Nanoparticle modified quantum dot MOF (Metal Organic Framework) material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of organic detection, in particular to a nanoparticle modified quantum dot MOF material and a preparation method and application thereof. A zirconium-based double-ligand metal organic framework material is used as a carrier, a co-reaction accelerant Ti3C2 quantum dot is modified to enhance the electrochemical luminescence reaction efficiency, and copper-gold nanoparticles are loaded to amplify signals. The nanoparticle modified quantum dot MOF material provided by the invention can be prepared into an aptamer biosensor for accurately identifying malathion, and has high sensitivity and high selectivity. According to the invention, a nanoparticle modified quantum dot MOF material is coupled and combined with an aptamer, and an aptamer probe with high electrochemical luminescence activity and specific sensitivity to malathion is constructed. When the malathion acts on the aptamer probe, the malathion is combined with the aptamer in a high affinity manner, the aptamer probe is separated from the surface of the electrode, and meanwhile, an electrochemical luminescence signal is changed, so that the malathion residue in the agricultural product is rapidly detected.

Description

Technical Field

[0001] This invention relates to the field of organic detection technology, and in particular to a nanoparticle-modified quantum dot MOF material, its preparation method, and its application. Background Technology

[0002] Malathion, a typical example of organophosphorus pesticides, is effective in controlling a variety of pests and is widely used in agricultural pest management. Even though malathion is classified as a low-toxicity insecticide, its long-term improper use can still lead to excessive levels of malathion residues in the environment and food, which can then enter the human body through the food chain, causing damage to the liver and central nervous system, and in severe cases, death from poisoning. Therefore, detecting malathion residues in agricultural products helps ensure food safety and public health.

[0003] However, there is currently very little research on the detection of malathion, and conventional methods such as chromatography are mainly used for detection. The sensitivity and selectivity are insufficient, resulting in unsatisfactory accuracy of malathion detection results. Summary of the Invention

[0004] In view of this, the present invention provides a nanoparticle-modified quantum dot MOF material, its preparation method and application. The nanoparticle-modified quantum dot MOF material provided by the present invention can be prepared into an aptamer biosensor for accurate identification of malathion, with high sensitivity and high selectivity.

[0005] This invention provides a nanoparticle-modified quantum dot MOF material, comprising a zirconium-based dual-ligand metal-organic framework material, copper-gold nanoparticles loaded on the zirconium-based dual-ligand metal-organic framework material, and Ti3C2 quantum dots modified on the zirconium-based dual-ligand metal-organic framework material; the ligands of the zirconium-based dual-ligand metal-organic framework material are 1,3,6,8-tetra(4-carboxyphenyl)pyrene and mes-tetra(4-carboxyphenyl)porphyrin; the copper-gold nanoparticles comprise copper nanoparticles and gold nanoparticles coated on the surface of the copper nanoparticles.

[0006] Preferably, the structural unit of the zirconium-based dual-ligand metal-organic framework material is shown in Formula I: .

[0007] This invention also provides a method for preparing the nanoparticle-modified quantum dot MOF material described above, comprising the following steps: (1) A zirconium salt, 1,3,6,8-tetra(4-carboxyphenyl)pyrene, meso-tetra(4-carboxyphenyl)porphyrin, trifluoroacetic acid, benzoic acid and amide solvent were mixed and subjected to a coordination reaction to obtain zirconium-based dual-ligand metal-organic framework materials; (2) The zirconium-based dual-ligand metal-organic framework material is modified by mixing Ti3C2 quantum dot solution, copper-gold nanoparticle solution, N-hydroxysuccinimide, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and water to obtain the nanoparticle-modified quantum dot MOF material.

[0008] Preferably, the mass ratio of the zirconium salt to 1,3,6,8-tetra(4-carboxyphenyl)pyrene is 96~98:8; the mass ratio of 1,3,6,8-tetra(4-carboxyphenyl)pyrene to mes-tetra(4-carboxyphenyl)porphyrin is 3~5:1; the mass ratio of the zirconium salt to the volume ratio of trifluoroacetic acid is (96~98) mg:40 μL; and the mass ratio of the zirconium salt to benzoic acid is 96~98:1600.

[0009] Preferably, the coordination reaction is carried out at a temperature of 118-124 degrees Celsius and the holding time is 18-20 hours.

[0010] Preferably, the modification is performed at room temperature for 12 hours; the modification is carried out under oscillation conditions.

[0011] This invention also provides the application of the nanoparticle-modified quantum dot MOF material described in the above-described scheme or the nanoparticle-modified quantum dot MOF material prepared by the above-described scheme in the field of malathion detection.

[0012] The present invention also provides an aptamer biosensor, comprising a working electrode, the working electrode comprising an aptamer probe; the aptamer probe comprising a nanoparticle-modified quantum dot (MOF) material and an aptamer modified on the nanoparticle-modified quantum dot (MOF) material; the nanoparticle-modified quantum dot (MOF) material is the nanoparticle-modified quantum dot (MOF) material described in the above scheme or the nanoparticle-modified quantum dot (MOF) material obtained by the preparation method described in the above scheme; the nucleotide sequence of the aptamer is shown in SEQ ID NO.1.

[0013] Preferably, the working electrode further includes a glassy carbon electrode, and the aptamer probe is coated on the surface of the glassy carbon electrode.

[0014] This invention also provides a method for preparing the aptamer biosensor described above, comprising the following steps: (1) The solution of nanoparticle-modified quantum dot MOF material, aptamer solution, NHS solution and EDC solution were mixed and incubated to obtain aptamer probe; (2) The aptamer probe and the glassy carbon electrode are mixed and attached to obtain the working electrode; (3) Assemble the working electrode into a sensor to obtain the aptamer biosensor.

[0015] This invention provides a nanoparticle-modified quantum dot MOF material (ML-MOF / Ti3C2QDs / Cu@Au NPs). The invention uses a zirconium-based dual-ligand metal-organic framework as a carrier, modifies Ti3C2 quantum dots (QDs) as a co-reaction promoter to enhance electrochemiluminescence (ECL) reaction efficiency, and loads copper-gold nanoparticles (Cu@Au NPs) to amplify the signal. The nanoparticle-modified quantum dot MOF material provided by this invention can be fabricated into aptamer biosensors for the precise identification of malathion, exhibiting high sensitivity and high selectivity.

[0016] This invention also provides a method for preparing the nanoparticle-modified quantum dot MOF material described above. The preparation method provided by this invention is simple in steps, convenient to operate, safe, and suitable for industrial production.

[0017] This invention also provides the application of the nanoparticle-modified quantum dot MOF material described in the above-described scheme or the nanoparticle-modified quantum dot MOF material prepared by the above-described scheme in the field of malathion detection. The nanoparticle-modified quantum dot MOF material provided by this invention is suitable for use in preparing aptamer biosensors for accurate identification of malathion, and has broad application prospects.

[0018] This invention also provides an aptamer biosensor. This invention couples nanoparticle-modified quantum dot (MOF) materials with aptamers to construct aptamer probes (SPs) with high electrochemiluminescence activity and specific sensitivity to malathion. When malathion interacts with SPs on the sensor, it binds to the aptamer with high affinity, causing the SPs to detach from the electrode surface. Simultaneously, the electrochemiluminescence signal changes, thereby enabling rapid detection of malathion residues in agricultural products.

[0019] This invention utilizes electrochemiluminescence technology and the precise recognition characteristics of malathion pesticides by nucleic acid aptamers to construct an electrochemiluminescence aptamer biosensor with both high sensitivity and high selectivity, enabling rapid and accurate detection of malathion. The aptamer biosensor provided by this invention can selectively recognize malathion and has high sensitivity, solving the technical problem of inaccurate detection of malathion, and is suitable for electrochemiluminescence detection of malathion in vegetables.

[0020] This invention also provides a method for preparing the aptamer biosensor described above. The preparation method provided by this invention is low-cost, uses widely available raw materials, and has industrialization potential. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 ECL signal-time curves for different materials in Test Example 1; Figure labels: (a) GCE, (b) PCN-222 / GCE, (c) NU-1000 / GCE, (d) Cu@Au NPs / GCE, (e) Ti3C2QDs / GCE, (f) ML-MOF / GCE, (g) ML-MOF / Ti3C2QDs / GCE, (h) ML-MOF / Ti3C2QDs / Cu@Au NPs-Apt / GCE; Figure 2 A comparison of ECL intensity between the control group and different organophosphorus pesticides; Figure 3 ECL response diagram of the aptamer biosensor of the present invention to different concentrations of malathion; Figure 4 This is a linear trend graph showing the ECL intensity of the aptamer biosensor of the present invention as a function of the logarithm of malathion concentration. Figure 5 This is a graph showing the reproducibility results of the aptamer biosensor of the present invention; Figure 6 The figure shows the stability test results of the aptamer biosensor of the present invention. Figure 7 The diagram shows the process flow and testing mechanism of the aptamer biosensor prepared according to the present invention; wherein, (a) to (d) are the process steps of modifying quantum dot MOF materials with nanoparticles, and (e) to (f) are the preparation steps of the aptamer biosensor and its testing mechanism. Detailed Implementation

[0023] This invention provides a nanoparticle-modified quantum dot MOF material, comprising a zirconium-based dual-ligand metal-organic framework material, copper-gold nanoparticles loaded on the zirconium-based dual-ligand metal-organic framework material, and Ti3C2 quantum dots modified on the zirconium-based dual-ligand metal-organic framework material; the ligands of the zirconium-based dual-ligand metal-organic framework material are 1,3,6,8-tetra(4-carboxyphenyl)pyrene and mes-tetra(4-carboxyphenyl)porphyrin; the copper-gold nanoparticles comprise copper nanoparticles and gold nanoparticles coated on the surface of the copper nanoparticles.

[0024] In this invention, the structural unit of the zirconium-based dual-ligand metal-organic framework material is shown in Formula I: .

[0025] In this invention, the copper-gold nanoparticles are preferably copper-gold nanoparticles with a core-shell structure.

[0026] This invention also provides a method for preparing the nanoparticle-modified quantum dot MOF material described above, comprising the following steps: (1) A zirconium salt, 1,3,6,8-tetra(4-carboxyphenyl)pyrene (H4TBAPy), meso-tetra(4-carboxyphenyl)porphyrin (H2TCPP), trifluoroacetic acid (TFA), benzoic acid (C6H5COOH) and amide solvent were mixed and subjected to a coordination reaction to obtain a zirconium-based dual-ligand metal-organic framework material; (2) The zirconium-based dual-ligand metal-organic framework material is modified by mixing with Ti3C2 quantum dot (Ti3C2QD) solution, copper-gold nanoparticle (Cu@Au NPs) solution, N-hydroxysuccinimide (NHS), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (EDC) and water to obtain the nanoparticle-modified quantum dot MOF material.

[0027] This invention involves a coordination reaction of a zirconium salt, 1,3,6,8-tetra(4-carboxyphenyl)pyrene, mes-tetra(4-carboxyphenyl)porphyrin, trifluoroacetic acid, benzoic acid, and an amide solvent (denoted as the first mixture) to obtain a zirconium-based dual-ligand metal-organic framework material. In this invention, the zirconium salt is preferably ZrOCl2; and the ZrOCl2 is preferably zirconium dichloride octahydrate.

[0028] In this invention, the mass ratio of the zirconium salt to 1,3,6,8-tetra(4-carboxyphenyl)pyrene is preferably 96-98:8, more preferably 97:8.

[0029] In this invention, the mass ratio of 1,3,6,8-tetra(4-carboxyphenyl)pyrene to meso-tetra(4-carboxyphenyl)porphyrin is preferably 3 to 5:1, more preferably 4:1.

[0030] In this invention, the mass ratio of the zirconium salt to the volume ratio of trifluoroacetic acid is preferably (96~98) mg:40 μL, more preferably 97 mg:40 μL.

[0031] In this invention, the mass ratio of zirconium salt to benzoic acid is preferably 96-98:1600, more preferably 97:1600.

[0032] In this invention, the amide solvent is preferably N,N-dimethylformamide (DMF); the volume ratio of trifluoroacetic acid to the amide solvent is preferably 3~5:800, more preferably 4:800.

[0033] In this invention, the first mixing method preferably includes the following steps: ultrasonically premixing zirconium salt, trifluoroacetic acid, benzoic acid and amide solvent to obtain a premix, and then ultrasonically mixing the premix with 1,3,6,8-tetra(4-carboxyphenyl)pyrene and meso-tetra(4-carboxyphenyl)porphyrin.

[0034] In this invention, the ultrasonic premixing time is preferably 10 minutes; the ultrasonic mixing time is preferably 30 minutes.

[0035] In this invention, the temperature of the coordination reaction is preferably 118-124 degrees Celsius, more preferably 120 degrees Celsius, and the holding time is preferably 18-20 hours, more preferably 18 hours.

[0036] In this invention, the coordination reaction preferably includes a first post-treatment; the first post-treatment preferably includes the following steps: cooling the reaction system and then washing and drying the obtained product sequentially; the final cooling temperature is preferably room temperature; the washing preferably includes sequential amide washing and alcohol washing; the amide reagent used for amide washing is preferably N,N-dimethylformamide; the number of amide washings is preferably 3 or more; the alcohol used for alcohol washing is preferably methanol; the number of alcohol washings is preferably 2 or more; the drying temperature is preferably 120 degrees Celsius, and the holding time is preferably 24 hours.

[0037] After obtaining the zirconium-based dual-ligand metal-organic framework material, this invention modifies it by mixing the zirconium-based dual-ligand metal-organic framework material with Ti3C2 quantum dot solution, copper-gold nanoparticle solution, N-hydroxysuccinimide, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and water (denoted as the second mixture) to obtain the nanoparticle-modified quantum dot MOF material. In this invention, the mass ratio of the zirconium-based dual-ligand metal-organic framework material to the volume of the Ti3C2 quantum dot solution is preferably 20 mg:1 mL; the concentration of the Ti3C2 quantum dot solution is preferably not higher than 1 mg / mL, more preferably 1 mg / mL.

[0038] In this invention, the mass ratio of the zirconium-based dual-ligand metal-organic framework material to the volume of the copper-gold nanoparticle solution is preferably 20 mg: 2 mL; the concentration of the copper-gold nanoparticle solution is preferably 0.05~0.07 mg / mL, more preferably 0.062 mg / mL.

[0039] In this invention, the mass ratio of the zirconium-based dual-ligand metal-organic framework material to the molar amount of N-hydroxysuccinimide is preferably (18~22) g:1 mmol, more preferably 20 g:1 mmol.

[0040] In this invention, the molar ratio of N-hydroxysuccinimide to 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide is preferably 1:1 to 1.2, more preferably 1:1.

[0041] In this invention, the water is preferably deionized water or ultrapure water; the volume ratio of the Ti3C2 quantum dot solution to water is preferably 1:7.

[0042] In this invention, the second mixing method preferably includes the following steps: premixing zirconium-based dual-ligand metal-organic framework material and water to obtain a MOF solution, and then sequentially adding Ti3C2 quantum dot solution, copper-gold nanoparticle solution, NHS and EDC to the MOF solution and oscillating and mixing; the premixing is preferably ultrasonic mixing, and the premixing time is preferably 5 minutes.

[0043] In this invention, the modification temperature is preferably room temperature, and the heat preservation time is preferably 12 hours; the modification is preferably carried out under oscillation conditions.

[0044] In this invention, the modified process preferably further includes centrifuging, washing, and redispersing the resulting system sequentially; the washing is preferably water washing; the water used for washing is preferably ultrapure water; the number of washings is preferably 3 or more; the reagent used for redispersing the precipitate is preferably PBS buffer solution; the pH value of the PBS buffer solution is preferably 7.5.

[0045] This invention also provides the application of the nanoparticle-modified quantum dot MOF material described in the above-described scheme or the nanoparticle-modified quantum dot MOF material prepared by the above-described scheme in the field of malathion detection.

[0046] The nanoparticle-modified quantum dot MOF material provided by this invention is suitable for the precise identification of malathion and has broad application prospects.

[0047] The present invention also provides an aptamer biosensor, comprising a working electrode, the working electrode comprising an aptamer probe; the aptamer probe comprising a nanoparticle-modified quantum dot (MOF) material and an aptamer modified on the nanoparticle-modified quantum dot (MOF) material; the nanoparticle-modified quantum dot (MOF) material is the nanoparticle-modified quantum dot (MOF) material described in the above scheme or the nanoparticle-modified quantum dot (MOF) material obtained by the preparation method described in the above scheme; the nucleotide sequence of the aptamer is shown in SEQ ID NO.1.

[0048] SEQ ID NO.1: 5'-NH2-ATCCGTCACAACCTGCTCTTATACACAATTGTTTTTCTCTTAACTTCTTGACTGCTGGTGTTGGCTCCCGTAT-3'.

[0049] In this invention, the working electrode preferably further includes a glassy carbon electrode, and the aptamer probe is coated on the surface of the glassy carbon electrode.

[0050] This invention also provides a method for preparing the aptamer biosensor described above, comprising the following steps: (1) The solution of nanoparticle-modified quantum dot MOF material, aptamer solution, NHS solution and EDC solution were mixed and incubated to obtain aptamer probe (ML-MOF / Ti3C2QDs / Cu@Au NPs-Apt, abbreviated as SPs). (2) The aptamer probe and the glassy carbon electrode are mixed and attached to obtain the working electrode; (3) Assemble the working electrode into a sensor to obtain the aptamer biosensor.

[0051] In this invention, the mass concentration of the solution of the nanoparticle-modified quantum dot MOF material is preferably 1 mg / mL; the solvent in the solution of the nanoparticle-modified quantum dot MOF material is preferably water.

[0052] In this invention, the concentration of the aptamer solution is preferably 250 nM; the solvent of the aptamer solution is preferably PBS buffer solution (pH 7.5).

[0053] In this invention, the volume ratio of the solution of the nanoparticle-modified quantum dot MOF material to the aptamer solution is preferably 1:1.

[0054] In this invention, the concentration of the NHS solution is preferably 50 mM; the solvent of the NHS solution is preferably PBS buffer solution (pH 7.5); the concentration of the EDC solution is preferably 50 mM; and the solvent of the EDC solution is preferably PBS buffer solution (pH 7.5).

[0055] In this invention, the volume ratio of the aptamer solution to the NHS solution is preferably 200:1; the volume ratio of the NHS solution to the EDC solution is preferably 1:1.

[0056] In this invention, the incubation is preferably carried out under oscillation conditions; the incubation temperature is preferably room temperature; and the incubation time is preferably 12 hours.

[0057] In this invention, the incubation process preferably further includes sequentially performing solid-liquid separation and precipitation dissolution on the resulting product; the solid-liquid separation is preferably centrifugation. This invention removes unbound Apt and unreacted NHS and EDC through solid-liquid separation.

[0058] In this invention, the reagent used for dissolving the precipitate is preferably a PBS buffer solution; the pH value of the PBS buffer solution is preferably 7.5.

[0059] To further illustrate the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0060] Example 1 This embodiment prepares a nanoparticle-modified quantum dot MOF material, and the process flow is as follows: Figure 7 As shown in a~d, the specific steps are as follows: (1) Synthesis of Ti3C2MXene quantum dots (QDs): 1.6 g of LiF was added to a polytetrafluoroethylene reactor liner containing 20 mL of concentrated hydrochloric acid (concentration of 9 M), and stirred for 10 minutes. Then, 1 g of Ti3AlC2 was slowly added to the above solution (each addition was made only after the bubbles disappeared). After the addition was completed, the temperature was maintained at 45 degrees Celsius, and the mixture was stirred continuously for 48 hours to obtain a black solution. The prepared black solution was centrifuged, the bottom product was collected, and it was repeatedly washed with deionized water until the pH of the upper solution was 6 and it gradually became turbid. The product was mixed with water and shaken evenly, and N2 was introduced. The mixture was sonicated for 2 hours under ice-water bath conditions. Then, it was centrifuged at 3500 rpm for 1 hour, the upper black liquid was collected, dried, and the powder was collected to obtain monolayer or few-layer Ti3C2 powder.

[0061] Hydrothermal synthesis: 40 mg of the prepared Ti3C2 powder was ultrasonically dispersed in 40 mL of ultrapure water, and the pH was adjusted to 9 with ammonia. The reaction was carried out in a reactor at 180°C for 1 hour, centrifuged, filtered (PTFE membrane, 0.2 μm pore size), and Ti3C2 QDs were collected.

[0062] (2) Synthesis of Cu@Au NPs: Under ice bath conditions, copper sulfate pentahydrate (50 μL, 0.1 M) aqueous solution and sodium citrate (50 μL, 0.1 M) aqueous solution were added to 20 mL of KI aqueous solution (KI concentration was 1 mM) to obtain a mixed solution. Then, 1 mL of freshly prepared NaBH4 solution (3.8 mg NaBH4 dissolved in 4 mL of water) was rapidly injected into the mixed solution and stirred vigorously at 750 rpm to obtain a copper nanoparticle (Cu NPs) solution.

[0063] After 15 minutes, 50 μL of HAuCl4 aqueous solution (0.1 M) was slowly added to the prepared Cu NPs solution, with vigorous stirring to prevent Au NPs from agglomerating and to ensure that Au NPs could grow and distribute uniformly on the surface of Cu NPs. The remaining NaBH4 in the Cu NPs solution was then used to reduce tetrachloroauric acid trihydrate to form Au NPs. The Au NPs were then centrifuged, washed, and dried to obtain Cu@Au NPs, which were stored at 4°C for later use.

[0064] (3) Synthesis of zirconium-based dual-ligand metal-organic framework materials: In a round-bottom flask, 97 mg of zirconium dichloride octahydrate, 40 μL of trifluoroacetic acid, and 1.6 g of benzoic acid were mixed with 8 mL of DMF to obtain a mixture. The mixture was then sonicated for 10 minutes to dissolve the raw materials. Subsequently, H4TBAPy and H2TCPP in a mass ratio of 4:1 were added to the round-bottom flask, and the mixture was sonicated for 30 minutes. The round-bottom flask was heated to 120°C for 18 hours, then cooled to room temperature. The product was washed three times with DMF and twice with methanol. Afterward, it was dried in a drying oven at 120°C for 24 hours to obtain a zirconium-based dual-ligand metal-organic framework powder, denoted as ML-MOF.

[0065] (4) Preparation of ML-MOF / Ti3C2QDs / Cu@Au NPs materials: 20 mg of ML-MOF powder was dispersed in 7 mL of deionized water and sonicated for 5 minutes to obtain an ML-MOF solution. Then, 1 mL of the prepared Ti3C2QD solution (concentration 1 mg / mL) and 2 mL of Cu@Au NPs solution (concentration 0.062 mg / mL) were added to the ML-MOF solution, along with 20 μL of NHS (concentration 50 mM) and 20 μL of EDC (concentration 50 mM), to obtain a light red solution. The light red solution was shaken for 12 hours to mix thoroughly, then centrifuged. The product was washed three times with ultrapure water, and the precipitate was redispersed with 5 mL of PBS buffer solution (pH=7.50) to obtain the ML-MOF / Ti3C2QDs / Cu@Au NPs material.

[0066] Example 2 The preparation method in this embodiment is the same as that in Example 1, except that H4TBAPy and H2TCPP in a mass ratio of 3:1 are added to a round-bottom flask.

[0067] Example 3 The preparation method in this embodiment is the same as in Example 1, except that H4TBAPy and H2TCPP in a mass ratio of 5:1 are added to a round-bottom flask.

[0068] Example 4 This embodiment prepares an aptamer biosensor, and the process flow is as follows: Figure 7 As shown in e~f, the ML-MOF / Ti3C2QDs / Cu@Au NPs material prepared in Example 1 was carried out using the following specific steps: (1) Take 4 mL of a uniformly dispersed ML-MOF / Ti3C2QDs / Cu@Au NPs solution (concentration 1 mg / mL) and place it in a centrifuge tube. Add 20 μL of NHS (concentration 50 mM) and 20 μL of EDC (concentration 50 mM), as well as 4 mL of aptamer solution (Apt, concentration 250 nM). Then, incubate with shaking at room temperature for 12 hours. Remove unbound Apt and unreacted NHS and EDC by centrifugation. Then, dissolve the precipitate with PBS buffer solution (pH=7.50) to obtain the aptamer probe.

[0069] (2) Au NPs are dropped onto the surface of the glassy carbon electrode. The cDNA is fixed by forming Au-S bonds between the cDNA and the Au NPs. Then, 5 μL of bovine serum albumin (BSA, 0.05 wt%) solution is added to block the non-specific binding sites exposed on the electrode surface. The obtained aptamer probe is attached to the glassy carbon electrode (GCE, Φ=3 mm) to obtain the working electrode.

[0070] Test Example 1 The aptamer probe of Example 4 was detected using a three-electrode system, such as... Figure 7 As shown in f, the specific steps are as follows: Using the working electrode prepared in Example 4, a platinum wire electrode as the counter electrode, and an Ag / AgCl electrode (containing saturated potassium chloride) as the reference electrode, the sensor is assembled to obtain the aptamer biosensor.

[0071] Using the aforementioned aptamer biosensor as an ECL sensing platform and K2S2O8 as a co-reactant, following Example 4, different materials were modified on the GCE surface to test the enhancement of luminescence signal. The modified materials included (a) GCE, (b) PCN-222 / GCE, (c) NU-1000 / GCE, (d) Cu@Au NPs / GCE, (e) Ti3C2QDs / GCE, (f) ML-MOF / GCE, (g) ML-MOF / Ti3C2QDs / GCE, and (h) ML-MOF / Ti3C2QDs / Cu@Au NPs-Apt / GCE. The synthesis steps of PCN-222 and NU-1000 metal-organic framework materials are as follows: Synthesis of PCN-222 metal-organic framework: 125 mg of zirconium dichloride octahydrate, 1 mL of hydrochloric acid (analytical grade), and 5 mL of DMF were added to a glass vial and sonicated for 30 minutes to dissolve all the powder. Then, 40 mg of H2TCPP and 10 mL of DMF were added to the glass vial and sonicated for 30 minutes. The glass vial was heated to 120°C and held at that temperature for 18 hours, then cooled to room temperature. The product was washed three times with DMF and twice with methanol to obtain a white powder. The prepared white powder was dried in a drying oven at 120°C for 24 hours to obtain the PCN-222 metal-organic framework.

[0072] Synthesis of NU-1000 metal-organic framework material: In a glass bottle, 50 mg of zirconium dichloride octahydrate and 732 mg of benzoic acid were dissolved in 4 mL of DMF and sonicated for 10 minutes to obtain a suspension. The prepared suspension was heated at 100°C for 1 hour, then cooled to room temperature. 20 mg of H4TBAPy and 20 μL of trifluoroacetic acid were added to the glass bottle, and the mixture was sonicated for 30 minutes. The glass bottle was heated to 100°C and held at that temperature for 18 hours, then cooled to room temperature. The solution was then washed three times with DMF and twice with methanol to obtain a powder. The prepared powder was dried in a drying oven at 120°C for 24 hours to obtain the NU-1000 metal-organic framework material.

[0073] The preparation process of ML-MOF / Ti3C2QDs composite material is similar to that of ML-MOF / Ti3C2QDs / Cu@Au NPs material, except that the addition of 2 mL of Cu@Au NPs solution is replaced with the addition of 2 mL of ultrapure water before the subsequent synthesis steps.

[0074] The test results for this test case are as follows: Figure 1 As shown. According to Figure 1It can be seen that bare GCE, PCN-222 / GCE, and Cu@AuNPs / GCE do not show significant ECL signals, while Ti3C2QDs / GCE and NU-1000 / GCE electrodes exhibit some ECL signals. Modifying ML-MOF / GCE onto a glassy carbon electrode produces a high ECL signal (18233 au), because the conductive ligand H2TCPP and the polycyclic aromatic hydrocarbon ligand H4TBAPy are combined to synthesize a zirconium-based dual-ligand metal-organic framework material with high ECL efficiency. When the ML-MOF / Ti3C2QDs composite material is modified onto GCE, the ECL signal reaches 21080 au; and when the ML-MOF / Ti3C2QDs / Cu@Au NPs material is modified onto GCE, the ECL signal reaches a maximum of 25903 au. This indicates that the ML-MOF / Ti3C2QDs / Cu@Au NPs-K2S2O8 system proposed in this invention can serve as an excellent luminescent composite material for synthesizing aptamer probes.

[0075] Test Example 2 The specificity of the aptamer probe prepared in Example 4 was tested, and malathion ( M) and common organophosphorus pesticides (trichlorfon, diazinon, profenofos, chlorpyrifos, triazophos, and glyphosate, all at concentrations of... M) was used as the research object, and the test was conducted according to the method for detecting malathion in Test Example 1. Organophosphorus pesticides were used as a blank group. The test results are as follows: Figure 2 As shown.

[0076] according to Figure 2 As can be seen, compared with the aptamer biosensor containing malathion, the ECL signal intensity of common organophosphorus pesticides is relatively high and basically consistent with the ECL signal of the blank sample. Only the presence of malathion causes a significant decrease in the ECL signal, which is attributed to the specific binding of the aptamer to malathion. Therefore, these phenomena indicate that the aptamer biosensor of the present invention has good specificity for malathion.

[0077] Test Example 3 ML-MOF was synthesized under optimal experimental conditions (H2TCPP and H4TBAPy mass ratio of 1:4; luminescent probe was synthesized with aptamer at a concentration of 250 nM; pH of the reaction was 7.5; incubation time of malathion with aptamer was 30 minutes; S2O8...). 2- The response of the aptamer biosensor of this invention at different concentrations of malathion was recorded at a solution concentration of 0.02 mol / L. The results are as follows: Figure 3 As shown.

[0078] according to Figure 3It can be seen that as the concentration of malathion increases, the ECL intensity also increases, covering a concentration range of [missing information]. M to M.

[0079] The aptamer biosensor of this invention exhibits a linear relationship between the ECL response value and the logarithm (lgc) of malathion concentration, as shown in the specific standard curve. Figure 4 As shown. According to Figure 4 It can be seen that the corresponding calibration curve equation is: Correlation coefficient (R) 2 The value is 0.9948, and the calculated limit of detection (LOD) is... M (Signal-to-noise ratio S / N=3). It is evident that the aptamer biosensor of this invention exhibits a wide detection range and a low detection limit for the rapid detection of malathion in agricultural products.

[0080] Test Example 4 The reproducibility of the aptamer biosensor of the present invention was tested by applying the same concentration of malathion to both the same batch and different batches. M) underwent three parallel measurements, and the results are as follows: Figure 5 As shown. According to Figure 5 It can be seen that the relative standard deviation (RSD) between different batches is 3.07%, and the relative standard deviation within the same batch is 0.60%. Furthermore, the ECL signal magnitudes of the two groups were similar under the same conditions, indicating that the aptamer biosensor of the present invention has good reproducibility.

[0081] Test Example 5 The stability of the aptamer biosensor of the present invention was tested at various concentrations. After 10 consecutive scans of malathion under M, the fluctuation of ECL intensity was analyzed, and the results are as follows: Figure 6 As shown. According to Figure 6 As can be seen, the ECL intensity changes very little, with a relative standard deviation (RSD) of 1.34%, indicating that the aptamer biosensor of the present invention has acceptable stability.

[0082] Test Example 6 The practicality of the aptamer biosensor of this invention was tested, with spinach, apple, and Pu-erh tea leaves selected as quality control samples. ML-MOF was synthesized under optimal experimental conditions (H2TCPP and H4TBAPy mass ratio of 1:4; aptamer concentration of 250 nM for luminescent probe synthesis; reaction pH of 7.5; incubation time of malathion and aptamer of 30 minutes; S2O8… 2-At a solution concentration of 0.02 mol / L, electrochemiluminescence analysis was performed. The supernatant of the three quality control samples was mixed with PBS buffer solution (pH=7.5) containing 0.02 M K2S2O8 at a volume ratio of 1:4. Data was collected according to the ECL detection method of Test Example 1. The results are shown in Table 1.

[0083] Table 1. Recovery rates of malathion in different quality control samples (n=3)

[0084] As shown in Table 1, the recoveries of malathion in the three quality control samples ranged from 91.80% to 106.7%, with RSDs below 6.5%, indicating that the aptamer biosensor of this invention has high precision and good accuracy. These results demonstrate that the aptamer biosensor constructed in this invention is a good tool for detecting malathion and has practical application value in agricultural products.

[0085] The embodiments of the present invention have been described above; however, these embodiments are merely illustrative and not intended to limit the scope of the invention. Although various embodiments have been described above, this does not mean that the measures in the embodiments cannot be used advantageously in combination. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of the invention, and all such substitutions and modifications should fall within the scope of the invention.

Claims

1. A nanoparticle-modified quantum dot MOF material, characterized in that, The invention includes a zirconium-based dual-ligand metal-organic framework material, copper-gold nanoparticles loaded on the zirconium-based dual-ligand metal-organic framework material, and Ti3C2 quantum dots modified on the zirconium-based dual-ligand metal-organic framework material. The ligands of the zirconium-based dual-ligand metal-organic framework material are 1,3,6,8-tetra(4-carboxyphenyl)pyrene and mes-tetra(4-carboxyphenyl)porphyrin; The copper-gold nanoparticles include copper nanoparticles and gold nanoparticles coated on the surface of the copper nanoparticles.

2. The nanoparticle-modified quantum dot MOF material according to claim 1, characterized in that, The structural unit of the zirconium-based dual-ligand metal-organic framework material is shown in Formula I: 。 3. The method for preparing the nanoparticle-modified quantum dot MOF material according to any one of claims 1 to 2, characterized in that, Includes the following steps: (1) A zirconium salt, 1,3,6,8-tetra(4-carboxyphenyl)pyrene, meso-tetra(4-carboxyphenyl)porphyrin, trifluoroacetic acid, benzoic acid and amide solvent were mixed and subjected to a coordination reaction to obtain zirconium-based dual-ligand metal-organic framework materials; (2) The zirconium-based dual-ligand metal-organic framework material is modified by mixing Ti3C2 quantum dot solution, copper-gold nanoparticle solution, N-hydroxysuccinimide, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and water to obtain the nanoparticle-modified quantum dot MOF material.

4. The preparation method according to claim 3, characterized in that, The mass ratio of the zirconium salt to 1,3,6,8-tetra(4-carboxyphenyl)pyrene is 96~98:8; The mass ratio of 1,3,6,8-tetra(4-carboxyphenyl)pyrene to mes-tetra(4-carboxyphenyl)porphyrin is 3~5:1; The mass ratio of the zirconium salt to the volume ratio of trifluoroacetic acid is (96~98) mg:40 μL; The mass ratio of zirconium salt to benzoic acid is 96~98:1600.

5. The preparation method according to claim 3 or 4, characterized in that, The coordination reaction is carried out at a temperature of 118-124 degrees Celsius for 18-20 hours.

6. The preparation method according to claim 3, characterized in that, The modification was performed at room temperature for 12 hours. The modification is performed under oscillating conditions.

7. The application of the nanoparticle-modified quantum dot MOF material according to any one of claims 1 to 2 or the nanoparticle-modified quantum dot MOF material obtained by the preparation method according to any one of claims 3 to 6 in the field of malathion detection.

8. An aptamer biosensor, characterized in that, Includes a working electrode, wherein the working electrode includes an aptamer probe; The aptor probe comprises a nanoparticle-modified quantum dot MOF material and an aptor modified on the nanoparticle-modified quantum dot MOF material; The nanoparticle-modified quantum dot MOF material is the nanoparticle-modified quantum dot MOF material according to any one of claims 1 to 2 or the nanoparticle-modified quantum dot MOF material obtained by the preparation method according to any one of claims 3 to 6; The nucleotide sequence of the aptamer is shown in SEQ ID NO.

1.

9. The aptamer biosensor according to claim 8, characterized in that, The working electrode also includes a glassy carbon electrode, and the aptamer probe is coated on the surface of the glassy carbon electrode.

10. A method for preparing the aptamer biosensor according to any one of claims 8 to 9, characterized in that, Includes the following steps: (1) The solution of nanoparticle-modified quantum dot MOF material, aptamer solution, NHS solution and EDC solution were mixed and incubated to obtain aptamer probe; (2) The aptamer probe and the glassy carbon electrode are mixed and attached to obtain the working electrode; (3) Assemble the working electrode into a sensor to obtain the aptamer biosensor.

Images