Preparation method and application of PdPt bimetallic nanozyme

Abstract

The present invention belongs to the field of analytical detection and relates to the continuous detection of sulfide ions and mercury ions, and in particular refers to the preparation method and application of PdPt bimetallic nanozymes using yam polysaccharide as a template. The present application prepares a yam polysaccharide solution by dissolving yam polysaccharide in distilled water. Then, a mixed solution of potassium tetrachloroplatinate and palladium chloride is added dropwise to the yam polysaccharide solution, and the PdPt nanozyme is obtained by high-temperature stirring, centrifugation, and vacuum drying. The PdPt nanozyme prepared by the present invention can be used for continuous detection of sulfide ions and mercury ions with high sensitivity, and can realize on-site visual detection.

Description

Technical Field

[0001] The present invention belongs to the field of analysis and detection, and relates to S 2- and Hg 2+ Continuous detection of ions, particularly a preparation method and application of a PdPt bimetallic nanozyme. Background Art

[0002] Sulfide ion (S 2- ) as a form of sulfide, plays an important role in biogeochemical processes. The presence of excessive sulfur ions in water systems can cause great harm to ecosystems and human survival. Continuous exposure to high concentrations of sulfide can cause mucous membrane irritation, unconsciousness, and respiratory paralysis. Mercury is widely used in electronic or electrical products, pesticides, and chlorine and potassium hydroxide production, resulting in mercury ions (Hg 2+ ) is inevitably discharged into the ecological environment. 2+ It can damage human organs and the immune system, and its accumulation in the human body can lead to Minamata disease, chronic mercury poisoning, etc. Therefore, it is of great significance to construct highly selective and sensitive sulfur ion and mercury ion detection sensors. Publication No. CN110567950A discloses a method for detecting sulfur ions. The detection system of this method is a silver nanoparticle solution, ascorbic acid and mercuric nitrate solution, and the color change of the solution is achieved by producing new compounds; Patent CN106008354A discloses a compound for detecting mercury ions. The fluorescent unit and the recognition unit of the compound can both bind to mercury ions and can be used as a new type of dual-function mercury ion sensor, showing a staged fluorescence response to mercury ions. The compound can also recognize silver ions, and the detection is achieved based on the performance of the compound group.

[0003] Currently reported methods for detecting sulfur and mercury ions include electrochemistry, titration, capillary electrophoresis, chromatography, fluorescence, chemiluminescence, atomic absorption spectroscopy, and inductively coupled plasma-mass spectrometry. However, most of these methods suffer from the disadvantages of expensive equipment and high costs, and can only detect one type of ion. Nanozymes have attracted much attention due to their enzyme-like activity, low cost, ease of large-scale production, minimal environmental impact, high stability, and long-term storage. Therefore, it is crucial to develop a low-cost, easy-to-use nanozyme colorimetric detection method that can achieve on-site analysis and detection based on the change in solution color, and has the characteristics of high sensitivity and visualization. Summary of the Invention

[0004] To solve the above technical problems, the present invention proposes a method and application of preparing PdPt nanozymes using yam polysaccharide as a template.

[0005] The technical solution of the present invention is achieved as follows:

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

[0007] Yam polysaccharide was dissolved in distilled water and ultrasonically obtained to obtain a yam polysaccharide solution. Then, potassium tetrachloroplatinate solution and palladium chloride solution were mixed under stirring in a water bath and added dropwise to the yam polysaccharide solution until the color of the solution gradually changed from yellow to black. The solution was centrifuged and vacuum dried to obtain PdPt nanozyme.

[0008] The concentration of the above-mentioned yam polysaccharide is 0.1~10 mg / mL.

[0009] The concentrations of the potassium tetrachloroplatinate solution and the palladium chloride solution are the same, 1-3 mM, and the volume ratio is 1:1.

[0010] In the above preparation process, the high-temperature stirring rate is 400-600 rpm; the high-temperature stirring temperature is 50-80°C, and the time is 1-6 hours.

[0011] During the above preparation process, the color of the solution gradually changes from yellow to black.

[0012] The nanozyme is composed of C, O, Pd and Pt elements, and is spherical, black powder with a particle size of less than 10 nm.

[0013] The above-mentioned PdPt nanozyme is used in the visual continuous detection of sulfur ions and mercury ions for the purpose of non-disease diagnosis and treatment.

[0014] The application of the above-mentioned PdPt nanozyme is achieved by following the steps below:

[0015] Add the test solution to the mixed solution containing PdPt nanozyme and 3,3',5,5'-tetramethylbenzidine to react and observe the color change of the reaction solution. If the color of the PdPt solution changes from blue to colorless within 15-25 minutes, it means that the solution contains S 2- ions, and the reaction solution system is PdPt-TMB-S 2- Continuing to add dropwise, PdPt-TMB-S was observed within 5 to 10 minutes. 2- The solution system changes from colorless to blue, indicating that it contains Hg 2+ ion.

[0016] In the above application, the reaction temperature range of the solution is 20°C~45°C, and the pH value of the reaction solution is 3~6.

[0017] In the above application, the final concentration of PdPt nanozyme was 30 μg / mL, and the final concentration of TMB was 0.14 mM.

[0018] In the above applications, PdPt nanozymes detect S2- The ion concentration range is 0.5~8 μM; PdPt-TMB-S 2- System detection Hg 2+ The ion concentration range is 2.5 to 30 μM.

[0019] Furthermore, the absorbance value of S in the test solution can be detected. 2- and Hg 2+ The concentration of ions was quantitatively detected.

[0020] The present invention has the following beneficial effects:

[0021] 1. The present invention does not introduce organic solvents, and only uses yam polysaccharide as a reducing agent and stabilizer to prepare PdPt nanozymes. This method is simple and easy to operate, and the reaction conditions are mild and pollution-free. The prepared PdPt nanozymes can be used for continuous detection of S 2- and Hg 2+ ions, with high sensitivity, can realize on-site visual detection, which is conducive to commercial promotion and application.

[0022] 2. The PdPt nanozyme prepared by the present invention has oxidase-like activity. Sulfide ions are strong reducing agents. Under the catalysis of PdPt nanozymes, sulfur ions quickly reduce blue oxTMB to colorless TMB. Therefore, the PdPt-TMB system can visually detect sulfur ions. When Hg is added to the above system, 2+ After ionization, sulfur ions are more likely to react with Hg 2+ ions bind, resulting in the restoration of the blue color of the solution. 2- The solution system can visualize Hg 2+ ions for detection. This work not only provides a basis for the continuous detection of S 2- and Hg 2+ Ions provide a simple and economical method and make a certain contribution to environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 any creative work.

[0024] Figure 1 This is a transmission electron microscopy image of the PdPt nanozyme prepared in the present invention.

[0025] Figure 2 This is the EDS energy spectrum of the PdPt nanozyme prepared in the present invention.

[0026] Figure 3 The absorbance change at 652 nm of the PdPt nanozyme prepared in the present invention for detecting different concentrations of sulfide ions. The inset is a digital photo of the visual detection of sulfide ions.

[0027] Figure 4 The absorbance change value at 652 nm of the PdPt nanozyme and sulfide ion system prepared by the present invention for detecting different concentrations of mercury ions. The inset is a digital photo of the visual detection of mercury ions.

[0028] Figure 5 Visualize the effects of sulfur ions on other common anions.

[0029] Figure 6 To visualize the effects of other common metal ions on the detection of mercury ions. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all 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.

[0031] Example 1

[0032] The preparation method of PdPt nanozyme in this embodiment comprises the following steps:

[0033] Prepare 2 mM solutions of potassium tetrachloroplatinate and palladium chloride, respectively. Weigh 6 mg of yam polysaccharide and dissolve it in 6 mL of distilled water. Ultrasonicate for 2 minutes to prepare the yam polysaccharide solution. Then, mix the potassium tetrachloroplatinate solution and palladium chloride solution (1:1 by volume) and add it dropwise to the yam polysaccharide solution. Stir in a 70°C water bath (600 rpm) for 4 hours. Stop the reaction when the solution changes color from yellow to black. Centrifuge and vacuum dry to obtain PdPt nanozyme powder.

[0034] Electron microscopy images of PdPt nanozymes Figure 1 As shown by Figure 1 It can be seen that the prepared PdPt nanozymes have a spherical appearance and a particle size of less than 10 nm. The EDS spectrum of PdPt nanozymes is shown in Figure 2. Figure 2 As shown, it shows that the nanozyme is composed of C, O, Pd and Pt elements.

[0035] Example 2

[0036] The preparation method of PdPt nanozyme in this embodiment comprises the following steps:

[0037] Prepare 1 mM solutions of potassium tetrachloroplatinate and palladium chloride, respectively. Weigh 4 mg of yam polysaccharide and dissolve it in 4 mL of distilled water. Ultrasonicate for 1 minute to prepare the yam polysaccharide solution. Then, mix the potassium tetrachloroplatinate solution and palladium chloride solution (1:1 by volume) and add it dropwise to the yam polysaccharide solution. Stir in an 80°C water bath (600 rpm) for 6 hours. Stop the reaction when the solution changes color from yellow to black. Centrifuge and vacuum dry to obtain PdPt nanozyme powder.

[0038] Example 3

[0039] The preparation method of PdPt nanozyme in this embodiment comprises the following steps:

[0040] Prepare 3 mM solutions of potassium tetrachloroplatinate and palladium chloride, respectively. Weigh 8 mg of yam polysaccharide and dissolve it in 8 mL of distilled water. Ultrasonicate for 4 minutes to prepare the yam polysaccharide solution. Then, mix the potassium tetrachloroplatinate solution and palladium chloride solution (1:1 by volume) and add it dropwise to the yam polysaccharide solution. Stir in a 60°C water bath (500 rpm) for 3 hours. Stop the reaction when the solution changes color from yellow to black. Centrifuge and vacuum dry to obtain PdPt nanozyme powder.

[0041] Example 4

[0042] The preparation method of PdPt nanozyme in this embodiment comprises the following steps:

[0043] Prepare 3 mM solutions of potassium tetrachloroplatinate and palladium chloride, respectively. 80 mg of yam polysaccharide was dissolved in 8 mL of distilled water and sonicated for 4 minutes to prepare the yam polysaccharide solution. The potassium tetrachloroplatinate solution and palladium chloride solution (1:1 by volume) were then added dropwise to the yam polysaccharide solution. Stir in a 60°C water bath (500 rpm) for 3 hours. The reaction was stopped when the solution color changed from yellow to black. The reaction was then centrifuged and dried under vacuum to obtain PdPt nanozyme powder.

[0044] Example 5

[0045] The preparation method of PdPt nanozyme in this embodiment comprises the following steps:

[0046] Prepare 1 mM solutions of potassium tetrachloroplatinate and palladium chloride, respectively. Weigh 0.8 mg of yam polysaccharide and dissolve it in 8 mL of distilled water. Ultrasonicate the mixture for 3 minutes to prepare the yam polysaccharide solution. Then, mix the potassium tetrachloroplatinate solution and palladium chloride solution (1:1 by volume) and add it dropwise to the yam polysaccharide solution. Stir in a 70°C water bath (400 rpm) for 4 hours. Stop the reaction when the solution changes color from yellow to black. Centrifuge the mixture and vacuum dry it to obtain PdPt nanozyme powder.

[0047] Application Examples

[0048] Continuous detection of S using the PdPt nanozyme prepared in Example 1 2- and Hg 2+ ion:

[0049] 1. S 2- Ion detection

[0050] In a mixed solution of PdPt nanozyme, 3,3',5,5'-tetramethylbenzidine (TMB) and acetic acid-sodium acetate buffer solution (pH 4), sodium sulfide solution of different concentrations was added, respectively, at 0, 0.5, 1.5, 2.5, 4.5, 5.5, 6, 7, and 8 μM, so that the final concentration of PdPt nanozyme was 30 μg / mL and the final concentration of TMB was 0.14 mM. The color of the solution changed from blue to colorless within 15 to 25 minutes, as shown in FIG. Figure 3 As shown in the illustration, the absorbance value is detected and fitted into the curve. Figure 3 As shown, the sulfide ion has a good linear relationship in the concentration range of 0.5~8 μM, and the linear equation is A0-A=0.13713 c +0.000730129 (R 2 =0.9864), the detection limit was calculated to be 0.02729 μM. Figure 3 As shown in the illustration, the prepared PdPt nanozyme can detect sulfide ions by changing color from blue to colorless, which can be visualized with the naked eye.

[0051] 2. Hg 2+ Detection of ions

[0052] Then, mercury ions at different concentrations of 0, 2.5, 5, 10, 15, 17.5, 20, 25, and 30 μM were added to the mixed solution after the reaction in step 1. The color of the solution changed from colorless to blue within 5 to 10 minutes. Figure 4 As shown in the illustration, detect its absorbance value. Figure 4 As shown, mercury ions have a good linear relationship in the concentration range of 2.5 to 30 μM, and the linear equation is A0-A=0.02515 [Hg 2+ ]+0.06596(R 2 =0.990), the detection limit was calculated to be 0.2576 μM. Figure 4 As shown in the illustration, the prepared PdPt-TMB-S 2- The system can detect mercury ions visually with the naked eye through color change, that is, from colorless to blue.

[0053] 3. Verify the selectivity of the above nanozymes

[0054] ① Common anions, including F - 、Cl - , I - 、Ac - , ClO - 、NO3 - 、SO4 2- 、CO3 2- PO4 3- 、S 2- , so that the final concentration of ions is 50 μM, the final concentration of PdPt nanozyme is 30 μg / mL, and the final concentration of TMB is 0.14 mM. Figure 5 As shown in the figure, the color of the solution changes from blue to colorless only when sulfur ions are added, indicating that PdPt nanozyme has strong anti-interference ability and is highly selective for the detection of sulfur ions.

[0055] ② Common metal ions, including Hg, were added to a mixed solution of PdPt nanozyme, 3,3',5,5'-tetramethylbenzidine (TMB), acetic acid-sodium acetate buffer solution (pH 4) and sodium sulfide (0.5 mM). 2+ , Ca 2+ 、Cu 2+ 、Mn 2+ 、Zn 2 + 、Fe 3+ 、Co 2+ , K + 、Cr2O7 2- , so that the final concentration of metal ions is 50 μM, the final concentration of PdPt nanozyme is 30 μg / mL, and the final concentration of TMB is 0.14 mM. Figure 6 As shown in the figure, only when mercury ions are added, the color of the solution changes from colorless to blue, indicating that PdPt-TMB-S 2- The system has strong anti-interference ability and is highly selective for the detection of mercury ions.

[0056] The above proves that the PdPt nanozyme prepared in Example 1 can be used for continuous detection of sulfur ions and mercury ions. This method is simple and easy to operate, and the reaction conditions are mild and pollution-free. 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 principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An application of a PdPt nanozyme in visually and continuously detecting sulfur ions and mercury ions for purposes other than disease diagnosis and treatment, characterized in that: The detection steps are as follows: adding the test solution to a mixed solution containing PdPt nanozyme and 3,3',5,5'-tetramethylbenzidine to react, and observing the color change of the reaction solution; The nanozyme is composed of C, O, Pd and Pt elements and is in the form of a spherical, black powder with a particle size of less than 10 nm. The preparation steps are as follows: dissolve yam polysaccharide in distilled water, obtain yam polysaccharide solution by ultrasound, then mix potassium tetrachloroplatinate solution and palladium chloride solution under stirring in a water bath, add them dropwise to the yam polysaccharide solution until the color of the solution gradually changes from yellow to black, centrifuge and vacuum dry to obtain PdPt nanozyme.

2. The use according to claim 1, characterized in that: The concentration of the yam polysaccharide is 0.1-10 mg / mL.

3. The use according to claim 2, characterized in that: The concentrations of the potassium tetrachloroplatinate solution and the palladium chloride solution are the same, 1-3 mM, and the volume ratio is 1:

1.

4. The use according to any one of claims 1 to 3, characterized in that: The stirring speed of the water bath is 400-600 rpm and the temperature is 50-80°C.

5. The use according to claim 4, characterized in that: The reaction concentration of the PdPt nanozyme was 30 μg / mL, and the reaction concentration of 3,3',5,5'-tetramethylbenzidine was 0.14 mM.

6. The use according to claim 5, characterized in that: The reaction conditions are temperature 20-45°C and pH 3-6.

7. The use according to claim 6, characterized in that: If the color of the reaction solution changes from blue to colorless within 15 to 25 minutes, it means that the solution contains S. 2- ions, the solution system is PdPt-TMB-S 2- Continuing to add dropwise, PdPt-TMB-S was observed within 5 to 10 minutes. 2- The solution system changes from colorless to blue, indicating that it contains Hg 2+ ion.

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