A palladium nanozyme and its preparation method and application

Abstract

The present invention belongs to the field of analytical detection, and relates to the detection of vitamin C and mercury ions, and particularly refers to a palladium nanozyme and a preparation method and application thereof. The present invention comprises soaking waste tea in distilled water, boiling and filtering to obtain a waste tea extract, and then dropping the waste tea extract into PdCl 2 The palladium nanozyme prepared by the present invention can continuously detect vitamin C and mercury ions, has high sensitivity, and can realize on-site visual detection.

Description

Technical Field

[0001] The invention belongs to the field of analysis and detection, relates to the detection of vitamin C and mercury ions, and particularly refers to a palladium nanozyme and a preparation method and application thereof. Background Art

[0002] Vitamin C is a water-soluble vitamin essential to the human body. Vitamin C can effectively prevent anemia, sepsis and other diseases, and has the effect of improving immunity and reducing cardiovascular diseases. Vitamin C has been widely used in pharmaceutical and food fields as an antioxidant. Since the human body cannot synthesize vitamin C by itself, it can only be obtained from fruits and vegetables. Therefore, it is of great significance to quickly and accurately detect vitamin C in food or medicine. Mercury ion is a heavy metal ion that is not easily degraded and easily enriched in the human body, endangering human health. The World Health Organization (WHO) has stipulated that the maximum allowable value of mercury in drinking water is 30 nM. Therefore, it is of great significance to quickly and accurately detect the content of mercury ions in water.

[0003] Common detection methods for vitamin C and mercury ions include chromatography, fluorescence, electrochemical method, inductively coupled plasma mass spectrometry, etc., but most of these methods have the disadvantages of expensive equipment and high cost, and can only detect one. Publication number CN115646486A discloses a graphene-loaded palladium nanozyme, which synthesizes graphene-loaded nanozymes by sedimentation precipitation method, which is used for catalytic antibacterial and cannot be used for detection; Publication number CN113522360A discloses a Ag-CD@GO ternary nano-mimetic enzyme for detecting mercury ions, and the preparation method of the mimetic enzyme is complex and costly, and is not suitable for large-scale popularization. Therefore, it is crucial to develop a low-cost, easy-to-operate detection method. The colorimetric detection method can realize on-site analysis and detection according to the change of solution color, and this method has the characteristics of high sensitivity and visualization. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a palladium nanozyme and a preparation method and application thereof.

[0005] The technical solution of the present invention is achieved in this way:

[0006] The palladium nanozyme provided by the present invention is prepared according to the following steps:

[0007] Soak the waste tea leaves and tea stems in distilled water, boil at 50-80℃ for 10-30min, filter and obtain the waste tea extract. Add the waste tea extract dropwise into a PdCl2 hydrochloric acid solution, stir at 40-60℃ for 0.5-2h, centrifuge and freeze-dry to obtain the palladium nanozyme.

[0008] The concentration of the above-mentioned waste tea in distilled water is 0.04~0.06g / mL.

[0009] The final concentration of the PdCl2 solution in the above reaction system is 40~80 μg / mL.

[0010] During the above preparation process, the color of the solution changes from yellow to black.

[0011] The particle size range of the above-mentioned palladium nanozyme is 30nm~40nm.

[0012] The application of the above-mentioned palladium nanozyme particularly refers to the visual continuous detection of vitamin C and mercury ions.

[0013] The application of the above-mentioned palladium nanozyme is achieved according to the following steps:

[0014] The test solution is added to the mixed solution of palladium nanozyme and 3,3',5,5'-tetramethylbenzidine (TMB). If the solution changes from blue to colorless within 1min to 5min, it means that vitamin C is contained. If the solution changes from colorless to blue again within 10min to 40min, it means that mercury ions are also contained in the test solution. At the same time, the absorbance value is detected to detect the concentration of vitamin C and mercury ions in the test solution.

[0015] In the above application, the reaction temperature range of the solution is 30°C to 35°C, and the pH value of the reaction solution is 3.5.

[0016] In the above application, the final concentration of palladium nanozyme was 20 μg / mL, and the final concentration of TMB was 2 mM.

[0017] In the above application, the concentration range of vitamin C detected by palladium nanozyme is 10-80 μM. The concentration range of mercury ion detected by palladium nanozyme and vitamin C system is 50-350 μM.

[0018] The present invention has the following beneficial effects:

[0019] 1. The present invention only uses discarded tea leaves and tea stem extracts as reducing agents and stabilizers to prepare palladium nanozymes. The method is simple and easy to operate and the reaction conditions are very mild. The prepared palladium nanozymes can continuously detect vitamin C and mercury ions with high sensitivity and can realize on-site visual detection, which is conducive to commercial promotion and application.

[0020] 2. The palladium nanozyme prepared by the present invention has oxidase-like activity. VC is a common antioxidant with strong reducing agent. Under the catalysis of palladium nanozyme, VC can quickly reduce blue oxTMB to colorless TMB. Therefore, the Pd / TMB system can visually detect VC. 2+ , due to VC and Hg2+ The affinity is strong, generating VC-Hg 2+ The complex resulted in the blue color of the solution returning to normal. Therefore, the Pd / TMB / VC system can be used to visually detect mercury ions. This work not only provides a new method for the detection of mercury ions by VC and Hg 2+ The detection provides a simple and economical method and makes a certain contribution to environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 This is a scanning electron microscope image of the palladium nanozyme prepared according to the present invention.

[0023] Figure 2 The palladium nanozyme prepared by the present invention detects the absorbance change value at 652nm of VC with different concentrations.

[0024] Figure 3 Digital photos for visual detection of VC.

[0025] Figure 4 To visualize the effects of other biological small molecules on VC.

[0026] Figure 5 The palladium nanozyme and VC system prepared by the present invention detects the absorbance change value at 652nm of mercury ions with different concentrations.

[0027] Figure 6 Digital photograph for visualization of detected mercury ions.

[0028] Figure 7 To visualize the effects of other common metal ions on the detection of mercury ions. DETAILED DESCRIPTION

[0029] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Example 1

[0031] The preparation method of the palladium nanozyme of this embodiment comprises the following steps:

[0032] Soak 4g of waste tea leaves and tea stems in 100mL of distilled water, boil at 80℃ for 10min, filter and set aside. Weigh 17.73mg of PdCl2 and add 20mL of dilute HCl (the concentration of PdCl2 hydrochloric acid solution is 8.8 mg / mL), and sonicate until completely dissolved. Add the waste tea extract dropwise into the 20mL PdCl2 solution to make the final concentration of PdCl2 60 μg / mL, stir at 60℃ for 2h, stop the reaction when the color of the solution changes from yellow to black, centrifuge, and freeze-dry to obtain palladium nanozyme.

[0033] Electron microscopy images of palladium nanozymes Figure 1 As shown by Figure 1 It can be seen that the prepared palladium nanozymes are spherical in appearance, with a particle size of about 30~40nm.

[0034] Example 2

[0035] The preparation method of the palladium nanozyme of this embodiment comprises the following steps:

[0036] Soak 6g of waste tea leaves and tea stems in 100mL of distilled water, boil at 50℃ for 10min, filter and set aside. Weigh 17.73mg of PdCl2 and add 20mL of dilute HCl (the concentration of PdCl2 hydrochloric acid solution is 8.8 mg / mL), and sonicate until completely dissolved. Add the waste tea extract dropwise into the 20mL PdCl2 solution to make the final concentration of PdCl2 40μg / mL, stir at 40℃ for 0.5h, stop the reaction when the color of the solution changes from yellow to black, centrifuge, and freeze-dry to obtain palladium nanozyme.

[0037] Example 3

[0038] The preparation method of the palladium nanozyme of this embodiment comprises the following steps:

[0039] Soak 5g of waste tea leaves and tea stems in 100mL of distilled water, boil at 70℃ for 20min, filter and set aside. Weigh 17.73mg of PdCl2 and add 20mL of dilute HCl (the concentration of PdCl2 hydrochloric acid solution is 8.8 mg / mL), and sonicate until completely dissolved. Add the waste tea extract dropwise into the 20mL PdCl2 solution to make the final concentration of PdCl2 80 μg / mL, stir at 55℃ for 1h, stop the reaction when the color of the solution changes from yellow to black, centrifuge, and freeze-dry to obtain palladium nanozyme.

[0040] Example 4

[0041] The preparation method of the palladium nanozyme of this embodiment comprises the following steps:

[0042] Soak 4g of waste tea leaves and tea stems in 100mL of distilled water, boil at 80℃ for 10min, filter and set aside. Weigh 17.73mg of PdCl2 and add 20mL of dilute HCl (the concentration of PdCl2 hydrochloric acid solution is 8.8 mg / mL), and sonicate until completely dissolved. Add the waste tea extract dropwise into the 20mL PdCl2 solution to make the final concentration of PdCl2 50 μg / mL, stir at 50℃ for 1.5h, and stop the reaction when the color of the solution changes from yellow to black, centrifuge, and freeze-dry to obtain palladium nanozyme.

[0043] Application Examples

[0044] The palladium nanozyme prepared in Example 1 was used to continuously detect vitamin C and mercury ions:

[0045] 1. Detection of vitamin C

[0046] In a mixed solution of palladium nanozyme (80 μL, 0.5 mg / mL) and 3,3',5,5'-tetramethylbenzidine (TMB) (200 μL, 2 mM) and acetic acid-sodium acetate buffer solution (1.5 mL, pH 3.5), 0, 10, 20, 40, 60, 65, 70, and 80 μM vitamin C solutions were added. The color of the solution changed from blue to colorless within 1 to 5 minutes. Figure 3 As shown, the absorbance value was detected and fitted into a curve.

[0047] like Figure 2 As shown, vitamin C has a good linear relationship in the concentration range of 10~80μM, and the linear equation is A0-A=0.01424 c +0.04276(R 2 =0.99595). The calculated detection limit was 0.421 μM. Figure 3 To visualize the digital photos of VC, Figure 3 It can be seen that the prepared palladium nanozyme can detect VC molecules through color change, that is, blue turns into colorless, and can be visualized with the naked eye.

[0048] 2. Continuous detection of mercury ions

[0049] Continue to add different concentrations of mercury ions to the mixed solution after reaction 1. Within 10 to 40 minutes, the results are as follows: Figure 6 As shown, detect its absorbance value. Figure 5 As shown, mercury ions have a good linear relationship in the concentration range of 50~350μM, and the linear equation is A0-A=2.75786 c +0.05943(R 2 =0.99156). The calculated detection limit was 1.63 μM.

[0050] Figure 6 Digital photos for visual detection of mercury ions were taken by Figure 6 It can be seen that the prepared palladium nanozyme / TMB / VC system can detect mercury ions visually with the naked eye through color change, that is, from colorless to blue.

[0051] 3. Verify the selectivity of the above nanozymes

[0052] ① Common biological small molecules, including glutathione, dopamine, cysteine, cystine, leucine, histidine, serine, alanine, phenylalanine and valine, were added to a mixed solution of palladium nanozyme (80 μL, 0.5 mg / mL) and 3,3',5,5'-tetramethylbenzidine (TMB) (200 μL, 2 mM) and acetic acid-sodium acetate buffer solution (1.5 mL, pH 3.5) to make the final concentration of the small molecules 60 μM. The color of the solution changed from blue to colorless. Figure 4 shown.

[0053] Figure 4 The effects of other small biomolecules on the visual detection of VC are Figure 4 It can be seen that common biological small molecules have no obvious effect on the color change of the solution, indicating that palladium nanozymes have strong anti-interference ability and are highly selective for the detection of VC.

[0054] ② Common metal ions, including Ca, Mg and Mg, were added to a mixed solution of palladium nanozyme (80 μL, 0.5 mg / mL), 3,3',5,5'-tetramethylbenzidine (TMB) (200 μL, 2 mM) and acetic acid-sodium acetate buffer solution (1.5 mL, pH 3.5). 2 + , Cu 2+ , Mn 2+ , Zn 2+ , Fe 3+ ,Co 2+ , K + 、Na + , so that the final concentration of metal ions is 0.3 mM, the solution changes as Figure 7 shown.

[0055] Figure 7 The effects of other common metal ions on the visual detection of mercury ions are shown in Table 1. Figure 7 It can be seen that common metal ions have no obvious effect on the color change of the solution, indicating that the palladium nanozyme / TMB / VC system has strong anti-interference ability and is highly selective for the detection of mercury ions.

[0056] The above proves that the palladium nanozyme prepared in Example 1 is used for continuous detection of vitamin C and mercury ions. The method is simple and easy to operate and the reaction conditions are very mild. It is expected to achieve on-site visual detection, which is conducive to commercial promotion and application.

[0057] 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, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An application of a palladium nanozyme in visually and continuously detecting vitamin C and mercury ions for the purpose of non-disease diagnosis and treatment, characterized in that: The preparation steps of palladium nanozyme are as follows: soaking the waste tea in distilled water, boiling and filtering to obtain the waste tea extract, then dropping the waste tea extract into a PdCl2 hydrochloric acid solution, stirring at high temperature, centrifuging, and freeze-drying to obtain the palladium nanozyme; The high temperature stirring temperature is 40~60℃ and the time is 0.5~2h The waste tea is waste tea leaves and tea stems, and the concentration of the waste tea in distilled water is 0.04-0.06 g / mL; The detection steps are as follows: adding the test solution to a mixed solution containing palladium nanozyme and 3,3',5,5'-tetramethylbenzidine, and observing the color change of the reaction solution under the conditions of 30-35°C and pH 3.5; If the color of the solution changes from blue to colorless within 1min~5min, it means that the solution contains vitamin C. Based on the palladium nanozyme, 3,3',5,5'-tetramethylbenzidine, and vitamin C system, if the color of the solution changes from colorless to blue within 10min~40min, it means that mercury ions are contained.

2. The use according to claim 1, characterized in that: The concentration of the PdCl2 hydrochloric acid solution is 8.8 mg / mL, and the hydrochloric acid is dilute hydrochloric acid.

3. The use according to claim 2, characterized in that: In the reaction system, the final concentration of PdCl2 is 40~80 μg / mL.

4. The use according to any one of claims 1 to 3, characterized in that: The cooking temperature is 50-80° C. and the cooking time is 10-30 min.

5. The use according to claim 4, characterized in that: The palladium nanozyme is spherical, black powder, and has a particle size of 30-40 nm.

6. The use according to claim 5, characterized in that: The reaction concentration of the palladium nanozyme is 20 μg / mL, and the reaction concentration of 3,3',5,5'-tetramethylbenzidine is 2 mM.

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