Fluorescent composite hydrogel as well as preparation method and application thereof

Abstract

The invention provides fluorescent composite hydrogel as well as a preparation method and application thereof, and belongs to the technical field of fluorescent gold nano-cluster composite hydrogel. The method comprises the following steps: mixing and stirring a methyl thiouracil alkali solution and a chloroauric acid solution to obtain a gold nano-cluster solution; uniformly mixing an arginine solution with the gold nano-cluster solution, and incubating to obtain the fluorescent probe; and combining the obtained fluorescent probe with agarose hydrogel to obtain the fluorescent composite hydrogel. The invention also provides the fluorescent composite hydrogel obtained by the preparation method. The invention also provides application of the fluorescent composite hydrogel in fluorescence detection of fenitrothion. The novel fluorescent composite hydrogel obtained by the invention has the advantages of simple and mild preparation method, short time consumption, high sensitivity and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of fluorescent gold nanocluster composite hydrogels, and specifically relates to a fluorescent composite hydrogel and a preparation method and application thereof. Background Art

[0002] Compared with other fluorescent materials, the synthesis process of gold nanoclusters is mild and environmentally friendly, and they are widely used in fluorescence detection, bioimaging, catalysis and other fields. However, so far, most of the reported gold nanoclusters have disadvantages such as low fluorescence intensity and poor chemical stability, which greatly limit their application. Therefore, improving the fluorescence properties of gold nanoclusters is the key to their development. Among the various methods to improve the fluorescence properties of gold nanoclusters, ligand coating can enable the ligand to form a coordination bond with the metal center of the gold nanocluster, which can significantly improve the luminescence intensity and stability of the cluster, and the ligand can carry different functional groups, making the gold nanoclusters have more functional possibilities.

[0003] According to the Food and Agriculture Organization of the United Nations, 40% of the world's crop yields are lost to insect pests each year. For this reason, the use of pesticides has become ubiquitous and has become an important means to increase crop yields and control pests and diseases. However, the widespread use of pesticides has also brought about hazards that cannot be ignored. Pesticide residues can penetrate into the human body through the food chain, posing potential risks to health and causing long-term and far-reaching harm to the ecological environment. These hazards include acute poisoning incidents, chronic health problems, loss of biodiversity, soil and water pollution, etc. FTN is a commonly used organophosphorus pesticide that is widely used to control pests in cereals, fruits and trees. Therefore, it is of certain significance to develop a convenient and reliable method for detecting the content of FTN.

[0004] Fluorescence detection technology has become an effective analytical method and is widely used in the detection of various substances due to its advantages such as simple operation, high specificity, rapid response and low cost. Summary of the invention

[0005] The purpose of the present invention is to provide a fluorescent composite hydrogel and a preparation method and application thereof. The present invention combines arginine, methylthiouracil and gold nanoclusters to prepare a gold nanocluster fluorescent probe with better fluorescence properties, and then combines the gold nanoclusters with agarose hydrogel to make a hydrogel sensing platform. Based on the static quenching mechanism of gold nanoclusters and fenitrothion, the composite hydrogel is used for fluorescence detection of the organophosphorus pesticide fenitrothion.

[0006] The present invention first provides a method for preparing a fluorescent composite hydrogel, comprising the following steps:

[0007] Step 1: Mixing and stirring the methylthiouracil base solution and the chloroauric acid solution to obtain a gold nanocluster solution;

[0008] Step 2: Evenly mix the arginine solution and the gold nanocluster solution synthesized in step 1, and incubate to obtain a fluorescent probe;

[0009] Step 3: Combine the fluorescent probe obtained in step 2 with agarose hydrogel to obtain a fluorescent composite hydrogel.

[0010] Preferably, in the step 1, the volume ratio of the methylthiouracil alkaline solution to the chloroauric acid solution is 1:1, and the molar ratio of methylthiouracil to chloroauric acid is (2:1)-(5:1).

[0011] Preferably, in the step 1, the concentration of the alkali in the methylthiouracil alkali solution is 0.2-0.22M.

[0012] Preferably, the base in the methylthiouracil alkaline solution is sodium hydroxide.

[0013] Preferably, in the step 1, the stirring time is 60-80 min and the stirring speed is 300-400 rpm.

[0014] Preferably, in step 2, the volume ratio of the arginine solution to the gold nanocluster solution synthesized in step 1 is (8:1)-(9:1).

[0015] Preferably, the concentration of arginine in step 2 is 30-40 mM.

[0016] Preferably, in step 2, the incubation temperature is 35-40° C. and the incubation time is 3-5 h.

[0017] The present invention also provides the fluorescent composite hydrogel obtained by the preparation method.

[0018] The present invention also provides application of the fluorescent composite hydrogel in fluorescence detection of fenitrothion.

[0019] Beneficial Effects of the Invention

[0020] The present invention provides a fluorescent composite hydrogel and a preparation method and application thereof. The method effectively overcomes the disadvantages of weak fluorescence intensity and poor stability of gold nanoclusters by coating arginine and methylthiouracil on gold nanoclusters. Combining gold nanoclusters with agarose hydrogel effectively overcomes the disadvantages of poor stability of gold nanoclusters. Based on the static quenching mechanism of gold nanoclusters and fenitrothion, the fluorescent composite hydrogel is used for fluorescence detection of organophosphorus pesticide fenitrothion. The novel fluorescent composite hydrogel obtained by the present invention has the advantages of simple and mild preparation method, short time consumption, high sensitivity, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1This is the fluorescence emission spectrum of the gold nanoclusters induced by the double-layer ligand coating strategy prepared in Example 1;

[0022] Figure 2 This is the fluorescence emission spectrum of the gold nanoclusters induced by the double-layer ligand coating strategy prepared in Example 2;

[0023] Figure 3 This is a fluorescence emission spectrum of the gold nanoclusters induced by the double-layer ligand coating strategy prepared in Example 3;

[0024] Figure 4 This is the fluorescence emission spectrum of the gold nanoclusters induced by the double-layer ligand coating strategy prepared in Example 4;

[0025] Figure 5 This is a fluorescence emission spectrum of the gold nanoclusters induced by the double-layer ligand coating strategy prepared in Example 5;

[0026] Figure 6 This is a picture of the detection of the double-layer ligand-coated fluorescent gold nanocluster composite hydrogel prepared in Example 1 of the present invention;

[0027] Figure 7 This is a linear relationship diagram between the R value extracted from the double-layer ligand-coated fluorescent gold nanocluster composite hydrogel mobile phone prepared in Example 5 of the present invention and the concentration of fenitrothion. DETAILED DESCRIPTION

[0028] The embodiments of the present invention are further described by the following examples. The following are only preferred embodiments of the present invention, which are used to illustrate the present invention and do not limit the present invention in any way. Without departing from the technical solution of the present invention, any changes or modifications made to the present invention that are easily implemented by a person of ordinary skill in the art will fall within the scope of the claims of the present invention.

[0029] The present invention first provides a method for preparing a fluorescent composite hydrogel, the method comprising:

[0030] Step 1: dissolving methylthiouracil in an alkaline solution to obtain a methylthiouracil alkaline solution, and mixing the methylthiouracil alkaline solution with a chloroauric acid solution under vigorous stirring conditions, wherein the stirring time is preferably 60-80 min, and the stirring speed is preferably 300-400 rpm.

[0031] A gold nanocluster solution is obtained; the volume ratio of the methylthiouracil base solution to the chloroauric acid solution is preferably 1:1, and the molar ratio of the methylthiouracil to the chloroauric acid is preferably (2:1)-(5:1),

[0032] The concentration of the alkali in the methylthiouracil alkali solution is 0.2-0.22M, and the alkali in the methylthiouracil alkali solution is sodium hydroxide.

[0033] Step 2: Incubate the arginine solution with the gold nanocluster solution obtained in step 1. The incubation temperature is preferably 35-40°C, the incubation time is preferably 3-5h, the volume ratio of the arginine solution to the gold nanocluster solution synthesized in step 1 is preferably (8:1)-(9:1), and the concentration of arginine is preferably 30-40mM.

[0034] Step 3: Combine the fluorescent probe obtained in step 2 with agarose hydrogel to obtain a fluorescent composite hydrogel. The agarose hydrogel is obtained by adding ultrapure water to agarose and heating it to 100°C. The mass of agarose g: volume ml of the fluorescent probe is preferably 0.2: (2-3).

[0035] The present invention also provides the fluorescent composite hydrogel obtained by the preparation method.

[0036] The present invention also provides application of the fluorescent composite hydrogel in fluorescence detection of fenitrothion.

[0037] The application method specifically comprises the following steps:

[0038] Take 2-3 ml of the fluorescent composite hydrogel and use 1 mg / ml of fenitrothion for fluorescence detection.

[0039] Example 1

[0040] Step 1: Synthesis of gold nanoclusters:

[0041] 800 mmol of methylthiouracil was dissolved in 10 ml of 0.22 M sodium hydroxide, and 1 ml of 80 mM methylthiouracil base solution and 1 ml of 25 mM chloroauric acid solution (3.2:1) were uniformly mixed under vigorous stirring conditions. The gold nanocluster solution was obtained by continuous stirring for 80 min.

[0042] Step 2: Synthesis of double-layer ligand-coated gold nanoclusters:

[0043] 1 mL of 30 mM arginine solution was added to the gold nanocluster solution in step 1 and incubated at 37° C. for 3 h to obtain double-layer ligand-coated gold nanoclusters.

[0044] Step 3: Synthesis of double-layer ligand-coated fluorescent gold nanocluster composite hydrogel:

[0045] Take 0.2g agarose, add 40ml ultrapure water, heat to 100°C, take 2-3ml fluorescent probe, mix with agarose and cool to room temperature to prepare a double-layer ligand-coated fluorescent gold nanocluster composite hydrogel.

[0046] Step 4: Fluorescence detection based on double-layer ligand-coated fluorescent gold nanocluster composite hydrogel:

[0047] Take 2-3 ml of fluorescent gold nanocluster composite hydrogel, add 1 mg / ml fenitrothion solution, and perform fluorescence detection. Figure 1 This is the fluorescence emission spectrum of the fluorescent gold nanoclusters coated with double-layer ligands prepared in Example 1. Figure 1 This indicates that the fluorescent probe reaches its maximum emission at 570 nm and has strong red fluorescence emission.

[0048] Example 2

[0049] Step 1: Synthesis of gold nanoclusters:

[0050] Dissolve 750 mmol of methylthiouracil in 10 ml of 0.22 M sodium hydroxide, and then evenly mix 1 ml of 75 mM methylthiouracil base solution and 1 ml of 25 mM chloroauric acid solution (3:1) under vigorous stirring. Continue stirring for 80 min to obtain a gold nanocluster solution.

[0051] Step 2: Synthesis of double-layer ligand-coated gold nanoclusters:

[0052] 1 mL of 30 mM arginine solution was added to the gold nanocluster solution in step 1 and incubated at 37° C. for 3 h to obtain double-layer ligand-coated gold nanoclusters.

[0053] Step 3: Synthesis of double-layer ligand-coated fluorescent gold nanocluster composite hydrogel:

[0054] Take 0.2g agarose, add 40ml ultrapure water, heat to 100°C, take 2-3ml fluorescent probe, mix with agarose and cool to room temperature to prepare a double-layer ligand-coated fluorescent gold nanocluster composite hydrogel.

[0055] Step 4: Fluorescence detection based on double-layer ligand-coated fluorescent gold nanocluster composite hydrogel:

[0056] Take 2-3 ml of fluorescent gold nanocluster composite hydrogel, add 1 mg / ml fenitrothion solution, and perform fluorescence detection. Figure 2 This is the fluorescence emission spectrum of the fluorescent gold nanoclusters coated with double-layer ligands prepared in Example 2. Figure 2 This indicates that the fluorescent probe reaches maximum emission at 570 nm and has strong red fluorescence emission, but the intensity is lower than that in Example 1.

[0057] Example 3

[0058] Step 1: Synthesis of gold nanoclusters:

[0059] Dissolve 1000 mmol of methylthiouracil in 10 ml of 0.22 M sodium hydroxide, and then evenly mix 1 ml of 100 mM methylthiouracil base solution and 1 ml of 25 mM chloroauric acid solution (4:1) under vigorous stirring. Continue stirring for 80 min to obtain a gold nanocluster solution.

[0060] Step 2: Synthesis of double-layer ligand-coated gold nanoclusters:

[0061] 1 mL of 30 mM arginine solution was added to the gold nanocluster solution in step 1 and incubated at 37° C. for 3 h to obtain double-layer ligand-coated gold nanoclusters.

[0062] Step 3: Synthesis of double-layer ligand-coated fluorescent gold nanocluster composite hydrogel:

[0063] Take 0.2g agarose, add 40ml ultrapure water, heat to 100°C, take 2-3ml fluorescent probe, mix with agarose and cool to room temperature to prepare a double-layer ligand-coated fluorescent gold nanocluster composite hydrogel.

[0064] Step 4: Fluorescence detection based on double-layer ligand-coated fluorescent gold nanocluster composite hydrogel:

[0065] Take 2-3 ml of fluorescent gold nanocluster composite hydrogel, add 1 mg / ml fenitrothion solution, and perform fluorescence detection. Figure 3 This is the fluorescence emission spectrum of the fluorescent gold nanoclusters coated with double-layer ligands prepared in Example 3. Figure 3 This indicates that the fluorescent probe reaches maximum emission at 570 nm and has strong red fluorescence emission, but the intensity is lower than that in Example 1.

[0066] Example 4

[0067] Step 1: Synthesis of gold nanoclusters:

[0068] 800 mmol of methylthiouracil was dissolved in 10 ml of 0.22 M sodium hydroxide, and 1 ml of 80 mM methylthiouracil base solution and 1 ml of 25 mM chloroauric acid solution (3.2:1) were uniformly mixed under vigorous stirring conditions. The gold nanocluster solution was obtained by continuous stirring for 80 min.

[0069] Step 2: Synthesis of double-layer ligand-coated gold nanoclusters:

[0070] 1 mL of 40 mM arginine solution was added to the gold nanocluster solution in step 1 and incubated at 37° C. for 3 h to obtain double-layer ligand-coated gold nanoclusters.

[0071] Step 3: Synthesis of double-layer ligand-coated fluorescent gold nanocluster composite hydrogel:

[0072] Take 0.2g agarose, add 40ml ultrapure water, heat to 100°C, take 2-3ml fluorescent probe, mix with agarose and cool to room temperature to prepare a double-layer ligand-coated fluorescent gold nanocluster composite hydrogel.

[0073] Step 4: Fluorescence detection based on double-layer ligand-coated fluorescent gold nanocluster composite hydrogel:

[0074] Take 2-3 ml of fluorescent gold nanocluster composite hydrogel, add 1 mg / ml fenitrothion solution, and perform fluorescence detection. Figure 4 This is the fluorescence emission spectrum of the fluorescent gold nanoclusters coated with double-layer ligands prepared in Example 4. Figure 4 This indicates that the fluorescent probe reaches maximum emission at 570 nm and has strong red fluorescence emission, but the intensity is lower than that in Example 1.

[0075] Example 5

[0076] Step 1: Synthesis of gold nanoclusters:

[0077] 800 mmol of methylthiouracil was dissolved in 10 ml of 0.22 M sodium hydroxide, and 1 ml of 80 mM methylthiouracil base solution and 1 ml of 25 mM chloroauric acid solution (3.2:1) were uniformly mixed under vigorous stirring. The gold nanocluster solution was obtained by continuous stirring for 80 min.

[0078] Step 2: Synthesis of double-layer ligand-coated gold nanoclusters:

[0079] 1 mL of 30 mM arginine solution was added to the gold nanocluster solution in step 1 and incubated at 37° C. for 4 h to obtain double-layer ligand-coated gold nanoclusters.

[0080] Step 3: Synthesis of double-layer ligand-coated fluorescent gold nanocluster composite hydrogel:

[0081] Take 0.2g agarose, add 40ml ultrapure water, heat to 100°C, take 2-3ml fluorescent probe, mix with agarose and cool to room temperature to prepare a double-layer ligand-coated fluorescent gold nanocluster composite hydrogel.

[0082] Step 4: Fluorescence detection based on double-layer ligand-coated fluorescent gold nanocluster composite hydrogel:

[0083] Take 2-3 ml of fluorescent gold nanocluster composite hydrogel, add 1 mg / ml fenitrothion solution, and perform fluorescence detection. Figure 5 This is the fluorescence emission spectrum of the fluorescent gold nanoclusters coated with double-layer ligands prepared in Example 5. Figure 5This indicates that the fluorescent probe reaches maximum emission at 570 nm and has strong red fluorescence emission, but the intensity is lower than that in Example 1.

[0084] Fluorescent gold nanocluster composite hydrogel for fluorescence sensing of fenitrothion:

[0085] Take 2 cm of the double-layer ligand-coated gold nanocluster composite hydrogel in Example 1 3 1 mg / mL fenitrothion was added to measure the fluorescence spectrum. Fenitrothion was added to the fluorescent hydrogel of Example 1, and the excitation wavelength was 365 nm. Figure 6 The double-layer ligand-coated fluorescent gold nanocluster composite hydrogel prepared in Example 1 of the present invention detects fenitrothion; according to Figure 6 It can be seen that as the volume of the fenitrothion solution added gradually increases (0-350 μL), the R value in the mobile phone RGB recognition gradually decreases. Figure 7 The linear relationship diagram of the R value of the double-layer ligand-coated fluorescent gold nanocluster composite hydrogel prepared in Example 1 of the present invention and the concentration of fenitrothion is shown in FIG. Figure 7 It can be seen that the fluorescence intensity ratio shows a good linear relationship with the concentration of fenitrothion.

Claims

1. A method for preparing a fluorescent composite hydrogel, characterized in that: The following steps are involved: Step 1: Mixing and stirring the methylthiouracil base solution and the chloroauric acid solution to obtain a gold nanocluster solution; Step 2: Evenly mix the arginine solution and the gold nanocluster solution synthesized in step 1, and incubate to obtain a fluorescent probe; Step 3: Combine the fluorescent probe obtained in step 2 with agarose hydrogel to obtain a fluorescent composite hydrogel.

2. The method for preparing a fluorescent composite hydrogel according to claim 1, characterized in that: In the step 1, the volume ratio of the methylthiouracil alkaline solution to the chloroauric acid solution is 1:1, and the molar ratio of the methylthiouracil to the chloroauric acid is (2:1)-(5:1).

3. The method for preparing a fluorescent composite hydrogel according to claim 1, characterized in that: In the step 1, the concentration of the alkali in the methylthiouracil alkali solution is 0.2-0.22M.

4. The method for preparing a fluorescent composite hydrogel according to claim 1, characterized in that: The alkali in the methylthiouracil alkali solution is sodium hydroxide.

5. The method for preparing a fluorescent composite hydrogel according to claim 1, characterized in that: In the step 1, the stirring time is 60-80 min and the stirring speed is 300-400 rpm.

6. The method for preparing a fluorescent composite hydrogel according to claim 1, characterized in that: In the step 2, the volume ratio of the arginine solution to the gold nanocluster solution synthesized in the step 1 is (8:1)-(9:1).

7. The method for preparing a fluorescent composite hydrogel according to claim 1, characterized in that: The concentration of arginine in step 2 is 30-40 mM.

8. The method for preparing a fluorescent composite hydrogel according to claim 1, characterized in that: In the step 2, the incubation temperature is 35-40° C. and the incubation time is 3-5 h.

9. The fluorescent composite hydrogel obtained by the preparation method according to claim 1.

10. Use of the fluorescent composite hydrogel according to claim 9 in fluorescence detection of fenitrothion.

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