Preparation method of electrochemical sensor for in-situ growth of AuPt nanoparticles based on ZnNi bimetal organic framework

Abstract

The invention relates to a preparation method and application of an electrochemical sensor for in-situ growth of AuPt nanoparticles based on a ZnNi bimetal organic framework. A modification material ZnNi-MOF (at) AuPtNPs is dropwise added to the surface of a pretreated electrode, then a DNA hairpin H1 is added and fixed to the modification material through a gold-sulfur bond, meanwhile, a 3D-DNA Walker effect can be started through a target Cd < 2 + >, and a large number of DNA single chains S1 are obtained. The method comprises the following steps: adding a supernatant and a DNA hairpin H2 subjected to magnetic separation to an electrode modified with a DNA hairpin H1 in a dropwise manner so as to generate a CHA cycle reaction, and then adding a DNA hairpin H3 and a DNA hairpin H4 in a dropwise manner so as to trigger a hyperbranched HCR signal amplification strategy, so that more methylene blue is connected to the electrode, and an electric signal in a system is enhanced. And quantitative analysis of cadmium ions is realized by using electric signal change corresponding to the concentration change of methylene blue on the surface of the electrode caused before and after addition of Cd < 2 + >. The prepared electrochemical sensor shows relatively high sensitivity, relatively wide detection range, good selectivity and excellent practical application capability.

Description

Technical Field

[0001] The present invention relates to a preparation method and application of an electrochemical sensor based on in-situ growth of AuPt nanoparticles on a ZnNi bimetallic organic framework. Background Art

[0002] Heavy metals are a common type of pollutant that accumulate in the environment due to their non-biodegradability and pose important biological and environmental problems. Among heavy metals, cadmium ions (Cd 2+ 2+) are considered to be one of the most toxic non-essential metal ions. Due to various human activities, such as plastic stabilizers, phosphate fertilizers, paints, and pigments, cadmium pollution is frequently found in soil, water, and air. Cd 2+ exposure to the human body can cause a variety of serious diseases. Cadmium has been classified as a Group 1 carcinogen by the International Agency for Research on Cancer (IARC) and ranks seventh in the Agency for Toxic Substances and Disease Registry (ATSDR). Therefore, developing a method for detecting Cd 2+ in food, environmental, and biological samples is of great significance.

[0003] Currently, there are many detection methods for Cd 2+ such as differential potentiometric stripping analysis (DPSA), graphite furnace atomic absorption spectrometry (GF-AAS), hydride generation atomic fluorescence spectrometry (HG-AFS), inductively coupled plasma mass spectrometry (ICP-MS), dithizone colorimetry (DC), etc. They can generally achieve sensitive and accurate determination of Cd 2+ However, most of them require the use of cumbersome and expensive instruments or complex operation procedures and are not suitable for on-site real-time detection. Various chemical and biosensing technologies have been explored as alternative methods for rapid and economical detection of trace cadmium pollutants, such as fluorescence, colorimetry, etc. Although these detection technologies have made great progress, they sometimes face problems such as relatively complex design or synthesis processes and even unsatisfactory detection performance. Therefore, developing sensitive, simple, and rapid methods or strategies for detecting Cd 2+ remains a challenge.

[0004] In recent years, the biorecognition element - DNAzyme has attracted extensive attention in the field of metal ion detection due to its ease of design and modification. DNAzyme is a DNA sequence with high catalytic activity for specific substrates obtained by in vitro selection. It has strong thermal and chemical stability and has been combined with various signal transduction methods for readout, such as colorimetry, electrochemistry, and fluorescence. Among them, the electrochemical sensor has attracted much attention for quantitative analysis due to its high sensitivity, simple instrument operation, and low cost. To meet the requirements of higher detection sensitivity in complex samples, various signal amplification strategies are often introduced. For example, CHA (catalytic hairpin self-assembly), HCR (hybridization chain reaction), and enzyme-assisted signal amplification methods. Among them, CHA and HCR, as enzyme-free isothermal signal amplification methods, are simple in design, economical and efficient, and have received extensive attention. Metal-organic framework materials (MOFs) have been widely used in electrochemical aptasensors to improve their electrode performance due to their large surface area, high porosity, good electrocatalytic activity, etc. Among them, bimetallic MOFs combine two metal centers and have more active sites and adsorption sites than monometallic MOFs. Therefore, they can provide more active centers in chemical reactions, thus enhancing the efficiency of catalytic reactions and conductive activity.

[0005] The present invention aims at the problems existing in the prior art and provides an electrochemical sensor based on the in-situ growth of AuPt nanoparticles on a ZnNi bimetallic organic framework for detecting Cd 2+ . By using DNAzyme cleavage as the internal driving force to drive the DNAWalker technology and then introducing magnetic separation technology, not only the interference of false positive signals is reduced, but also the detection sensitivity and selectivity of the sensor for Cd 2+ are significantly improved. And the reducibility of the bimetallic MOF material itself on the electrode can load more metal particles, increase the electrode conductivity, and play a role in signal amplification. At the same time, CHA and hyperbranched HCR signal amplification technologies are used. Hyperbranched HCR provides more sites for the embedding of signal tags compared with traditional HCR technology, realizing further signal amplification and reducing costs. The electrochemical sensor strategy based on the present invention overcomes the problems existing in the prior art and has the characteristics of strong specificity, low cost, and good stability, which is conducive to the popularization and application of the invention. Summary of the Invention

[0006] The preparation method of the electrochemical sensor based on the in-situ growth of AuPt nanoparticles on a ZnNi bimetallic organic framework is carried out according to the following steps: (1) Preparation of ZnNi bimetallic organic framework: The one-pot solvothermal method was used to prepare the ZnNi bimetallic organic framework. Terephthalic acid was dissolved in dimethylacetamide and soluble zinc salt was dissolved in anhydrous ethanol. The two solutions were then evenly mixed by ultrasound, and transition metal nickel salt was added. After stirring for a period of time, the mixture was transferred to a high-pressure reactor for incubation. The product was collected by high-speed centrifugation and washed with anhydrous ethanol. The ZnNi bimetallic organic framework was obtained by vacuum drying to constant weight.

[0007] (2) Preparation of bimetallic nanocomposites: Precious metal nanoparticles are generated in situ on the ZnNi bimetallic organic framework by a redox method. The above nanomaterials are first ultrasonically dispersed in water and then added with a precious metal solution to mix evenly. Dispersants and reducing agents are then added and stirred thoroughly. The mixture is centrifuged at high speed and dried to a constant weight to obtain the bimetallic nanocomposites.

[0008] (3) Preparation of MBs@ S-DNA / DNAzyme system: S-DNA is loaded on MBs through the strong binding interaction between biotin on S-DNA and streptavidin coated on the surface of magnetic beads (MBs). Then, DNAzyme forms a double-stranded structure by complementary base pairing with S-DNA in the manner of a DNA walker. The beads are then magnetically separated and washed with buffer. After removing the supernatant, the MBs@ S-DNA / DNAzyme system is successfully constructed.

[0009] (4) Construction of electrochemical sensor: The bimetallic nanocomposite was fixed on the surface of the gold electrode by physical adsorption, the sulfur-modified DNA hairpin H1 was fixed on the material by gold-sulfur bond, and the active site was blocked with 6-mercapto-1-ethanol. Then, Cd-containing 2+ Standard solution of Cd 2+-The DNAzyme is activated, the rA site of S-DNA is cleaved and a single-stranded DNA S1 is released. At the same time, the released DNAzyme continues to bind to the next S-DNA as a walking strand, and finally cuts off more single-stranded DNA S1. After magnetic separation, the supernatant is aspirated. The supernatant is dropped onto the gold electrode. The single-stranded DNA S1 on the gold electrode can open the DNA hairpin H1 to form double-stranded DNA due to base complementary pairing. Then, the DNA hairpin H2 is dropped onto the gold electrode. Since some bases are exposed after the single-stranded DNA S1 and the DNA hairpin H1 form double-stranded DNA, the DNA hairpin H2 can be opened and the single-stranded DNA S1 can be replaced. The free single-stranded DNA S1 will continue the CHA cycle. Then, the DNA hairpin H3 and the DNA hairpin H4 are dropped onto the gold electrode. Since the DNA hairpin H2 and the DNA hairpin H1 form a double-stranded structure and protrude a sequence, this sequence can trigger hyperbranched HCR of the DNA hairpin H3 and the DNA hairpin H4, providing more sites for the subsequent embedding of signal tags. Then, the electrode is immersed in the solution of signal tags, taken out after a period of time, and the electrode is rinsed with buffer solution. Finally, the electrode is placed in the buffer solution, and the electrochemical signal of the signal tags is detected by square wave voltammetry. By adding Cd 2+ The change in the response signal before and after can be used for quantitative analysis of Cd 2+ for quantitative analysis.

[0010] Further defined, in step (1), the soluble zinc salt is one or more of zinc chloride, zinc sulfate, zinc carbonate, zinc nitrate hexahydrate, etc.; the ultrasonic time is 30 s to 60 s; the transition metal nickel salt is one or more of nickel acetylacetonate, nickel chloride, nickel nitrate, nickel perchlorate, etc.; the stirring time is 20 min to 30 min; the incubation temperature is 100 °C to 150 °C; the incubation time is 4 h to 5 h.

[0011] Further defined, in step (2), the noble metal solution is one or more of chloroauric acid, chloroplatinic acid, palladium acetate, rhodium nitrate; the dispersant is one or more of polyvinylpyrrolidone, polymethyl methacrylate, polystyrene, polyamide; the reducing agent is one or more of sodium borohydride, ascorbic acid, citrate, hydrazine hydrate.

[0012] Further defined, in step (3), the volume of the MBs is 1 to 10 μL.

[0013] Further defined, in step (4), the signal tag is one or more of thionine, methylene blue, ferrocene.

[0014] Further defined, in steps (3) and (4), the sequence of the S-DNA is: 5’-TGACCCTCCCACCCATACCGC / rA / ACGCGATACCCACCCTCCC-3’, where the 3’ end is modified with biotin and contains an rA site in the middle; the sequence of the DNAzyme is: 5’-GGGTGGGTATGGCGTTCGATAGTTAAAAGCGGTATGG-3’; the sequence of the DNA hairpin H1 is: 5’-CGGTATGGGTGGGAGGGTCACCCATGTACGCCCTCCCACCCAT-3’, where the 3’ end is modified with a thiol group; the sequence of the DNA hairpin H2 is: 5’-GGAGGGCGTACATGGGTGACCCTCCCACCCATCACCCATGTACGTGTGCCTATTATGTCTCCTCCTT-3’; the sequence of the DNA hairpin H3 is: 5’-AAGGAGGAGACATAATAGGCACACTCACCACATCCTCCTTGATCCAT-3’; the sequence of the DNA hairpin H4 is: 5’-GTGTGCCTATTATGTCTCCTCCTTGTGTGCCTATTATGTCTCCTCCTTATGGATCAAGGAGGATGTGGTGA-3’.

[0015] Further defined, in steps (3) and (4), the concentration of the DNA strand is 1 - 2 μM, the volume used is 5 - 10 μL, and the incubation time is 0.5 h - 2.5 h.

[0016] Further defined, in steps (3) and (4), the buffer is one or more of Buffer I, Tris-HCl, PBS, HEPE, and phosphate buffer solution.

[0017] Compared with the prior art, the present invention has the following remarkable advantages: 1. The present invention successfully prepares a ZnNi bimetallic organic framework nanocomposite, improves the electrochemical activity of the electrode, and realizes the optimization of the sensor performance.

[0018] 2. The present invention utilizes the specific recognition of cadmium ions by cadmium ion DNAzyme to improve the selectivity and accuracy of the electrochemical sensor.

[0019] 3. The present invention adopts the DNA Walker technology to improve the sensitivity and selectivity of the sensor and enhance the specificity of detection.

[0020] 4. The present invention ingeniously combines the catalytic hairpin self-assembly strategy and the hyperbranched hybrid chain reaction technology, providing more embedding sites for signal tags and realizing signal amplification.

[0021] The above description is only an overview of the technical solution of the present invention. In order to understand the technical means of the present invention more clearly and implement it according to the content of the specification, the following is a detailed description of the preferred embodiments of the present invention. Brief Description of the Drawings

[0022] Figure 1 It is a schematic diagram of the preparation process of the sensor of the present invention.

[0023] Figure 2 It is the square wave voltammetry results of the sensor constructed in Example 1 of the present invention before (solid line) and after (dashed line) adding Cd 2+ before.

[0024] Figure 3 It is the standard curve of the sensor constructed in Example 1 of the present invention for detecting Cd 2+

[0025] Figure 4 It is the specificity of the sensor constructed in Example 1 of the present invention for Cd 2+ and the selectivity for Cd 2+ in the presence of other interfering ions. Detailed Description of the Invention

[0026] The following further describes in detail the specific embodiments of the present invention in conjunction with the drawings and examples. The following examples are used to illustrate the present invention, but are not used to limit the scope of the present invention. Example

[0027] The preparation method of an electrochemical sensor based on the in-situ growth of AuPt nanoparticles on a ZnNi bimetallic organic framework is as Figure 1 shown.

[0028] The preparation method of an electrochemical sensor based on the in-situ growth of AuPt nanoparticles on a ZnNi bimetallic organic framework includes the following steps: ​(1)The ZnNi bimetallic organic framework nanomaterial (ZnNi-MOF) was prepared by the hydrothermal method. 0.017 g of terephthalic acid weighed accurately was dissolved in 16 mL of dimethylacetamide, and this solution was called solution A. Another solution was obtained by dissolving 0.035 g of zinc nitrate hexahydrate in 9.6 mL of absolute ethanol, labeled as solution B. Solutions A and B were uniformly mixed by ultrasonication for 30 s, then 0.053 g of nickel acetylacetonate was added, and it was kept under stirring for 30 min to obtain a light green solution, which was transferred to a stainless-steel autoclave lined with polytetrafluoroethylene and heated at 150 °C for 4 h. After cooling to room temperature, it was washed three times with absolute ethanol to remove unreacted impurities. The light green powder was collected by centrifugation and dried to a constant weight in vacuo at 60 °C to obtain ZnNi-MOF.

[0029] (2)The bimetallic nanocomposite (ZnNi-MOF@AuPtNPs) was prepared by the in-situ growth method. 3 mg of ZnNi-MOF was weighed and ultrasonically dispersed in 1 mL of water. In addition, 150 μL of 1% HAuCl4 and 150 μL of K2PtCl6 (1%) were added thereto, and magnetic stirring was carried out for 10 minutes. Secondly, 2 mL of 2 mg / mL PVP was added to the above solution, and ultrasonication was carried out for 10 minutes. Thirdly, 2 mL of freshly prepared 3.75 mg / mL NaBH4 was slowly added dropwise (one drop per second), and then magnetic stirring was carried out for 30 minutes. Finally, the mixture was washed with pure water, collected by centrifugation, and dried to a constant weight in vacuo at 60 °C to obtain ZnNi-MOF@AuPtNPs.

[0030] (3)4 μL of 10 mg / mL MBs was added to a 200 μL centrifuge tube, and after vortex mixing, it was washed three times with 50 μL of Buffer I. 5 μL of 2 μM S-DNA and 5 μL of 0.2 μM DNAzyme were added to the centrifuge tube, incubated in a water bath thermostatic oscillator at 37 °C for 2 h, the mixture was magnetically separated and washed three times with Buffer I. Subsequently, the supernatant was removed, and the MBs@S-DNA / DNAzyme system was successfully constructed.

[0031] (4) First, 5 μL of 1 mg / mL ZnNi-MOF@AuPtNPs was dropped onto the surface of the gold electrode and incubated in a thermostatic and humidostatic chamber at 37 °C for 90 min. Then, the electrode was washed with Tris-HCl buffer solution to remove the unadsorbed ZnNi-MOF@AuPtNPs. Subsequently, 5 μL of 1 μM DNA hairpin H1 was added and incubated at 37 °C for 1.5 h, and then the electrode was washed. 5 μL of 0.1 mM MCH blocker was added and incubated at 37 °C for 1 h to block the unbound sites. 10 μL of cadmium ion standard solutions with different concentrations were added to the MBs@S-DNA / DNAzyme system and incubated at 37 °C for 30 min. Cd 2+ activated the rA site on S-DNA to cleave the single-stranded DNA S1. After magnetic separation, the supernatant was aspirated and dropped onto the above-modified electrode and incubated at 37 °C for 1 h. The single-stranded DNA S1 in the supernatant opened the DNA hairpin H1, exposing part of the sequence. 5 μL of 1 μM DNA hairpin H2 was added to the electrode and incubated at 37 °C for 1 h. The exposed sequence on the electrode would open the DNA hairpin H2, and the single-stranded DNA S1 was released, performing the CHA cycle. Then, 5 μL of the mixture of 2 μM DNA hairpin H3 and DNA hairpin H4 was dropped onto the gold electrode. Since the DNA hairpin H2 and DNA hairpin H1 formed a double-stranded structure and protruded a segment of sequence, this sequence could initiate hyperbranched HCR of DNA hairpin H3 and DNA hairpin H4, providing more sites for the embedding of methylene blue (MB). Then, the electrode was immersed in 1 mL of 8 mM MB solution and incubated in a thermostatic and humidostatic chamber at 37 °C for 30 min and then taken out. The electrode was rinsed with Tris-HCl buffer solution to remove the physically adsorbed MB. Finally, the electrode was placed in PBS buffer solution, and the electrochemical signal of the signal tag was detected by square wave voltammetry. By adding Cd 2+ The change in the response signal before and after could be used for quantitative analysis of Cd 2 + .

[0032] (5) Establishment of the standard curve: 10 μL of cadmium ion standard solutions with different concentrations were added to step (4) to obtain sample detection solutions with different gradients. After incubation, electrical signals were obtained. The logarithm of the cadmium ion concentration was used as the abscissa, and the difference in the current signals was used as the ordinate for linear fitting to establish the standard curve of the sensor for cadmium ions.

[0033] As Figure 2 shown, the cyclic voltammetry results of the sensor constructed in Example 1 of the present invention before (solid line) and after (dashed line) adding cadmium ions with different concentrations are presented.

[0034] As Figure 3 shown, the standard curve of the sensor constructed in Example 1 of the present invention for detecting cadmium ions is presented. Example

[0035] A method for preparing an electrochemical sensor based on in-situ growth of AuPt nanoparticles on a ZnNi bimetallic organic framework and its practical application, including the following steps: (1) To verify that the prepared electrochemical sensor based on in-situ growth of AuPt nanoparticles on a ZnNi bimetallic organic framework has specific recognition for cadmium ions, cadmium ion standards were added to deionized water to make the concentration of cadmium ions 50 nM; other interfering ion standard solutions were prepared using deionized aqueous solutions, and the concentration of each was 10 mM. The signal intensity corresponding to the ordinate is the current intensity of different targets and the current intensity after mixing different targets. The above-mentioned several different interfering ion standards were detected according to the detection system constructed in Example 1, and the detection results are as Figure 4 shown, indicating that the method of the present invention has high selectivity for cadmium ions. Example

[0036] A method for preparing an electrochemical sensor based on in-situ growth of AuPt nanoparticles on a ZnNi bimetallic organic framework and its practical application, including the following steps: (1) Food sample treatment: The tea was treated with reference to the national standard with slight modification. The actual sample was pretreated by microwave digestion. Weighed 0.5 g of the sample and added it together with 8 mL of HNO3 and 2 mL of H2O2 into the tank of the microwave digestion furnace. The reaction temperature, pressure, heating time, and holding time were set to 180 °C, 400 psi, 12 min, and 15 min respectively. After digestion, the tank containing the digestion solution was heated on a hot plate to expel the acid in the digestion solution, and finally cooled at room temperature. The standard addition method was used to obtain the food extract. The tap water was treated with reference to the method in the reference. The tap water passed through a syringe filter with a diameter of 0.45 µm to obtain a 10 mL volume of filtrate, and the standard addition method was used to obtain the food extract.

[0037] (2) Sample detection: Take 10 µL of the food extract, measure the electrical signal according to steps (1)-(4) of Example 1, and substitute it into the standard curve to obtain the concentration of cadmium ions in the sample.

[0038] (3) When using tea as the food sample for determination, based on the addition amount of 10 nmol / L, cadmium ion standards with 0.1 times and 100 times of the reference amount were added to the tea respectively. Take 10 µL of the sample solution, measure the electrical signal according to steps (1)-(4) of Example 1, substitute it into the standard curve detected in Example 1 to obtain the concentration of cadmium ions in the sample. Each sample was measured 3 times and the average value was taken, and the average recovery rate of the prepared electrochemical sensor was calculated to be 100.8%-116.4%.

[0039] It is verified that the prepared electrochemical sensor shows advantages such as fast response speed, high sensitivity, good selectivity, wide detection range, good reproducibility and stability in the detection of cadmium ions. The detection of actual samples shows that the prepared sensor has very good practical application value.

[0040] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

[0041] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. Preparation method of an electrochemical sensor based on in-situ growth of AuPt nanoparticles on a ZnNi bimetallic organic framework, characterized in that, The following steps are involved: (1) Synthesis of ZnNi bimetallic nanocomposites: Terephthalic acid is dissolved in dimethylacetamide, and soluble zinc salt is dissolved in anhydrous ethanol. The two solutions are uniformly mixed by ultrasound, and then transition metal nickel salt is added. After stirring for a period of time, the mixture is transferred to a high-pressure reactor for incubation. The product is collected by high-speed centrifugation, washed with anhydrous ethanol, and vacuum dried to constant weight to obtain a ZnNi bimetallic organic framework ZnNi-MOF. ZnNi-MOF combines two metal centers and has more active sites and adsorption sites than single metal MOF. Through the reducibility of ZnNi-MOF itself, in situ generation of To grow AuPt nanoparticles, firstly, the ZnNi-MOF nanomaterial is ultrasonically dispersed in water, and a soluble gold salt and a soluble platinum salt solution are added and mixed evenly, then a dispersant and a reducing agent are added and fully stirred, centrifuged at high speed, and dried to a constant weight to obtain a ZnNi bimetallic nanocomposite material ZnNi-MOF@AuPtNPs; ZnNi-MOF is loaded with AuPt nanoparticles by an in-situ growth method, so that the loaded AuPt nanoparticles are more stable and not easy to fall off or aggregate, and the synergistic effect between the bimetallic AuPt nanoparticles can produce a stronger catalytic performance of a single metal nanoparticle; (2)Construction of the electrochemical sensor: First, the ZnNi bimetallic nanocomposite ZnNi-MOF@AuPtNPs was dropped onto the surface of the pretreated electrode, and the material was physically adsorbed on the electrode surface. Then, the DNA hairpin H1 was dropped and fixed to the material through Au-S bonds. At the same time, the MBs@S-DNA / DNAzyme system was constructed. The DNA duplex S-DNA / DNAzyme was immobilized on the surface of magnetic beads MBs through the strong binding force between streptavidin and biotin. In the presence of the target, the DNA walker DNA Walker motion occurred in the magnetic bead MBs system, and the DNAzyme was activated to cleave the DNA single strand S-DNA, cutting off the DNA single strand S1. The released DNAzyme served as the walking strand and continued to bind to the next DNA single strand S-DNA. After magnetic separation, a large amount of DNA single strand S1 was obtained in the supernatant. The supernatant after magnetic separation and the DNA hairpin H2 were dropped onto the surface of the gold electrode modified with the DNA hairpin H1 to initiate the catalytic hairpin assembly CHA cycle. The DNA hairpin H2 was fixed on the electrode by forming a double strand with the DNA hairpin H1. The DNA hairpin H3 and the DNA hairpin H4 were dropped. Since the DNA hairpin H2 and the DNA hairpin H1 formed a double strand structure and protruded a sequence, this sequence could initiate the hybridization chain reaction hyperbranched HCR signal amplification strategy between the DNA hairpin H3 and the DNA hairpin H4, providing more sites for the subsequent embedding of signal tags. After the electrode undergoing hyperbranched HCR was immersed in the solution of signal tags for a period of time and then taken out, finally the electrode was placed in a buffer solution, and the electrochemical signal was detected by square wave voltammetry. Thus, the electrochemical sensor based on the in-situ growth of AuPt nanoparticles on the ZnNi bimetallic organic framework was prepared.

2. The preparation method of the electrochemical sensor based on in-situ growth of AuPt nanoparticles on ZnNi bimetallic organic framework according to claim 1, characterized in that, In step (1), the soluble zinc salt is one or more of zinc chloride, zinc sulfate, zinc carbonate, zinc nitrate hexahydrate, etc.; the ultrasonic time is 30 s to 60 s; the transition metal nickel salt is one or more of nickel acetylacetonate, nickel chloride, nickel nitrate, nickel perchlorate, etc.; the stirring time is 20 min to 30 min; the incubation temperature is 100 °C to 150 °C; the incubation time is 4 h to 5 h; the soluble gold salt is one or more of chloroauric acid, chloroplatinic acid, palladium acetate, rhodium nitrate; the soluble platinum salt is one or more of chloroauric acid, chloroplatinic acid, palladium acetate, rhodium nitrate; the dispersant is one or more of polyvinylpyrrolidone, polymethyl methacrylate, polystyrene, polyamide; the reducing agent is one or more of sodium borohydride, ascorbic acid, citrate, hydrazine hydrate.

3. The preparation method of the electrochemical sensor based on in-situ growth of AuPt nanoparticles on ZnNi bimetallic organic framework according to claim 1, wherein, In step (2), the volume of the MBs is 1 to 10 μL; the concentration of the DNA strand is 1 to 2 μM; the volume used is 5 to 10 μL; the buffer is one or more of Buffer I, Tris-HCl, PBS, HEPE, and phosphate buffer solution; the signal tag is one or more of thionine, methylene blue, and ferrocene; the soaking time is 20 min to 30 min.

4. The preparation method of the electrochemical sensor based on in-situ growth of AuPt nanoparticles on ZnNi bimetallic organic framework according to claim 1, characterized in that, In step (2), the sequence of the single-stranded DNA S-DNA is: 5’-TGACCCTCCCACCCATACCGC / rA / ACGCGATACCCACCCTCCC-3’, where the 3’ end is modified with biotin and contains an rA site in the middle; the sequence of the DNAzyme is: 5’-GGGTGGGTATGGCGTTCGATAGTTAAAAGCGGTATGG-3’; the sequence of the DNA hairpin H1 is: 5’-CGGTATGGGTGGGAGGGTCACCCATGTACGCCCTCCCACCCAT-3’, where the 3’ end is modified with a sulfhydryl group; the sequence of the DNA hairpin H2 is: 5’-GGAGGGCGTACATGGGTGACCCTCCCACCCATCACCCATGTACGTGTGCCTATTATGTCTCCTCCTT-3’; the sequence of the DNA hairpin H3 is: 5’-AAGGAGGAGACATAATAGGCACACTCACCACATCCTCCTTGATCCAT-3’; the sequence of the DNA hairpin H4 is: 5’-GTGTGCCTATTATGTCTCCTCCTTGTGTGCCTATTATGTCTCCTCCTTATGGATCAAGGAGGATGTGGTGA-3’.

Images