阅读说明：本技术 一种用于选择性检测农药阿特拉津的光电化学分析方法 (Photoelectrochemical analysis method for selectively detecting pesticide atrazine ) 是由 范丽芳 梁桂芳 张彩云 梁文婷 刘雪峰 郭玉晶 董川 于 2019-11-19 设计创作，主要内容包括：本发明涉及一种用于选择性检测农药阿特拉津的光电化学分析方法,为了解决采用传统分析方法对农药阿特拉津检测时成本高、操作复杂以及选择性差的技术问题。本发明的光电化学分析方法是通过阳极氧化的方法在钛板上原位生长均匀直立的TiO<Sub>2</Sub>NTs；然后利用水热法将BiOI纳米化花负载在TiO<Sub>2</Sub>NTs上；最后利用共价键合作用将末端修饰氨基的适配体固定在BiOI/TiO<Sub>2</Sub> NTs上制备得到。本发明的光电分析方法不仅对阿特拉津能进行高灵敏的分析,检测限可达0.5pM,而且具有好的选择性和抗干扰能力,可以实现对复杂环境水中阿特拉津的定量分析。(The invention relates to a photoelectrochemical analysis method for selectively detecting pesticide atrazine, and aims to solve the technical problems of high cost, complex operation and poor selectivity when the traditional analysis method is adopted to detect the pesticide atrazine. The photoelectrochemical analysis method of the invention is to grow uniform and upright TiO on a titanium plate in situ by an anodic oxidation method 2 NTs; then a hydrothermal method is utilized to load the BiOI nano flower on TiO 2 On NTs; finally, the aptamer with the modified amino at the tail end is fixed on the BiOI/TiO by utilizing the covalent bonding effect 2 Prepared on NTs. The photoelectric analysis method disclosed by the invention not only can be used for carrying out high-sensitivity analysis on the atrazine, the detection limit can reach 0.5pM, but also has good selectivity and anti-interference capability, and can be used for realizing quantitative analysis on the atrazine in the water in the complex environment.)

1. A photoelectrochemical analysis method for selectively detecting pesticide atrazine is characterized by comprising the following steps: the method comprises the following steps:

(1) the photoelectric chemical sensor for detecting atrazine is prepared as follows:

1) adopting a titanium plate as an anode and a platinum sheet as a cathode, keeping the distance between the electrodes to be 1cm, and placing the titanium plate into a container containing 0.2-0.5 wt% of NH₄F. In 1-4 wt% deionized water ammonium fluoride-ethylene glycol electrolyte, under magnetic stirring, setting the potential to be 50-75V, anodizing for 1-5 h at 25 ℃, taking out the titanium plate, ultrasonically cleaning the titanium plate with deionized water for 20-60 s, drying the titanium plate, then placing the titanium plate into a muffle furnace for calcining, keeping the titanium plate at 400-500 ℃ for 2-3 h, and then cooling to room temperature to obtain TiO₂NTs；

2) Synthesizing BiOI by a hydrothermal method, and reacting 2.0-5.0 mmol of Bi (NO)₃)₃·5H₂O and KI with the same mole number are respectively dissolved, and then the KI solution is slowly added into Bi (NO)₃)₃·5H₂Stirring for 30min in O solution, mixing KI solution with Bi (NO)₃)₃·5H₂Transferring the mixed solution of the O solution into a high-pressure reaction kettle, and preparing the TiO prepared in the step 1)₂Placing NTs in a high-pressure reaction kettle, reacting for 5-8 h at 145-160 ℃, after the reaction is finished, naturally cooling the high-pressure reaction kettle to room temperature, taking out the electrode, washing the electrode with deionized water, and drying to obtain the BiOI/TiO₂NTs electrodes;

3) 10 μ L of 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride and 20 μ L N-hydroxysuccinimide were added dropwise to the solution obtained in step 2) respectivelyBiOI/TiO of₂Reacting for 0.5-1 h at 60 ℃ on an area of 1 square centimeter in the middle of the NTs electrode, and then dripping 40 mu L of 2.0-5.0 mu M aptamer with amino-modified tail end on the BiOI/TiO₂Reacting for at least 1h in an area of 1 square centimeter in the middle of the surface of the NTs electrode, washing unreacted aptamer by using 0.1M Tris-HCl buffer solution with the pH of 7.41, and finally dripping 1.0-3.0 wt% of bovine serum albumin on the BiOI/TiO₂And (3) on the area of 1 square centimeter in the middle of the surface of the NTs electrode, preventing the occurrence of nonspecific adsorption, and preparing the photoelectrochemical sensor for detecting the atrazine.

(2) Preparing a plurality of atrazine standard solutions with different concentrations;

(3) the photoelectrochemical sensor for selectively detecting the pesticide atrazine is used as a working electrode, a saturated calomel electrode is used as a reference electrode, and a platinum sheet electrode is used as a counter electrode to form a three-electrode system; taking a phosphate buffer solution with the pH value of 0.1M being 7.41 as an electrolyte solution, taking a xenon lamp with the concentration of 100mW/cm as an excitation light source, adding the prepared low-concentration atrazine standard solution into a three-electrode system, incubating for 30-50 min at room temperature, applying a bias voltage of 0.0V under the irradiation of visible light, recording the photocurrent response under the concentration by adopting an I-t technology, sequentially measuring the photocurrent responses of the atrazine standard solutions with the rest concentrations by adopting the method, and establishing a standard working curve by utilizing the relation between the relative change value of the photocurrent and the atrazine standard concentration;

(4) respectively measuring 25pM of atrazine and 100 times of atrazine concentration of malathion, simazine, polychlorinated biphenyl 126, p-nitrochlorobenzene and polychlorinated biphenyl 77 interferents under the same condition by adopting the three-electrode system in the step 2), respectively recording the photocurrent changes of the atrazine and each interferent, and inspecting the selectivity and the anti-interference capability of the photoelectric analysis method according to the relative change of the photocurrent;

(5) adding the environmental water sample to be measured into a three-electrode system, measuring the photocurrent response of the environmental water sample to be measured, and substituting the photocurrent response into the standard working curve in the step 2), thereby obtaining the concentration of the atrazine in the environmental water sample to be measured.

2. The photoelectrochemical analysis method for the selective detection of the pesticide atrazine according to claim 1, characterized in that: TiO described in step 1)₂In the NTs calcining process, the heating rate and the cooling rate are both 5 ℃/min.

3. The photoelectrochemical analysis method for the selective detection of the pesticide atrazine according to claim 1, characterized in that: step 2) the prepared TiO₂And placing the NTs electrode in a high-pressure reaction kettle, wherein the reaction time is 6 h.

4. The photoelectrochemical analysis method for the selective detection of the pesticide atrazine according to claim 1, characterized in that: the concentration of 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride in step 3) was 20mg mL^-1The concentration of N-hydroxysuccinimide is 10mg mL^-1。

5. The photoelectrochemical analysis method for the selective detection of the pesticide atrazine according to claim 1, characterized in that: in the step (2), the concentration range of the prepared atrazine standard solution is 1-600 pM.

6. The photoelectrochemical analysis method for the selective detection of the pesticide atrazine according to claim 1, characterized in that: the wavelength of the visible light in the step (3) is 420 nm.

Technical Field

The invention belongs to the field of electrochemical analysis, and relates to a photoelectrochemical analysis method for detecting pesticide atrazine.

Background

Atrazine is a triazine herbicide and has been widely used in the agricultural production field since a long time ago. The atrazine has a stable structure, is easy to flow and is not easy to degrade, so that residues are left in soil, surface water and agricultural products. The study finds that atrazine, at very low concentrations, poses serious risks to the endocrine system of animals and humans, and it has a potential carcinogenic effect, increasing the risk of breast and ovarian cancer in women exposed to it for a long time. Therefore, the search for a rapid, reliable, high-sensitivity and high-selectivity analysis method has very important significance for detecting the pesticide atrazine in the environment.

At present, the detection method of atrazine mainly comprises gas chromatography, high performance liquid chromatography and enzyme-linked immunosorbent assay. Although the traditional instrument can perform accurate evaluation, the instrument is expensive in equipment, complex in operation and long in experiment time. The requirements of the enzyme-linked immunosorbent assay on the test environment are severe. Compared with the method, the photoelectrochemical analysis method has the advantages of miniaturization of instruments, convenient operation, high sensitivity, environmental friendliness, easy realization of on-line monitoring and the like, and is concerned in the detection of environmental pollutants.

Since a great amount of hydroxyl radicals and oxygen anions having strong oxidizing property are generated in the photoelectrochemical detection, most of the pairs of contaminants are oxidized, and thus, the photoelectrochemical analysis method lacks selectivity. The invention utilizes the photoelectrochemistry analysis method to detect atrazine, and how to obtain high selectivity is a very key factor while obtaining high-sensitivity detection. Therefore, it is necessary to introduce some recognition elements on the photoactive surface to selectively recognize atrazine. In the existing reports, antibodies and molecular imprinting materials are mostly used as recognition elements to realize the selective detection of atrazine. However, the antibody is easy to deteriorate under strong acid and strong base, so that the requirements on the conditions such as operation temperature, pH and the like are strict, and the antibody is not beneficial to further application; the synthesis process of the molecular imprinting material is complicated, and the elution step of the imprinted molecules is complex. The aptamer is a short single-chain oligonucleotide sequence capable of specifically recognizing a target, and has the advantages of stable property, easiness in synthesis, easiness in chemical modification and the like compared with an antibody and a molecular imprinting material. Therefore, the aptamer is used as an identification element to be modified on the surface of the photoelectric active electrode, the high sensitivity of photoelectrochemistry and the specific identification function of the aptamer are combined, a high-sensitivity and high-selectivity photoelectric analysis method is established for quickly, accurately detecting the pesticide atrazine in the environment in real time, and a new analysis method can be provided for the detection of the pesticide atrazine.

Disclosure of Invention

The invention aims to solve the problems of high cost, complex operation, poor selectivity and low sensitivity of the existing atrazine detection method, and provides a simple, rapid, high-sensitivity and high-selectivity photoelectrochemical analysis method for detecting pesticide atrazine, and the method has the advantages of energy conservation and environmental protection.

In order to solve the technical problems, the invention adopts the technical scheme that:

in-situ growth of TiO on Ti plate by anodic oxidation₂NTs, then loading the BiOI nano flower on TiO by adopting a hydrothermal method₂NTs surface, preparing the BiOI/TiO with photoelectrochemical activity₂NTs base electrodes. And then modifying the aptamer molecules with selective recognition function on atrazine on the surface of the photoactive electrode by utilizing covalent bonding reaction to prepare the prepared photoelectrochemical sensor for detecting atrazine, and establishing an efficient photoelectrochemical analysis method for detecting pesticide atrazine in the environment.

The invention provides a photoelectrochemical analysis method for selectively detecting pesticide atrazine, which is characterized by comprising the following steps: the method comprises the following steps:

(1) the photoelectric chemical sensor for detecting atrazine is prepared as follows:

1) adopting titanium plate as anode and platinum sheet as cathode, and holding electrodeThe distance between the two plates is 1cm, and the titanium plate is placed in a chamber containing 0.2 to 0.5 wt% of NH₄F. In 1-4 wt% deionized water ammonium fluoride-ethylene glycol electrolyte, under magnetic stirring, setting the potential to be 50-75V, anodizing for 1-5 h at 25 ℃, taking out a titanium plate, ultrasonically cleaning for 20-60 s with deionized water, drying the titanium plate, calcining in a muffle furnace, keeping the temperature at 400-500 ℃ for 2-3 h, and cooling to room temperature to obtain TiO₂NTs；

2) Synthesizing BiOI by a hydrothermal method, and reacting 2.0-5.0 mmol of Bi (NO)₃)₃·5H₂O and KI with the same mole number are respectively dissolved, and then the KI solution is slowly added into Bi (NO)₃)₃·5H₂Stirring for 30min in O solution, mixing KI solution with Bi (NO)₃)₃·5H₂Transferring the mixed solution of the O solution into a high-pressure reaction kettle, and preparing the TiO prepared in the step 1)₂Placing NTs in a high-pressure reaction kettle, reacting for 5-8 h at 145-160 ℃, after the reaction is finished, naturally cooling the high-pressure reaction kettle to room temperature, taking out the electrode, washing the electrode with deionized water, and drying to obtain the BiOI/TiO₂NTs electrodes;

3) dripping 10 mu L of 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride and 20 mu of L N-hydroxysuccinimide on the BiOI/TiO obtained in the step 2) respectively₂Reacting for 0.5-1 h at 60 ℃ on an area of 1 square centimeter in the middle of the NTs electrode, and then dripping 40 mu L of 2.0-5.0 mu M aptamer with amino-modified tail end on the BiOI/TiO₂Reacting for at least 1h in an area of 1 square centimeter in the middle of the surface of the NTs electrode, washing unreacted aptamer by using 0.1M Tris-HCl buffer solution with the pH of 7.41, and finally dripping 1.0-3.0 wt% of bovine serum albumin on the BiOI/TiO₂And (3) on the area of 1 square centimeter in the middle of the surface of the NTs electrode, preventing the occurrence of nonspecific adsorption, and preparing the photoelectrochemical sensor for detecting the atrazine. (ii) a

(2) Preparing a plurality of atrazine standard solutions with different concentrations;

(3) the photoelectrochemical sensor for selectively detecting the pesticide atrazine is used as a working electrode, a saturated calomel electrode is used as a reference electrode, and a platinum sheet electrode is used as a counter electrode to form a three-electrode system; taking a phosphate buffer solution with the pH value of 0.1M being 7.41 as an electrolyte solution, taking a xenon lamp with the concentration of 100mW/cm as an excitation light source, adding the prepared low-concentration atrazine standard solution into a three-electrode system, incubating for 30-50 min at room temperature, applying a bias voltage of 0.0V under the irradiation of visible light, recording the photocurrent response under the concentration by adopting an I-t technology, sequentially measuring the photocurrent responses of the atrazine standard solutions with the rest concentrations by adopting the method, and establishing a standard working curve by utilizing the relation between the relative change value of the photocurrent and the atrazine standard concentration;

(4) respectively measuring 25pM of atrazine and 100 times of atrazine concentration of malathion, simazine, polychlorinated biphenyl 126, p-nitrochlorobenzene and polychlorinated biphenyl 77 interferents under the same condition by adopting the three-electrode system in the step (3), respectively recording the photocurrent changes of the atrazine and each interferent, and inspecting the selectivity and the anti-interference capability of the photoelectric analysis method according to the relative change of the photocurrent;

(5) and (4) adding the environmental water sample to be detected into a three-electrode system, measuring the photocurrent response of the environmental water sample to be detected, and substituting the photocurrent response into the standard working curve in the step (3), so as to obtain the concentration of the atrazine in the environmental water sample to be detected.

Further, the TiO in the step 1) of preparing the photoelectrochemical sensor for detecting atrazine₂In the NTs calcining process, the heating rate and the cooling rate are both 5 ℃/min.

Further, the step 2) of preparing the photoelectrochemical sensor for detecting atrazine₂And NTs is placed in a hydrothermal kettle, and the reaction time is 6 h.

Further, the concentration of the 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride in the step 3) of preparing the photoelectrochemical sensor for detecting atrazine is 20mg mL^-1The concentration of N-hydroxysuccinimide is 10mg mL^-1。

And (3) further, in the step (2), the concentration range of the prepared atrazine standard solution is 1-600 pM.

Further, the wavelength of the visible light in the step (3) is 420 nm.

The invention has the beneficial effects that: the invention grows uniform and upright TiO on a titanium plate by an anodic oxidation method₂NTs, loading bismuth oxyiodide (BiOI) on TiO by hydrothermal method₂On NTs, forming a p-n heterostructure, BiOI and TiO₂The NTs have matched band gap width, and the formed composite material increases the absorption of visible light, promotes the separation of electrons and holes, and effectively improves the photoelectric conversion efficiency.

The invention utilizes covalent bonding effect to fix the aptamer with the modified amino at the tail end on the photoelectrochemical active BiOI/TiO₂And on NTs, the prepared photoelectrochemical sensor has very good stability. The sensor stability was tested by switching the light source on and off several times under 420nm illumination. The test result shows that the photocurrent density is basically kept unchanged at least within 1700s, which indicates that the sensor has better stability. Meanwhile, the constructed sensor is placed at 4 ℃ for 10 days and then is detected for 25pM atrazine, and the result shows that the photocurrent response of the sensor is 95.7% of the original response signal, and further proves that the sensor has better stability.

The invention introduces the aptamer to the surface of the photoactive electrode, and the aptamer has higher affinity and specificity recognition capability to atrazine to be detected, so that the aptamer captures atrazine in the presence of a target analyte atrazine to form an atrazine aptamer compound on a sensing interface, thereby obviously reducing photocurrent signals. And other pollutants which are similar in structure or coexist in the environment cause smaller photocurrent change. The photoelectrochemistry analysis method is proved to have good selectivity on ATZ.

The instrument adopted in the invention is cheap and easy to obtain, the method is simple and convenient to operate, the detection limit can reach 0.5pM, and the method is one of the most sensitive analysis methods for detecting atrazine at present; meanwhile, the photoelectrochemistry analysis method has good stability and reproducibility, has strong anti-interference capability in a complex environment system, and can be used for detecting the pesticide atrazine in the environment.

Drawings

FIG. 1A shows a positive view of the present inventionMedium TiO prepared by polar oxidation method₂NTs, FIG. 1B Supported BiOI nanoflower BiOI/TiO₂SEM pictures of NTs;

FIG. 2 is an i-t curve diagram of the photocurrent varying with the atrazine concentration when the photoelectrochemical analysis method of the present invention detects atrazine;

FIG. 3 is a quantitative graph of the photoelectrochemical analysis method of the present invention for atrazine detection;

FIG. 4 is a graph showing the selectivity of the photoelectrochemical analysis method of the present invention to atrazine and other interferents;

FIG. 5 is an i-t curve diagram of a photoelectrochemical sensor prepared according to the present invention under repeated excitation of visible light at 420 nm.

Detailed Description

The invention is further illustrated with reference to the following figures and examples.