Portable chlorpyrifos pesticide residue detection equipment based on MOF-based biosensor

Abstract

The invention discloses portable chlorpyrifos pesticide residue detection equipment based on an MOF-based biosensor, and belongs to the technical field of biosensors. The device is composed of a main body structure, a camera module, an LED light supplementing lamp strip, a power supply, a switch module, a storage module, a main control module, a display module and a groove, wherein the storage module and the main control module are located on a PCB, and the groove is used for containing the MOF-based biosensor. In the detection process, the whole equipment is a darkroom, and an LED light supplement lamp in the main body structure is used as a light source. Except the groove which can be stretched outwards, other parts of the equipment are inseparable and unopenable whole bodies, so that external interference of ambient light in the detection process can be effectively avoided. The single chip microcomputer is used for simplifying complicated operation steps in the pesticide residue detection process, the pesticide residue concentration result is obtained by detecting the change degree of the color of the biosensor, high-precision pesticide residue concentration detection is achieved by reducing errors in the experiment operation process, and automation and marketization are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of biosensors, and in particular relates to a portable chlorpyrifos pesticide residue detection device based on an MOF-based biosensor. Background Art

[0002] Pesticides, as substances that can prevent, destroy, expel and reduce pests, play an important role in the prevention and control of agriculture, forestry, animal husbandry and their products and environmental sanitation. However, improper use of pesticides can cause water pollution, soil pollution and food safety problems, and even seriously endanger human life and health. Among various pesticides, organophosphorus pesticides are the mainstay of the pesticide family, accounting for about 40% of the total global pesticide use. At present, for the field of pesticide detection, traditional physical and chemical analysis methods such as chromatography and spectral analysis are commonly used detection methods. However, this method is usually limited by professional analytical instruments and equipment, and needs to be carried out in a professional laboratory environment. At the same time, it also requires the analysis of professional researchers to obtain the concentration of pesticide residues. Due to the disadvantages of these methods such as high time consumption and complex operation steps, they are not conducive to the demand for on-site detection of pesticides. Therefore, it is of great significance to provide an easy-to-operate, low-cost and portable pesticide residue detection device. Summary of the invention

[0003] The purpose of the present invention is to overcome the problems of poor test stability, cumbersome test methods, inconvenient to carry and low selectivity in the existing pesticide detection technology, and provide a portable chlorpyrifos pesticide residue detection device based on MOF-based biosensor. The present invention uses a single-chip microcomputer to simplify the complicated operation steps in the pesticide residue detection process, obtains the pesticide residue concentration result by detecting the degree of change in the color of the biosensor, and reduces the error in the experimental operation process to achieve high-precision pesticide residue concentration detection, and realize automation and marketization.

[0004] The portable chlorpyrifos pesticide residue detection device based on MOF-based biosensor of the present invention is designed by industrial software Candence and Keil respectively. The structure of the device is modeled and designed by SolidWorks and manufactured by 3D printer. The structure of the detection device is as follows: Figure 4 As shown, it consists of a main structure, a camera module, an LED fill light strip, a power supply and switch module, a storage module and a main control module located on a PCB board, a display module, and a groove for placing a MOF-based biosensor; the main structure is a rectangular parallelepiped of 120 mm (length) × 143 mm (width) × 180 mm (height); the camera module is located above the inside of the main structure ( Figure 4The camera module and the upper cover are pulled out to the top of the main structure for ease of understanding). The LED fill light strip is located on the upper side of the main structure as the ambient light source for the entire device. The groove for placing the biosensor (the groove can be inserted and pulled out through the slide rail) is placed at the bottom of the main structure. The power supply and the switch (the power supply is responsible for the power supply of the entire device, and the switch is responsible for the opening and closing of the entire device) are embedded in parallel at the bottom of the side of the main structure. The storage module and the main control module are arranged on the PCB board, which are connected to the display module and the camera module through a hardware interface ( Figure 4 The PCB board and LCD screen are pulled out to the front of the main structure for ease of understanding); the display module is set in front of the PCB board to output the results of pesticide residue detection. During the detection process, the entire device is a dark room, using the LED fill light inside the main structure as the light source. Except for the groove that can be stretched outward, the rest of the device is a non-disassembled and non-openable whole. The design of the entire device can effectively avoid external interference from ambient light during the detection process.

[0005] The entire pesticide residue detection equipment mainly consists of the following modules:

[0006] MOF-based biosensors for converting concentration information of chlorpyrifos pesticide into color information;

[0007] A camera, used to take a picture of the color information of the biosensor;

[0008] The storage module is an SD card soldered on the PCB board, which is used to store the images taken by the camera;

[0009] The main control module is a single-chip microcomputer STM32F407 soldered on the PCB board, which is used to control the camera to capture images of the MOF-based biosensor and analyze the images captured by the camera; the camera is connected to the single-chip microcomputer on the PCB board through wires;

[0010] The display module uses an LCD touch screen to display the touch screen function of the device and the test results.

[0011] The method comprises adding 75 mg of polylactic acid-co-glycolic acid (PLGA) and 7.5 mg of bovine serum albumin (BSA) to 1-3 mL of deionized water, and then adding 2 mL of 0.1 M zinc acetate dihydrate and 2 mL of 1.2 M dimethylimidazole, and aging for 3-5 hours; rotating at 5000-8000 r min -1After centrifugation at a speed of 3 to 8 minutes, a white precipitate of ZIF-8 of the MOF material is obtained, and then deionized water is added for shaking and washing, and the precipitate is obtained by centrifugation at the same speed for 3 to 8 minutes; the above-mentioned "washing after centrifugation" operation steps are repeated 2 to 3 times, and finally the obtained precipitate is diluted to 1 mL with deionized water to obtain a ZIF-8 solution of the star-shaped MOF material; 25 μL of ZIF-8 solution, 50 μL of 10 mM iodothioacetylcholine (ATCH) and 50 μL of PBS buffer with a pH of 8.5 are added to the enzyme-labeled well to construct a MOF-based biosensor.

[0012] The steps of analyzing the image taken by the camera are as follows:

[0013] (1) Add a chlorpyrifos pesticide solution with a concentration of 0.05 ng / mL to 50 ng / mL to the MOF-based biosensor, react at 37°C for 20 to 30 min, then add 35 uL of 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) with a concentration of 2 mg / mL, and then place the biosensor with the chlorpyrifos pesticide to be tested into the pesticide residue detection equipment through the groove;

[0014] (2) The color information generated by the biosensor is photographed by a camera to obtain multiple images corresponding to the concentration of chlorpyrifos pesticide. The RGB three channels of each pixel in each image are stripped using a single-chip microcomputer STM32F407, and the G / B ratios of the G channel and the B channel of all pixels in each image are calculated. The G / B ratios of all pixels in the image are averaged to obtain the G / B mean of the image. Finally, the "100-fold logarithm of the chlorpyrifos pesticide concentration Log(100*chlorpyrifos)" is used as the horizontal coordinate, and the G / B mean is used as the vertical coordinate to fit the "G / B mean-100-fold logarithm of the chlorpyrifos pesticide concentration Log(100*chlorpyrifos)" linear relationship curve y=0.56log(100*chlorpyrifos)+6.39;

[0015] (3) Using a camera to take a picture of the color information generated by the biosensor under the chlorpyrifos pesticide solution with an unknown residual concentration to obtain an image, using a single-chip microcomputer STM32F407 to strip the RGB three channels of each pixel in the image, calculating the G / B ratio of the G channel and the B channel of all pixels in the image, averaging the G / B ratios of all pixels to obtain a G / B mean, and then substituting the G / B mean into the relationship curve obtained in step (4), thereby calculating the chlorpyrifos pesticide residue concentration; finally, storing the test results and image information through an SD card, and displaying the test results through a display module.

[0016] The mechanism of the present invention is as follows:

[0017] Based on the enzyme-mimicking activity of the prepared MOF material ZIF-8, the hydrolysis of ATCH can be effectively catalyzed, and the product of ATCH hydrolysis, choline, can react with DTNB to generate the yellow substance TNB. The introduction of chlorpyrifos pesticide can enhance the enzyme-mimicking activity of the MOF material, thereby promoting the hydrolysis process, generating more TNB, and making the color of the entire biosensor output more yellow, thereby achieving the conversion of the chlorpyrifos pesticide residue concentration into a color change, and realizing the basis for quantitative analysis of chlorpyrifos pesticide. Further combined with the camera module of the pesticide residue detection equipment to collect the image information of the biosensor and the analysis of the image by STM32, the concentration of chlorpyrifos pesticide in the sample is calculated according to the linear relationship between the pixel G / B mean and the chlorpyrifos pesticide concentration, so as to realize on-site detection of pesticides.

[0018] The present invention has the following characteristics:

[0019] (1) The pesticide residue detection device based on a single-chip microcomputer prepared by the present invention has the advantages of strong anti-interference ability and high selectivity, and quantitative detection is performed by analyzing the color output by the biosensor;

[0020] (2) The present invention has the advantages of low construction cost, good stability, and simple operation. Combined with a single-chip microcomputer, it realizes portable on-site detection of chlorpyrifos pesticides;

[0021] (3) The present invention shows great potential in constructing portable detection equipment to achieve instant testing and marketization. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 : The morphology characterization diagram of the MOF material in Example 1 illustrates the star-shaped structure of the MOF material ZIF-8 synthesized by the present invention;

[0023] Figure 2 : The change of image color of the biosensor in Example 2 under different concentrations of chlorpyrifos pesticide solution, Figure 2 The concentrations of chlorpyrifos pesticide from left to right are 0.05ng / mL, 0.1ng / mL, 0.25ng / mL, 0.5ng / mL, 1ng / mL, 2.5ng / mL, 5ng / mL, 10ng / mL, 25ng / mL, and 50ng / mL. It can be seen that as the concentration of chlorpyrifos pesticide increases, the color of the biosensor output gradually turns yellow;

[0024] Figure 3 : Linear relationship diagram of the mean value of G / B and the concentration of chlorpyrifos pesticide in Example 4, Figure 3The horizontal axis is the logarithm of the concentration of chlorpyrifos pesticide (log(100*chlorpyrifos)), and the vertical axis is the mean value of G / B. It can be seen that the mean value of G / B has a good linear relationship with the concentration of chlorpyrifos pesticide.

[0025] Figure 4 : Schematic diagram of the pesticide residue detection equipment in Example 4. DETAILED DESCRIPTION

[0026] Example 1: Preparation of MOF material ZIF-8

[0027] First, 75 mg of poly(lactic-co-glycolic acid) (PLGA) and 7.5 mg of bovine serum albumin (BSA) were added to 1 mL of deionized water, followed by 2 mL of 0.1 M zinc acetate dihydrate and 2 mL of 1.2 M dimethylimidazole, and then aged for 4 h. Then, the mixture was heated at 6000 r min. -1 After centrifugation at a speed of 5 min, a white precipitate of ZIF-8 of the MOF material was obtained, and then water was added for shaking and washing, and then centrifuged at the same speed for 5 min to obtain a precipitate; the above "centrifugation and washing operation steps" were repeated twice, and finally the volume was fixed to 1 mL of deionized water to obtain a ZIF-8 solution of the MOF material.

[0028] Example 2: Preparation of biosensor

[0029] 25 μL of the ZIF-8 solution of the MOF material obtained in Example 1, 50 μL of 10 mM iodothioacetylcholine (ATCH) and 50 μL of PBS buffer at pH 8.5 were added to the enzyme-labeled well to construct a MOF-based biosensor, and then a known concentration of chlorpyrifos pesticide solution (concentration range 0.05 ng / mL to 50 ng / mL) was added, and the reaction was carried out at 37°C for 25 minutes, and then 35 μL of 2 mg / mL 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) was added.

[0030] Example 3: Portable pesticide detection equipment analyzes the color produced by the biosensor

[0031] The biosensor obtained in Example 2 is placed into the main structure of the pesticide residue detection device through the groove, and the detection icon is pressed through the LCD touch screen. The camera module in the device takes an image containing color information of the biosensor. The single-chip microcomputer has a program for processing and analyzing data (the program is written in C language, mainly realizing the control function of the single-chip microcomputer to the camera, LCD touch screen, and storage module and the image analysis and processing function), and the G / B mean of all pixels in the image will be obtained. By changing the concentration of the chlorpyrifos pesticide solution in the biosensor, different G / B mean values ​​can be obtained, and the linear relationship curve of "G / B mean value-100 times the logarithm of the chlorpyrifos pesticide concentration" is fitted by regression analysis.

[0032] Example 4: Detection of pesticide residue concentration by portable pesticide detection equipment

[0033] A chlorpyrifos pesticide solution of unknown concentration is added to the biosensor, and the camera module captures an image of the biosensor containing color information. The G / B mean of all pixels in the image is obtained by a program in the computer, and then substituted into the linear relationship curve obtained in Example 3 to calculate the concentration of the chlorpyrifos pesticide solution. Finally, the detection result and image information are stored through an SD card, and the detection result is displayed through an LCD touch screen in the liquid crystal display module.

Claims

1. A portable chlorpyrifos pesticide residue detection device based on MOF-based biosensor, characterized by: It consists of a 3D printed main structure, a camera module, an LED fill light strip, a power supply and switch module, a storage module and a main control module on a PCB board, a display module and a groove for placing a MOF-based biosensor; the camera module is located at the upper part of the main structure, and the LED fill light strip is located at the upper side of the main structure, serving as the ambient light source for the entire device; the groove for placing the biosensor is placed at the bottom of the main structure, and the groove can be extended and pulled out through a slide rail; the power supply and the switch are embedded in parallel at the bottom of the side of the main structure; the storage module and the main control module are arranged on the PCB board, which are connected to the display module and the camera module through a hardware interface; the display module is arranged in front of the PCB board to output the results of pesticide residue detection; during the detection process, the entire device is a darkroom, using the LED fill light inside the main structure as the light source.

2. A portable chlorpyrifos pesticide residue detection device based on MOF-based biosensor according to claim 1, characterized in that: The MOF-based biosensor is used to convert the concentration information of the chlorpyrifos pesticide into color information; the camera is used to take pictures of the color information of the biosensor; the storage module is an SD card welded on the PCB board, which is used to store the images taken by the camera; the main control module is a single-chip microcomputer STM32F407 welded on the PCB board, which is used to control the camera to take images of the MOF-based biosensor and analyze the images taken by the camera; the camera is connected to the single-chip microcomputer on the PCB board through wires; the display module uses an LCD touch screen, which is used for the touch screen function of the equipment and the display of detection results.

3. A portable chlorpyrifos pesticide residue detection device based on MOF-based biosensor according to claim 1, characterized in that: 75 mg of polylactic acid-glycolic acid copolymer and 7.5 mg of bovine serum albumin were added to 1-3 mL of deionized water, and then 2 mL of 0.1 M zinc acetate dihydrate and 2 mL of 1.2 M dimethylimidazole were added, and the mixture was aged for 3-5 hours; the mixture was heated at 5000-8000 r min -1 After centrifugation at a speed of 3 to 8 minutes, a white precipitate of ZIF-8 of the MOF material is obtained, and then deionized water is added for shaking and washing, and the precipitate is obtained by centrifugation at the same speed for 3 to 8 minutes; the above-mentioned "washing after centrifugation" operation steps are repeated 2 to 3 times, and finally the obtained precipitate is fixed to 1 mL with deionized water to obtain a ZIF-8 solution of the star-shaped MOF material; 25 μL of ZIF-8 solution, 50 μL of 10 mM iodothioacetylcholine and 50 μL of PBS buffer with a pH of 8.5 are added to the enzyme-labeled well to construct a MOF-based biosensor.

4. A portable chlorpyrifos pesticide residue detection device based on MOF-based biosensor according to claim 2, characterized in that: The steps to analyze the images taken by the camera are as follows: (1) Add a chlorpyrifos pesticide solution with a concentration of 0.05 ng / mL to 50 ng / mL to the MOF-based biosensor, react at 37°C for 20 to 30 min, then add 35 μL of 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) with a concentration of 2 mg / mL, and then place the biosensor with the chlorpyrifos pesticide to be tested into the pesticide residue detection equipment through the groove; (2) The color information generated by the biosensor is photographed by a camera to obtain multiple images corresponding to the concentration of chlorpyrifos pesticide. The RGB three channels of each pixel in each image are stripped using a single-chip microcomputer STM32F407, and the G / B ratios of the G channel and the B channel of all pixels in each image are calculated. The G / B ratios of all pixels in the image are then averaged to obtain the G / B mean of the image. Finally, the "100-fold logarithm of the chlorpyrifos pesticide concentration Log(100*chlorpyrifos)" is used as the horizontal coordinate, and the G / B mean is used as the vertical coordinate to fit the "G / B mean-100-fold logarithm of the chlorpyrifos pesticide concentration Log(100*chlorpyrifos)" linear relationship curve y=0.56log(100*chlorpyrifos)+6.39; (3) Using a camera to take a picture of the color information generated by the biosensor under the chlorpyrifos pesticide solution with an unknown residual concentration to obtain an image, using a single-chip microcomputer STM32F407 to strip the RGB three channels of each pixel in the image, calculating the G / B ratio of the G channel and the B channel of all pixels in the image, averaging the G / B ratios of all pixels to obtain a G / B mean, and then substituting the G / B mean into the relationship curve obtained in step (4), thereby calculating the chlorpyrifos pesticide residue concentration; finally, storing the test results and image information through an SD card, and displaying the test results through a display module.

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