A preparation method of bimetallic MOFs hydrogel for hydrogen peroxide detection

Abstract

This invention belongs to the field of colorimetric detection and discloses a method for preparing a bimetallic MOF hydrogel for hydrogen peroxide detection. The invention uses Zr / Ce-MOF with peroxidase activity as the material. The principle is to utilize the peroxidase activity of Zr / Ce-MOF to catalyze the decomposition of hydrogen peroxide into hydroxyl radicals, which then oxidize TMB to form blue oxTMB. By utilizing the characteristic of hydrophilic hydrogels to enrich the hydrophilic catalytic product oxTMB (blue), the detection sensitivity and portability are greatly improved. The bimetallic MOF hydrogel for hydrogen peroxide detection provided by this invention is extremely simple to operate, highly portable, and exhibits high detection sensitivity and a wide linear range.

Description

Technical Field

[0001] The invention belongs to the field of colorimetric detection, and relates to a preparation method of a bimetallic organic metal framework derivative (Zr / Ce-MOF) hydrogel and an application of hydrogen peroxide colorimetric detection. Background Art

[0002] Hydrogen peroxide (H 2 O 2 ) is an important chemical material and green environmental protection product, widely used in textile, papermaking, chemical environmental protection, medical and other industries. 2 O 2 It has strong oxidizing properties, is toxic to cells, and has certain carcinogenicity. 2 O 2 When used in food, medicine, cosmetics and other fields, its content must be strictly controlled, otherwise it will cause serious damage to human health. 2 O 2 Rapid and accurate detection of H is of great significance for ensuring food safety and physiological health. 2 O 2 The detection methods are also constantly updated and iterated. According to different detection principles, H 2 O 2 The detection methods can be divided into spectrophotometry, chemiluminescence, fluorescence and chromatography. Chemiluminescence has the advantages of high sensitivity, good visibility and low detection limit, but its application range is limited. For example, the widely used luminol luminescent agent needs to be used in an alkaline environment to ensure high luminescence efficiency. Chromatography is usually used to measure H 2 O 2 Fluorescence method is an effective method to measure H concentration in biological samples, but its complicated operation process limits its further application. 2 O 2 During detection, there are disadvantages such as being easily interfered by background fluorescence, requiring a darkroom detection environment, and being unable to detect on-site, which limits the further application of this method in biological systems.

[0003] Colorimetric biosensing has attracted increasing attention due to its practicality, simplicity and low cost. The traditional colorimetric sensing method is a rapid analytical strategy that uses the naked eye to compare the color depth of a colored solution to qualitatively or semi-quantitatively identify a substance, so it is also called visual colorimetry. Because the color change can be read by the naked eye, colorimetric biosensing does not require complex and expensive instruments and can be used for instant diagnosis and on-site analysis. 2 O 2In the presence of H 2 O 2 However, the peroxidase-like enzymes used are mostly nanomaterials, and their catalytic performance is easily affected by the aggregation and polydispersity of nanomaterials, which affects the detection performance to a certain extent. Therefore, the detection of hydrogen peroxide in a solution system requires ultrasound to completely disperse the nanomaterials, which is not conducive to the development of portable colorimetric sensors.

[0004] Hydrogel is a type of hydrophilic material with a three-dimensional network structure made of natural or synthetic materials. It is loose and porous inside, contains a large amount of water, and is usually relatively soft. Secondly, since hydrogels usually use non-biotoxic polymer materials as components of the internal network, they have high biocompatibility and can directly fit with human skin. These advantages make hydrogels show good prospects in the application of wearable devices. Based on this, we envisioned a hydrogel sensor made of Zr / Ce-MOF with peroxidase activity, which can quickly, accurately and conveniently detect H in the solution on site. 2 O 2 The content. Summary of the invention

[0005] The present invention aims to provide a Zr / Ce-MOF hydrogel colorimetric sensor with the advantages of high accuracy, high sensitivity, and wide measurement range. The hydrogel sensor has a simple preparation process and low cost, and can achieve rapid quantitative detection of H 2 O 2 purpose.

[0006] The present invention is achieved through the following specific technical solutions:

[0007] A method for preparing a bimetallic MOFs hydrogel for hydrogen peroxide detection comprises the following steps:

[0008] Step 1: Preparation of Zr / Ce bimetallic MOFs materials:

[0009] First, Ce(NO 3 ) 3 6H 2 O was dissolved in N,N-dimethylformamide DMF and stirred for 20-30 minutes, which was recorded as solution A;

[0010] Trimesic acid H 3 BTC and ZrCl 4 Dissolve in a mixture of acetic acid HAc and DMF and stir for 20 to 30 minutes, which is referred to as solution B;

[0011] At room temperature, solution A was added to solution B, stirred evenly and then subjected to solvent thermal reaction. The obtained substance was washed with DMF, deionized water and ethanol, and the solid was placed in a vacuum drying oven to obtain Zr / Ce-MOF material.

[0012] Step 2: Preparation of hydrogel film containing Zr / Ce-MOF:

[0013] The Zr / Ce-MOF powder obtained in step (1) is ultrasonically dispersed in water. After dispersion, sodium alginate is added under magnetic stirring, which is referred to as solution C. Solution C is added to a mold, and then bubbles are removed.

[0014] Anhydrous calcium chloride (CaCl 2 ) and polyacrylic acid (PAA) are dissolved in water and stirred evenly, which is recorded as solution D; the mold containing solution C is immersed in solution D to obtain a hydrogel film after immersion.

[0015] In step 1,

[0016] Ce(NO 3 ) 3 6H 2 O、ZrCl 4 , H 3 The dosage ratio of BTC is 0.1-0.5mmol: 0.5-1mmol: 1-2mmol;

[0017] In the mixed solution of HAc acetate and DMF, the volume ratio of HAc acetate and DMF is 2-5mL:5-15mL;

[0018] The conditions of the solvothermal reaction are 120-150°C, 24h.

[0019] In step 2,

[0020] In solution C, the ratio of Zr / Ce-MOF powder, water, and sodium alginate is 1-30 mg: 1 mL: 10-30 mg;

[0021] The mold material used is polytetrafluoroethylene.

[0022] In solution D, CaCl 2 The dosage ratio of PAA and water is 100-200 mg: 3-5 mg: 20-30 mL; the average molecular weight of polyacrylic acid PAA powder is 2000;

[0023] The bimetallic MOFs hydrogel prepared by the present invention is used for detecting hydrogen peroxide, and the detection steps are as follows:

[0024] TMB colorimetric detection:

[0025] TMB was dissolved in ethanol to prepare a TMB ethanol solution.

[0026] The H 2 O 2 Prepare different concentrations of H by diluting them in distilled water. 2 O 2 Aqueous solution.

[0027] During the detection process, TMB solution and different concentrations of H 2 O 2 After being mixed evenly with NaAc-HAc solution in proportion, the mixture was dropped onto the hydrogel film. After complete reaction at a certain temperature, the grayscale value of the color was analyzed using Adobe Photoshop 2020 software. In addition, the photography process was carried out under LED light to ensure the stability of the ambient light conditions. The unreacted hydrogel film was photographed under light, and the image was named Image A. The image of the hydrogel after reaction was named Image B. Therefore, the ΔR value was the difference between the grayscale values ​​of Image B and Image A. The ΔR value was used as a color parameter and lnC(H 2 O 2 ) has a good linear relationship.

[0028] Among them, the concentration of TMB ethanol solution is 10mM;

[0029] The concentration of NaAc-HAc buffer solution was 0.1 M and the pH was 3-5;

[0030] The concentration range of hydrogen peroxide is 80-10 5 μM;

[0031] The usage ratio of TMB solution, hydrogen peroxide solution and buffer solution is 30 μL:50 μL:400 μL.

[0032] The reaction temperature is 30-50°C; the reaction time is 20-40 minutes.

[0033] The beneficial effects of the present invention are:

[0034] (1) The Zr / Ce-MOF prepared by the solvothermal method in the present invention not only has excellent peroxidase activity, but also the stability of the material is greatly improved.

[0035] (2) The Zr / Ce-MOF prepared in the present invention can realize sensitive H 2 O 2 Colorimetric detection, 80~10 5 In the concentration range of μM, the ΔR value is used as a color parameter and H 2 O 2 The logarithm of the concentration had a good linear relationship, and the detection limit was as low as 26.67μM.

[0036] (3) Compared with the traditional detection method, the H 2 O 2 The colorimetric detection method has the advantages of easy operation, simple equipment, low detection cost, and portability and wearability. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The scanning electron microscope characterization images of Zr-MOF (A), Ce-MOF (B) and Zr / Ce-MOF (C) prepared in Example 1; (D) is the X-ray diffraction pattern of Zr / Ce-MOF;

[0038] Figure 2 This is the X-ray photoelectron spectrum of Zr / Ce-MOF;

[0039] Figure 3 The peroxidase activity comparison chart of Zr-MOF, Ce-MOF and Zr / Ce-MOF;

[0040] Figure 4 Schematic diagram for constructing a hydrogel sensor;

[0041] Figure 5 This is the optimization selection diagram of temperature (A), catalyst dosage (B), time (C), and pH (D);

[0042] Figure 6 Standard curve for the hydrogel sensor detecting hydrogen peroxide. DETAILED DESCRIPTION

[0043] The present invention is described in detail below with reference to examples, but the present invention is not limited to these embodiments.

[0044] Comparative Example 1

[0045] Preparation of Zr-MOF

[0046] H 3 BTC (70.6 mg, 0.336 mmol) and ZrCl 4 (233 mg, 1 mmol) was dissolved in a mixed solution of 5.6 mL of HAc and 10 mL of DMF and stirred for 30 minutes. After stirring evenly, the solvent thermal reaction was carried out at 135°C for 24 hours. The obtained substance was washed with DMF, deionized water and ethanol, and the solid was placed in a vacuum drying oven to obtain the Zr-MOF material.

[0047] Comparative Example 2

[0048] Preparation of Ce-MOF

[0049] Will Ce(NO 3 ) 3 6H 2O (4.34 g, 10 mmol) was dissolved in 45 mL of water and stirred for 30 min, which was recorded as solution A. 3 BTC (2.1 g, 10 mmol) was dissolved in 5 mL of water and 5 mL of ethanol solution and stirred for 30 min, which was recorded as solution B. Solution A was dripped into solution B drop by drop and stirred at 60 °C for 1 h; the obtained material was washed with deionized water and ethanol, and the solid was placed in a vacuum drying oven to obtain Ce-MOF material.

[0050] Embodiment 1:

[0051] (1) Preparation of Zr / Ce-MOF

[0052] Will Ce(NO 3 ) 3 6H 2 O (174 mg, 0.4 mmol) was dissolved in 5 mL DMF and stirred for 30 min, which was recorded as solution A.

[0053] ZrCl 4 (140 mg, 0.6 mmol) and H 3 BTC (70.6 mg, 0.33 mmol) was dissolved in 12.5 mL DMF and 3.2 mL HAc and stirred for 30 min, which was recorded as solution B.

[0054] At room temperature, solution A was added to solution B and stirred vigorously. The mixture was placed in an oven at 135°C for 24 hours. The obtained material was washed with DMF, deionized water and ethanol, and the solid was placed in a vacuum drying oven to obtain the material Zr / Ce-MOF.

[0055] Figure 1 SEM images of (A) Zr-MOF, (B) Ce-MOF and (C) Zr / Ce-MOF prepared in Example 1. (D) XRD patterns of synthesized Zr-MOF and Zr / Ce-MOF. The SEM image shows the size and morphology of the material, and the doping of Ce reduces the size of the material. The XRD spectrum of Zr-MOF is consistent with the standard Zr-MOF spectrum, indicating the successful preparation of Zr-MOF. Comparing the XRD diffraction peaks of Zr-MOF and Zr / Ce-MOF, the incorporation of Ce into the Zr-MOF crystal does not affect the integrity of the Zr-MOF crystal structure.

[0056] Figure 2 XPS spectra: (A) C 1s; (B) O 1s; (C) Zr 3d; (D) Ce 3d. The surface chemical composition and electronic state of Zr / Ce-MOF were characterized, indicating that Ce was successfully incorporated into Zr-MOF. 3+ and Ce 4+exists in Zr / Ce-MOF in the form of.

[0057] Figure 3 The grayscale value changes of the colors of Zr-MOF, Ce-MOF and Zr / Ce-MOF when TMB is catalyzed to form oxTMB in the presence of hydrogen peroxide, indicating that the synthesized Zr / Ce bimetallic MOF has stronger peroxidase activity.

[0058] (2) Preparation of Zr / Ce-MOF hydrogel

[0059] like Figure 4 As shown, the construction process of the hydrogel sensor is:

[0060] 5 mg Zr / Ce-MOF powder was ultrasonically dispersed in 1 mL water. After dispersion, 20 mg sodium alginate was added under magnetic stirring to form solution C.

[0061] In another beaker, dissolve 188 mg of anhydrous calcium chloride and 3 mg of PAA in 30 mL of water and stir well to form solution D.

[0062] 200 μL of solution C was added to the mold, and then the bubbles were removed. The mold was immersed in solution D to obtain a circular hydrogel film with d = 1.5 cm.

[0063] (3) Hydrogen peroxide detection and grayscale value recognition

[0064] In order to select appropriate detection conditions for hydrogel sensors, we optimized the reaction temperature, Zr / Ce-MOF catalyst dosage, reaction time, and pH value of the reaction solution:

[0065] The catalyst dosage in the fixed hydrogel was 5 mg mL -1 , the pH of the reaction solution is 3 and the reaction time is 20 min, and the gray value difference of the hydrogel before and after the reaction is compared at different reaction temperatures (20-60°C);

[0066] The reaction temperature was fixed at 40 °C, the pH of the reaction solution was 3, and the reaction time was 20 min. The results showed that the reaction time of different catalyst dosages (1 mg mL -1 -30mg·mL -1 ) The gray value difference before and after the hydrogel reaction;

[0067] The reaction temperature was fixed at 40 °C and the catalyst dosage in the hydrogel was 5 mg mL -1 The pH value of the reaction solution was 3, and the gray value difference of the hydrogel before and after the reaction was compared at different reaction times (10-60min);

[0068] The reaction temperature was fixed at 40 °C and the catalyst dosage in the hydrogel was 5 mg ml -1The reaction time was 20 min, and the gray value difference before and after the hydrogel reaction was compared at different reaction pH values ​​(2-8).

[0069] Figure 5 The effects of (A) reaction temperature, (B) Zr / Ce-MOF catalyst dosage, (C) reaction time, and (D) pH value of the mixed solution on the peroxidase-like catalytic activity. In each figure, the gray value change under the maximum activity condition is set as 100%, and the ordinate is the relative activity (%). TMB was dissolved in ethanol to prepare a 10 mM TMB ethanol solution. The purchased H 2 O 2 (30%) was continuously diluted in distilled water to prepare different concentrations of H 2 O 2 During the test, 30 μL TMB solution, 50 μL H 2 O 2 After being evenly mixed with 400 μL NaAc-HAc (pH=3) solution, the mixed solution was dropped into the hydrogel film and detected after the reaction was complete. In order to realize portable biosensing, Adobe Photoshop 2020 software was used to analyze the grayscale value of the color. In addition, the photography process was carried out under LED light to ensure the stability of ambient light conditions. The unreacted hydrogel film was photographed under light, and the image was taken as image A. The image of the hydrogel after the reaction was named image B. Therefore, the ΔR value is the difference between the grayscale values ​​of image B and image A. The ΔR value as a color parameter has a good linear relationship with lnC.

[0070] Figure 6 This is the standard curve of the hydrogel sensor for detecting hydrogen peroxide, and the linear equation is ΔR = -67.850 + 40.2873logC H2O2 , correlation coefficient 0.9925, detection limit 26.67μM.

[0071] Embodiment 2:

[0072] (1) Preparation of Zr / Ce-MOF

[0073] Will Ce(NO 3 ) 3 6H 2 O (187 mg, 0.43 mmol) was dissolved in 5 mL DMF and stirred for 30 min, which was recorded as solution A.

[0074] ZrCl 4 (133 mg, 0.57 mmol) and H 3 BTC (70.6 mg, 0.33 mmol) was dissolved in 12.5 mL DMF and 3.2 mL HAc and stirred for 30 min, which was recorded as solution B.

[0075] At room temperature, solution A was added to solution B and stirred vigorously. The mixture was placed in an oven at 135°C for 24 hours. The obtained material was washed with DMF, deionized water and ethanol, and the solid was placed in a vacuum drying oven to obtain the material Zr / Ce-MOF.

[0076] Steps (2) and (3) are the same as steps (2) and (3) of Example 1.

[0077] Embodiment 3:

[0078] (1) Preparation of Zr / Ce-MOF

[0079] Will Ce(NO 3 ) 3 6H 2 O (145 mg, 0.33 mmol) was dissolved in 5 mL DMF and stirred for 30 min, which was recorded as solution A.

[0080] ZrCl 4 (155 mg, 0.67 mmol) and H 3 BTC (70.6 mg, 0.33 mmol) was dissolved in 12.5 mL DMF and 3.2 mL HAc and stirred for 30 min, which was recorded as solution B.

[0081] At room temperature, solution A was added to solution B and stirred vigorously. The mixture was placed in an oven at 135°C for 24 hours. The obtained material was washed with DMF, deionized water and ethanol, and the solid was placed in a vacuum drying oven to obtain the material Zr / Ce-MOF.

[0082] Steps (2) and (3) are the same as steps (2) and (3) of Example 1.

Claims

1. A method for preparing a bimetallic MOFs hydrogel for hydrogen peroxide detection, characterized in that: The steps include: First, Ce(NO3)3·6H2O was dissolved in N,N-dimethylformamide DMF and stirred, which was recorded as solution A; Dissolve trimesic acid H3BTC and ZrCl4 in a mixed solution of acetic acid HAc and DMF and stir, which is referred to as solution B; At room temperature, solution A was added to solution B, stirred evenly and then subjected to solvent thermal reaction. The obtained substance was washed with DMF, deionized water and ethanol, and the solid was placed in a vacuum drying oven to obtain Zr / Ce-MOF material. The usage ratio of Ce(NO3)3·6H2O, ZrCl4 and H3BTC is 0.1-0.5mmol:0.5-1mmol:1-2mmol; Step 2: Preparation of hydrogel film containing Zr / Ce-MOF: The Zr / Ce-MOF powder obtained in step (1) is ultrasonically dispersed in water. After dispersion, sodium alginate is added under magnetic stirring, which is referred to as solution C. Solution C is added to a mold, and then bubbles are removed. Anhydrous calcium chloride CaCl2 and polyacrylic acid PAA are dissolved in water and stirred evenly, which is recorded as solution D; a mold containing solution C is immersed in solution D to obtain a hydrogel film after immersion.

2. The preparation method according to claim 1, characterized in that In step 1, In the mixed solution of HAc acetate and DMF, the volume ratio of HAc acetate and DMF is 2-5mL:5-15mL; The stirring time of solution A and solution B is 20-30 minutes.

3. The preparation method according to claim 1, characterized in that: In step 1, the conditions of the solvothermal reaction are 120-150° C., 24 h.

4. The preparation method according to claim 1, characterized in that: In step 2, in solution C, the ratio of Zr / Ce-MOF powder, water, and sodium alginate is 1-30 mg: 1 mL: 10-30 mg; the mold material used is polytetrafluoroethylene.

5. The preparation method according to claim 1, characterized in that: In step 2, in solution D, the usage ratio of CaCl2, PAA and water is 100-200 mg: 3-5 mg: 20-30 mL; the average molecular weight of polyacrylic acid PAA powder is 2000.

6. Use of the bimetallic MOFs hydrogel prepared by the preparation method according to any one of claims 1 to 5 for detecting hydrogen peroxide.

7. The use according to claim 6, characterized in that The detection steps are: Dissolving TMB in ethanol to prepare an ethanol solution of TMB; The purchased H2O2 was diluted in distilled water step by step to prepare H2O2 aqueous solutions of different concentrations; During the detection process, TMB solution, H2O2 of different concentrations, and NaAc-HAc solution were mixed evenly in proportion and then dropped on the hydrogel film. After complete reaction at a certain temperature, the grayscale value of the color was analyzed using Adobe Photoshop 2020 software; The unreacted hydrogel film was photographed under light, and the image was named Image A. The image of the hydrogel after reaction was named Image B. The ΔR value was the difference between the grayscale values ​​of Image B and Image A. The ΔR value as a color parameter had a good linear relationship with lnC(H2O2).

8. The use according to claim 7, characterized in that The concentration of TMB ethanol solution is 10mM; the concentration of NaAc-HAc buffer solution is 0.1M, pH is 3-5; the concentration range of hydrogen peroxide is 80-10 5 μM; the usage ratio of TMB solution, hydrogen peroxide solution and buffer solution is 30μL:50μL:400μL.

9. The use according to claim 7, characterized in that The reaction temperature is 30-50°C; the reaction time is 20-40 minutes.

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