Preparation method and application of copper nanocluster composite

Abstract

The invention discloses a preparation method and application of a copper nanocluster complex, belonging to the technical field of fluorescence sensing. The preparation method of the copper nanocluster complex comprises the following steps: preparing copper nanoclusters with glutathione as both a ligand and a reducing agent, preparing melamine-formaldehyde resin microspheres, mixing the prepared copper nanoclusters with the melamine-formaldehyde resin microspheres to prepare a copper nanocluster complex probe, and by utilizing the melamine-formaldehyde resin microspheres to adjust the aggregation-induced emission enhancement phenomenon of the copper nanoclusters, the problems of poor stability and low fluorescence quantum yield of the copper nanoclusters are solved, and the prepared copper nanocluster complex probe achieves high sensitivity and selectivity detection of methyl parathion, and has the advantages of simple preparation process, low price and sensitive detection performance.

Description

Technical Field

[0001] The invention relates to the field of fluorescence sensing, and in particular to a preparation method and application of a copper nanocluster composite. Background Art

[0002] Metal nanoclusters are composed of several to dozens of metal atoms and exhibit molecular-like properties. They have good physical, electrical and optical properties. They also have the advantages of small size, low cytotoxicity and good biocompatibility. Therefore, metal nanoclusters have been widely used in fields such as fluorescence sensing, bioimaging, catalysis and electronic devices. Compared with other common metal nanoclusters such as gold, silver, and platinum, copper is relatively abundant on the earth and inexpensive. The preparation cost of copper nanoclusters is low and the synthesis process is simple and environmentally friendly. However, due to the high surface energy of copper nanoclusters, they are easily oxidized in the air, and their application is usually limited by weak fluorescence and poor stability. Therefore, developing methods to improve the fluorescence properties of copper nanoclusters is the key to expanding their applications.

[0003] Methyl parathion (MP), as a typical organophosphorus pesticide, has been widely used to reduce plant diseases and insect pests and prevent crop yields from decreasing. However, it has also been found that MP can cause serious health problems for humans. It damages the central nervous system by inhibiting acetylcholinesterase. Even at very low concentrations, MP can cause neuronal dysfunction, organ failure, fetal abnormalities, cancer, and even death. At present, some analytical techniques have been used for the detection of MP pesticides, such as gas chromatography, gas chromatography-mass spectrometry, chemiluminescence, surface enhanced Raman spectroscopy, electrochemical analysis, and enzyme-linked immunosorbent assay. Although the above methods are very important for the detection of MP, their practical application is still limited by some inevitable shortcomings, such as complex pretreatment processes, high costs, and the need for skilled operation. As can be seen from the above, the existing MP detection methods have the disadvantages of difficult process and operation, and are difficult to be promoted and applied.

[0004] Therefore, it is necessary to provide a preparation method and application of a copper nanocluster composite to solve the above problems. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the embodiments of the present invention is to provide a preparation method and application of a copper nanocluster composite to solve the problems in the above-mentioned background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for preparing a copper nanocluster composite comprises the following steps:

[0008] S1. Synthesis of copper nanoclusters: by volume, 10 parts of a 5 mM copper nitrate aqueous solution and 1-10 parts of a 5-50 mM glutathione solution were mixed at room temperature, and sodium hydroxide solution was added dropwise to adjust the pH, and the mixture was stirred for 15 min to obtain a copper nanocluster solution;

[0009] S2. Synthesis of melamine-formaldehyde resin microspheres: 1.25 g of melamine and 1.8 g of paraformaldehyde were mixed in 100 mL of distilled water, the mixture was heated and stirred at 50° C. for 30 min, 100 μL of formic acid was added, and the heating and stirring were continued for 60 min to obtain a melamine-formaldehyde resin microsphere aqueous solution;

[0010] S3. Synthesis of copper nanocluster complex: The copper nanocluster solution prepared in S1 and the melamine-formaldehyde resin microsphere aqueous solution prepared in S2 are mixed, and stirred at room temperature to obtain an aggregation-induced fluorescence enhanced copper nanocluster complex.

[0011] As a further embodiment of the present invention, the molar ratio of copper nitrate to glutathione in step S1 is (5:1)-(1:10).

[0012] As a further solution of the present invention, in step S1, sodium hydroxide solution is added to adjust the pH value of the solution to 5-6.

[0013] As a further embodiment of the present invention, the temperature for continuous stirring in step S1 is 0-20°C.

[0014] As a further solution of the present invention, the particle size of the melamine-formaldehyde resin microspheres prepared in step S2 is about 80 nm.

[0015] As a further solution of the present invention, the amount of formic acid added in step S2 is 100 μL.

[0016] As a further embodiment of the present invention, in step S3, the molar ratio of the copper nanocluster solution to the melamine-formaldehyde resin microsphere aqueous solution is 1:(0.5-1.2).

[0017] As a further solution of the present invention, the stirring time of the copper nanocluster solution and the melamine-formaldehyde resin microsphere aqueous solution in step S3 is 2-10 min.

[0018] An application of a copper nanocluster complex, wherein the copper nanocluster complex probe is used for fluorescence detection of methyl parathion.

[0019] In summary, compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0020] The present invention utilizes melamine-formaldehyde resin microspheres to regulate the aggregation-induced emission enhancement phenomenon of copper nanoclusters, thereby solving the problems of poor stability and low fluorescence quantum yield of copper nanoclusters. The prepared copper nanocluster composite probe achieves high sensitivity and selectivity for the detection of methyl parathion, and has the effects of simple preparation process, low price and sensitive detection performance.

[0021] In order to more clearly illustrate the structural features and effects of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a fluorescence emission spectrum of the copper nanocluster composite prepared in Inventive Example 1.

[0023] Figure 2 This is a fluorescence emission spectrum of the copper nanocluster complex prepared in Inventive Example 2.

[0024] Figure 3 This is a fluorescence emission spectrum of the copper nanocluster composite prepared in Inventive Example 3.

[0025] Figure 4 This is a fluorescence emission spectrum of the copper nanocluster complex prepared in Inventive Example 4.

[0026] Figure 5 This is a fluorescence emission spectrum of the copper nanocluster complex prepared in Inventive Example 5.

[0027] Figure 6 This is a transmission electron microscope image of the copper nanocluster composite prepared in Inventive Example 5.

[0028] Figure 7 This is a fluorescence emission spectrum of the copper nanocluster composite prepared in Example 5 of the invention when methyl parathion is added.

[0029] Figure 8 Graphs showing the fluorescence emission spectra of methyl parathion at different concentrations added to the copper nanocluster composite prepared in Example 5 of the invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0031] The specific implementation of the present invention is described in detail below in conjunction with specific embodiments.

[0032] Example 1

[0033] See also Figure 1 The method for preparing the copper nanocluster composite comprises the following steps:

[0034] S1. Synthesis of copper nanoclusters: by volume, 10 parts of 5 mM copper nitrate aqueous solution and 2 parts of 5 mM glutathione solution were mixed at room temperature (5:1), and sodium hydroxide solution (1 M) was added dropwise to adjust the pH to 6, and the copper nanocluster solution was obtained by continuous stirring at 20°C for 15 min;

[0035] S2. Synthesis of melamine-formaldehyde resin microspheres: 1.25 g of melamine and 1.8 g of paraformaldehyde were mixed in 100 mL of distilled water, the mixture was heated and stirred at 50° C. for 30 min, 100 μL of formic acid was added and continued to heat and stir for 60 min, and after cooling to room temperature, a melamine-formaldehyde resin microsphere aqueous solution was obtained;

[0036] S3, synthesis of copper nanocluster complex: 10 parts of the copper nanocluster solution prepared in step S1 and 5 parts of the melamine-formaldehyde resin microsphere aqueous solution prepared in step S2 were mixed (1:0.5), and stirred at room temperature for 2 minutes to obtain a copper nanocluster complex;

[0037] S4. Fluorescence sensing of copper nanocluster complex: 200 μL of copper nanocluster complex fluorescent probe was dissolved in deionized water, and different volumes of 100 ppm methyl parathion hydrolyzate solution were added, and diluted to 2.5 mL with Britton-Robinson buffer solution with pH = 4.0 for fluorescence detection.

[0038] Example 2

[0039] See also Figure 2 The method for preparing the copper nanocluster composite comprises the following steps:

[0040] S1. Synthesis of copper nanoclusters: by volume, 10 parts of 5 mM copper nitrate aqueous solution and 5 parts of 5 mM glutathione solution were mixed at room temperature (2:1), and sodium hydroxide solution (1 M) was added dropwise to adjust the pH to 6, and the copper nanocluster solution was obtained by continuous stirring at 15°C for 15 min;

[0041] S2. Synthesis of melamine-formaldehyde resin microspheres: 1.25 g of melamine and 1.8 g of paraformaldehyde were mixed in 100 mL of distilled water, the mixture was heated and stirred at 50° C. for 30 min, 100 μL of formic acid was added and continued to heat and stir for 60 min, and after cooling to room temperature, a melamine-formaldehyde resin microsphere aqueous solution was obtained;

[0042] S3, synthesis of copper nanocluster complex: 10 parts of the copper nanocluster solution prepared in step S1 and 7 parts of the melamine-formaldehyde resin microsphere aqueous solution prepared in step S2 were mixed (1:0.7), and stirred at room temperature for 4 minutes to obtain a copper nanocluster complex;

[0043] S4. Fluorescence sensing of copper nanocluster complex: 200 μL of copper nanocluster complex fluorescent probe was dissolved in deionized water, and different volumes of 100 ppm methyl parathion hydrolyzate solution were added, and diluted to 2.5 mL with Britton-Robinson buffer solution with pH = 4.0 for fluorescence detection.

[0044] Example 3

[0045] See also Figure 3 The method for preparing the copper nanocluster composite comprises the following steps:

[0046] S1. Synthesis of copper nanoclusters: by volume, 10 parts of 5 mM copper nitrate aqueous solution and 2 parts of 25 mM glutathione solution were mixed (1:1) at room temperature, and sodium hydroxide solution (1 M) was added dropwise to adjust the pH to 5, and the copper nanocluster solution was obtained by continuous stirring at 10°C for 15 min;

[0047] S2. Synthesis of melamine-formaldehyde resin microspheres: 1.25 g of melamine and 1.8 g of paraformaldehyde were mixed in 100 mL of distilled water, the mixture was heated and stirred at 50° C. for 30 min, 100 μL of formic acid was added and continued to heat and stir for 60 min, and after cooling to room temperature, a melamine-formaldehyde resin microsphere aqueous solution was obtained;

[0048] S3, synthesis of copper nanocluster complex: 10 parts of the copper nanocluster solution prepared in step S1 and 9 parts of the melamine-formaldehyde resin microsphere aqueous solution prepared in step S2 were mixed (1:0.9), and stirred at room temperature for 6 minutes to obtain a copper nanocluster complex;

[0049] S4. Fluorescence sensing of copper nanocluster complex: 200 μL of copper nanocluster complex fluorescent probe was dissolved in deionized water, and different volumes of 100 ppm methyl parathion hydrolyzate solution were added, and diluted to 2.5 mL with Britton-Robinson buffer solution with pH = 4.0 for fluorescence detection.

[0050] Example 4

[0051] See also Figure 4 The method for preparing the copper nanocluster composite comprises the following steps:

[0052] S1. Synthesis of copper nanoclusters: by volume, 10 parts of 5 mM copper nitrate aqueous solution and 10 parts of 25 mM glutathione solution were mixed at room temperature (1:5), and sodium hydroxide solution (1 M) was added dropwise to adjust the pH to 5, and the copper nanocluster solution was obtained by continuous stirring at 5°C for 15 min;

[0053] S2. Synthesis of melamine-formaldehyde resin microspheres: 1.25 g of melamine and 1.8 g of paraformaldehyde were mixed in 100 mL of distilled water, the mixture was heated and stirred at 50° C. for 30 min, 100 μL of formic acid was added and continued to heat and stir for 60 min, and after cooling to room temperature, a melamine-formaldehyde resin microsphere aqueous solution was obtained;

[0054] S3. Synthesis of copper nanocluster complex: 10 parts of the copper nanocluster solution prepared in step S1 and 10 parts of the melamine-formaldehyde resin microsphere aqueous solution prepared in step S2 were mixed (1:1), and stirred at room temperature for 8 minutes to obtain a copper nanocluster complex;

[0055] S4. Fluorescence sensing of copper nanocluster complex: 200 μL of copper nanocluster complex fluorescent probe was dissolved in deionized water, and different volumes of 100 ppm methyl parathion hydrolyzate solution were added, and diluted to 2.5 mL with Britton-Robinson buffer solution with pH = 4.0 for fluorescence detection.

[0056] Example 5

[0057] See also Figure 5 and Figure 6 The method for preparing the copper nanocluster composite comprises the following steps:

[0058] S1. Synthesis of copper nanoclusters: Mix 10 parts of 5 mM copper nitrate aqueous solution and 10 parts of 50 mM glutathione solution (1:10) by volume at room temperature, add sodium hydroxide solution (1 M) dropwise to adjust the pH to 5, and stir for 15 min at 0°C to obtain a copper nanocluster solution;

[0059] S2. Synthesis of melamine-formaldehyde resin microspheres: 1.25 g of melamine and 1.8 g of paraformaldehyde were mixed in 100 mL of distilled water, the mixture was heated and stirred at 50° C. for 30 min, 100 μL of formic acid was added and continued to heat and stir for 60 min, and after cooling to room temperature, a melamine-formaldehyde resin microsphere aqueous solution was obtained;

[0060] S3. Synthesis of copper nanocluster complex: 10 parts of the copper nanocluster solution prepared in step S1 and 1.2 parts of the melamine-formaldehyde resin microsphere aqueous solution prepared in step S2 were mixed (1:1.2), and stirred at room temperature for 10 minutes to obtain the copper nanocluster complex.

[0061] S4. Fluorescence sensing of copper nanocluster complex: 200 μL of copper nanocluster complex fluorescent probe was dissolved in deionized water, and different volumes of 100 ppm methyl parathion hydrolyzate solution were added, and diluted to 2.5 mL with Britton-Robinson buffer solution with pH = 4.0 for fluorescence detection.

[0062] The positive effects of the present invention are shown by the following specific test examples:

[0063] Copper nanocluster complex fluorescent probe fluorescence sensing organophosphorus pesticide methyl parathion: Different volumes of 100 ppm methyl parathion hydrolyzate solution were added to the copper nanocluster complex fluorescent probe of Example 5, the pH was adjusted to 4.0, the excitation wavelength was 345 nm, the emission wavelength was 570 nm, the excitation light source slit was 10 nm, the emission light source slit was 5 nm, and fluorescence detection was performed using a 1 cm × 1 cm cuvette. Figure 7 It can be seen that the addition of methyl parathion will cause a significant quenching of the probe's fluorescence. Figure 8 It can be seen that as the concentration of methyl parathion gradually increases, the fluorescence intensity gradually decreases, thereby achieving sensitive detection of methyl parathion.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a copper nanocluster composite, characterized in that: The following steps are involved: S1. Synthesis of copper nanoclusters: by volume, 10 parts of a 5 mM copper nitrate aqueous solution and 1-10 parts of a 5-50 mM glutathione solution were mixed at room temperature, and sodium hydroxide solution was added dropwise to adjust the pH, and the mixture was stirred for 15 min to obtain a copper nanocluster solution; S2. Synthesis of melamine-formaldehyde resin microspheres: 1.25 g of melamine and 1.8 g of paraformaldehyde were mixed in 100 mL of distilled water, the mixture was heated and stirred at 50° C. for 30 min, 100 μL of formic acid was added, and the heating and stirring were continued for 60 min to obtain a melamine-formaldehyde resin microsphere aqueous solution; S3, synthesizing a copper nanocluster complex: mixing the copper nanocluster solution prepared in S1 and the melamine-formaldehyde resin microsphere aqueous solution prepared in S2, and stirring at room temperature to obtain an aggregation-induced fluorescence enhanced copper nanocluster complex; In step S1, sodium hydroxide solution is added to adjust the pH value of the solution to 5-6; The temperature for continuous stirring in step S1 is 0-20°C; The particle size of the melamine-formaldehyde resin microspheres prepared in step S2 is 80 nm; In the step S3, the volume ratio of the copper nanocluster solution to the melamine-formaldehyde resin microsphere aqueous solution is 1:(0.5-1.2); In the step S3, the stirring time of the copper nanocluster solution and the melamine-formaldehyde resin microsphere aqueous solution is 2-10 minutes.

2. The use of the copper nanocluster composite prepared by the method of claim 1, characterized in that: The copper nanocluster complex is used for fluorescence detection of methyl parathion.

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