Electrochemical sensor based on dendrimer-functionalized Ni-MOFs nanocomposite material and its preparation method and application

Abstract

The present invention discloses an electrochemical sensor based on dendrimer functionalized Ni-MOFs nanocomposite material, a preparation method and an application thereof. First, the dendrimer functionalized Ni-MOFs nanocomposite material is prepared by using polyamidoamine dendrimer PAMAM, HITP ligand and NiCl2. Then, the obtained dendrimer functionalized Ni-MOFs nanocomposite material is used to modify a glassy carbon electrode to obtain a functionalized electrode. The functionalized electrode is used as a working electrode, a platinum electrode is used as a counter electrode, and an Ag / AgCl electrode is used as a reference electrode to form a three-electrode system, i.e., an electrochemical sensor based on the dendrimer functionalized Ni-MOFs nanocomposite material. The present invention is a Pb 2+ 、Cu 2+ The simultaneous quantitative detection of β-catenin provides an analytical method that is simple, effective, low-cost and highly sensitive.

Description

Technical Field

[0001] The present invention belongs to the field of heavy metal detection, and specifically relates to an electrochemical sensor for heavy metal detection based on dendrimer functionalized Ni-MOFs nanocomposite materials and a preparation method thereof. 2+ 、Cu 2+ Simultaneous detection applications. Background Art

[0002] Heavy metals mainly refer to chemical elements with potential biological toxicity, such as mercury (Hg), cadmium (Cd), lead (Pb), copper (Cu), zinc (Zn) and arsenic (As). Because of their high toxicity, difficulty in degradation, and continuous enrichment and amplification through the food chain, water and soil accumulation, they have a significant impact on organisms and the ecological environment. Exposure to lead exceeding the standard content can cause developmental delay, cardiovascular disease and high blood pressure in children. High concentrations of copper intake can cause leukemia and arthritis. Even small doses of heavy metals can cause serious damage to the human central nervous system, immune system, reproductive system and digestive system. Therefore, there is an urgent need for analytical techniques that can measure trace amounts of heavy metal ions to analyze Pb in natural water bodies and drinking water. 2+ 、Cu 2+ The content is detected and evaluated. In addition, on-site detection of heavy metals often faces samples to be tested that are mixed with multiple heavy metal ions. Therefore, there is an urgent need for technology to detect multiple heavy metals simultaneously on-site. The current methods for heavy metal ion detection mainly include inductively coupled plasma mass spectrometry (ICP-MS), atomic absorption spectroscopy (AAS), atomic emission spectroscopy (AES) and other technologies. However, these technologies have complex sample pretreatment, long detection time, complex operating procedures, certain technical requirements for operators, expensive instrument costs and are not suitable for rapid simultaneous on-site detection. Therefore, there is an urgent need to develop a fast, simple, low-cost, and highly sensitive Pb 2+ 、Cu 2+ On-site simultaneous detection method. Summary of the Invention

[0003] The purpose of the present invention is to provide a preparation method and application of an electrochemical sensor based on a dendrimer functionalized Ni-MOFs nanocomposite material to overcome the problems existing in the prior art. The electrochemical sensor based on a dendrimer functionalized Ni-MOFs nanocomposite material of the present invention utilizes the dendrimer functionalized Ni-MOFs nanocomposite material to 2+ 、Cu 2+ After achieving sufficient enrichment and specific binding, according to Pb 2+ 、Cu 2+ It has different stripping potential windows and is used to detect Pb based on square wave stripping voltammetry. 2+ 、Cu2+ Rapid, highly specific, and highly sensitive simultaneous detection.

[0004] The present invention is achieved through the following technical solutions:

[0005] The preparation method of the electrochemical sensor based on the dendrimer functionalized Ni-MOFs nanocomposite material comprises the following steps:

[0006] (1) Preparation of dendrimer-functionalized Ni-MOFs nanocomposites;

[0007] (2) The glassy carbon electrode is modified with the dendrimer-functionalized Ni-MOFs nanocomposite obtained in step (1) to obtain a functionalized electrode, and the functionalized electrode is used as a working electrode, a platinum electrode is used as a counter electrode, and an Ag / AgCl electrode is used as a reference electrode to form a three-electrode system, thereby obtaining an electrochemical sensor based on the dendrimer-functionalized Ni-MOFs nanocomposite.

[0008] Furthermore, step (1) specifically includes:

[0009] (1.1) Dissolve viscous polyamidoamine dendrimer (PAMAM) in ultrapure water to obtain a PAMAM solution.

[0010] (1.2) Dissolving the HITP ligand in the PAMAM solution and dissolving NiCl2 in the PAMAM solution to obtain the HITP ligand solution and the NiCl2 solution, respectively;

[0011] (1.3) Transfer the HITP ligand solution and NiCl2 solution obtained in (1.2) to a light-shielded container and stir to obtain a mixed solution;

[0012] (1.4) Add ammonia water to the mixed solution obtained in (1.3), stir at constant temperature, and mix to react;

[0013] (1.5) After the reaction is completed, remove the original solution from the light-shielded container, cool it to room temperature, and then centrifuge to precipitate the solid precipitate;

[0014] (1.6) Wash the obtained solid precipitate several times with ultrapure water, and centrifuge the precipitate after each wash;

[0015] (1.7) The washed solid is vacuum dried, ground into powder, and sealed for storage to obtain a dendrimer-functionalized Ni-MOFs nanocomposite material.

[0016] Furthermore, the concentration of the PAMAM solution in step (1.1) is 0.5 to 1 mM;

[0017] In step (1.2), PAMAM solution is used to dissolve the HITP ligand and NiCl2, respectively, to prepare a 2-3.5 mg / mL HITP solution and a 9.25-16.2 mg / mL NiCl2 solution;

[0018] In step (1.3), the volume ratio of the HITP ligand solution to the PAMAM solution in the NiCl2 solution is 6:1 to 9:1;

[0019] The volume ratio of the amount of ammonia water added in step (1.4) to the PAMAM solution in the mixed solution is 250 μL:8 mL.

[0020] Furthermore, in step (1.3), the stirring rate is 550 rpm and the stirring time is 10 min;

[0021] In step (1.4), the reaction temperature is 65°C, the stirring rate is 550 rpm, and the stirring time is 16 to 22 h;

[0022] The centrifugal separation in step (1.5) was performed at a speed of 12000 rpm for 5 min.

[0023] In step (1.6), the sample was washed with ultrapure water five times, each washing for 2 minutes, and the centrifugal separation speed was 12000 rpm for 5 minutes;

[0024] The vacuum drying temperature in step (1.7) is 37°C and the time is 24h.

[0025] Furthermore, the glassy carbon electrode is modified with the dendrimer-functionalized Ni-MOFs nanocomposite obtained in step (1) to obtain a functionalized electrode, specifically comprising:

[0026] (2.1) Polishing a glassy carbon electrode with aluminum oxide powder to obtain a polished electrode;

[0027] (2.2) The polished electrode obtained in (2.1) is scanned by cyclic voltammetry in a K4Fe(CN)6 / K3Fe(CN)6 solution to obtain the voltage difference ΔP between the cathode and the anode in the cyclic voltammogram;

[0028] (2.3) until △P is less than or equal to the preset value, otherwise repeat steps (2.1) to (2.2);

[0029] (2.4) dispersing the dendrimer-functionalized Ni-MOFs nanocomposite material in ultrapure water, ultrasonically dispersing the material, and then centrifuging the supernatant to obtain a dendrimer-functionalized Ni-MOFs nanocomposite material dispersion solution;

[0030] (2.5) The dendrimer macromolecule functionalized Ni-MOFs nanocomposite dispersion solution obtained in (2.4) is added dropwise to the surface of the clean glassy carbon electrode obtained in (2.3), and allowed to dry under dust-free conditions to form a thin film to obtain a functionalized electrode.

[0031] Furthermore, in step (2.1), the glassy carbon electrode is polished in sequence with alumina powder having a particle size range of 1.5 to 2.0 μm and a particle size range of 0.5 μm to 1.0 μm;

[0032] The concentration of the K4Fe(CN)6 / K3Fe(CN)6 solution in step (2.2) is 5 mM;

[0033] The preset value in step (2.3) is 80mV.

[0034] Furthermore, in step (2.4), the dendrimer-functionalized Ni-MOFs nanocomposite was dispersed in ultrapure water at a concentration of 1 to 1.5 mg / mL, ultrasonically dispersed at a power of 540 W for 1 h, and then centrifuged at a speed of 3000 rpm for 5 min to obtain the supernatant;

[0035] In step (2.5), the dendrimer functionalized Ni-MOFs nanocomposite dispersion solution obtained in (2.4) is added dropwise to the surface of the clean glassy carbon electrode obtained in (2.3). The ratio of the dendrimer functionalized Ni-MOFs nanocomposite dispersion solution to the glassy carbon electrode area is 2.5 μL:1 mm 2 , dried under dust-free conditions and formed into a thin film to obtain a functional electrode.

[0036] The electrochemical sensor based on the dendrimer-functionalized Ni-MOFs nanocomposite material was prepared by the above-mentioned preparation method.

[0037] Electrochemical sensor based on dendrimer-functionalized Ni-MOFs nanocomposites in Pb 2+ 、Cu 2+ Simultaneous detection applications.

[0038] Further, the following steps are included:

[0039] (3.1) The three-electrode system was placed in 0.2 mM sodium acetate-acetic acid buffer containing the target heavy metal, and the target heavy metal was enriched and stripped using square wave anodic stripping voltammetry and an electrochemical workstation;

[0040] (3.2) Pb is concentrated at a potential of -1.2 V. 2+ 、Cu 2+ The deposition time was 450s, and the target heavy metal solution was magnetically stirred at a speed of 500rpm to make Pb 2+、Cu 2+ Fully enriched;

[0041] (3.3) After the deposition, heavy metals were dissolved with a scanning range of -1.2V to 0.4V, a frequency of 25Hz, an amplitude of 25mV, and a potential increment of 4mV to obtain Pb 2+ 、Cu 2+ The dissolution peak of Pb 2+ 、Cu 2+ Simultaneous quantitative detection.

[0042] Compared with the prior art, the present invention has the following beneficial technical effects:

[0043] This method first realizes the synthesis of dendrimer functionalized Ni-MOFs nanocomposite materials; the surface of glassy carbon electrode is modified by dendrimer functionalized Ni-MOFs nanocomposite materials; the functionalized electrode is subjected to square wave stripping voltammetry to measure the Pb 2+ 、Cu 2+ The test results show that the sensor is simple and effective, low cost, high sensitivity, and can simultaneously detect Pb 2+ 、Cu 2+ Based on the high conductivity, high specific surface area and multi-active groups of dendrimer-functionalized Ni-MOFs nanocomposites, the electrochemical sensor is Pb 2+ 、Cu 2+ Simultaneous detection provides a fast, simple, and highly sensitive analytical method and is suitable for Pb 2+ 、Cu 2+ Simultaneous on-site testing.

[0044] Specifically, the present invention uses dendrimer-functionalized Ni-MOFs nanocomposites and square wave stripping voltammetry for the first time to achieve the 2+ 、Cu 2+ Simultaneous quantitative detection has the advantages of low cost, convenient operation, high sensitivity, etc. 2+ 、Cu 2+ The detection method has the advantages of simple operation steps, low cost, lower detection limit, and can achieve Pb 2+ 、Cu 2+ The advantages of on-site simultaneous detection overcome the shortcomings of existing methods such as high production cost, complex detection process and difficulty in simultaneously detecting heavy metals. Based on the above advantages, the present invention can be used to detect heavy metal content in natural water bodies and drinking water in the field of environmental monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. The following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0046] Figure 1 The synthesis of dendrimer-functionalized Ni-MOFs nanocomposites, the preparation of electrochemical sensors and the 2+ 、Cu 2+ Schematic diagram of simultaneous quantitative detection;

[0047] Figure 2 is a SEM image of the dendrimer-functionalized Ni-MOFs nanocomposite (Example 1);

[0048] Figure 3 The cyclic voltammograms of the glassy carbon electrode surface modified with dendrimer functionalized Ni-MOFs nanocomposite materials of the present invention (Example 1) are shown.

[0049] Figure 4 The present invention is based on the surface modification of glassy carbon electrode dendrimer macromolecule functionalized Ni-MOFs nanocomposite material and the simultaneous detection of Pb before and after Ni-MOFs. 2+ 、Cu 2+ Square wave stripping voltammogram (Example 1);

[0050] Figure 5 The electrochemical sensor constructed based on the glassy carbon electrode surface modified with dendritic macromolecule functionalized Ni-MOFs nanocomposite material can detect Pb in the presence of other interfering ions. 2+ 、Cu 2+ Specificity result diagram of simultaneous detection;

[0051] Figure 6 The electrochemical sensor constructed based on the modification of dendrimer functionalized Ni-MOFs nanocomposite material to different concentrations of Pb 2+ 、Cu 2+ The square wave stripping voltammetry curve and concentration linear fitting diagram detected simultaneously.

[0052] Figure 7 This is the cyclic voltammogram of the glassy carbon electrode surface modified with dendrimer functionalized Ni-MOFs nanocomposite material of the present invention (Example 2);

[0053] Figure 8 The present invention is based on the glassy carbon electrode surface modified with dendritic macromolecule functionalized Ni-MOFs nanocomposite material to simultaneously detect Pb 2+、Cu 2+ Square wave stripping voltammogram (Example 2);

[0054] Figure 9 This is the cyclic voltammogram of the glassy carbon electrode surface modified with dendrimer functionalized Ni-MOFs nanocomposite material of the present invention (Example 3);

[0055] Figure 10 The present invention is based on the glassy carbon electrode surface modified with dendritic macromolecule functionalized Ni-MOFs nanocomposite material to simultaneously detect Pb 2+ 、Cu 2+ Square wave stripping voltammogram (Example 3). DETAILED DESCRIPTION

[0056] The present invention is described in further detail below:

[0057] The preparation method of the electrochemical sensor based on the dendrimer functionalized Ni-MOFs nanocomposite material comprises the following steps:

[0058] (1) Preparation of dendrimer-functionalized Ni-MOFs nanocomposites, specifically:

[0059] (1.1) Dissolve some viscous polyamidoamine dendrimer (PAMAM) in ultrapure water to prepare a 0.5–1 mM PAMAM solution.

[0060] (1.2) Dissolve the HITP ligand (2,3,6,7,10,11-hexxaaminotriphenylene, HITP) in the PAMAM solution obtained in (1.1). Dissolve NiCl2 in the PAMAM solution to prepare a 2-3.5 mg / mL HITP solution and a 9.25-16.2 mg / mL NiCl2 solution.

[0061] (1.3) Transfer the two solutions obtained in (1.2) to a brown glass bottle with a volume ratio of HITP ligand solution to PAMAM solution in NiCl2 solution of 6:1 to 9.1. Mix under magnetic stirring at 550 rpm for 10 min.

[0062] (1.4) Add ammonia water to the mixed solution obtained in (1.3) at a volume ratio of 250 μL:8 mL. Place the mixture in a 65°C water bath with magnetic stirring at 550 rpm and allow to react for 16–22 h.

[0063] (1.5) After the reaction is complete, remove the original solution from the brown glass bottle, cool it to room temperature, and then centrifuge it for precipitation (12000 rpm, 5 min);

[0064] (1.6) Wash the obtained solid precipitate with ultrapure water for 2 min. Centrifuge the precipitate (12000 rpm, 5 min) to remove the unreacted precursor. Repeat this process 5 times.

[0065] (1.7) Finally, the obtained solid was vacuum dried at 37°C for 24 hours, ground into powder and sealed for storage.

[0066] (2) Modifying a glassy carbon electrode with the dendrimer-functionalized Ni-MOFs nanocomposite obtained in step (1) to obtain a functionalized electrode, specifically comprising:

[0067] (2.1) polishing the glassy carbon electrode with alumina powders with particle sizes ranging from 1.5 to 2.0 μm and 0.5 to 1.0 μm, respectively;

[0068] (2.2) The polished electrode obtained in (2.1) was scanned by cyclic voltammetry in a 5 mM K4Fe(CN)6 / K3Fe(CN)6 solution to obtain the voltage difference ΔP between the cathode and the anode in the cyclic voltammogram;

[0069] (2.3) until ΔP is less than or equal to 80 mV, otherwise repeat steps (2.1) to (2.2);

[0070] (2.4) Dispersing the dendrimer-functionalized Ni-MOF nanocomposite in ultrapure water at a concentration of 1-1.5 mg / mL, ultrasonically dispersing at 540 W for 1 h, and then centrifuging at 3000 rpm for 5 min to obtain the supernatant;

[0071] (2.5) The dendrimer functionalized Ni-MOFs nanocomposite dispersion solution obtained in (2.4) was added dropwise to the surface of the clean glassy carbon electrode obtained in (2.3). The volume (μL) of the dendrimer functionalized Ni-MOFs nanocomposite dispersion solution and the area (mm2) of the glassy carbon electrode were proportional to the volume of the dispersion solution. 2 ) ratio is 2.5:1, and the film is formed by drying under dust-free conditions to obtain a functional electrode.

[0072] The functionalized electrode was used as the working electrode, the platinum electrode as the counter electrode, and the Ag / AgCl electrode as the reference electrode to form a three-electrode system, namely, the electrochemical sensor of dendrimer-functionalized Ni-MOFs.

[0073] Electrochemical sensor based on dendrimer-functionalized Ni-MOFs nanocomposites in Pb 2+、Cu 2+ At the same time, the application of detection includes the following steps:

[0074] (3.1) The three-electrode system was placed in 0.2 mM sodium acetate-acetic acid buffer (pH 5) containing the target heavy metal. Based on square wave anodic stripping voltammetry, the target heavy metal was enriched and stripped using an electrochemical workstation to achieve simultaneous quantitative detection of heavy metals.

[0075] (3.2) Pb is concentrated at a potential of -1.2 V. 2+ 、Cu 2+ The deposition time was 450s, and the target heavy metal solution was magnetically stirred at a speed of 500rpm to make Pb 2+ 、Cu 2+ Fully enriched;

[0076] (3.3) After the deposition, heavy metals were dissolved with a scanning range of -1.2V to 0.4V, a frequency of 25Hz, an amplitude of 25mV, and a potential increment of 4mV to obtain Pb 2+ 、Cu 2+ The dissolution peak of Pb 2+ 、Cu 2+ Simultaneous quantitative detection.

[0077] (3.4) After the test is completed, scan the working electrode at a cleaning potential of 0.6 V for 180 seconds to clean the residual heavy metals and prepare it for the next test, that is, cycle to steps (3.2) to (3.3).

[0078] The present invention will be described in detail below in conjunction with embodiment, and the following detailed description is the description of embodiment, and is intended to provide further detailed description to the present invention. Unless otherwise indicated, all technical terms adopted in the present invention are identical with the meaning generally understood by those of ordinary skill in the art of the application. The terms used in the present invention are only to describe specific embodiments, and are not intended to be limited to the exemplary embodiments according to the present invention. In the following examples, methods used and experimental equipment are conventional methods and instruments unless otherwise specified.

[0079] Example 1

[0080] The preparation method of the electrochemical sensor based on the dendrimer functionalized Ni-MOFs nanocomposite material comprises the following steps:

[0081] (1) Preparation of dendrimer-functionalized Ni-MOFs nanocomposites, specifically:

[0082] (1.1) Remove a portion of the viscous polyamidoamine dendrimer (PAMAM) and dissolve it in ultrapure water to prepare a 0.5 mM PAMAM solution.

[0083] (1.2) Dissolve the HITP ligand (2,3,6,7,10,11-hexxaaminotriphenylene, HITP) and NiCl2 in PAMAM solution to prepare a 3.5 mg / mL HITP solution and a 16.2 mg / mL NiCl2 solution.

[0084] (1.3) Transfer the two solutions obtained in (1.2) to a brown glass bottle at a volume ratio of 7:1 and mix under magnetic stirring at 550 rpm for 10 min.

[0085] (1.4) Based on the volume ratio of ammonia water added to the mixed solution in (1.3) (250 μL:8 mL), add the corresponding amount of ammonia water to the mixed solution obtained in (1.3), place it in a 65°C constant temperature water bath with magnetic stirring at 550 rpm, and mix and react for 16 hours;

[0086] (1.5) After 16 h, remove the original solution from the brown glass bottle, cool it to room temperature, and then centrifuge to separate the sediment (12000 rpm, 5 min);

[0087] (1.6) Wash the obtained solid precipitate with ultrapure water for 2 min. Centrifuge the precipitate (12000 rpm, 5 min) to remove the unreacted precursor. Repeat this process 5 times.

[0088] (1.7) Finally, the obtained solid was vacuum dried at 37°C for 24 h, ground into powder, and sealed for storage.

[0089] (2) Modifying a glassy carbon electrode with the dendrimer-functionalized Ni-MOFs nanocomposite obtained in step (1) to obtain a functionalized electrode, specifically comprising:

[0090] (2.1) polishing the glassy carbon electrode with alumina powders with particle sizes ranging from 1.5 to 2.0 μm and 0.5 to 1.0 μm, respectively;

[0091] (2.2) The polished electrode obtained in (2.1) was scanned by cyclic voltammetry in a 5 mM K4Fe(CN)6 / K3Fe(CN)6 solution to obtain the voltage difference ΔP between the cathode and the anode in the cyclic voltammogram;

[0092] (2.3) until ΔP is less than or equal to 80 mV, otherwise repeat steps (2.1) to (2.2);

[0093] (2.4) The dendrimer-functionalized Ni-MOF nanocomposite was dispersed in ultrapure water at a concentration of 1.5 mg / mL, ultrasonically dispersed at 540 W for 1 h, and then centrifuged at 3000 rpm for 5 min, after which the supernatant was collected.

[0094] (2.5) The dendrimer functionalized Ni-MOFs nanocomposite dispersion solution obtained in (2.4) was added dropwise to the surface of the clean glassy carbon electrode obtained in (2.3). The volume (μL) of the dendrimer functionalized Ni-MOFs nanocomposite dispersion solution and the area (mm2) of the glassy carbon electrode were proportional to the volume of the dispersion solution. 2 ) ratio is 2.5:1, and the film is formed under dust-free conditions to obtain a functional electrode.

[0095] The functionalized electrode was used as the working electrode, the platinum electrode as the counter electrode, and the Ag / AgCl electrode as the reference electrode to form a three-electrode system, namely, an electrochemical sensor of the dendrimer macromolecule functionalized Ni-MOFs nanocomposite material.

[0096] Electrochemical sensor based on dendrimer-functionalized Ni-MOFs nanocomposites in Pb 2+ 、Cu 2+ At the same time, the application of detection includes the following steps:

[0097] (3.1) The three-electrode system was placed in 0.2 mM sodium acetate-acetic acid buffer (pH 5) containing the target heavy metal. Based on square wave anodic stripping voltammetry, the target heavy metal was enriched and stripped using an electrochemical workstation to achieve simultaneous quantitative detection.

[0098] (3.2) Pb is concentrated at a potential of -1.2 V. 2+ 、Cu 2+ The deposition time was 450s, and the target heavy metal solution was magnetically stirred at a speed of 500rpm to make Pb 2+ 、Cu 2+ Fully enriched;

[0099] (3.3) After the deposition, heavy metals were dissolved with a scanning range of -1.2V to 0.4V, a frequency of 25Hz, an amplitude of 25mV, and a potential increment of 4mV to obtain Pb 2+ 、Cu 2+ The dissolution peak of Pb 2+ 、Cu 2+ Simultaneous quantitative detection.

[0100] (3.4) After the test is completed, scan the working electrode at a cleaning potential of 0.6 V for 180 seconds to clean the residual heavy metals and prepare it for the next test, that is, cycle to steps (3.2) to (3.3).

[0101] Figure 1 This is a diagram showing the preparation process of dendrimer-functionalized Ni-MOFs nanocomposites and the preparation process and detection principle of electrochemical sensors for heavy metal detection.

[0102] Figure 2 This is a SEM image of a dendrimer-functionalized Ni-MOFs nanocomposite. The dendrimer-functionalized Ni-MOFs nanocomposite exhibits a rough, sheet-like stacking structure with multiple pores and gaps within the material, resulting in a high specific surface area and abundant sites for the deposition of heavy metal ions.

[0103] Figure 3 The cyclic voltammograms of the glassy carbon electrode before and after modification with the dendrimer-functionalized Ni-MOFs nanocomposite. The cyclic voltammograms of the functionalized electrode show a pair of redox peaks, which are generated by the redox reaction of potassium ferrocyanide / potassium ferrocyanide. The double peaks in the cyclic voltammogram of the electrode modified with the dendrimer-functionalized Ni-MOFs nanocomposite significantly increase, exceeding the conductivity of the bare electrode, which is beneficial for electrochemical sensor detection of Pb. 2+ 、Cu 2+ Improved sensitivity.

[0104] Figure 4 It is based on the surface modification of glassy carbon electrode with dendrimer-functionalized Ni-MOFs nanocomposites and the simultaneous detection of Pb by Ni-MOFs. 2+ 、Cu 2+ The peak currents of the square wave stripping voltammogram at -0.6V and -0.1V represent the peak currents of Pb 2+ and Cu 2+ The enrichment content of PAMAM / Ni-MOFs is the highest, among which PAMAM / Ni-MOFs has the highest dissolution peak, indicating that it has the highest enrichment content of heavy metals. This indirectly proves that the modification of PAMAM provides Ni-MOFs with multiple amino active groups. Based on the principle of chelation reaction between heavy metal ions and amino groups, the sensor realizes the detection of Pb 2+ 、Cu 2+ High enrichment and quantitative detection.

[0105] Figure 5 It is an electrochemical sensor system based on glassy carbon electrode surface modified with dendrimer functionalized Ni-MOFs nanocomposite materials. 2+ 、Cu 2+Specificity result diagram of simultaneous detection. Ions in natural water bodies can interfere with the detection process of target heavy metal ions, thereby affecting the accuracy of the test results. Interfering ions may 2+ and Pb 2+ Metal ions co-deposit on the electrode, thereby competing for deposition sites. 2+ and Pb 2+ Under the condition of , the anti-interference performance of the sensor was studied, and the interfering ions (K + 、Na + , Ca 2+ Mg 2+ 、Fe 2+ 、Hg 2+ and As 3+ and Cd 2+ After mixing heavy metal ion solution (Mixture)), Cu 2+ and Pb 2+ The peak currents of the dissolution of Cu decreased to some extent, but still retained more than 80% of the current value. 2+ and Pb 2+ At the same time, the detection process showed high selectivity.

[0106] Figure 6 The electrochemical sensor system based on the modification of dendrimer functionalized Ni-MOFs nanocomposite material can detect different concentrations of Pb 2+ 、Cu 2+ The square wave stripping voltammetry curve and concentration linear fitting diagram of the simultaneous detection. It can be seen from the figure that the electrochemical sensor constructed based on the modification of dendrimer functionalized Ni-MOFs nanocomposite material is sensitive to Pb 2+ 、Cu 2+ Effective simultaneous quantitative detection was achieved, and the peak current showed a gradient increase with increasing concentration, which indirectly proved that the sensor was sensitive to Pb 2+ 、Cu 2+ Highly sensitive detection characteristics, the detection range is 1~100μg / L, Pb 2+ 、Cu 2+ The detection limits of Pb and Br are 1.21μg / L and 0.77μg / L respectively. The above experiments show that the electrochemical sensor system constructed based on the modification of dendrimer-functionalized Ni-MOFs composite materials in this study can detect different concentrations of Pb. 2+ 、Cu 2+ The electrochemical sensor technology for simultaneous detection is not only simple to operate, easy to implement and low in cost, but also has a low detection limit and good linearity, which is a promising technology for portable Pb 2+ 、Cu 2+At the same time, the development of detection equipment provides a favorable research direction.

[0107] Example 2

[0108] The preparation method of the electrochemical sensor based on the dendrimer functionalized Ni-MOFs nanocomposite material comprises the following steps:

[0109] (1) Preparation of dendrimer-functionalized Ni-MOFs nanocomposites, specifically:

[0110] (1.1) Remove a portion of the viscous polyamidoamine dendrimer (PAMAM) and dissolve it in ultrapure water to prepare a 0.75 mM PAMAM solution.

[0111] (1.2) Dissolve the HITP ligand (2,3,6,7,10,11-hexxaaminotriphenylene, HITP) and NiCl2 in PAMAM solution to prepare a 2.75 mg / mL HITP solution and a 12.7 mg / mL NiCl2 solution.

[0112] (1.3) Transfer the two solutions obtained in (1.2) to a brown glass bottle at a volume ratio of 9:1 and mix under magnetic stirring at 550 rpm for 10 min.

[0113] (1.4) Based on the volume ratio of ammonia water added to the mixed solution in (1.3) (250 μL:8 mL), add the corresponding amount of ammonia water to the mixed solution obtained in (1.3), place it in a 65°C constant temperature water bath with magnetic stirring at 550 rpm, and mix and react for 19 hours;

[0114] (1.5) After 19 h, remove the original solution from the brown glass bottle, cool it to room temperature, and then centrifuge to separate the sediment (12000 rpm, 10 min);

[0115] (1.6) Wash the obtained solid precipitate with ultrapure water for 2 min. Centrifuge the precipitate (12000 rpm, 5 min) to remove the unreacted precursor. Repeat this process 5 times.

[0116] (1.7) Finally, the obtained solid was vacuum dried at 37°C for 24 h, ground into powder, and sealed for storage.

[0117] (2) Modifying a glassy carbon electrode with the dendrimer-functionalized Ni-MOFs nanocomposite obtained in step (1) to obtain a functionalized electrode, specifically comprising:

[0118] (2.1) polishing the glassy carbon electrode with alumina powders with particle sizes ranging from 1.5 to 2.0 μm and 0.5 to 1.0 μm, respectively;

[0119] (2.2) The polished electrode obtained in (2.1) was scanned by cyclic voltammetry in a 5 mM K4Fe(CN)6 / K3Fe(CN)6 solution to obtain the voltage difference ΔP between the cathode and the anode in the cyclic voltammogram;

[0120] (2.3) until ΔP is less than or equal to 80 mV, otherwise repeat steps (2.1) to (2.2);

[0121] (2.4) The dendrimer-functionalized Ni-MOF nanocomposite was dispersed in ultrapure water at a concentration of 1.25 mg / mL, ultrasonically dispersed at 540 W for 1 h, and then centrifuged at 3000 rpm for 5 min to obtain the supernatant.

[0122] (2.5) The dendrimer-functionalized Ni-MOFs nanocomposite dispersion solution obtained in (2.4) was added dropwise to the surface of the clean glassy carbon electrode obtained in (2.3). The volume (μL) of the dendrimer-functionalized Ni-MOFs nanocomposite dispersion solution and the glassy carbon area (mm 2 ) ratio is 2.5:1, and the film is formed by drying under dust-free conditions to obtain a functional electrode.

[0123] The functionalized electrode was used as the working electrode, the platinum electrode as the counter electrode, and the Ag / AgCl electrode as the reference electrode to form a three-electrode system, namely, the electrochemical sensor of dendrimer-functionalized Ni-MOFs.

[0124] Electrochemical sensor based on dendrimer-functionalized Ni-MOFs nanocomposites in Pb 2+ 、Cu 2+ At the same time, the application of detection includes the following steps:

[0125] (3.1) The three-electrode system was placed in 0.2 mM sodium acetate-acetic acid buffer (pH 5) containing the target heavy metal. Based on square wave anodic stripping voltammetry, the target heavy metal was enriched and stripped using an electrochemical workstation to achieve simultaneous quantitative detection.

[0126] (3.2) Pb is concentrated at a potential of -1.2 V. 2+ 、Cu 2+ The deposition time was 450s, and the target heavy metal solution was magnetically stirred at a speed of 500rpm to make Pb 2+ 、Cu 2+ Fully enriched;

[0127] (3.3) After the deposition, heavy metals were dissolved with a scanning range of -1.2V to 0.4V, a frequency of 25Hz, an amplitude of 25mV, and a potential increment of 4mV to obtain Pb 2+ 、Cu 2+ The dissolution peak of Pb 2+ 、Cu 2+ Simultaneous quantitative detection.

[0128] (3.4) After the test is completed, scan the working electrode at a cleaning potential of 0.6 V for 180 seconds to clean the residual heavy metals and prepare it for the next test, that is, cycle to steps (3.2) to (3.3).

[0129] Figure 7 The cyclic voltammogram of the dendrimer-functionalized Ni-MOFs nanocomposite modified on the surface of the glassy carbon electrode is shown. The double peak value in the cyclic voltammogram of the electrode modified with the dendrimer-functionalized Ni-MOFs nanocomposite reaches 2.4 mA, which shows high conductivity, which is basically consistent with the conductivity characterization results in Example 1, and is beneficial to the sensor's detection of Pb. 2+ 、Cu 2+ Improved detection sensitivity.

[0130] Figure 8 It is based on the surface modification of glassy carbon electrode with dendrimer functionalized Ni-MOFs nanocomposite material to detect 100 μg / L of Pb 2+ 、Cu 2+ The square wave stripping voltammogram is basically consistent with the heavy metal enrichment performance characterization results in Example 1. The square wave stripping voltammogram containing two high dissolution peaks shows that the sensor can achieve Pb 2+ 、Cu 2+ Detection.

[0131] Example 3

[0132] The preparation method of the electrochemical sensor based on the dendrimer functionalized Ni-MOFs nanocomposite material comprises the following steps:

[0133] (1) Preparation of dendrimer-functionalized Ni-MOFs nanocomposites, specifically:

[0134] (1.1) Remove a portion of the viscous polyamidoamine dendrimer (PAMAM) and dissolve it in ultrapure water to prepare a 1 mM PAMAM solution.

[0135] (1.2) Dissolve the HITP ligand (2,3,6,7,10,11-hexxaaminotriphenylene, HITP) and NiCl2 in PAMAM solution to prepare a 2 mg / mL HITP solution and a 9.25 mg / mL NiCl2 solution.

[0136] (1.3) Transfer the two solutions obtained in (1.2) to a brown glass bottle at a volume ratio of 6:1 and mix under magnetic stirring at 550 rpm for 10 min.

[0137] (1.4) Add ammonia water to the mixed solution obtained in (1.3), place in a 65°C constant temperature water bath, and stir magnetically at 550 rpm for 22 hours;

[0138] (1.5) After 22 h, remove the original solution from the brown glass bottle, cool it to room temperature, and then centrifuge to separate the sediment (12000 rpm, 10 min);

[0139] (1.6) Wash the obtained solid precipitate with ultrapure water for 2 min. Centrifuge the precipitate (12000 rpm, 5 min) to remove the unreacted precursor. Repeat this process 5 times.

[0140] (1.7) Finally, the obtained solid was vacuum dried at 37°C for 24 h, ground into powder, and sealed for storage.

[0141] (2) Modifying a glassy carbon electrode with the dendrimer-functionalized Ni-MOFs nanocomposite obtained in step (1) to obtain a functionalized electrode, specifically comprising:

[0142] (2.1) polishing the glassy carbon electrode with alumina powders with particle sizes ranging from 1.5 to 2.0 μm and 0.5 to 1.0 μm, respectively;

[0143] (2.2) The polished electrode obtained in (2.1) was scanned by cyclic voltammetry in a 5 mM K4Fe(CN)6 / K3Fe(CN)6 solution to obtain the voltage difference ΔP between the cathode and the anode in the cyclic voltammogram;

[0144] (2.3) until ΔP is less than or equal to 80 mV, otherwise repeat steps (2.1) to (2.2);

[0145] (2.4) The dendrimer-functionalized Ni-MOF nanocomposite was dispersed in ultrapure water at a concentration of 1 mg / mL, ultrasonically dispersed at 540 W for 1 h, and then centrifuged at 3000 rpm for 5 min to obtain the supernatant.

[0146] (2.5) The dendrimer-functionalized Ni-MOFs nanocomposite dispersion solution obtained in (2.4) was added dropwise to the surface of the clean glassy carbon electrode obtained in (2.3). The volume (μL) of the dendrimer-functionalized Ni-MOFs nanocomposite dispersion solution and the glassy carbon area (mm 2 ) ratio is 2.5:1, and the film is formed by drying under dust-free conditions to obtain a functional electrode.

[0147] The functionalized electrode was used as the working electrode, the platinum electrode as the counter electrode, and the Ag / AgCl electrode as the reference electrode to form a three-electrode system, namely, the electrochemical sensor of dendrimer-functionalized Ni-MOFs.

[0148] Electrochemical sensor based on dendrimer-functionalized Ni-MOFs nanocomposites in Pb 2+ 、Cu 2+ At the same time, the application of detection includes the following steps:

[0149] (3.1) The three-electrode system was placed in 0.2 mM sodium acetate-acetic acid buffer (pH 5) containing the target heavy metal. Based on square wave anodic stripping voltammetry, the target heavy metal was enriched and stripped using an electrochemical workstation to achieve simultaneous quantitative detection.

[0150] (3.2) Pb is concentrated at a potential of -1.2 V. 2+ 、Cu 2+ The deposition time was 450s, and the target heavy metal solution was magnetically stirred at a speed of 500rpm to make Pb 2+ 、Cu 2+ Fully enriched;

[0151] (3.3) After the deposition, heavy metals were dissolved with a scanning range of -1.2V to 0.4V, a frequency of 25Hz, an amplitude of 25mV, and a potential increment of 4mV to obtain Pb 2+ 、Cu 2+ The dissolution peak of Pb 2+ 、Cu 2+ Simultaneous quantitative detection.

[0152] (3.4) After the test is completed, scan the working electrode at a cleaning potential of 0.6 V for 180 seconds to clean the residual heavy metals and prepare it for the next test, that is, cycle to steps (3.2) to (3.3).

[0153] Figure 9The cyclic voltammogram of the dendrimer-functionalized Ni-MOFs nanocomposite modified on the surface of the glassy carbon electrode is shown. The double peak value in the cyclic voltammogram of the electrode modified with the dendrimer-functionalized Ni-MOFs nanocomposite reaches 2.4 mA, which shows high conductivity, which is basically consistent with the conductivity characterization results in Example 1, and is beneficial to the sensor's detection of Pb. 2+ 、Cu 2+ Improved detection sensitivity.

[0154] Figure 10 It is based on the surface modification of glassy carbon electrode with dendrimer functionalized Ni-MOFs nanocomposite material to detect 100 μg / L of Pb 2+ 、Cu 2+ The square wave stripping voltammogram shows that the introduction of PAMAM provides amino groups for the nanocomposite material, which can specifically capture Pb 2+ 、Cu 2+ The peak heights of the two dissolution peaks in the figure represent the Pb 2+ 、Cu 2+ The deposition content is basically consistent with the heavy metal enrichment performance characterization results of the dendrimer-functionalized Ni-MOFs nanocomposite material in Example 1.

[0155] Although the present invention has been disclosed above in terms of preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A method for preparing an electrochemical sensor based on dendrimer-functionalized Ni-MOFs nanocomposite material, characterized in that: The following steps are involved: (1) Preparation of dendrimer-functionalized Ni-MOFs nanocomposites; specifically including: (1.1) Dissolve the viscous polyamidoamine dendrimer (PAMAM) in ultrapure water to obtain a PAMAM solution. (1.2) Dissolve the HITP ligand in the PAMAM solution, and dissolve NiCl2 in the PAMAM solution to obtain the HITP ligand solution and the NiCl2 solution, respectively; (1.3) Transfer the HITP ligand solution and NiCl2 solution obtained in (1.2) to a light-shielded container and stir to obtain a mixed solution; (1.4) Add ammonia water to the mixed solution obtained in (1.3), stir at a constant temperature, and allow to react; (1.5) After the reaction is complete, remove the original solution from the light-shielded container, cool it to room temperature, and then centrifuge to precipitate the solid precipitate. (1.6) Wash the obtained solid precipitate several times with ultrapure water, centrifuging the precipitate after each wash; (1.7) The washed solid is vacuum dried, ground into powder, and sealed for storage to obtain a dendrimer-functionalized Ni-MOFs nanocomposite material; (2) The glassy carbon electrode is modified with the dendrimer-functionalized Ni-MOFs nanocomposite obtained in step (1) to obtain a functionalized electrode. The functionalized electrode is used as a working electrode, a platinum electrode is used as a counter electrode, and an Ag / AgCl electrode is used as a reference electrode to form a three-electrode system, thereby obtaining an electrochemical sensor based on the dendrimer-functionalized Ni-MOFs nanocomposite.

2. The method for preparing an electrochemical sensor based on dendrimer-functionalized Ni-MOFs nanocomposite material according to claim 1, wherein: The concentration of the PAMAM solution in step (1.1) is 0.5–1 mM; In step (1.2), PAMAM solution was used to dissolve the HITP ligand and NiCl2, respectively, to prepare a 2-3.5 mg / mL HITP solution and a 9.25-16.2 mg / mL NiCl2 solution. In step (1.3), the volume ratio of the HITP ligand solution to the PAMAM solution in the NiCl2 solution is 6:1 to 9:1; The volume ratio of the ammonia solution added in step (1.4) to the PAMAM solution in the mixed solution is 250 µL:8 mL.

3. The method for preparing an electrochemical sensor based on dendrimer-functionalized Ni-MOFs nanocomposite material according to claim 1, wherein: In step (1.3), the stirring rate was 550 rpm and the stirring time was 10 min; In step (1.4), the reaction temperature is 65°C, the stirring rate is 550 rpm, and the stirring time is 16-22 h; The centrifugation speed in step (1.5) was 12,000 rpm for 5 min. Wash with ultrapure water five times in step (1.6), each wash for 2 minutes, and centrifuge at 12,000 rpm for 5 minutes; The vacuum drying temperature in step (1.7) is 37°C and the time is 24 h.

4. The method for preparing an electrochemical sensor based on dendrimer-functionalized Ni-MOFs nanocomposite material according to claim 1, characterized in that: The glassy carbon electrode is modified with the dendrimer-functionalized Ni-MOFs obtained in step (1) to obtain a functionalized electrode, specifically comprising: (2.1) Polishing a glassy carbon electrode with aluminum oxide powder to obtain a polished electrode; (2.2) Scan the polished electrode obtained in (2.1) by cyclic voltammetry in a K4Fe(CN)6 / K3Fe(CN)6 solution to obtain the voltage difference ΔP between the cathode and the anode in the cyclic voltammogram; (2.3) until △P is less than or equal to the preset value, otherwise repeat steps (2.1) to (2.2); (2.4) dispersing the dendrimer-functionalized Ni-MOFs nanocomposite material in ultrapure water, ultrasonically dispersing the material, and then centrifuging the supernatant to obtain a dendrimer-functionalized Ni-MOFs nanocomposite material dispersion solution; (2.5) Add the dendrimer macromolecule functionalized Ni-MOFs nanocomposite dispersion solution obtained in (2.4) dropwise onto the surface of the clean glassy carbon electrode obtained in (2.3), and allow to dry under dust-free conditions to form a thin film to obtain a functionalized electrode.

5. The method for preparing an electrochemical sensor based on dendrimer-functionalized Ni-MOFs nanocomposite material according to claim 4, wherein: In step (2.1), the glassy carbon electrode is polished with alumina powder with a particle size range of 1.5-2.0 µm and alumina powder with a particle size range of 0.5 µm-1.0 µm, respectively; The concentration of the K4Fe(CN)6 / K3Fe(CN)6 solution in step (2.2) is 5 mM; The preset value in step (2.3) is 80 mV.

6. The method for preparing an electrochemical sensor based on dendrimer-functionalized Ni-MOFs nanocomposite material according to claim 4, wherein: In step (2.4), the dendrimer-functionalized Ni-MOFs nanocomposite was dispersed in ultrapure water at a concentration of 1-1.5 mg / mL, ultrasonically dispersed at a power of 540 W for 1 h, and then centrifuged at 3000 rpm for 5 min to obtain the supernatant; In step (2.5), the dendrimer functionalized Ni-MOFs nanocomposite dispersion solution obtained in (2.4) is added dropwise to the surface of the clean glassy carbon electrode obtained in (2.3). The area ratio of the dendrimer functionalized Ni-MOFs nanocomposite dispersion solution to the glassy carbon electrode is 2.5 μL:1 mm 2 , dried under dust-free conditions and formed into a thin film to obtain a functional electrode.

7. Electrochemical sensor based on dendrimer-functionalized Ni-MOFs nanocomposite material, characterized in that: The method is prepared according to any one of claims 1 to 6.

8. The electrochemical sensor based on the dendrimer functionalized Ni-MOFs nanocomposite material according to claim 7 is 2+ 、Cu 2+ Simultaneous detection applications.

9. The use according to claim 8, characterized in that The following steps are involved: (3.1) Place the three-electrode system in 0.2 mM sodium acetate-acetic acid buffer containing the target heavy metal, and perform enrichment and stripping of the target heavy metal using square wave anodic stripping voltammetry and an electrochemical workstation; (3.2) Pb is subjected to an enrichment potential of -1.2 V. 2+ 、Cu 2+ The deposition time was 450 s, and the target heavy metal solution was magnetically stirred at a speed of 500 rpm to make Pb 2+ 、Cu 2+ Fully enriched; (3.3) After the deposition, heavy metals were dissolved in a scanning range of -1.2 V to 0.4 V, a frequency of 25 Hz, an amplitude of 25 mV, and a potential increment of 4 mV to obtain Pb 2+ 、Cu 2+ The dissolution peak of Pb 2+ 、Cu 2+ Simultaneous quantitative detection.

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