Methyl paraoxon detection test strip based on oxygen vacancy-cerium dioxide and preparation method of methyl paraoxon detection test strip

Abstract

The invention discloses a methyl paraoxon pesticide detection test strip based on oxygen vacancy-cerium dioxide and a preparation method of the methyl paraoxon pesticide detection test strip, and belongs to the technical field of biosensors. The test strip is characterized in that a large amount of oxygen vacancy-cerium dioxide is loaded. The oxygen vacancy-cerium dioxide nano enzyme can show simulated phosphatase activity under specific conditions, and the enzyme activity can cut off P-O and P-S bonds of organophosphorus pesticides and promote methyl paraoxon to be hydrolyzed into a yellow product p-nitrophenol. The detection limit of a nano-enzyme system is discussed, so that the portable visual quantitative detection of the paraoxon methyl pesticide is realized. The test strip established on the basis of the principle can quickly detect paraoxon methyl, has the advantages of simplicity and convenience in operation, high sensitivity, low cost and the like, and provides a new method for instant test of paraoxon methyl pesticide.

Description

Technical Field

[0001] The present invention belongs to the technical field of biosensors, and specifically relates to a biosensor based on oxygen vacancy-cerium dioxide (VECeO 2 The invention discloses a methyl paraoxon (MP) detection test strip for NPs and a preparation method thereof. Background Art

[0002] Methyl paraoxon (MP) is a highly toxic, highly effective and widely used organophosphorus pesticide. Its abuse causes residue problems that seriously damage the ecological environment and endanger human health. In the field of food safety, the detection of pesticide residues, especially on-site detection, is becoming increasingly important. At present, traditional methods for detecting MP pesticide residues include high performance liquid chromatography, mass spectrometry, etc. However, these detection methods have the disadvantages of high cost, complex operation and poor portability, which greatly limit their practical application. Therefore, it is very important to develop a simple, rapid and highly sensitive detection method.

[0003] In tropical fruit producing areas in southern China, the ambient temperature for on-site detection of pesticide residues is usually over 40°C. In some areas, although traditional enzyme-based colorimetric assays are widely used for rapid detection of pesticides, the activity of natural enzymes is greatly affected by temperature and cannot meet the requirements of on-site detection in areas with relatively high temperatures. Since the discovery of nanozymes, they have been applied in various fields due to their excellent enzyme-mimicking activity and wide range of reaction conditions. For example, simulated organophosphorus hydrolases are used in the detection of organophosphorus pesticides. Nanomaterials themselves have the characteristics of controllable modification. The activity of specially designed and modified nanozymes is close to that of natural enzymes. In recent years, cerium dioxide has attracted great attention in the field of colorimetric sensing as a popular metal oxide. The designed cerium dioxide has a large number of oxygen vacancy sites. The presence of oxygen vacancies can change the electronic structure and chemical properties of cerium dioxide, making it have higher redox activity. Because of its simple preparation and good thermal stability, it can solve the problem of temperature limitation of natural enzyme activity and realize the research of MP pesticide residue rapid detection test strips in complex environments. Summary of the invention

[0004] The purpose of the present invention is to provide a novel method for detecting cerium dioxide (VECeO) based on oxygen vacancy. 2 The invention discloses a methyl paraoxon (MP) detection test strip for NPs. The test strip can detect MP pesticide residues in samples simply, quickly and with high sensitivity.

[0005] The present invention is based on VECeO 2 The mechanism of the NPs pesticide detection test strip is as follows: when MP is added to the sample, under certain conditions, VECeO 2NPs exhibit simulated phosphatase activity, which can cut the PO and PS bonds in organophosphorus pesticides, causing MP to generate a yellow product, p-nitrophenol, which in turn causes the color of the test strip to change (e.g. Figure 1 This detection method utilizes VECeO 2 The enzyme-mimicking activity of NPs provides an efficient and convenient method for the detection of MP pesticide residues.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] The invention discloses a method based on VECeO 2 The preparation method of the MP pesticide detection test strip of NPs comprises the following steps:

[0008] (1) Preparation of VECeO 2 NPs: 0.1~0.268mmol L -1 CeCl 3 7H 2 O is dissolved in 10-15 mL of deionized water, and 0.1-0.5 mL of 30% HO is added. 2 O 2 , then add 0.1-1.5 mL 30% NH 4 ·OH, heated to 100°C, stirred for 20 minutes to obtain a yellow dispersion. After cooling, centrifuged (8000 rpm, 10 minutes) to obtain a yellow precipitate, namely VECeO 2 NPs. Wash with deionized water three times until pH is neutral, freeze in -80℃ refrigerator for 12 hours, and freeze-dry for 12 hours to obtain yellow powder VECeO 2 NPs are reserved.

[0009] (2) Preparation of test strips: First, VECeO 2 NPs powder is added to 1-20 mL NMM (0.45 M) solution for later use. Next, process the MP solution. Take 100-400 μL MP solution (100 ppm standard) and mix it with 700-2400 μL NMM (0.45 M) solution to make the volume ratio of MP to NMM in the mixed solution be 1:1-6. Then, immerse the test strip in a solution containing 1-1.2 mg mL -1 VEC 2 NPs solution, soaked and shaken for 1 to 3 hours. After the above steps, the VECeO-based 2 Detection strips of methyl paraoxon pesticide based on NPs.

[0010] Beneficial effects of the present invention

[0011] (1) VECeO-based2 The MP activity test strips of NPs have the advantages of high enzyme activity and easy preparation, and can be used to perform rapid qualitative analysis of MPs by utilizing enzyme-mimicking properties.

[0012] (2) The test strip used in the present invention has the advantages of simple construction process, easy operation, fast response speed, low cost, etc. 2 The MP detection method of NPs was used to construct paper-based sensors to achieve on-site handheld and portable detection of MPs.

[0013] The present invention is based on VECeO 2 The test strips for the MP activity of NPs are portable and quick, and can meet the needs of on-site pesticide residue detection in areas with higher temperatures, and have great potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 : VECeO synthesized in Example 1 2 Schematic diagram of the mechanism of detection of methyl paraoxon by MP test strips of NPs.

[0015] Figure 2 : VECeO in Example 2 2 Temperature optimization of NPs-catalyzed methyl paraoxon.

[0016] Figure 3 : VECeO in Example 3 2 Concentration optimization of NPs-catalyzed methylparaoxon.

[0017] Figure 4 : VECeO prepared in Example 4 2 Linear regression curve of catalytic methyl paraoxon of NPs.

[0018] Figure 5 : Test strip preparation and color development flow chart described in Example 5. DETAILED DESCRIPTION

[0019] Example 1: Oxygen vacancy-cerium dioxide-catalyzed methyl paraoxon

[0020] (1)VECeO 2 Synthesis of NPs

[0021] Take 100 mg CeCl 3 7H 2 O (0.268 mmol) was dissolved in 15 mL of deionized water, and 0.5 mL of 30% H 2 O 2 and 1.5 mL 30% NH 4·OH, heated to 100℃ and stirred for 20 minutes to obtain a yellow dispersion. Centrifuged at 8000 rpm for 3 minutes to obtain a yellow precipitate, namely VECeO 2 NPs were washed with deionized water three times until pH was neutral, frozen in a refrigerator at -80 °C for 12 hours, and then freeze-dried for 12 hours to obtain yellow powder VECeO 2 NPs are reserved.

[0022] (2) Colorimetric analysis of methyl paraoxon

[0023] Place 200 μL VECeO 2 NPs (10 mmol) were mixed with 100 μL deionized water, 200 μL MP standard solution (100 ppm) and 1000 μL pH = 10 Tris-HCl. After reacting for 15 minutes, the mixture was centrifuged at 8000 rpm for 3 minutes to remove the precipitate, and the color of the supernatant was recorded with a camera.

[0024] Example 2: Different concentrations of VECeO 2 NPs catalyze the synthesis of methyl paraoxon

[0025] Prepare 200 μL VECeO at different concentrations (2, 4, 5, 7, 8, 10 mM) 2 NPs, 200 μL MP solution (50 ppm) and 1000 μL Tris-HCl (pH = 10) were added, and the reaction was continued for 15 minutes. 2 As the concentration of NPs increases, the color changes from colorless to yellow. After centrifugation (8000 rpm, 3 minutes), the supernatant was taken and analyzed by UV spectroscopy at a wavelength of 400 nm. The results are as follows Figure 2 shown.

[0026] Example 3: VECeO 2 Relationship between NPs catalytic activity of methyl paraoxon and temperature

[0027] Take 200 μL of 10 mM VECeO 2 NPs, add 200 μL MP (50 ppm) solution and 1000 μL Tris-HCl (pH = 10) buffer, react for 10 minutes, then centrifuge at 8000 rpm for 3 minutes, remove the precipitate and take the supernatant, perform UV spectroscopy analysis at 400 nm, the results are as follows Figure 3 shown.

[0028] Example 4: VECeO 2 Linear regression curve of NPs catalyzed methyl paraoxon

[0029] Take 200 μL of the prepared 10 mM VECeO 2NPs solution, 1000 μL Tris-HCl buffer, 200 μL MP solution of different concentrations (1 ppm, 5 ppm, 10 ppm, 20 ppm, 40 ppm, 60 ppm, 80 ppm, 100 ppm) and 100 μL deionized water were added, reacted for 15 min, centrifuged (8000 rpm, 3 min), the supernatant was taken, and UV spectroscopy was performed at a wavelength of 400 nm. The obtained data were used to draw a standard curve. The results are shown in Figure 4 shown.

[0030] Example 5: Test strip preparation

[0031] Cut the test strip (Beisheng glass fiber filter paper) into 1cm*1cm square slices and immerse it in 1.2mg mL - 1 VEC 2 The mixed solution of NPs and NMM (0.45 M, pH = 10) was shaken for 1 h to obtain VECeO 2 NPs pesticide detection test strip. Add the test strip to a mixed solution containing 400μL 100ppm MP and 2400μL NMM (0.45M) and react for 30 minutes until the test strip turns yellow. Figure 5 shown.

Claims

1. A methyl paraoxon pesticide detection test strip based on oxygen vacancy-cerium dioxide, characterized in that: It is composed of oxygen vacancy-cerium dioxide loaded on the test strip.

2. A method for preparing a methyl paraoxon pesticide detection test strip based on oxygen vacancy-cerium dioxide, the steps of which are as follows: A. Synthesis of oxygen vacancy-cerium dioxide: 0.268mmol L -1 CeCl3·7H2O was dissolved in 10-15mL deionized water, followed by the addition of 0.5mL H2O2; the solution was transferred to a round-bottom flask, and 1.5mL NH4·OH was added and stirred vigorously; the temperature was raised to 100°C for 20 minutes to obtain a yellow dispersion; the mixture was cooled and centrifuged at 8000 rpm for 10 minutes to obtain a yellow precipitate; the mixture was washed three times with deionized water until the pH was neutral; the mixture was frozen and lyophilized for 12 hours to obtain yellow powdered VECeO2NPs, i.e., oxygen vacancy-cerium dioxide; B. Preparation of methyl paraoxon pesticide test strips: VECeO2 NPs powder was added to 1-20 mL of 0.45 M NMM solution to prepare a VECeO2 NPs solution. The test strip was immersed in a 0.45 M NMM solution containing 1-1.2 mg mL -1 VECeO2 NPs were soaked in the solution and shaken for 1 to 3 hours; the MP solution was treated with the NMM solution and mixed, and the volume ratio of 100 ppm methyl paraoxon 100-400 μL and 0.45 M NMM 700-2400 μL was 1:1-6.

3. The method for preparing the oxygen vacancy-cerium dioxide methyl paraoxon pesticide detection test strip according to claim 2, characterized in that: In step B: the VECeO2NPs concentration was finally selected to be 10mM, and the temperature was finally selected to be 60℃.

4. The method for preparing the oxygen vacancy-cerium dioxide methyl paraoxon pesticide detection test strip according to claim 2, characterized in that: In step B: VECeO2 NPs concentration was 1.2 mg mL -1 The infiltration and shaking time was 1.5 h, the NMM volume in the MP solution was 2400 μL, and the methyl paraoxon volume was 400 μL.

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