阅读说明：本技术 一种用于特异性检测丙溴磷的电化学发光适配体传感器及其制备方法和应用 (Electrochemical luminescence aptamer sensor for specifically detecting profenofos, and preparation method and application thereof ) 是由 郭业民 孙霞 张梅 史孝杰 李发兰 于 2021-08-17 设计创作，主要内容包括：本发明提供了一种用于特异性检测丙溴磷的电化学发光适配体传感器及其制备方法和应用,具体属于电化学发光检测领域。包括：(1)纳米金多壁碳纳米管(AuNPs@MWCNTs)和具有核壳结构的纳米金银复合材料(Au@AgNPs)的制备；(2)电化学发光适配体传感器的制备；(3)将AuNPs@MWCNTs与Au@AgNP共同修饰到铂金电极表面,提高电化学发光的灵敏度和稳定性,随后负载适配体即可获得电化学发光适配体传感器,该传感器可特异性识别丙溴磷,检测范围为100 fg/mL～1µg/mL,最低检测限为5.32 fg/mL。本发明检测丙溴磷的灵敏度高、特异性强、操作简单。(The invention provides an electrochemiluminescence aptamer sensor for specifically detecting profenofos, and a preparation method and application thereof, and particularly belongs to the field of electrochemiluminescence detection. The method comprises the following steps: (1) preparing nano gold multi-walled carbon nanotubes (AuNPs @ MWCNTs) and nano gold and silver composite materials (Au @ AgNPs) with a core-shell structure; (2) preparing an electrochemiluminescence aptamer sensor; (3) the AuNPs @ MWCNTs and Au @ AgNP are jointly modified on the surface of a platinum electrode, the sensitivity and stability of electrochemical luminescence are improved, then an aptamer is loaded, and an electrochemical luminescence aptamer sensor can be obtained, can specifically recognize profenofos, and has the detection range of 100 fg/mL-1 mug/mL and the minimum detection limit of 5.32 fg/mL. The method for detecting the profenofos has the advantages of high sensitivity, strong specificity and simple operation.)

1. An electrochemiluminescence aptamer sensor for specifically detecting profenofos, which is characterized in that: the electrochemical luminescence aptamer sensor is formed by loading an aptamer on the surface of a platinum electrode modified by a composite material Au @ AgNPs/AuNPs @ MWCNTs, and is used for detecting profenofos through electrochemical luminescence.

2. The electrochemiluminescent aptamer sensor for specific detection of profenofos as in claim 1, wherein: the nucleotide sequence of the profenofos aptamer is shown as the following 5 '-SH-AAGCTTGCTTTATAGCCTGCAGCGATTCTTGATCGGAAAAGGCTGAGAGCTACGC-3'.

3. The method for preparing an electrochemiluminescence aptamer sensor for specifically detecting profenofos according to claim 1, wherein the electrochemiluminescence aptamer sensor comprises the following steps: the preparation method comprises the following steps:

s1, preparing a nano gold multi-walled carbon nanotube (AuNPs @ MWCNTs): adding 2.0 mg of carboxyl functionalized multi-walled carbon nano-tube into 4 mL of 1% polyethyleneimine solution (PEI), and performing ultrasonic dispersion; centrifuging for 10 min to remove excess PEI; then, re-dispersing the residual precipitate by using 2 mL of ultrapure water to prepare PEI functionalized MWCNTs; 1mL of the nanogold solution (AuNPs) is added into 1mL of the prepared PEI functionalized MWCNTs solution dropwise, stirred overnight, and black solid obtained by centrifugation is redispersed in 2 mL of phosphate buffer solution (pH = 7.4), so that the AuNPs @ MWCNTs solution is obtained;

s2 preparation of nano gold and silver composite material (Au @ AgNPs) with core-shell structure: firstly, respectively adding 12 mu L L-ascorbic acid (AA: 100 mM), 3 mu L silver nitrate (AgNO 3: 100 mM) and 15 mu L sodium hydroxide (NaOH: 100 mM) into 2 mL of prepared AuNPs (15 nm) solution, and adjusting the pH value of the mixed solution to about 8.5; then slowly stirring the solution for 30 min at a constant speed by using a magnetic stirrer, and then centrifuging the solution for 20 min at 1800 rpm; after removal of the supernatant, the remaining liquid was redispersed in 10 mL of ultrapure water, at which point one addition was complete; repeating the steps and adding four times to complete the synthesis of Au @ AgNPs;

s3 construction of sensor

Polishing the platinum electrode, sequentially performing ultrasonic treatment by using a mixed solution of absolute ethyl alcohol and deionized water, and drying by using nitrogen; drying the surface of the pretreated platinum electrode at room temperature after being modified by 1 mu L of AuNPs @ MWCNTs solution; dripping 1 mu L of 0.01M luminol on the surface of the platinum electrode, and naturally drying at room temperature; then dropping 1 muL of Au @ AgNPs solution on the surface of the platinum electrode, and drying in the air; dropping 1 muL of profenofos aptamer sensor on the surface of the platinum electrode, and drying in the air; and then soaking the modified platinum electrode in 0.5% BSA to block non-specific sites to obtain BSA/aptamer/Au @ AgNPs/luminol/AuNPs @ MWCNTs/PE.

4. A method for detecting profenofos based on an electrochemiluminescence aptamer sensor is characterized by comprising the following steps: an electrochemiluminescence aptamer sensor as claimed in any one of claims 1 to 3 is used as a working electrode, saturated calomel is used as a reference electrode, a platinum wire electrode is used as a counter electrode to form a three-electrode system, profenofos in a sample is quantitatively captured on the surface of the sensor, and the generated luminescence signal is used for detecting the profenofos.

5. The application of the electrochemiluminescence aptamer sensor for detecting profenofos according to claim 4, is characterized by comprising the following specific steps:

A1. containing hydrogen peroxide (H)₂O₂) Preparation of PBS buffer solution of (1): 10 nM H was prepared in 0.1mol/L PBS buffer pH 9.0₂O₂PBS buffer solution of

A2. Preparing standard solutions of profenofos with different concentrations: accurately weighing a certain amount of profenofos, preparing a 10 mug/mL profenofos solution by using PBS (pH = 7.4), and diluting the solution to obtain a series of profenofos standard solutions with different concentrations, wherein the concentration range is 100 fg/mL-1 mug/mL

A3. Optimization of sensor conditions: respectively optimizing the concentration of the aptamer, the pH value of PBS buffer base solution and the incubation time of the profenofos and the aptamer; preparing the profenofos aptamer with different concentrations, wherein the concentration range is 1 nM-10⁴nM; preparation of different pH values containing 10 nM hydrogen peroxide (H)₂O₂) The pH of the PBS buffer solution is 7.0-10.0; controlling the incubation time of the profenofos and the aptamer within the range of 20 minutes to 70 minutes; the optimal experimental conditions are obtained by optimizing the relevant conditions influencing the sensor, so that the performance of the aptamer sensor is exerted to the maximum extent

A4. Drawing a standard curve: placing the electrochemiluminescence aptamer sensor in the profenofos standard solution with different concentrations prepared in the step A2, soaking for the same time, enabling the electrochemiluminescence aptamer sensor to be combined with profenofos, then taking out and leaching to be used as a working electrode, taking saturated calomel as a reference electrode, forming a three-electrode system by using a platinum wire electrode as a counter electrode, and taking the hydrogen peroxide (H) containing hydrogen peroxide (H) in the step A1₂O₂) The PBS buffer solution is electrolyte and is measured in an electrochemical luminescence workstation; recording the luminous intensity-time curve, establishing the electrochemical luminescence aptamer sensor combining the luminous intensity of profenofos and the luminous intensity of profenofos standard solutionThe linear relation of the logarithm of the concentration of the profenofos is obtained to obtain a corresponding linear regression equation

A5. Detection of profenofos in a sample: the sample is pretreated and then put into an electrochemiluminescence aptamer sensor to be soaked for the same time, so that the electrochemiluminescence aptamer sensor is combined with profenofos, then the sample is taken out and washed to be used as a working electrode, the method of the step A4 is adopted to detect the luminous intensity, and the concentration of the profenofos in the sample is calculated according to a linear regression equation.

Technical Field

The invention belongs to the field of electrochemical luminescence detection, and relates to an electrochemical luminescence aptamer sensor for specifically detecting profenofos and a detection method thereof.

Background

Profenofos is a broad-spectrum efficient, medium-toxicity and low-residue organophosphorus insecticide, has a non-systemic insecticidal and acaricidal agent with contact poisoning and stomach poisoning effects, has a conduction effect and ovicidal activity, is mainly used for crops such as cotton, corn, beet, soybean, potato, vegetables, tobacco and the like, and prevents and treats pests (particularly lepidoptera pests) and mites; the organophosphorus pesticide can inhibit the activity of acetylcholinesterase in vivo and can cause the dysfunction and death of neurons, thereby causing the damage of nervous system, and serious diseases such as organ damage, teratogenesis, carcinogenesis, mutation and the like can occur when the organophosphorus pesticide with low dose is taken in for a long time or through diet.

At present, methods for detecting profenofos include microbiological method, gas chromatography-mass spectrometry (GC-MS), enzyme-linked immunosorbent assay (ELISA), high performance liquid chromatography-mass spectrometry (HPLC-MS), photoelectrochemical analysis (PEC), electrochemical method and the like; however, most of analytical methods have high instrument operation speciality, complex pretreatment process and long time consumption, and particularly, false positives easily appear on the results of the microbiological method and the detection cost of the chromatographic method is high, so that the methods are difficult to popularize in the market for field detection; based on this, it is necessary and extremely important to develop a simple, rapid and highly selective method for detecting profenofos.

The aptamer serving as a novel recognition element is simple and rapid to synthesize, low in cost, good in selectivity, stable in property and easy to modify and mark, and is an excellent antibody replacing recognition element; electrochemiluminescence (ECL), also known as electrochemiluminescence, is a combination and extension of chemiluminescence and electrochemistry, and thus it has the advantages of chemiluminescence methods such as high sensitivity, wide linear range, convenient observation and simple instrumentation; meanwhile, the method has many incomparable advantages of a chemiluminescence method, such as good reproducibility, stable reagent, easy control and the like; and an external light source is not required to be introduced, the luminous intensity spectrum is collected under the assistance of optical instruments such as a photomultiplier and the like, and the relation between the luminous intensity spectrum and the object to be detected is established, so that the microanalysis is realized.

Disclosure of Invention

The invention aims to provide an electrochemiluminescence aptamer sensor for detecting profenofos, which has the advantages of high sensitivity, good reproducibility, good selectivity and wide linear range.

The invention is based on that the aptamer is loaded on the surface of the platinum electrode modified by the nano composite material, and the electrostatic interaction between the nano gold multi-walled carbon nano tube (AuNPs @ MWCNTs) and the nano gold-silver composite material (Au @ AgNPs) with the core-shell structure is fully utilized to be jointly modified on the surface of the platinum electrode, so that the sensitivity and the stability of electrochemical luminescence are obviously improved; the sensitivity of the sensor is improved due to the improvement of conductivity and electrochemical performance, and the AuNPs @ MWCNTs and Au @ AgNPs have a synergistic effect;

the preparation process of the sensor is as follows:

drying the surface of a pretreated Platinum Electrode (PE) at room temperature after modification of 1 mu L of AuNPs @ MWCNTs solution; and then dropping 1 mu L of 0.01M luminol on the surface of the platinum electrode, and naturally drying at room temperature. Then dropping 1 muL of Au @ AgNPs solution on the surface of the platinum electrode, and drying in the air; dropping 1 muL of profenofos aptamer sensor on the surface of the platinum electrode, and drying in the air; and then soaking the modified PE electrode in 0.5% BSA to block non-specific sites to obtain the electrochemiluminescence aptamer sensor: BSA/aptamer/Au @ AgNPs/luminol/AuNPs @ MWCNTs/PE.

Further, the platinum electrode pretreatment steps are as follows: the electrodes need to be polished with 0.05 mm alumina powder in a mixture of 98% ethanol and ultrapure water 1: 1 for 3 min, then thoroughly cleaning with ultrapure water, and drying with nitrogen.

Further, the aptamer nucleotide sequence used by the electrochemical luminescence aptamer sensor is 5 '-SH-AAGCTTGCTTTATAGCCTGCAGCGATTCTTGATCGGAAAAGGCTGAGAGCTACGC-3'.

Further, the preparation method of the nano gold multi-walled carbon nanotube (AuNPs @ MWCNTs) is as follows: adding 2.0 mg of carboxyl functionalized multi-walled carbon nano-tube into 4 mL of 1% polyethyleneimine solution (PEI), performing ultrasonic dispersion, centrifuging for 10 min to remove redundant PEI, and re-dispersing the residual precipitate with 2 mL of ultrapure water to prepare PEI functionalized MWCNTs; 1mL of the nanogold solution (AuNPs) was added dropwise to 1mL of the prepared PEI-functionalized MWCNTs solution, stirred overnight, and the black solid obtained by centrifugation was redispersed in 2 mL of phosphate buffer (pH = 7.4), at which time the AuNPs @ MWCNTs solution was obtained.

Further, the preparation method of the nano gold and silver composite material (Au @ AgNPs) with the core-shell structure comprises the following steps: first, 12 μ L L-ascorbic acid (AA: 100 mM), 3 μ L silver nitrate (AgNO)₃: 100 mM) and 15 μ L of sodium hydroxide (NaOH: 100 mM) are respectively added into 2 mL of prepared AuNPs (15 nm) solution, and the pH value of the mixed solution is adjusted to about 8.5; then uniformly stirring the solution for 30 min by using a magnetic stirrer, and then centrifuging the solution for 20 min at 1800 rpm; after removal of the supernatant, the remaining liquid was redispersed in 10 mL of ultrapure water, at which point the first addition was complete; and repeating the steps and adding four times to complete the synthesis of the Au @ AgNPs.

A method for detecting profenofos based on an electrochemiluminescence aptamer sensor, which comprises the following steps: the electrochemical luminescence aptamer sensor is used as a working electrode, saturated calomel is used as a reference electrode, a platinum wire electrode is used as a counter electrode to form a three-electrode system, the profenofos in a sample is quantitatively captured on the surface of the sensor, and the generated luminescence signal is used for detecting the profenofos.

Further, the method comprises the following specific steps:

step 1, containing hydrogen peroxide (H)₂O₂) Preparation of PBS buffer solution of (1): 10 nM H was prepared in 0.1mol/L PBS buffer pH 9.0₂O₂PBS buffer solution of (4);

step 2, preparing standard profenofos solutions with different concentrations: accurately weighing a certain amount of profenofos, preparing a 10 mug/mL profenofos solution by using PBS (pH = 7.4), and then diluting the solution to obtain a series of profenofos standard solutions with different concentrations, wherein the concentration range is 100 fg/mL-1 mug/mL.

Step 3, drawing a standard curve: placing the electrochemical luminescence aptamer sensor in the profenofos standard solution with different concentrations prepared in the step 2, soaking for the same time to enable the electrochemical luminescence aptamer sensor to be combined with profenofos, taking out and leaching to serve as a working electrode, taking saturated calomel as a reference electrode, forming a three-electrode system by a platinum wire electrode as a counter electrode, and taking the hydrogen peroxide (H) containing solution obtained in the step 1 as a reference electrode₂O₂) The PBS buffer solution is electrolyte and is measured in an electrochemical luminescence workstation; and recording a luminous intensity-time curve, and establishing a linear relation between the luminous intensity of the electrochemiluminescence aptamer sensor combined with the profenofos and a logarithmic value of the concentration of the profenofos in the profenofos standard solution to obtain a corresponding linear regression equation.

And 4, detecting the profenofos in the sample: the sample is pretreated and then put into an electrochemiluminescence adapter sensor to be soaked for the same time, so that the electrochemiluminescence adapter sensor is combined with profenofos, then the sample is taken out and washed to be used as a working electrode, the method in the step 3 is adopted to detect the luminous intensity, and the concentration of the profenofos in the sample is calculated according to a linear regression equation.

The invention fully utilizes the advantages of the aptamer and the electrochemical luminescence sensor, successfully realizes the sensitive detection of the profenofos by the mechanism of enhancing the strength of the electrochemical luminescence reminding signal of the profenofos, and the sensing platform can specifically identify the detected profenofos and has high selectivity. The detection range is 100 fg/mL-1 mug/mL, and the lowest detection limit is 5.32 fg/mL (S/N = 3). The method for detecting the profenofos has the advantages of simple operation, good selectivity, low detection cost and high sensitivity. The invention has important significance for popularizing the practical application of the aptamer sensor in the aspects of environment and food safety.

Drawings

FIG. 1 example 1A calibration curve of the luminescence intensity of an incorporated profenofos sensor versus the log of profenofos concentration.

FIG. 2 specific detection of profenofos by the sensor of example 1.

In the figure 2, a is fenthion, b is chlorpyrifos, c is acetamiprid, d is phoxim, e is malathion, f is the mixed pesticide of fenthion, chlorpyrifos, acetamiprid, phoxim and malathion, g is profenofos, and h is the mixture of all the pesticides.

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

The invention will be further described in detail with reference to the following examples:

example 1:

(1) preparation of nano gold multi-walled carbon nanotubes (AuNPs @ MWCNTs):

adding 2.0 mg of carboxyl functionalized multi-walled carbon nanotubes into 4 mL of 1% polyethyleneimine solution (PEI), performing ultrasonic dispersion, centrifuging for 10 min to remove redundant PEI, and then re-dispersing the remaining precipitate with 2 mL of ultrapure water to prepare PEI functionalized MWCNTs; 1mL of the nanogold solution (AuNPs) was added dropwise to 1mL of the prepared PEI-functionalized MWCNTs solution, stirred overnight, and the black solid obtained by centrifugation was redispersed in 2 mL of phosphate buffer (pH = 7.4), at which time the AuNPs @ MWCNTs solution was obtained.

(2) Preparation of nano gold and silver composite material (Au @ AgNPs) with core-shell structure:

first, 12 μ L L-ascorbic acid (AA: 100 mM), 3 μ L silver nitrate (AgNO)₃: 100 mM) and 15 μ L of sodium hydroxide (NaOH: 100 mM) are respectively added into 2 mL of prepared AuNPs (15 nm) solution, and the pH value of the mixed solution is adjusted to about 8.5; then uniformly stirring the solution for 30 min by using a magnetic stirrer, and then centrifuging the solution for 20 min at 1800 rpm; after removal of the supernatant, the remaining liquid was redispersed in 10 mL of ultrapure water, at which point the first addition was complete; and repeating the steps and adding four times to complete the synthesis of the Au @ AgNPs.

(3) Construction of the sensor

Polishing the platinum electrode, sequentially performing ultrasonic treatment by using a mixed solution of absolute ethyl alcohol and deionized water, and drying by using nitrogen; drying the surface of the pretreated platinum electrode at room temperature after being modified by 1 mu L of AuNPs @ MWCNTs solution; dripping 1 mu L of 0.01M luminol on the surface of the platinum electrode, and naturally drying at room temperature; then dropping 1 muL of Au @ AgNPs solution on the surface of the platinum electrode, and drying in the air; dropping 1 muL of profenofos aptamer sensor on the surface of the platinum electrode, and drying in the air; then soaking the modified platinum electrode in 0.5% BSA to block non-specific sites to obtain an electrochemiluminescence aptamer sensor; the aptamer sequence used was 5 '-SH-AAGCTTGCTTTATAGCCTGCAGCGATTCTTGATCGGAAAAGGCTGAGAGCTACGC-3'.

(4) Optimization of sensor conditions

In order to enable the performance of the aptamer sensor to be exerted to the maximum extent under the optimal experimental conditions, the concentration of the aptamer, the pH value of the test base solution and the incubation time of the profenofos and the aptamer are respectively optimized, and the result shows that the sensor reaches the optimal experimental conditions when the concentration of the aptamer is 100nM, the test pH value is 9.0 and the incubation time of the profenofos and the aptamer is 40 minutes.

(5) Drawing of standard curve

A three-electrode system is formed by taking a modified electrode BSA/aptamer/Au @ AgNPs/luminol/AuNPs @ MWCNTs/PE as a working electrode, a platinum electrode as an auxiliary electrode, saturated calomel as a reference electrode and a platinum wire electrode as a counter electrode, and is placed in a series of profenofos concentrations containing 10 nM of H₂O₂pH =9.0 was measured in an electrochemiluminescence workstation in a buffer solution of 0.1mol/L PBS; recording a luminous intensity-time curve, establishing a linear relation between the luminous intensity of the electrochemiluminescence aptamer sensor combined with the profenofos and a logarithmic value of the profenofos concentration in the profenofos standard solution, and obtaining a corresponding linear regression equation as follows: i is_ECL= 2815.56058-597.11635 logC (ng/mL), correlation coefficient (R)²) The detection limit is calculated to be 0.99941 and is 5.32 fg/mL (S/N = 3), and the detection range of the linear regression equation is 100 fg/mL-1 mug/mL.

(6) Detection of samples

Firstly, cleaning vegetables, removing soil, airing the vegetables, and cutting the vegetables into 2 x 2mm (200 mg) or so; then, 2 mL of profenofos with different concentrations and 2 mL of water are sprayed on the surface of the vegetable, and the vegetable is placed for 24 hours at room temperature; 9 mL of PBS (0.1M, pH 7.5) and 1mL of acetone were added; finally, centrifuging for 10 min at 10000 rpm in a centrifuge; and (3) filtering the supernatant by using a 0.22mm filter membrane, adding the obtained filtrate into a 0.1mol/L PBS buffer solution containing 10 nM to adjust the pH to 9.0, taking 9 mL of the obtained solution for electrochemical luminescence analysis, recording the luminescence intensity, and calculating the concentration of the profenofos in the sample to be detected according to the linear regression equation obtained in the step (5).

The electrochemiluminescence sensor for detecting profenofos prepared in the embodiment 1 is subjected to anti-interference detection, wherein working electrodes incubated by aptamers are respectively tested in standard pesticide solutions of fenthion, chlorpyrifos, acetamiprid, phoxim, malathion and profenofos, and then the working electrodes are detected in a mixture of the substances, the detection result is shown in fig. 2, as can be seen from fig. 2, the modified electrodes with excellent electrochemical properties have a selective recognition effect on profenofos after incubation of the aptamers on the modified electrodes, and the detection influence of other pesticide interferents on the profenofos is slight, so that the working electrodes can realize the anti-interference selective detection of the profenofos.

Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.