阅读说明：本技术 用于啶虫脒和吡虫啉联合毒性评价的电化学细胞传感器的构建方法及其应用 (construction method and application of electrochemical cell sensor for acetamiprid and imidacloprid combined toxicity evaluation ) 是由 李在均 徐丹 李瑞怡 孙秀兰 于 2019-09-02 设计创作，主要内容包括：本发明涉及一种用于啶虫脒和吡虫啉联合毒性评价的电化学细胞传感器的构建方法及其应用,属于细胞的检测技术领域。其首先制备尺寸可控的Ag/His-GQD/rGO三维复合材料,复合材料修饰到玻碳电极上后,L-半胱氨酸通过巯基结合到复合材料上,再将已经活化的叶酸通过酰胺键与L-半胱氨酸结合,固定细胞,通过电化学阻抗技术进行测定,制得电化学细胞传感器。本发明通过与三维复合材料的结合,可以提供更多的结合位点,提高传感器的灵敏度。构建的传感器结合电化学阻抗技术可以快速用于Hep G2细胞的测定,且成本比较低。本发明通过Hep G2细胞传感器的构建,可用于农药毒性的评价,在农药联合毒性评价方面具有良好的应用前景。(the invention relates to a construction method and application of an electrochemical cell sensor for acetamiprid and imidacloprid combined toxicity evaluation, and belongs to the technical field of cell detection. The method comprises the steps of firstly preparing an Ag/His-GQD/rGO three-dimensional composite material with controllable size, modifying the composite material on a glassy carbon electrode, then combining L-cysteine on the composite material through sulfydryl, combining activated folic acid with the L-cysteine through amido bond, fixing cells, and measuring through an electrochemical impedance technology to prepare the electrochemical cell sensor. The invention can provide more binding sites and improve the sensitivity of the sensor by combining with the three-dimensional composite material. The constructed sensor can be rapidly used for the measurement of Hep G2 cells by combining the electrochemical impedance technology, and the cost is low. The construction of the Hep G2 cell sensor can be used for evaluating the toxicity of the pesticide, and has a good application prospect in the aspect of evaluating the combined toxicity of the pesticide.)

1. the construction method of the electrochemical cell sensor for the acetamiprid and imidacloprid combined toxicity evaluation is characterized by comprising the following steps of: firstly, preparing a silver nanoparticle/histidine functionalized graphene quantum dot/reduced graphene oxide Ag/His-GQD/rGO three-dimensional composite material with controllable size, modifying the composite material on the surface of a glassy carbon electrode, then combining L-cysteine with the composite material through sulfydryl, combining activated folic acid with the L-cysteine through amido bond, fixing cells, and determining through an electrochemical impedance technology to prepare the electrochemical cell sensor.

2. The method for constructing the electrochemical cell sensor for the joint toxicity evaluation of acetamiprid and imidacloprid as claimed in claim 1, wherein the preparation method of the three-dimensional composite material with controllable size is as follows: weighing graphite oxide, dispersing the graphite oxide in water, performing ultrasonic treatment to obtain a dispersion liquid, and adding histidine-functionalized graphene quantum dots under a stirring condition to obtain a uniform dispersion liquid; adjusting the solution to be neutral by using NaOH, slowly adding a silver nitrate solution, precipitating with the increase of the amount of silver nitrate, centrifuging, and washing to obtain Ag/His-GQD/GO; and (3) carrying out freeze drying on the sample, and finally carrying out high-temperature reduction under the protection of nitrogen to obtain the Ag/His-GQD/rGO three-dimensional composite material.

3. the method for constructing the electrochemical cell sensor for the joint toxicity evaluation of acetamiprid and imidacloprid as claimed in claim 2, wherein the preparation method of the three-dimensional composite material with controllable size is as follows: silver nitrate with different concentrations is prepared, and the particle size and distribution of the silver nanoparticles are regulated and controlled according to the added amount of the silver nitrate.

4. The method for constructing the electrochemical cell sensor for the joint toxicity evaluation of acetamiprid and imidacloprid as claimed in claim 1, wherein the sensor is constructed by the following steps:

(1) The Ag/His-GQD/rGO three-dimensional composite material is dissolved in DMF, chitosan is added dropwise after ultrasonic treatment, the mixture is continuously subjected to ultrasonic treatment until the mixture is uniformly dispersed, a micro-sampler is used for transferring and taking the solution to be dropped on the surface of a treated glassy carbon electrode, and the mixture is placed overnight;

(2) L-cysteine is bound to the electrode through the sulfydryl of the L-cysteine;

(3) Activating folic acid by 1-ethyl- (3-dimethylaminopropyl) carbodiimide hydrochloride)/(N-hydroxysuccinimide, and then modifying the folic acid on the surface of an electrode by carrying out amide reaction with L-cysteine to prepare the electrochemical cell sensor.

5. The application of the electrochemical cell sensor for the joint toxicity evaluation of the acetamiprid and the imidacloprid is characterized in that: the determination of the cell concentration is achieved by modifying and incubating the cells on the counter electrode.

6. the use of an electrochemical cell sensor according to claim 5 for the combined toxicity assessment of acetamiprid and imidacloprid, wherein the cell assay method is as follows: and taking out the constructed electrochemical cell sensor, putting the cells which are stimulated by the acetamiprid and the imidacloprid standard substance into the electrochemical cell sensor, incubating the cells for 7 to 9 hours at 37 ℃, and investigating the change of an electrode interface by measuring an impedance value, thereby realizing the measurement of the cells and simultaneously realizing the combined toxicity evaluation of the acetamiprid and the imidacloprid.

7. Use of an electrochemical cell sensor according to claim 5 for the combined toxicity assessment of acetamiprid and imidacloprid, characterized in that: the cells are Hep G2 cells.

Technical Field

The invention relates to a construction method and application of an electrochemical cell sensor for acetamiprid and imidacloprid combined toxicity evaluation, in particular to a preparation method and application of a silver nanoparticle/histidine functionalized graphene quantum dot/reduced graphene three-dimensional composite material with controllable size, and belongs to the technical field of cell detection.

Background

With the development of agriculture, various pesticides such as organic phosphorus, carbamates, chloronicotinyl and the like are continuously appeared, wherein the chloronicotinyl pesticide is widely used as a novel pesticide in insect prevention and pest resistance of agriculture. It is characterized by that it utilizes the control of nicotinic acetylcholine receptor existed in insect nervous system to block normal conduction of insect central nervous system, and can make the potential balance of nerve synaptic membrane be damaged, and can induce the paralysis of insect so as to make death. At present, 11 types of nicotinoyl chloride pesticides are registered in China, wherein the registration number of imidacloprid, acetamiprid and thiamethoxam is three. The excessive and frequent use of pesticides, especially the combined use of multiple pesticides, inevitably has great influence on the ecological environment and the health of human beings. Methods for the evaluation and analysis of the combined toxicity of pesticides are therefore of increasing importance, in particular with regard to the determination of whether the combined toxicity of the mixed pesticides is enhanced (synergistic), diminished (antagonistic) or unaffected (additive) by the interaction between the components.

the electrochemical sensor has the advantages of high response speed, high sensitivity, good stability, large miniaturization potential, high cost performance and the like, and is widely used for detecting cells. In order to improve the sensitivity of the sensor, various signal amplification strategies have appeared, wherein the nanomaterial amplification strategy is widely used for the construction of the sensor. Graphene has attracted much attention because of its advantages such as good mechanical properties, high electrical conductivity, and high specific surface area. However, two-dimensional graphene is agglomerated through pi-pi stacking, so that the specific surface area of the graphene is reduced and the conductivity of the graphene is deteriorated, which greatly limits the application of the graphene in a sensor. The three-dimensional graphene such as aerogel, sponge and foam has large specific surface area and pores, and can accelerate the electron transfer rate and greatly improve the agglomeration problem of the graphene. In order to further improve the sensitivity of the sensor, the composite material prepared by combining graphene and other nano materials is widely researched. Noble metal nanoparticles have large surface area, unique catalytic performance and good electrochemical performance, and have been used for sensor construction, such as Au, Pt, Pd, Ag, and the like. The catalytic performance of the nanoparticles is often determined by the particle size and the dispersity of the nanoparticles, and the nanoparticles with small particle size and high dispersity generally have better catalytic performance. To date, many nanoparticles with different morphologies have been synthesized by different strategies to improve their catalytic properties, such as triangular, hexagonal, flower-like and plate-like. However, noble metal nanoparticles are unstable in surface potential and easily agglomerate, which leads to a decrease in specific surface area and catalytic ability, and thus cannot fully utilize the good catalytic performance of the nanoparticles. Not only is the specific surface area increased by the combination of graphene and noble metal, thereby increasing the immobilization capacity of the analyte, but also a concerted catalytic effect is shown, resulting in better performance and more sensitive reactions than using graphene or noble metal nanoparticles alone. To date, composites of graphene and noble metal nanoparticles have been widely used. There are many ways to combine the two, for example, first preparing the noble metal nanoparticles and the graphene separately, and then obtaining the composite material by simple physical mixing. This bonding not only results in leaching of the silver nanoparticles during washing, but also results in agglomeration of the nanoparticles due to the weak bonding force between graphene and nanoparticles. And combining the oxygen-containing group with negative charge on the surface of the graphite oxide with the metal salt with positive charge, and reducing by using a reducing agent to obtain the in-situ reduction method. Although this approach improves the bond strength between graphene and nanoparticles, the size of the nanoparticles is difficult to control in the process, resulting in nanoparticles of different sizes being dispersed on the graphene sheet. There are other strategies such as nitrogen doping, amine functionalization, etc. Despite these efforts, these methods still fail to achieve uniform dispersion of size-controllable nanoparticles on graphene.

Disclosure of Invention

The invention aims to overcome the defects and provides a construction method and application of an electrochemical cell sensor for joint toxicity evaluation of acetamiprid and imidacloprid, wherein the electrochemical cell sensor is constructed on the basis of a silver nanoparticle/histidine functionalized graphene quantum dot/reduced graphite oxide (Ag/His-GQD/rGO) three-dimensional composite material with controllable size, so that joint toxicity evaluation of imidacloprid and acetamiprid on Hep G2 cells is realized.

The technical scheme includes that the construction method of the electrochemical cell sensor for acetamiprid and imidacloprid combined toxicity evaluation comprises the steps of firstly preparing a silver nanoparticle/histidine functionalized graphene quantum dot/reduced graphene oxide Ag/His-GQD/rGO three-dimensional composite material with controllable size, modifying the composite material on a glassy carbon electrode, then combining L-cysteine on the composite material through sulfydryl, combining activated folic acid with L-cysteine through amido bond, fixing cells, and measuring through an electrochemical impedance technology to obtain the electrochemical cell sensor.

Further, the preparation method of the three-dimensional composite material with controllable size comprises the following steps: weighing graphite oxide, dispersing the graphite oxide in water, performing ultrasonic treatment to obtain a dispersion liquid, and adding histidine-functionalized graphene quantum dots under a stirring condition to obtain a uniform dispersion liquid; adjusting the solution to be neutral by using NaOH, slowly adding a silver nitrate solution, precipitating with the increase of the amount of silver nitrate, centrifuging, and washing to obtain Ag/His-GQD/GO; and (3) carrying out freeze drying on the sample, and finally carrying out high-temperature reduction under the protection of nitrogen to obtain the Ag/His-GQD/rGO three-dimensional composite material.

Further, the preparation method of the three-dimensional composite material with controllable size comprises the following steps: silver nitrate with different concentrations is prepared, and the particle size and distribution of the silver nanoparticles are regulated and controlled according to the added amount of the silver nitrate.

Further, the construction method of the sensor for the acetamiprid and imidacloprid combined toxicity evaluation is as follows:

(1) The Ag/His-GQD/rGO three-dimensional composite material is dissolved in DMF, chitosan is added dropwise after ultrasonic treatment, the mixture is continuously subjected to ultrasonic treatment until the mixture is uniformly dispersed, a micro-sampler is used for transferring and taking the solution to be dropped on the surface of a treated glassy carbon electrode, and the mixture is placed overnight;

(2) L-cysteine is bound to the electrode through the sulfydryl of the L-cysteine;

(3) Activating folic acid by 1-ethyl- (3-dimethylaminopropyl) carbodiimide hydrochloride)/(N-hydroxysuccinimide, and then modifying the folic acid on the surface of an electrode by carrying out amide reaction with L-cysteine to prepare the electrochemical cell sensor.

The invention also aims to provide application of the electrochemical cell sensor for evaluating the joint toxicity of the acetamiprid and the imidacloprid, which realizes the measurement of cell concentration and the evaluation of the joint toxicity of pesticides by modifying and incubating cells on an electrode.

Further, the cell assay method is as follows: and taking out the constructed electrochemical cell sensor, putting the cells stimulated by the acetamiprid and the imidacloprid standard into the electrochemical cell sensor, incubating the cells at 37 ℃ for 7 to 9 hours, and inspecting the change of an electrode interface by measuring an impedance value so as to realize the measurement of the cells and the evaluation of the combined toxicity.

Further, the cells were Hep G2 cells.

The invention has the beneficial effects that: the invention can combine more combining sites by combining with the three-dimensional composite material, thereby improving the sensitivity of the sensor. The constructed sensor can be rapidly used for the measurement of Hep G2 cells by combining the electrochemical impedance technology, and the cost is low.

The construction of the Hep G2 cell sensor can be used for evaluating the toxicity of the pesticide, and has a good application prospect in the aspect of evaluating the combined toxicity of the pesticide.

Drawings

FIG. 1-A is a fluorescence spectrum diagram of different mass ratios of GO and GO/His-GQD.

FIG. 1-B is a graph of the different mass ratios of GO and GO/His-GQD versus the degree of fluorescence quenching.

FIG. 2 is an SEM image of an Ag/His-GQD/rGO composite.

FIG. 3 is a TEM and elemental analysis of Ag/His-GQD/rGO composites.

FIG. 4-A is the GO and GO/His-GQD infrared spectra.

FIG. 4-B is an XRD spectrum of the Ag/His-GQD/rGO composite material.

Detailed Description

The invention will be further described with reference to the accompanying drawings.

CHI660D electrochemical workstation used in the present invention (Shanghai Chenghua); HITACHI S4800 field emission scanning electron microscope; JEM-2100(HR) transmission electron microscope (JEOL Ltd., Japan); nicolet iS50 FT-IR Fourier Infrared Spectroscopy (Sammer Feishell science, USA); CuK α radiation X-ray diffraction (XRD) was measured on D8 Advance (brueck, germany); fluorescence spectrophotometer (Warran, USA).

the invention adopts graphite, citric acid, histidine, sodium hydroxide and silver nitrate (AgNO)₃) Phosphate buffered saline (PBS, 0.01M, pH 7.40), Hep G2 cells, L-cysteine, 1-ethyl- (3-dimethylaminopropyl) carbodiimide hydrochloride)/(N-hydroxysuccinimide), folic acid, acetamiprid, and imidacloprid standards were prepared.

A preparation method for constructing a cell sensor based on a size-controllable silver nanoparticle/histidine functionalized graphene quantum dot/reduced graphene oxide (Ag/His-GQD/rGO) three-dimensional composite material comprises the following steps:

1. The synthesis of the silver nanoparticle/histidine functionalized graphene quantum dot/reduced graphene oxide material with controllable size comprises the following steps:

(1) Weighing 0.3 g of graphene oxide, dispersing in 100 mL of deionized water, performing ultrasonic treatment for 3h to obtain a dispersion solution, and slowly adding 0.375 g of His-GQD under the stirring of 700 r/min. Then, regulating the acidity of the solution to pH 7.00 by using 1mol/L NaOH solution;

0.2 mol/L AgNO was added dropwise thereto₃Gradually precipitating in water solution, centrifuging to collect solid, washing with deionized water for several times, and collecting solid. And (3) drying in vacuum at the temperature of 60 ℃ to obtain Ag/His-GQD/GO. And (3) freeze-drying the sample, placing the dried sample in a tube furnace, heating to 300 ℃ at the speed of 2 ℃/min under the protection of nitrogen, keeping annealing reduction for 3h, and cooling at room temperature to obtain the Ag/His-GQD/rGO composite material.

(2) Silver nitrate with different amounts is combined with His-GQD/GO, and the size of the silver nanoparticles is regulated and controlled by adding different amounts of silver nitrate.

2. And (3) constructing a sensor:

Glassy carbon electrode coated with Al₂O₃Polishing, then respectively performing ultrasonic treatment in deionized and ethanol solutions for 10min, and blow-drying with nitrogen for later use. Dispersing the prepared Ag/His-GQD/rGO composite material into a DMF solution, adding 1.0 wt% of Chitosan (CS), and carrying out ultrasonic treatment for 1 h to obtain a dispersion liquid (2 mg/mL). 10 μ L of the dispersion was dropped onto the surface of the treated GCE and allowed to stand at room temperature until dry. The activated folate is then modified to the electrode by subsequent modification of the L-cysteine.

3. cell assay:

Hep G2 was fixed to the electrode surface and measured by electrochemical impedance technique to obtain a Hep G2 cell sensor. The constructed Hep G2 cell sensor stimulates Hep G2 cells by combining two pesticides (acetamiprid and imidacloprid), and then measures the magnitude of impedance value by using an electrochemical communication technology to evaluate the combined toxicity of the pesticides.

fig. 1 is a fluorescence spectrum of graphene oxide of 1mg/mL and histidine functionalized graphene quantum dots with different mass ratios. As the GO/His-GQD mass ratio increases, the fluorescence intensity decreases continuously due to fluorescence quenching caused by energy resonance transfer, which also demonstrates successful binding of His-GQD to GO. When the mass ratio of GO to His to GQD reaches 0.8, the fluorescence intensity has no obvious change. Therefore, the present invention employs GO/His-GQD in a mass ratio of 0.8.

fig. 2 shows a silver nanoparticle/histidine functionalized graphene quantum dot/graphite oxide composite SEM.

The SEM of the silver nanoparticle/histidine functionalized graphene quantum dot/graphite oxide composite material shows that the composite material has a three-dimensional shape consisting of folded sheets and silver nanoparticles, and the silver nanoparticles are uniformly distributed on two sides of the rGO sheets. This is because the His-GQDs acts as a stabilizer, firmly fixing the silver nanoparticles on the graphene sheet. In addition, silver nano particles are embedded between the rGO sheets, so that the distance between the rGO sheets is increased, a three-dimensional net structure is formed, and the silver nano particles can be uniformly dispersed on the graphene sheets.

Fig. 3 shows TEM and elemental analysis of silver nanoparticle/histidine functionalized graphene quantum dot/graphite oxide composite.

A picture, a silver nanoparticle/histidine functionalized graphene quantum dot/graphite oxide composite material TEM, silver nanoparticles are fixed on a rGO sheet, and the average size of the silver nanoparticles is 25 nm. The inset in fig. B is a High Resolution TEM (HRTEM), with a lattice spacing of 0.205 nm corresponding to the (200) plane of the Ag crystal. In addition, detailed composition of elements was analyzed using Element Mapping Images (EMIs) (C diagram), and Ag, N elements were observed.

Fig. 4 shows infrared spectra of graphene oxide and graphene oxide/histidine-functionalized graphene quantum dots and XRD of silver nanoparticle/histidine-functionalized graphene quantum dots/graphite oxide composite material.

Graph A, from top to bottom, shows the infrared spectra of GO and GO/His-GQD, for graphite oxide, 3400 cm ^{- 1}, 1773 cm^{- 1}, 1674 cm ^{- 1}, 1102 cm^-1And 1029 cm^{– 1}the-OH peak, C = O stretching, C = C stretching, C-O stretching vibration, and epoxy vibration correspond to each other. GO is combined with His-GQD, and vibrates corresponding 3134cm at-N-H, C = N, C-N^{- 1},1587 cm^{- 1},1355 cm^-1a new peak appeared demonstrating successful binding of His-GQD to GO surface. FIG. B is an XRD spectrum of the Ag/His-GQD/rGO composite material, wherein the diffraction angles are respectively 38.3 degrees, 44.4 degrees, 64.5 degrees and 77.5 degrees, and the diffraction angles correspond to reflection peaks (111), (200) and (220) of a cubic Ag crystal (JCPDS number 65-2871)And (311).

In summary, Ag/His-GQD/rGO composites were successfully synthesized.