CN114199968A - Preparation method and application of cooperative catalysis electrochemical sensor - Google Patents
Preparation method and application of cooperative catalysis electrochemical sensor Download PDFInfo
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Abstract
The invention belongs to the technical field of electrochemical sensing analysis, and particularly relates to a preparation method and application of a co-catalytic electrochemical sensor. The invention designs and synthesizes an electrochemical sensing interface modified by MOF mimic enzyme and AuNPs, and adds an electroactive material Methylene Blue (MB) into the electrochemical sensing interface, prepares the MOF by a solvothermal method, and further directly mixes the MOF with the AuNPs to prepare the AuNP/MOF composite material; based on the concerted catalysis of AuNP/MOF and excellent electron transmission capacity of MB, the catalytic performance of the sensing interface is further improved, and amplified current signals are obtained; the AuNP/MOF material has high recoverability, can be recycled for multiple times, and saves economic cost; meanwhile, an electrochemical DNA sensor is constructed by utilizing the specific recognition effect of the aptamer on lead ions, and the Pb in a complex matrix sample is realized2+Sensitive and accurate detection ofAnd (6) measuring.
Description
Technical Field
The invention belongs to the technical field of electrochemical sensing analysis, and particularly relates to a preparation method and application of a co-catalytic electrochemical sensor.
Background
Heavy metals have serious effects on ecological environment and food safety due to their characteristics of difficult degradation, easy enrichment, strong toxicity and the like, and harm human health in a chronic poisoning manner. Lead is a toxic heavy metal which is extremely harmful to human bodies, and therefore, the world health organization clearly stipulates the limit standard of lead in different substrates such as water bodies and agricultural products. The traditional heavy metal detection methods comprise atomic absorption spectrometry, inductively coupled plasma mass spectrometry, X-ray fluorescence spectrometry and the like, and although the methods have high accuracy, the methods have the defects of expensive equipment, complex operation, long time consumption and the like. In recent years, the developed sensing analysis methods such as fluorescence, electrochemistry, Raman and the like are generally concerned due to the advantages of simplicity, rapidness, strong specificity and the like; among them, the electrochemical sensing method plays an increasingly important role in heavy metal detection because of its advantages such as easy portability and high sensitivity.
In the construction process of an electrochemical sensing system, the catalytic performance of a sensing interface plays an important role in improving the detection sensitivity. Recently, nanoenzymes, especially metal-organic framework Materials (MOFs), have been used as mimic enzymes in sensing analysis to amplify electrochemical signals due to their advantages of high catalytic activity, good stability, and easy synthesis. However, there are two disadvantages in this application, on one hand, MOF needs to be immobilized to the sensing interface by means of biomolecules, which affect the electrocatalytic properties of MOF to some extent due to poor conductivity properties of biomolecules; on the other hand, tetramethylbenzidine-hydrogen peroxide (TMB-H) is selected2O2) The system is a catalytic base solution, biomimetic catalysis is realized by utilizing the hydrogen peroxide simulation enzyme catalytic property of the single MOF, and the catalytic efficiency is relatively low. In order to further realize the detection of trace and even ultra-trace heavy metals, the research and development of an electrochemical sensing interface simulating the concerted catalysis of enzyme and other materials is particularly important. For example, the prior literature reports that MOFs are prepared by combining them with noble metals (e.g., nanogold AuNPs) via electrostatic adsorptionThe composite material is used as a fluorescence, Raman and electrochemical sensing substrate. However, due to the poor conductivity of MOF, its modification at the electrochemical sensing interface largely hinders the electron transfer at the sensing interface, thereby affecting the detection sensitivity. Therefore, the establishment of a high-sensitivity electrochemical sensing analysis method is an urgent problem to be solved by fully playing the synergistic catalytic action of the MOF and the noble metal and further selecting a high-efficiency electroactive substance to improve the electron transport capacity of a sensing interface.
Disclosure of Invention
Aiming at the defects of the prior art, the invention designs and synthesizes an electrochemical sensing interface modified by MOF mimic enzyme and AuNPs, and adds an electroactive substance Methylene Blue (MB) into the electrochemical sensing interface, prepares the MOF by a solvothermal method, and further directly mixes the MOF with the AuNPs to prepare the AuNP/MOF composite material; obtaining an amplified current signal based on the concerted catalysis of AuNP/MOF and excellent electron transmission capacity of MB; meanwhile, an electrochemical DNA sensor is constructed by utilizing the specific recognition effect of the aptamer on lead ions, and the Pb in a complex matrix sample is realized2+The sensitivity and the accuracy of detection are improved.
In order to achieve the above purpose, the specific steps of the invention are as follows:
(1) weighing 2-amino terephthalic acid (NH)2-BDC) and ferric chloride hexahydrate (FeCl)3·6H2O), adding the mixture into Dimethylformamide (DMF), ultrasonically mixing the mixture uniformly, then putting the mixture into a polytetrafluoroethylene reaction kettle, then adding acetic acid, reacting the mixture in an oil bath kettle, and cooling, centrifuging, washing and drying the mixture to obtain a product, namely MIL-88;
(2) preparation of AuNPs solution:
adding chloroauric acid into pure water to obtain a chloroauric acid aqueous solution, heating to boil, adding a trisodium citrate solution, stopping stirring and heating when the solution becomes wine red in color, cooling to room temperature, centrifuging, collecting precipitate, and redissolving in water to obtain an AuNPs solution;
(3) preparation of AuNP/MOF concerted catalysis material:
weighing the MIL-88 prepared in the step (1), adding into deionized water, and uniformly stirring to obtain a mixed solution; then adding the AuNPs solution prepared in the step (2) into the mixed solution, stirring, centrifuging and washing to obtain an AuNP/MOF material, and dissolving the AuNP/MOF material in Tris-HCl to obtain an AuNP/MOF solution;
(4) the establishment of the electrochemical DNA sensor comprises the following steps:
and (3) dripping the AuNP/MOF solution prepared in the step (3) on the surface of a glassy carbon electrode, drying at room temperature, dripping target DNA (namely DNA carrying an electroactive material Methylene Blue (MB), purchased from Shanghai biological engineering Co., Ltd.), and reacting at room temperature to obtain the electrochemical DNA sensor.
Further, in the step (1), the dosage relationship of the 2-amino terephthalic acid, ferric trichloride hexahydrate, dimethylformamide and acetic acid is 0.05-5 g: 0.1-5 g: 5-50 mL: 0.1-10 mL; the volume of the polytetrafluoroethylene is 10-80 mL.
Further, the ultrasonic time in the step (1) is 2-10 min; the reaction temperature in the oil bath pot is 100-150 ℃, and the reaction time is 2-10 h; the drying temperature is 50-100 ℃, and the drying time is 12-48 h.
Further, in the step (2), the mass concentration of the chloroauric acid aqueous solution is 1-5%, and the mass concentration range of the trisodium citrate solution is 1-4%; the dosage relationship between the chloroauric acid aqueous solution and the trisodium citrate solution is 50-150 mu L: 2-10 mL.
Further, the mass concentration range of the AuNPs solution in the step (2) is 8-12%.
Further, in the step (3), the dosage relationship between the MIL-88 and the deionized water is 4-10 mg: 4-10 mL; the dosage relation of the mixed solution and the AuNPs solution is 1-10 mL: 2-10 mL; the stirring time is 1-8 h; the concentration of the AuNP/MOF solution is 1 mg/mL.
Further, in the step (4), the volume ratio of the AuNP/MOF solution to the target DNA dropwise is 1-2: 1 to 3.
Furthermore, the dosage of the AuNP/MOF solution is 4-10 mu L.
Further, the reaction time in the step (4) is 1-5 h at room temperature.
Further, the concentration range of the target DNA in the step (4) is 20-40 mu M; wherein the target DNA is the DNA carrying the electroactive substance MB; the sequence is as follows:
5’-MB-GCATCTCTCTCTGAAGTAGCGCCGCCGTCCGTATAGGGTATACGGrAGGAAG AGAGAGATGCAAAA-SH-(CH2)6-3’。
co-catalytic electrochemical sensor based for Pb2+The detection comprises the following specific steps:
(1) preparing a series of Pb with concentration gradient2+A standard solution, and then immersing the electrochemical DNA sensor prepared as described above into Pb2+In a standard solution, an electrochemical DNA sensor corresponds to a concentration of Pb2+A standard solution; detecting and recording current reduction value on CHI630D electrochemical workstation, and establishing electrochemical signal and Pb2+Standard linear relationship of solution concentration: Δ I ═ f × k + g, where Δ I is the current reduction value and k is Pb2+Logarithm of concentration, f and g are coefficients and constants;
(2) pb in sample to be measured2+And (3) detection of concentration:
placing an electrochemical DNA sensor in Pb2+Detecting and recording a current reduction value on an electrochemical workstation in the solution to be detected; substituting the standard linear relation into the standard linear relation established in the step (1) to obtain Pb in the solution to be detected2+To Pb in the presence of2+High sensitivity detection.
Further, Pb in the step (1)2+The concentration range of the solution is 0-10-3M。
The invention has the beneficial effects that:
(1) the sensing interface material disclosed by the invention is simple to prepare and strong in catalytic activity, not only plays a synergistic catalytic action of high-stability MOF and AuNPs, but also combines excellent electron transport capacity of MB, and can meet the requirement of high-sensitivity electrochemical detection of heavy metal under specific conditions.
(2) The AuNP/MOF material can be directly fixed on the surface of an electrode without intermediate media such as biological materials and the like, so that the distance between the AuNP/MOF material and the surface of the electrode is shortened, the electron transfer efficiency is improved, and the sensitivity of heavy metal detection is further improved.
(3) The AuNP/MOF material provided by the invention has high recoverability, can be recycled for multiple times, and saves economic cost.
(4) The electrochemical DNA sensor disclosed by the invention utilizes the aptamer to specifically identify the heavy metal in the complex matrix, so that the anti-interference capability of a sensing system is improved, and the accuracy of heavy metal detection is enhanced.
Drawings
FIG. 1 is a scanning electron micrograph of MIL-88.
FIG. 2 is a transmission electron micrograph of MIL-88.
FIG. 3 is a diagram of a Fourier Infrared spectrometer for MIL-88.
FIG. 4 is a scanning electron micrograph of AuNPs/MIL-88.
FIG. 5 is a transmission electron micrograph of AuNPs/MIL-88.
FIG. 6 is a graph of DPV response current of various modified electrodes in Tris-HCl containing MB.
FIG. 7 is Pb2+Standard curve of detection.
Detailed Description
The embodiments of the present invention will be described in detail below with reference to the accompanying drawings: the embodiments are performed on the premise of the technical scheme of the invention, and detailed implementation steps and specific operation processes are given, but the scope of the invention is not limited to the following embodiments.
The target DNA used in the present invention was purchased from Biotechnology engineering (Shanghai) Ltd.
Example 1:
(1) weighing 0.0650g NH2BDC and 0.1320g FeCl3·6H2Adding 10mL of DMF (dimethyl formamide), ultrasonically mixing for 2min, adding into a 30mL polytetrafluoroethylene reaction kettle, adding 0.1mL of acetic acid, and putting the reaction kettle into an oil bath kettle to react for 3h at 110 ℃; after the reaction is finished, after the reaction kettle is naturally cooled to room temperature, washing the product obtained through centrifugation by using DMF (dimethyl formamide), ethanol and pure water in sequence, and finally drying for 12 hours at the temperature of 50 ℃ by using a vacuum drying oven to obtain a reddish brown product, namely MIL-88;
(2) preparation of AuNPs:
adding chloroauric acid into pure water to prepare a chloroauric acid aqueous solution with the mass concentration of 2.5%; heating by using an electric furnace, stirring to boil, slowly adding 2mL of trisodium citrate solution with the mass concentration of 1.5%, continuously heating and stirring, stopping stirring and heating when the solution becomes wine red, cooling to room temperature, centrifuging, and redissolving the obtained precipitate in water to obtain AuNPs solution with the mass concentration of 9%;
(3) preparation of AuNP/MOF concerted catalysis material:
weighing 4mg of MIL-88, adding into 4mL of deionized water, and uniformly mixing to obtain a mixed solution; then directly adding 3mL of mixed solution into 5mL of AuNPs solution, magnetically stirring for 3h, after stirring, centrifugally collecting precipitates, washing the precipitates for three times by using ultrapure water to obtain an AuNPs/MIL-88 synergistic catalytic material, and then adding into Tris-HCl (pH 7.0) to obtain 1mg/mL of AuNPs/MIL-88 solution for later use;
(4) construction of electrochemical DNA sensor:
dripping 4 mu L of AuNPs/MIL-88 solution with the concentration of 1mg/mL on the surface of a glassy carbon electrode, naturally drying at room temperature, and then dripping 6 mu L of 20 mu M target DNA on the surface of the electrode; after incubation at 37 ℃ for 2h, the DNA not bound to AuNPs/MIL-88 was washed out with deionized water to obtain an electrochemical DNA sensor.
Pb2+The detection method comprises the following steps:
(1) preparing a series of Pb with concentration gradient2+Standard solutions with concentrations of 0 and 10 respectively-12、10-11、10-10、10-9、10-8、10-7And M. The electrochemical DNA sensor was then immersed in Pb2+In a standard solution, an electrochemical DNA sensor corresponds to a concentration of Pb2+A standard solution; detecting and recording current reduction value on CHI630D electrochemical workstation, and establishing electrochemical signal and Pb2 +Standard linear relationship of solution concentration: Δ I3.30423 logCPb 2++0.818(R2＝0.9987)；
(2) And (3) actual sample detection:
the invention further provides a high-sensitivity electrochemical analysis method for the synergistic catalysis of the sensing interface, which is used for the Pb in the tea2+The use of detection.
Firstly, preprocessing 5 different tea leaves, digesting in a microwave digestion instrument, then heating on a temperature-controlled electric heating plate, then filtering and fixing the volume; respectively taking 6mL of the sample solution as a solution to be detected, then placing the electrochemical DNA sensor in the solution to be detected, recording a corresponding current reduction value, and substituting the corresponding current reduction value into the standard linear relation established in the step (1) to obtain Pb in the solution to be detected2+The concentration of (c); and a standard recovery method is used for carrying out a recovery experiment on the Longjing tea sample to obtain a recovery rate of 98.7-101.6%.
Comparing the detection result of the electrochemical analysis method with that of High Performance Liquid Chromatography (HPLC), as shown in Table 1, the sensor prepared by the invention has wide linear range and higher recovery rate than the HPLC method, which indicates that the invention can satisfy Pb2+The requirement of accurate and sensitive detection for Pb in actual samples2+Is possible.
TABLE 1 comparison of this electrochemical analysis with HPLC detection
The reasons for the high sensitivity and strong specificity of the invention are as follows: (1) the integrated sensing interface has the functions of cooperatively catalyzing reactants and doubly amplifying electric signals, not only utilizes the strong electron transmission characteristic of AuNPs, but also combines the high-efficiency biomimetic catalysis advantage of MOF; based on the concerted catalysis of AuNPs and MOF on MB, the electrochemical signal amplification is realized, thereby improving the sensitivity of electrochemical detection. (2) The AuNP/MOF composite material prepared by the invention can be directly fixed on the surface of the electrode without intermediate media such as biological materials and the like, so that the gap between the AuNP/MOF composite material and the surface of the electrode is reduced, the electronic transmission capability of a sensing interface is improved, and the detection sensitivity is further improved. (3) Using DNA for Pb2+The electrochemical sensor is constructed by the specific recognition function of the method, the anti-interference capability is strong, and the interference of other components in a complex matrix sample is avoided, so that a more accurate analysis result is obtained.
FIG. 1 is a scanning electron micrograph of MIL-88, from which it can be seen that MIL-88 is a regular octahedron with an average particle size of about 300nm and no other impurities in the background, indicating that the MIL-88 prepared is structurally stable and uniform in size. Successful synthesis of MIL-88 was also further demonstrated in conjunction with FIG. 2 (transmission electron micrograph of MIL-88, 100 nm).
FIG. 3 is a plot of a Fourier Infrared spectrometer for MIL-88 showing MIL-88 at 770cm-1Has C-H stretching vibration at 1434cm-1Stretching vibration in the presence of-O-C-O-, at 3327cm-1、3453cm-1In the presence of NH2The stretching vibration of (2).
Fig. 4 and 5 are a scanning electron micrograph and a transmission electron micrograph of AuNPs/MIL-88, respectively, and it can be seen from these photographs that when the MIL-88 modifies AuNPs, a large amount of AuNPs uniformly adhere to the surface of MIL-88, confirming the successful preparation of AuNPs/MIL-88.
Example 2:
(1) weighing 1.1238g NH2BDC and 2.2420g FeCl3·6H2And O, adding 30mL of DMF, ultrasonically mixing for 5min, adding into a 50mL polytetrafluoroethylene reaction kettle, adding 2mL of acetic acid, putting the reaction kettle into an oil bath kettle, reacting for 4h at 130 ℃, after the reaction is finished, naturally cooling the reaction kettle to room temperature, washing the centrifuged product by sequentially using DMF, ethanol and pure water, and finally drying for 24h at 70 ℃ by using a vacuum drying oven to obtain a reddish brown product, namely MIL-88.
(2) Preparation of AuNPs:
adding chloroauric acid into pure water to prepare a chloroauric acid aqueous solution with the mass concentration of 1.5%; and then heating by using an electric furnace, stirring to boil, slowly adding 4mL of trisodium citrate solution with the mass concentration of 2.5%, continuously heating and stirring, stopping stirring and heating when the solution becomes wine red, cooling to room temperature, centrifuging, and redissolving the obtained precipitate in water to obtain the AuNPs solution with the mass concentration of 9.5%.
(3) Preparation of AuNP/MOF concerted catalysis material:
weighing 6mg of MIL-88, adding the MIL-88 into 6mL of deionized water, uniformly mixing, directly adding 5mL of the solution into 6mL of AuNPs solution, magnetically stirring for 5 hours, centrifuging after stirring, washing with ultrapure water for three times to obtain an AuNPs/MIL-88 synergistic catalytic material, and then storing in Tris-HCl (pH 7.0) to obtain 1mg/mL of AuNPs/MIL-88 solution for later use.
(4) Construction of electrochemical DNA sensor:
dripping 6 mu L of 1.0mg/mL AuNPs/MIL-88 solution on the surface of a glassy carbon electrode, naturally drying at room temperature, and then dripping 8 mu L of 30 mu M target DNA on the surface of the electrode; after incubation for 3h at 37 ℃, the DNA which is not combined with AuNPs/MIL-88 is washed by deionized water, and the electrochemical DNA sensor is obtained.
Pb2+The detection method comprises the following steps:
(1) preparing a series of Pb with different concentrations2+Standard solutions with concentrations of 0 and 10 respectively-13、10-12、10-11、10-10、10-9、10-8And M. The electrochemical DNA sensor was then immersed in Pb2+In a standard solution, an electrochemical DNA sensor corresponds to a concentration of Pb2+A standard solution; detecting and recording current reduction value on CHI630D electrochemical workstation, and establishing electrochemical signal and Pb2+Standard linear relationship of solution concentration: Δ I2.1297 logCPb 2++0.673(R2＝0.9963)
(2) And (3) actual sample detection:
the invention further provides a high-sensitivity electrochemical analysis method for the synergistic catalysis of the sensing interface, which is used for the Pb in the soil2+The use of detection.
Firstly, pretreating soil, digesting in a microwave digestion instrument, then heating on a temperature-controlled electric heating plate, then filtering, and fixing the volume. Respectively taking 6mL of the sample solution as a solution to be detected, then placing the electrochemical DNA sensor in the solution to be detected, recording a corresponding current reduction value, and substituting the corresponding current reduction value into the standard linear relation established in the step (1) to obtain Pb in the solution to be detected2+The concentration of (c); and a standard recovery method is used for carrying out a recovery experiment on the soil sample, so that the recovery rate is between 98.4 and 102.1 percent.
FIG. 6 is a graph of the response current of Differential Pulse Voltammetry (DPV) of various modified electrodes in Tris-HCl containing MB. Wherein, AuNPs/MIL-88/GCE refers to an electrode obtained by dripping 4 mu L of 1.0mg/mL AuNPs/MIL-88 solution on the surface of a glassy carbon electrode and naturally drying at room temperature; MIL-88/GCE refers to an electrode obtained by dripping 4 mu L of 1.0mg/mL MIL-88 solution on the surface of a glassy carbon electrode and naturally drying at room temperature; bare GCE refers to a bare electrode without any modification material. As shown in the figure, a small oxidation peak appears at-0.23V of the bare electrode, the current is 3.905 muA, when the MIL-88 is modified on the surface of the electrode, the current signal reaches 7.072 muA, and is obviously enhanced, which indicates that the MIL-88 has high-efficiency electrocatalytic activity on MB; the response current of the AuNPs/MIL-88 modified electrode to MB is increased to 8.488 muA, which is mainly due to the excellent electron transport capability of MB and the synergistic catalytic action of the MB and MIL-88.
Example 3:
(1) weighing 4.2050g NH2BDC and 3.1276g FeCl3·6H2And O, adding 40mL of DMF, ultrasonically mixing for 6min, adding into a 70mL polytetrafluoroethylene reaction kettle, adding 8mL of acetic acid, and putting the reaction kettle into an oil bath kettle to react for 6h at 150 ℃. After the reaction is finished, after the reaction kettle is naturally cooled to room temperature, washing the product obtained through centrifugation by using DMF, ethanol and pure water in sequence, and finally drying for 48 hours at 90 ℃ by using a vacuum drying oven to obtain a reddish brown product, namely MIL-88.
(2) Preparation of AuNPs:
adding chloroauric acid into pure water to prepare a chloroauric acid aqueous solution with the mass concentration of 1%; and then heating by using an electric furnace, stirring to boil, slowly adding 6mL of trisodium citrate solution with the mass concentration of 4%, continuously heating and stirring, stopping stirring and heating when the solution becomes wine red, cooling to room temperature, centrifuging, and redissolving the obtained precipitate in water to obtain the AuNPs solution with the mass concentration of 10%.
(3) Preparation of AuNP/MOF concerted catalysis material:
weighing 8mg of MIL-88, adding the MIL-88 into 8mL of deionized water, uniformly mixing, directly adding 6mL of the solution into 7mL of AuNPs solution, magnetically stirring for 6 hours, centrifuging and washing with ultrapure water for three times after stirring to obtain the AuNPs/MIL-88 synergistic catalytic material, and then storing in Tris-HCl (pH 7.0) to obtain 1mg/mL of AuNPs/MIL-88 solution for later use.
(3) Construction of electrochemical DNA sensor:
10 μ L of 1.0mg/mL AuNPs/MIL-88 solution was dropped on the surface of a glassy carbon electrode, and naturally dried at room temperature, followed by dropping 10 μ L of 40 μ M target DNA on the surface of the electrode. After incubation for 4h at 37 ℃, the DNA not bound to AuNPs/MIL-88 was washed with deionized water to obtain an electrochemical DNA sensor.
Pb2+The detection method comprises the following steps:
(1) preparing a series of Pb with different concentrations2+Standard solutions with concentrations of 0 and 10 respectively-14、10-13、10-12、10-11、10-10、10-9And M. The electrochemical DNA sensor was then immersed in Pb2+In a standard solution, an electrochemical DNA sensor corresponds to a concentration of Pb2+A standard solution; the recording current reduction was detected at the CHI630D electrochemical workstation, which established the electrochemical signal and Pb2+Standard linear relationship of solution concentration: Δ I1.0843 logCPb 2++2.527(R2＝0.9845)
(2) And (3) actual sample detection:
the invention further provides a high-sensitivity electrochemical analysis method for the sensing interface concerted catalysis in the method for analyzing Pb in spinach leaves2+The use of detection.
Firstly, preprocessing spinach leaves, digesting in a microwave digestion instrument, then heating on a temperature-controlled electric heating plate, then filtering, and fixing the volume. Respectively taking 6mL of the sample solution as a solution to be detected, then placing the electrochemical DNA sensor in the solution to be detected, recording a corresponding current reduction value, and substituting the corresponding current reduction value into the standard linear relation established in the step (1) to obtain Pb in the solution to be detected2+The concentration of (c); and performing a recovery experiment on the spinach leaf sample by a standard recovery method to obtain a recovery rate of 93.2-99.6%.
FIG. 7 is a graph showing the detection of different concentrations of Pb by the electrochemical DNA sensor in example 12+In which the abscissa is different Pb2+The logarithmic value of the concentration and the ordinate are the current change values. As can be seen from the figure, Pb2+Between concentration and MB current reduction value (Delta I)In good linear relationship, the linear regression equation is Δ I3.30423 log cPb 2++0.818(R20.9987). The result shows that the electrochemical DNA sensor is used for detecting Pb2+Has higher sensitivity and detection range, which is mainly attributed to the synergic catalysis of AuNPs/MIL-88 on MB and the excellent electron transport capability of MB.
In conclusion, the electrochemical sensing interface is constructed based on the MOF and the AuNPs, and the concerted catalysis of the MOF and the AuNPs on the MB, the excellent electron transfer capacity of the MB and the Pb of the DNA are combined2+Realizes the specific recognition of Pb in a complex matrix2 +Accurate, sensitive and rapid detection. The sensing system is simple to prepare, high in stability and strong in anti-interference capability, has a lower detection limit compared with other electrochemical methods, and provides a new technical support for high-sensitivity detection of heavy metals in matrixes such as environment, food and agricultural products.
Description of the drawings: the above embodiments are only used to illustrate the present invention and do not limit the technical solutions described in the present invention; thus, while the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted; all such modifications and variations are intended to be included herein within the scope of this disclosure and the present invention and protected by the following claims.
Claims (10)
1. A preparation method of a concerted catalysis electrochemical sensor is characterized by comprising the following steps:
(1) weighing 2-amino terephthalic acid and ferric trichloride hexahydrate, adding the weighed materials into dimethylformamide, ultrasonically mixing the materials uniformly, then putting the materials into a polytetrafluoroethylene reaction kettle, then adding acetic acid, reacting the materials in an oil bath kettle, and then cooling, centrifuging, washing and drying the materials to obtain a product, namely MIL-88;
(2) adding chloroauric acid into pure water to obtain a chloroauric acid aqueous solution, heating to boil, adding a trisodium citrate solution, stopping stirring and heating when the solution becomes wine red in color, cooling to room temperature, centrifuging, collecting precipitate, and redissolving in water to obtain an AuNPs solution;
(3) preparation of AuNP/MOF concerted catalysis material:
weighing the MIL-88 prepared in the step (1), adding into deionized water, and uniformly stirring to obtain a mixed solution; then adding the AuNPs solution prepared in the step (2) into the mixed solution, stirring, centrifuging and washing to obtain an AuNP/MOF material, and dissolving the AuNP/MOF material in Tris-HCl to obtain an AuNP/MOF solution;
(4) establishment of electrochemical DNA sensor:
and (3) dripping the AuNP/MOF solution prepared in the step (3) on the surface of a glassy carbon electrode, drying at room temperature, dripping target DNA (deoxyribonucleic acid), namely the DNA carrying the electroactive material MB, and reacting at room temperature after dripping the target DNA to obtain the electrochemical DNA sensor.
2. The preparation method of the co-catalytic electrochemical sensor as claimed in claim 1, wherein the 2-aminoterephthalic acid, ferric chloride hexahydrate, dimethylformamide and acetic acid in the step (1) are used in an amount relationship of 0.05-5 g: 0.1-5 g: 5-50 mL: 0.1-10 mL; the volume of the polytetrafluoroethylene is 10-80 mL; the ultrasonic time is 2-10 min; the reaction temperature in the oil bath pot is 100-150 ℃, and the reaction time is 2-10 h; the drying temperature is 50-100 ℃, and the drying time is 12-48 h.
3. The preparation method of the co-catalytic electrochemical sensor as claimed in claim 1, wherein the mass concentration of the chloroauric acid aqueous solution in step (2) is 1-5%, and the mass concentration of the trisodium citrate solution is 1-4%; the dosage relationship between the chloroauric acid aqueous solution and the trisodium citrate solution is 50-150 mu L: 2-10 mL.
4. The method for preparing the co-catalytic electrochemical sensor according to claim 1, wherein the mass concentration of the AuNPs solution in the step (2) is in a range of 8-12%.
5. The method for preparing a co-catalytic electrochemical sensor according to claim 1, wherein the MIL-88 and the deionized water in the step (3) are used in an amount relationship of 4-10 mg: 4-10 mL.
6. The preparation method of the co-catalytic electrochemical sensor according to claim 1, wherein the dosage relationship between the mixed solution and the AuNPs solution in the step (3) is 1-10 mL: 2-10 mL; the stirring time is 1-8 h; the concentration of the AuNP/MOF solution is 1 mg/mL.
7. The preparation method of the co-catalytic electrochemical sensor according to claim 1, wherein the volume ratio of the AuNP/MOF solution to the target DNA dropwise addition in the step (4) is 1-2: 1-3; the using amount of the AuNP/MOF solution is 4-10 mu L; the reaction time is 1-5 h under the room temperature condition.
8. The method for preparing a co-catalytic electrochemical sensor according to claim 1, wherein the concentration of the target DNA in the step (4) is in the range of 20 to 40 μ M; wherein the target DNA is the DNA carrying the electroactive substance MB; the sequence is as follows:
5’-MB-GCATCTCTCTCTGAAGTAGCGCCGCCGTCCGTATAGGGTATACGGrAGGAAGAGAGAGATGCAAAA-SH-(CH2)6-3’。
9. use of a fluorescent-colorimetric dual-mode sensor prepared according to any one of claims 1 to 8 for the detection of Pb2+The method is characterized by comprising the following steps:
(1) preparing a series of Pb with concentration gradient2+A standard solution, and then immersing the electrochemical DNA sensor in Pb2+In a standard solution, an electrochemical DNA sensor corresponds to a concentration of Pb2+A standard solution; detecting and recording current reduction value on CHI630D electrochemical workstation, and establishing electrochemical signal and Pb2+Standard linear relationship of solution concentration: Δ I ═ f × k + g, where Δ I is the current reduction value and k is Pb2+Logarithm of concentration, f and g are coefficients and constants;
(2) pb in sample to be measured2+Concentration ofDetection of (2):
placing an electrochemical DNA sensor in Pb2+Detecting and recording a current reduction value on an electrochemical workstation in the solution to be detected; substituting the standard linear relation into the standard linear relation established in the step (1) to obtain Pb in the solution to be detected2+To Pb in the presence of2+High sensitivity detection.
10. Use according to claim 9, characterized in that the Pb in step (1)2+The concentration range of the solution is 0-10-3M。
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