Electrochemiluminescence aptamer sensor for detecting perfluorooctanoic acid as well as preparation method and application of electrochemical luminescence aptamer sensor

Abstract

The invention provides a preparation method and application of an electrochemical luminescence aptamer sensor for detecting perfluorooctanoic acid (PFOA) in a water environment by adopting an apt / CHIT / Zn TCPP (at) MOF / GCE modified electrode based on an electrochemical luminescence method. The preparation method comprises the following steps: electrically depositing a zinc tetraphenylporphyrin functionalized metal organic framework (Zn TCPP-coated MOF / GCE) on a glassy carbon electrode (GCE), and further modifying an aptamer (apt) of chitosan (CHIT) and PFOA to prepare an apt / CHIT / Zn TCPP-coated MOF / GCE modified electrode. The modified electrode apt / CHIT / Zn TCPP (at) MOF / GCE prepared on the basis of an electrodeposition technology is low in detection limit and good in reproducibility, pretreatment of concentration and enrichment on a water environment sample is not needed due to high sensitivity, and analysis operation on PFOA is simple and easy to implement.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical detection, and specifically relates to an electrochemiluminescent aptamer sensor for detecting perfluorooctanoic acid (PFOA) based on a modified electrode apt / CHIT / ZnTCPP@MOF / GCE, and a preparation method and application thereof. Background Art

[0002] Perfluoroalkyl and polyfluoroalkyl compounds (PFASs) are widely used in the production of industrial products due to their excellent special properties, such as textiles, cosmetics, adhesives, electronic equipment, cleaning agents, firefighting foams, paper, cookware and food packaging materials. Due to the strong CF bond binding force in compounds such as PFASs, many PFASs can remain stable in the environment for a long time. With the widespread use of PFASs, they have been detected in various environmental media, such as the atmosphere, drinking water, and the bodies of wild animals. People may be exposed to PFASs through drinking water, food, and indoor environments contaminated by PFASs. Perfluorooctanoic acid (PFOA) is the most widely used PFASs in industrial production. Due to its environmental toxicity and bioaccumulation, it is currently regulated. The minimum detection mass concentration in my country's "Standard Test Methods for Drinking Water Part 8: Organic Matter Index" (GB / T 5750.8-2023) is stipulated as 5.0 ng / L. Studies have shown that drinking water is the main route of PFOA exposure besides dietary intake, but conventional water treatment processes are almost ineffective in treating PFOA. Therefore, it is very necessary to accurately grasp the concentration of PFOA in the water environment.

[0003] At present, PFOA is mostly detected by chromatography-mass spectrometry. At the same time, due to the extremely low analytical concentration of PFOA, water samples often need to be pre-treated by concentration and extraction. The above technical methods are difficult to popularize due to the use of large instruments or require complicated pre-treatment operations, etc., and the analysis cost is high, and it is difficult to achieve rapid on-site detection. Therefore, there is an urgent need for a cheap, simple, highly sensitive and specific analytical method for quantitatively detecting PFOA in water environments. Summary of the invention

[0004] The purpose of the present invention is to analyze and detect PFOA in water environments where the concentration of PFOA is extremely low. It usually requires sample pretreatment through concentration and enrichment before analysis and detection can be achieved. At the same time, since there are many organic substances and metal ions coexisting in the water environment, and their coexistence concentration is much greater than PFOA, the analysis of PFOA is often limited to chromatograph-mass spectrometry analysis or sample pretreatment for separation. The above technical methods are difficult to popularize due to the use of large instruments or require complicated pretreatment operations. This invention provides an electrochemiluminescent aptamer sensor for detecting perfluorooctanoic acid (PFOA) based on a modified electrode apt / CHIT / Zn TCPP@MOF / GCE, and its preparation method and application.

[0005] The present invention first provides an electrochemiluminescent aptamer sensor for detecting PFOA, comprising Zn TCPP@MOF, chitosan (CHIT) and an aptamer (apt) that specifically recognizes PFOA, which are sequentially modified on a conductive substrate to construct an apt / CHIT / Zn TCPP@MOF / GCE modified electrode. The nucleotide sequence of the aptamer is: GGC GTG GGGTGG TAG GCT GTA AAG GGG GTC.

[0006] The electrochemiluminescent sensor provided by the present invention is formed by electrodepositing Zn TCPP@MOF on GCE. Since the positively charged Zn TCPP and the negatively charged organic ligands attract each other through electrostatic interaction, a ZnTCPP@MOF with an intermediate phase structure is formed. The structure provides faster electron transfer kinetics and a larger specific surface area, thereby obtaining highly sensitive electroluminescence. When encountering a trace amount of PFOA, PFOA will cause quenching of the electroluminescence of Zn TCPP@MOF / GCE, and the quenching is proportional to the concentration of PFOA.

[0007] In addition, the present invention makes the luminescence of chitosan, which originally has weak fluorescence, stronger by introducing the interaction between chitosan and Zn TCPP@MOF / GCE on the modified electrode. In one embodiment of the present invention, zinc sulfate is added to the chitosan solution (the purpose of not using Zn TCPP@MOF is to avoid the emission peak of Zn TCPP@MOF), and its fluorescence emission is significantly enhanced. The electroluminescence intensity of the chitosan modified to the surface of the Zn TCPP@MOF electrode is higher than that of the unmodified chitosan Zn TCPP@MOF / GCE. This result also proves well that the addition of chitosan also improves the electroluminescence intensity of the modified electrode, that is, the sensitivity, due to the presence of zinc ions, indicating that chitosan and zinc ions synergistically improve the luminescence intensity.

[0008] Secondly, there are a great number of coexisting substances to be analyzed in the water environment. In order to obtain selective recognition of PFOA, an aptamer (apt) that specifically recognizes PFOA is introduced in the present invention. Since the chitosan modified on the Zn TCPP@MOF / GCE electrode also has an adhesive effect, apt can be firmly modified on the electrode surface. First, since the chitosan molecule has active hydroxyl and amino groups, it is easy to hydrogen bond with Zn TCPP@MOF, and the preparation of the modified electrode CHIT / Zn TCPP@MOF / GCE with stable electroluminescence intensity is realized. Furthermore, since the basic structural unit of chitosan is D-glucosamine, a plurality of such units are connected by β-1,4-glycosidic bonds to form a long chain, and the carbon chain skeleton part in the sugar residue has a certain hydrophobicity. Therefore, apt with a long-chain DNA hydrophobic structure is easily adsorbed on the surface of chitosan and is well anchored by the modified electrode CHIT / ZnTCPP@MOF / GCE, forming an apt / CHIT / Zn TCPP@MOF / GCE modified electrode with selective recognition and high sensitivity to PFOA.

[0009] In the electrochemiluminescent aptamer sensor for detecting PFOA of the present invention, Zn TCPP@MOF is prepared by an electrodeposition method, and the specific steps are as follows: (1) Preparation of Zn TCPP@MOF / GCE modified electrode electrodeposition solution Prepare an anhydrous ethanol solution of 1,3,5-benzenetricarboxylic acid (H3BTC) and zinc tetraphenylporphyrin (Zn TCPP); prepare an aqueous solution of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) and sodium nitrate (NaNO3); and mix the two to obtain an electrodeposition solution. Among them, the molar ratio of zinc nitrate hexahydrate to 1,3,5-benzenetricarboxylic acid is 1.8:1, the molar amount of Zn TCPP is 0.06%~0.12% of the molar amount of H3BTC, and the volume ratio of water to anhydrous ethanol is 1:1.

[0010] (2) Preparation of Zn TCPP@MOF / GCE modified electrode by electrodeposition Electrodeposition was carried out in the electrodeposition solution of step (1) using a three-electrode system, with the working electrode being GCE (3 mm in diameter), a platinum sheet electrode (1 x 1 cm 2 ) was used as the counter electrode and saturated calomel electrode (SCE) was used as the reference electrode. A constant voltage of -1.0 V to -1.6 V was applied for electrodeposition for 30 min to 70 min. After the electrode was taken out, it was thoroughly washed with deionized water to obtain the Zn TCPP@MOF / GCE modified electrode. The optimal deposition potential was -1.3 V and the deposition time was 1 h.

[0011] In the electrochemiluminescent aptamer sensor for detecting PFOA of the present invention, chitosan and aptamer are modified by drop coating method, and the specific method includes: preparing 1 wt% acetic acid aqueous solution, using the acetic acid aqueous solution to prepare a CHIT solution with a concentration of 0.25wt%, pipetting 5 μL of the solution and dripping it on the Zn TCPP@MOF / GCE electrode, and drying at room temperature to obtain CHIT / ZnTCPP@MOF / GCE. The dripping amount of CHIT solution will affect the sensitivity of the sensor modified electrode, and the optimal dripping amount is 5 μL. Using Tris-HCl (pH 7.5) buffer solution, the aptamer (apt) of PFOA is prepared into a solution with a concentration of 2 μmol / L. Pipet 2μL of apt solution and drip it on the CHIT / Zn TCPP@MOF / GCE electrode, and the incubation time is 4 to 5 h, so as to obtain the apt / CHIT / Zn TCPP@MOF / GCE modified electrode. Similarly, the amount of apt solution applied will also affect the sensitivity of the sensor, and the optimal amount is 2 μL.

[0012] The present invention also provides an application of the electrochemiluminescent aptamer sensor for detecting PFOA concentration, using the apt / CHIT / Zn TCPP@MOF / GCE modified electrode as a working electrode, a platinum electrode as an auxiliary electrode, and Ag / AgCl as a reference electrode to form a three-electrode system for detection, and the specific steps are as follows: S1. Preparation of PFOA standard solutions of different concentrations A series of PFOA standard solutions with different concentrations were prepared using 0.1 mol / L PBS buffer solution with pH 7.4, ranging from 1.0×10 -14 g / L~1.0×10 -7 g / L.

[0013] S2. Drawing of standard curve The apt / CHIT / Zn TCPP@MOF / GCE was used as the working electrode, Ag / AgCl as the reference electrode, and the platinum electrode as the counter electrode to form a three-electrode system. 5 μL of PFOA solutions of different concentrations were dripped on the surface of the apt / CHIT / Zn TCPP@MOF / GCE electrode and incubated for 10 min in an atmosphere containing 0.05 mol / L K 2 S 2 O 8 In PBS electrolyte, within the electrochemical window range of -1.6 to 0 V, the photomultiplier tube high voltage was 600 V, the amplification level was 3, and the scan rate was 0.1 V / s. Cyclic voltammetry scanning was performed, and the logarithmic value (logC) of the standard solution concentration and the change in luminescence intensity before and after the addition of PFOA (ΔECL) were recorded to obtain the linear regression equation for detecting PFOA.

[0014] S3. Actual sample testing After filtering the water environment sample, it can be directly analyzed and measured. Take 5 μL of the water sample to be tested and drop it on the surface of the apt / CHIT / Zn TCPP@MOF / GCE electrode, and detect the luminescence intensity according to the above step S2. According to the linear regression equation curve corresponding to step S2, the concentration of PFOA in the water environment sample can be obtained.

[0015] The present invention has developed a method with extremely low detection limit (the minimum detection limit is 3.6×10 -14 g / L) modified electrode apt / CHIT / Zn TCPP@MOF / GCE aptamer sensor was constructed with apt / CHIT / Zn TCPP@MOF / GCE as the working electrode to construct an electrochemiluminescence analysis method for quantitative detection of PFOA in water environment. Due to the high sensitivity of Zn TCPP@MOF electroluminescence and its internal hydrophobic structure has a strong adsorption effect on PFOA, the detection limit of PFOA by apt / CHIT / Zn TCPP@MOF / GCE modified electrode is as low as 3.6x10 -15 g / L( S / N = 3), at 1.0x10 -14 g / L ~ 1.0x10 -7 In the range of g / L, a good linear relationship is shown.

[0016] Since the detection limit of this method is much lower than the national standard (GB / T 5750.8-2023) of 5.0 ng / L, there is no need to perform pre-treatment such as concentration and enrichment on the sample during analysis. In addition, due to the use of PFOA aptamers, the selectivity of the modified electrode apt / CHIT / Zn TCPP@MOF / GCE for PFOA is greatly improved, and other metal ions and organic matter coexisting in the water environment do not interfere. The present invention not only has the advantages of good reproducibility, high sensitivity, strong specificity, wide linear range and simple instrumentation, but more importantly, it eliminates the need for sample pre-treatment, which has important practical significance for the application of rapid analysis of PFOA. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Are fluorescence spectra, where a, fluorescence spectrum of 1 mg / ml chitosan aqueous solution, b, fluorescence spectrum of 1 mg / ml chitosan and 1 mM zinc sulfate solution, excitation wavelength 220 nm.

[0018] Figure 2Electrochemiluminescence responses of different electrodes: a, bare GCE, b, Zn TCPP@MOF / GCE, c, CHIT / ZnTCPP@MOF / GCE, d, apt / CHIT / Zn TCPP@MOF / GCE, e, PFOA / apt / CHIT / Zn TCPP@MOF / GCE, at 0.05 mol / L K 2 S 2 O 8 PBS (0.1 mol / L pH 7.4) solution.

[0019] Figure 3 The response of the modified electrode apt / CHIT / Zn TCPP@MOF / GCE to PFOA; A. Response and stability to different concentrations of PFOA over time; B. Standard working curve of response to different concentrations of PFOA. DETAILED DESCRIPTION

[0020] In order to further illustrate the effect of the modified electrode apt / CHIT / Zn TCPP@MOF / GCE of the present invention in detecting PFOA in water environment, the following examples are given to further describe it in detail. Example 1

[0021] (1) Preparation of apt / CHIT / Zn TCPP@MOF / GCE modified electrode First, weigh 1.33 g, 4.5 mmol of zinc nitrate hexahydrate and 0.13 g, 1.5 mmol of sodium nitrate and dissolve them in 15 mL of deionized water, marked as solution A. Weigh 0.53 g, 2.5 mmol of 1,3,5-benzenetricarboxylic acid and about 1 mg, 0.0015 mmol of Zn TCPP and dissolve them in 15 mL of anhydrous ethanol, marked as solution B. Add solution B to solution A under vigorous stirring to form a mixed solution, which is the electrodeposition solution. Electrodeposition was carried out in the above electrodeposition solution using a three-electrode system, with the working electrode being GCE (3 mm in diameter), a platinum sheet electrode (1x1 cm 2 ) was used as the counter electrode and SCE was used as the reference electrode. Under stirring conditions, a voltage of -1.3 V was applied for 1 h. After the electrodeposition was completed, the working electrode was fully washed with deionized water to obtain the Zn TCPP@MOF / GCE modified electrode.

[0022] 5 μL of acetic acid aqueous solution with a concentration of 0.25 wt% CHIT (acetic acid concentration of 1 wt%) was dripped on the Zn TCPP@MOF / GCE electrode and dried at room temperature to obtain CHIT / Zn TCPP@MOF / GCE. 2 μL of apt solution with a concentration of 2 μmol / L was transferred and dripped on the CHIT / Zn TCPP@MOF / GCE electrode and incubated for 5 h to obtain the apt / CHIT / Zn TCPP@MOF / GCE modified electrode of the electrochemiluminescent sensor. The nucleotide sequence of the apt is: GGC GTG GGG TGG TAG GCT GTA AAGGGG GTC.

[0023] Figure 1 a is the fluorescence spectrum of 1 mg / ml chitosan aqueous solution with an excitation wavelength of 220 nm. Figure 1 b is the fluorescence spectrum of the chitosan solution with zinc sulfate added (1 mg / ml chitosan and 1 mM zinc sulfate solution). It can be seen from the figure that the original fluorescence of chitosan is significantly enhanced under the action of Zn ions.

[0024] (2) Drawing of PFOA standard curve Prepare a series of PFOA standard solutions with different concentrations (1.0x10 -14 g / L, 1.0x10 -13 g / L, 1.0x10 -12 g / L, 1.0x10 -11 g / L, 1.0x10 -10 g / L, 1.0x10 -9 g / L, 1.0x10 -8 g / L and 1.0x10 -7 g / L), 5 μL of PFOA solutions of different concentrations were dropped on the surface of apt / CHIT / Zn TCPP@MOF / GCE electrode, and after incubation for 10 min, the electrode was incubated in an atmosphere containing 0.05 mol / L K 2 S 2 O 8 Cyclic voltammetry (scan rate 0.1 V / s) was performed in the electrochemical window range of -1.6 to 0 V in PBS electrolyte, and the logarithmic value of the standard solution concentration (logC) and the change in luminescence intensity before and after the addition of PFOA (ΔECL) were recorded. The linear regression equation for the detection of PFOA was ΔECL = 15454.44 + 1062.28 Log C, and the correlation coefficient was R 2 = 0.9974, the detection limit is 3.6×10 -15 g / L(S / N = 3).

[0025] Figure 2 Different electrodes in 0.05 mol / L K 2 S 2 O 8 Electrochemiluminescence response in PBS (0.1 mol / L pH7.4) solution: a, bare GCE, b, Zn TCPP@MOF / GCE, c, CHIT / Zn TCPP@MOF / GCE, d, apt / CHIT / Zn TCPP@MOF / GCE, e, PFOA / apt / CHIT / Zn TCPP@MOF / GCE. As can be seen from the figure, Zn TCPP@MOF significantly improves the electroluminescence performance of GCE. The electroluminescence of CHIT / Zn TCPP@MOF / GCE after chitosan modification on the electrode surface ( Figure 2 c) compared with unmodified chitosan Zn TCPP@MOF / GCE ( Figure 2 b) has a high electroluminescence intensity, which also proves that the addition of chitosan also improves the luminescence intensity of the modified electrode due to the presence of zinc ions.

[0026] Figure 3 The response of the modified electrode apt / CHIT / Zn TCPP@MOF / GCE to PFOA, A is the response and stability to different concentrations of PFOA over time, B is the standard working curve of the response to different concentrations of PFOA. PBS: 0.1 mol / L pH 7.5 buffer containing 0.05 mol / L potassium persulfate; Scan rate: 0.1 V / s; Photomultiplier tube: 800 V; PFOA concentration from a to h: 1.0x10 -14 g / L, 1.0x10 -13 g / L, 1.0x10 -12 g / L, 1.0x10 -11 g / L, 1.0x10 -10 g / L, 1.0x10 -9 g / L, 1.0x10 -8 g / L and 1.0x10 -7 g / L.

[0027] (3) Actual sample testing 5 μL of filtered and impurity-free fish pond water was accurately extracted and dripped onto the surface of the apt / CHIT / Zn TCPP@MOF / GCE electrode, and the luminescence intensity was detected according to the above step (2). Based on the linear regression equation curve corresponding to step (2), the concentration of PFOA in the water environment sample can be obtained, and the results are listed in Table 1. Example 2

[0028] (1) Preparation of apt / CHIT / Zn TCPP@MOF / GCE modified electrode The difference between this embodiment and the embodiment is that the amount of Zn TCPP used is about 2 mg, 0.003 mmol.

[0029] (2) Drawing of PFOA standard curve Prepare a series of PFOA standard solutions with different concentrations (1.0x10 -14 g / L, 1.0x10 -13 g / L, 1.0x10 -12 g / L, 1.0x10 -11 g / L, 1.0x10 -10 g / L, 1.0x10 -9 g / L, 1.0x10 -8 g / L and 1.0x10 -7 g / L), 5 μL of PFOA solutions of different concentrations were dropped on the surface of apt / CHIT / Zn TCPP@MOF / GCE electrode, and after incubation for 10 min, the electrode was incubated in an atmosphere containing 0.05 mol / L K 2 S 2 O 8 Cyclic voltammetry (scan rate 0.1 V / s) was performed in the electrochemical window range of -1.6 to 0 V in PBS electrolyte, and the logarithmic value of the standard solution concentration (logC) and the change in luminescence intensity before and after the addition of PFOA (ΔECL) were recorded. The linear regression equation for the detection of PFOA was ΔECL = 15486.23 + 1089.81 Log C, and the correlation coefficient was R 2 = 0.9981, and the detection limit is 3.6×10 -15 g / L(S / N = 3).

[0030] (3) Actual sample testing 5 μL of filtered and impurity-free fish pond water was accurately extracted and dripped onto the surface of the apt / CHIT / Zn TCPP@MOF / GCE electrode, and the luminescence intensity was detected according to the above step (2). Based on the linear regression equation curve corresponding to step (2), the concentration of PFOA in the water environment sample can be obtained, and the results are listed in Table 1. Comparative Example 1

[0031] The Zn TCPP@MOF / GCE modified electrode was prepared using the same electrodeposition solution and electrodeposition conditions as in Example 1. The electrode was dripped with PFOA standard solution and incubated for 10 min. Then, electrochemiluminescence analysis was performed using the test conditions of Example 1. It was found that the electroluminescence was completely quenched and could not be used for detection. Comparative Example 2

[0032] The difference between this example and Example 1 is that chitosan was not added, that is, the ZnTCPP@MOF / GCE modified electrode was prepared according to the operation method of the example. 2 μL of apt solution with a concentration of 2 μmol / L was transferred and dripped on the Zn TCPP@MOF / GCE electrode and incubated for 5 h to obtain the apt / Zn TCPP@MOF / GCE modified electrode of the electrochemiluminescence sensor. According to the measurement conditions of Example 1, the electrochemiluminescence test was carried out, but the electrode apt / Zn TCPP@MOF / GCE could not obtain a stable electroluminescence intensity, so the test results were not recorded in Table 1. It can be seen that the use of chitosan is crucial to obtain a stable aptamer modified electrode.

[0033] Table 1 Test results of PFOA in fish pond water

[0034] Note: a is the average of three determinations. B ND means not detected.

[0035] As shown in the results in Table 1, the modified electrode apt / CHIT / Zn TCPP@MOF / GCE was used to detect the fish pond water samples in parallel three times, the relative standard deviation was less than 3%, and the spike recovery range was 98% to 103%. The above results show that the modified electrode apt / CHIT / Zn TCPP@MOF / GCE has good sensitivity and precision in the detection of PFOA.

[0036] The above embodiments are only used to illustrate the present invention, not to limit the present invention. Those skilled in the art may make various corresponding changes without departing from the scope of the present invention. Therefore, all technical solutions formed by equivalent replacement or equivalent modification belong to the protection scope of the present invention.

Claims

1. An electrochemiluminescent aptamer sensor for detecting perfluorooctanoic acid, characterized in that: The invention comprises an apt / CHIT / Zn TCPP@MOF / GCE modified electrode constructed by sequentially modifying the surface of a conductive substrate with Zn TCPP@MOF, chitosan, and a PFOA aptamer; the PFOA aptamer can specifically recognize perfluorooctanoic acid.

2. The electrochemiluminescent aptasensor for detecting perfluorooctanoic acid according to claim 1, characterized in that: The nucleotide sequence of the PFOA aptamer is: GGC GTG GGG TGG TAG GCT GTA AAG GGG GTC.

3. The electrochemiluminescent aptasensor for detecting perfluorooctanoic acid according to claim 1, characterized in that: The Zn TCPP@MOF is prepared by an electrodeposition method, wherein the preparation method of the electrodeposition solution comprises: preparing an anhydrous ethanol solution of 1,3,5-benzenetricarboxylic acid and tetraphenylporphyrin zinc; preparing an aqueous solution of hexahydrate zinc nitrate and sodium nitrate; and uniformly mixing the two to obtain an electrodeposition solution, wherein the molar ratio of hexahydrate zinc nitrate to 1,3,5-benzenetricarboxylic acid is 1.8:1, the molar amount of tetraphenylporphyrin zinc is 0.06% to 0.12% of the molar amount of 1,3,5-benzenetricarboxylic acid, and the volume ratio of water to anhydrous ethanol is 1:

1.

4. The electrochemiluminescent aptasensor for detecting perfluorooctanoic acid according to claim 1, characterized in that: The chitosan was modified by a drop coating method, specifically, a chitosan solution with a concentration of 0.25 wt% was prepared by using an acetic acid aqueous solution with a mass concentration of 1 wt%, and the chitosan solution was drop coated on the Zn TCPP@MOF / GCE electrode to obtain CHIT / ZnTCPP@MOF / GCE; the drop coating amount of the chitosan solution was 5 μL.

5. The electrochemiluminescent aptasensor for detecting perfluorooctanoic acid according to claim 1, characterized in that: The PFOA aptamer is modified by a drop coating method, specifically, the PFOA aptamer solution is transferred and drop coated on the CHIT / Zn TCPP@MOF / GCE electrode, and the incubation time is 4 to 5 hours, so as to obtain the apt / CHIT / Zn TCPP@MOF / GCE modified electrode; wherein the concentration of the PFOA aptamer solution is 2 μmol / L; and the drop coating amount of the PFOA aptamer solution is 2 μL.

6. Use of the electrochemiluminescent aptasensor according to claim 1 in detecting perfluorooctanoic acid, characterized in that: The steps include: S1. Preparation of PFOA standard solutions of different concentrations A series of PFOA standard solutions with different concentrations were prepared using 0.1 mol / L PBS buffer solution with pH 7.4, ranging from 1.0×10 -14 g / L~1.0×10 -7 g / L; S2. Drawing of standard curve Apt / CHIT / Zn TCPP@MOF / GCE was used as the working electrode, Ag / AgCl was used as the reference electrode, and platinum electrode was used as the counter electrode to form a three-electrode system. 5 μL of PFOA solution of different concentrations was dripped onto the surface of the apt / CHIT / Zn TCPP@MOF / GCE electrode. After incubation for 10 min, a cyclic voltammetry scan was performed to record the logarithmic value of the concentration of the standard solution and the change in the luminescence intensity before and after the addition of PFOA, and the linear regression equation for detecting PFOA was obtained. S3. Actual sample testing Take 5 μL of the water sample to be tested and drop it on the surface of the apt / CHIT / Zn TCPP@MOF / GCE electrode, and detect the luminescence intensity according to the above step S2; according to the linear regression equation corresponding to step S2, the concentration of PFOA in the water environment sample can be obtained.

7. Use of the electrochemiluminescent aptasensor according to claim 6 in detecting perfluorooctanoic acid, characterized in that: The cyclic voltammetry scan was performed in a PBS buffer solution containing 0.05 mol / L K2S2O8 as an electrolyte, the pH of the PBS buffer solution was 7.4, and the concentration thereof was 0.1 mol / L.

8. Use of the electrochemiluminescent aptamer sensor according to claim 6 in detecting perfluorooctanoic acid, characterized in that: The cyclic voltammetry scan is within the electrochemical window range of -1.6 to 0 V, the photomultiplier tube high voltage is 600 V, the amplification level is 3, and the scan rate is 0.1 V / s.

Images