detection limit is 0.067 μM (S / N=3). The linear regression equation is A652 nm=1.8117C+0.0069(R 2 =0.9978), where C is the concentration of hydrogen peroxide (expressed in mM).

[0064] Therefore, monoclinic lanthanum vanadate as a mimetic enzyme has a very low detection limit and ultra-high sensitivity in determining the concentration of hydrogen peroxide.

[0065] Embodiment 4

[0066] A monoclinic lanthanum vanadate is used as a simulated enzyme in the determination of glucose, comprising the following steps:

[0067] 1) Take phosphate buffered saline (PBS) with a pH value of 4.0 and a concentration of 50 mmol / L, 3,3',5,5'-tetramethylbenzidine ethanol solution (TMB ethanol solution) with a concentration of 8 mmol / L, glucose solution with a concentration of 5 mmol / L, and glucose oxidase solution with a concentration of 5 mg / mL, and set aside;

[0068] 2) adding water to the monoclinic lanthanum vanadate obtained in Example 1 to prepare a monoclinic lanthanum vanadate dispersion with a concentration of 100 μg / mL for later use;

[0069] 3) Take the glucose solution and add water to prepare glucose solutions with concentrations of 0, 0.005, 0.010, 0.025, 0.050, 0.100, 0.250, 0.500, 1.000, and 2.000 mmol / L, respectively;

[0070] 4) Take 10 centrifuge tubes with a volume of 1.5 mL, mark them as 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10, add 700 μL of the above-mentioned phosphate buffered saline (PBS), 100 μL of the above-mentioned TMB ethanol solution, 100 μL of the above-mentioned monoclinic lanthanum vanadate dispersion, 100 μL of the above-mentioned glucose solutions of different concentrations and 20 μL of the above-mentioned glucose oxidase solution, respectively, place them on a U-3900H UV-visible absorption spectrometer produced by Hitachi High-Technologies Corporation, and measure the absorbance-time curve at 652 nm.

[0071] By the attached Figure 6 and attached Figure 7 It can be seen that the absorbance value of the reaction system at 652nm increases with the increase of glucose concentration, and there is an obvious color change; it shows a linear growth trend in the low glucose concentration range, the linear regression equation is A652nm=2.5136C+0.0023, and the linear range is 5-100μM (R 2 =0.9964), the detection limit for glucose is 0.834 μM (S / N=3), and C is the concentration of glucose (expressed in mM).

[0072] This is because: in glucose detection, glucose oxidase (GOx) converts glucose into gluconic acid, and the generated hydrogen peroxide acts as LaVO 4substrate, which can effectively catalyze the oxidation of colorless TMB into a blue product for detecting glucose content. 4 The detection limit of the catalyst was low, which indicated that the sensor had extraordinary application potential in hydrogen peroxide and glucose determination.

[0073] Embodiment 5

[0074] Stability of a monoclinic lanthanum vanadate as a mimetic enzyme in the determination of hydrogen peroxide and glucose (I) Cyclic catalytic experiment

[0075] According to the method of centrifuge tube b in Example 2, 10 portions of the reaction system were prepared and placed on a U-3900H UV-visible absorption spectrometer produced by Hitachi High-Technologies Corporation to measure the absorbance at 625 nm. Figure 8 and 9 It can be seen that the absorbance and blue signal of all reaction systems at 652 nm did not change significantly, which indicates that the obtained reaction system has good stability.

[0076] (II) Selective Experiment

[0077] According to the method of the centrifuge tube No. d in Example 2, the substrates were prepared to contain hydrogen peroxide, Fe 3+ 、Al 3+ Br - 、NO 3 - , Glu, Fru, Gly, Lys and diluted AL reaction system, wherein the concentration of hydrogen peroxide in the reaction system is 0.5mM, Fe 3+ 、Al 3+ Br - 、NO 3 - The concentration of Glu, Fru, Gly, Lys and diluted AL in the reaction system is 10.0 mM, and 10 parts of the reaction system are obtained. 3+ 、Al 3+ Br - 、NO 3 - , Glu, Fru, Gly, Lys and diluted AL were used as interfering substances of hydrogen peroxide, so that hydrogen peroxide was replaced by different ions and biomacromolecules, while keeping all other conditions unchanged; the 10 solutions obtained were placed on the U-3900H UV-visible absorption spectrometer produced by Hitachi High-Technologies Corporation, and the absorbance at 625nm was measured. Fig.10It can be seen that under the same conditions, except for the diluted AL (containing 0.5 mM hydrogen peroxide) and hydrogen peroxide, the absorbance of the solutions in the other reaction systems did not increase significantly. This indicates that the monoclinic lanthanum vanadate of the present invention has good specificity when used as a mimetic enzyme to measure hydrogen peroxide.

[0078] According to the method of Example 4, a reaction system containing maltose, lactose, sucrose and fructose as substrates was prepared, wherein the concentrations of maltose, lactose, sucrose and fructose in the reaction system were all 10 mM, and 5 reaction systems were obtained; the 5 solutions obtained were placed on a U-3900H UV-visible absorption spectrometer produced by Hitachi High-Technologies Corporation, and the absorbance at 625 nm was measured. Fig.11 It can be seen that even though the concentration of the glucose analogue is 10 times that of glucose, the visual signal of the glucose analogue is still low, indicating that the detection of glucose has a high selectivity.

[0079] Therefore, compared with the prior art, the present invention has the following beneficial effects: the monoclinic lanthanum vanadate of the present invention has a cubic structure, is highly crystalline, has a large specific surface area, has a high active site, has good catalytic performance of simulating peroxidase, and is used as a simulated enzyme to determine the concentrations of hydrogen peroxide and glucose, and can quickly detect hydrogen peroxide; since glucose can be catalyzed by glucose oxidase to generate gluconic acid and hydrogen peroxide, the monoclinic lanthanum vanadate of the present invention also provides an indirect, rapid and accurate determination method for glucose detection, and this detection method has good selectivity, strong anti-interference ability, stable measurement results and good repeatability, and has been successfully used for the determination of glucose in human serum, and has potential application prospects in the fields of biomedicine and environmental testing.

[0080] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. Application of monoclinic lanthanum vanadate as a mimetic enzyme in the determination of hydrogen peroxide and glucose, characterized in that: The monoclinic lanthanum vanadate has a cubic structure, and the particle size of the monoclinic lanthanum vanadate is 400-500 nm. The monoclinic lanthanum vanadate is used as a simulated enzyme to directly measure the concentration of hydrogen peroxide, and the monoclinic lanthanum vanadate is used as a simulated enzyme to indirectly measure the concentration of glucose; The preparation method of the monoclinic lanthanum vanadate is: 1) Take lanthanum nitrate, add ultrapure water, stir, and obtain a lanthanum nitrate solution, the molar concentration of the lanthanum nitrate solution is 0.03-0.04mmol / mL; 2) taking ammonium metavanadate, adding ultrapure water, stirring, and obtaining an ammonium metavanadate solution, wherein the molar concentration of the ammonium metavanadate solution is 0.03-0.04 mmol / mL; 3) mixing the lanthanum nitrate solution obtained in step 1) with the ammonium metavanadate solution obtained in step 2), wherein the molar ratio of lanthanum nitrate to metavanadic acid is 1:1, and stirring evenly to obtain a mixed solution; 4) adjusting the pH value of the mixed solution obtained in step 3) to 3.5-4.5, placing the mixed solution in a reaction kettle, performing a hydrothermal reaction at 180° C. for 20-30 hours, taking the mixed solution out, and cooling the mixed solution; 5) Centrifuge, wash, and dry to obtain monoclinic lanthanum vanadate.

2. The use of the monoclinic lanthanum vanadate as a mimetic enzyme in the determination of hydrogen peroxide and glucose according to claim 1, characterized in that: The following steps are involved: Phosphate buffer, a test solution, 3,3',5,5'-tetramethylbenzidine ethanol solution and a monoclinic lanthanum vanadate dispersion are sequentially added to a reaction container, and the absorbance is measured on a UV-visible absorption spectrometer. The concentration of the test solution is obtained according to a linear equation between the absorbance and the concentration of the test solution. The test solution is a hydrogen peroxide solution or a glucose solution.

3. The use of the monoclinic lanthanum vanadate as a mimetic enzyme in the determination of hydrogen peroxide and glucose according to claim 2, characterized in that: The pH value of the phosphate buffer is 4, the molar concentration of the phosphate buffer is 50 mmol / L, and the molar ratio of the phosphate buffer to the test solution is 28-32:1; The molar concentration of the 3,3',5,5'-tetramethylbenzidine ethanol solution is 8 mmol / L, and the molar ratio of 3,3',5,5'-tetramethylbenzidine to the solution to be tested is 0.7-0.9:1; The mass concentration of the monoclinic lanthanum vanadate dispersion is 100 μg / mL, and the molar ratio of the monoclinic lanthanum vanadate to the solution to be tested is 0.03-0.05:

1.

4. The use of the monoclinic lanthanum vanadate as a mimetic enzyme in the determination of hydrogen peroxide and glucose according to claim 1, characterized in that: When the monoclinic lanthanum vanadate is used as a simulated enzyme to measure the concentration of hydrogen peroxide, the detection limit is 0.067 μM. When the monoclinic lanthanum vanadate is used as a simulated enzyme to measure the concentration of glucose, the detection limit is 0.834 μM.

5. The use of the monoclinic lanthanum vanadate as a mimetic enzyme in the determination of hydrogen peroxide and glucose according to claim 1, characterized in that: When the monoclinic lanthanum vanadate is used as a simulated enzyme to measure the concentration of hydrogen peroxide, the linear equation is A652 nm=1.8117C+0.0069; when the monoclinic lanthanum vanadate is used as a simulated enzyme to measure the concentration of glucose, the linear equation is A652 nm=2.5136C+0.0023, and the unit of C is mM.

6. The use of the monoclinic lanthanum vanadate as a mimetic enzyme in the determination of hydrogen peroxide and glucose according to claim 1, characterized in that: In the step 5), washing is performed by sequentially using ultrapure water and ethanol, and the number of washing times is 3-5 times.

7. The use of the monoclinic lanthanum vanadate as a mimetic enzyme in the determination of hydrogen peroxide and glucose according to claim 1, characterized in that: In the step 5), the rotation speed during centrifugation is 5000-6000 r / min, and the centrifugation time is 4-6 min.

8. The use of the monoclinic lanthanum vanadate as a mimetic enzyme in the determination of hydrogen peroxide and glucose according to claim 1, characterized in that: In the step 5), the drying is oven drying, the drying temperature is 50-70° C., and the drying time is 10-14 hours.

9. The use of the monoclinic lanthanum vanadate as a mimetic enzyme in the determination of hydrogen peroxide and glucose according to claim 1, characterized in that: In the monoclinic lanthanum vanadate, the molar ratio of lanthanum, vanadium and oxygen is 1:1:4.

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