A cerium oxide nanoszyme derivative and a preparation method thereof
By combining precipitation and hydrothermal methods with surface modification to prepare cerium oxide nanozyme derivatives, the problem of low catalytic activity of cerium oxide nanozymes was solved, enabling more efficient applications in biosensing and environmental remediation.
Patent Information
- Application Number
- CN202311067255.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-08-23
- Publication Date
- 2025-11-11
- Estimated Expiration
- 2043-08-23
AI Technical Summary
Existing cerium oxide nanozymes have low catalytic activity, and their preparation methods are complex and not environmentally friendly enough, making it difficult to meet the needs of biosensing and environmental remediation.
Cerium oxide nanorod precursors were prepared by precipitation, and surface modified by hydrothermal treatment. Cerium oxide nanozymes were then encapsulated with polymers to optimize the preparation process and improve catalytic activity and stability.
The prepared cerium oxide nanozyme derivatives have a larger specific surface area, good water dispersibility and excellent catalytic performance, which expands the types of nanozymes and are suitable for the fields of biosensing and environmental remediation.
Smart Images
Figure CN117085737B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of biosensing technology, specifically relating to a cerium oxide nanozyme derivative and its preparation method. Background Technology
[0002] Natural enzymes face significant limitations in application due to their stringent storage requirements, susceptibility to inactivation, and instability. Nanozymes, on the other hand, possess catalytic functions similar to natural enzymes while overcoming their inherent limitations. Due to their unique properties, nanozymes exhibit higher catalytic activity while maintaining greater stability compared to natural enzymes, attracting considerable attention. To date, various substances with excellent peroxidase or oxidase activities have been discovered, such as metal oxides and metal-organic frameworks (MOFs).
[0003] Cerium is the most abundant element in the lanthanides, and common cerium oxides are mainly cerium trioxide and cerium dioxide. This is because the valence state of the cerium ion can rapidly and reversibly change from Ce... 3+ Switch to Ce 4+ Therefore, nano-cerium oxide possesses activities such as superoxide dismutase (SOD), peroxidase (POD), and oxidase. Based on these excellent properties, nano-cerium oxide has been widely developed in fields such as biosensing, biomedicine, environmental remediation, and protection.
[0004] Currently, mainstream methods such as hydrothermal synthesis, solvothermal synthesis, chemical precipitation, and sol-gel methods are used to prepare cerium oxide nanoparticles. However, cerium oxide, as a nanozyme, still faces the challenge of low catalytic activity. Many innovative strategies, such as adjusting the surface morphology, size, or composition of cerium oxide nanoparticles, are being explored to improve its catalytic activity. Summary of the Invention
[0005] This invention addresses the shortcomings and deficiencies of current methods for preparing cerium oxide nanozymes by providing a novel cerium oxide nanozyme derivative and its preparation method.
[0006] This invention provides a method for preparing cerium oxide nanozyme derivatives, which involves preparing cerium oxide nanorod precursors by precipitation, treating the cerium oxide nanorod precursors with a hydrothermal method to obtain cerium oxide nanozymes, and then surface-modifying the cerium oxide nanozymes with a polymer to obtain cerium oxide nanozyme derivatives.
[0007] Preferably, the raw materials for preparing the cerium oxide nanorod precursor are cerium nitrate hexahydrate and sodium hydroxide.
[0008] Preferably, the molar ratio of cerium nitrate hexahydrate to sodium hydroxide is 1:10 to 1:1.
[0009] Preferably, the polymer is polypropylene, polyvinylpyrrolidone, sodium polystyrene sulfonate, polyvinyl alcohol, sodium dodecyl sulfate, sodium hyaluronate, chitosan, or dextran.
[0010] Preferably, it includes the following steps:
[0011] (1) Mix cerium nitrate hexahydrate solution and sodium hydroxide solution, stir at room temperature, transfer to oil bath, condense and reflux, and purify to obtain cerium oxide nanorod precursor after cooling to room temperature;
[0012] (2) The cerium oxide nanorod precursor was dispersed in a solvent by ultrasonic oscillation to obtain a yellow solution. The yellow solution was subjected to hydrothermal reaction for 1-12 h, and after cooling to room temperature, it was purified to obtain cerium oxide nanozyme.
[0013] (3) Dissolve the polymer and cerium oxide nanozyme separately, add the cerium oxide nanozyme solution dropwise into the polymer solution under constant stirring, and purify the cerium oxide nanozyme derivative after stirring at room temperature.
[0014] Preferably, the cerium oxide nanorod precursor is obtained by washing with deionized water and ethanol three times each, and then drying the resulting yellow solution at 80°C.
[0015] Preferably, in step (2) above, the ratio of cerium oxide nanorod precursor to solvent is 1g cerium oxide nanorod precursor: 100-500mL solvent, wherein the solvent is deionized water, the hydrothermal reaction is carried out in a polytetrafluoroethylene-lined hydrothermal reactor for 6-12h, and the cerium oxide nanoenzyme is obtained by washing with deionized water and ethanol alternately 3 times each, and drying the solution at 80℃.
[0016] Preferably, the mass ratio of the polymer to the cerium oxide nanozyme in step (3) is 1:10-10:1, the stirring speed at room temperature is 300-800 rpm and the time is 3h, and the purification to obtain the cerium oxide nanozyme derivative is to wash the yellow solution with deionized water and ethanol three times each to remove excess polymer, and then dry the solution at 80°C to obtain the cerium oxide nanozyme derivative.
[0017] The present invention also provides the application of the above preparation method in the preparation of cerium oxide nanozyme derivatives.
[0018] The present invention also provides cerium oxide nanozyme derivatives prepared by the above preparation method.
[0019] Advantages of this invention:
[0020] (1) The preparation process of cerium oxide nanozymes in this invention is simple, with a large specific surface area and many enzyme active sites.
[0021] (2) The polymer is used to simply encapsulate cerium oxide nanoparticles. The reaction conditions are mild, the preparation process is simple and easy, the cost is low, and it is environmentally friendly.
[0022] (3) The cerium oxide nanozyme derivative of the present invention has good water dispersibility and excellent catalytic properties.
[0023] (4) This invention expands the types of cerium oxide nanozymes and provides technical support for the preparation of novel cerium oxide nanozymes.
[0024] (5) The novel carbon oxide cerium nanozyme derivative prepared by the present invention has a lower surface charge and stronger adsorption of positively charged chromogenic substrates, which enriches the performance of cerium oxide nanozymes and expands the types of nanozymes.
[0025] The cerium oxide nanozyme derivative prepared by this invention not only has a high specific surface area, good water dispersibility and excellent catalytic performance, but also has the advantages of abundant raw material sources, simple and easy preparation process and no generation of toxic gases. It meets the characteristics of green chemistry such as green environmental protection and economic feasibility, and can be better applied in the fields of environmental governance and protection and biosensing. Attached Figure Description
[0026] Figure 1 This is a transmission electron microscope (TEM) image of the cerium oxide nanorod precursor prepared in Example 1.
[0027] Figure 2These are graphs showing the enhanced enzyme activity of cerium oxide nanozymes modified with different polymers obtained in Examples 5-7. A represents the absorbance change of substrate TMB in the 400-800 nm range after polyacrylic acid (PAA, Mw3000) was coated onto the surface of cerium oxide nanozymes at mass ratios of 10:1, 5:1, 1:1, 1:5, and 1:10. B represents the absorbance change of substrate TMB in the 400-800 nm range after polyvinylpyrrolidone (PVP, Mw3000) was coated onto the surface of cerium oxide nanozymes at mass ratios of 10:1, 5:1, 1:1, 1:5, and 1:10. C represents the absorbance change of substrate TMB in the 400-800 nm range after sodium dodecyl sulfate (SDS) was coated onto the surface of cerium oxide nanozymes at mass ratios of 10:1, 5:1, 1:1, 1:5, and 1:10. D represents the absorbance change of substrate TMB at 652 nm after polyacrylic acid (PAA, Mw3000) was coated onto the surface of cerium oxide nanozymes at mass ratios of 10:1, 5:1, 1:1, 1:5, and 1:10. E represents the absorbance change of substrate TMB at 652 nm after polyvinylpyrrolidone (PVP, Mw3000) was coated onto the surface of cerium oxide nanozymes at mass ratios of 10:1, 5:1, 1:1, 1:5, and 1:10. F represents the absorbance change of substrate TMB at 652 nm after sodium dodecyl sulfate (SDS) was coated onto the surface of cerium oxide nanozymes at mass ratios of 10:1, 5:1, 1:1, 1:5, and 1:10.
[0028] Figure 3These are graphs showing the enhanced enzyme activity of cerium oxide nanozymes modified with different polymers obtained in Examples 8-10. A represents the absorbance change of substrate TMB in the 400-800 nm range after sodium polystyrene sulfonate (PSS, Mw7000) was coated onto the surface of cerium oxide nanozymes at mass ratios of 10:1, 5:1, 1:1, 1:5, and 1:10. B represents the absorbance change of substrate TMB in the 400-800 nm range after polyacrylic acid (PAA, Mw45000) was coated onto the surface of cerium oxide nanozymes at mass ratios of 10:1, 5:1, 1:1, 1:5, and 1:10. C represents the absorbance change of substrate TMB in the 400-800 nm range after sodium hyaluronate (HA) was coated onto the surface of cerium oxide nanozymes at mass ratios of 10:1, 5:1, 1:1, 1:5, and 1:10. D represents the absorbance change of substrate TMB at 652 nm after sodium polystyrene sulfonate (PSS, Mw7000) was coated onto the surface of cerium oxide nanozymes at mass ratios of 10:1, 5:1, 1:1, 1:5, and 1:10. E represents the absorbance change of substrate TMB at 652 nm after polyacrylic acid (PAA, Mw45000) was coated onto the surface of cerium oxide nanozymes at mass ratios of 10:1, 5:1, 1:1, 1:5, and 1:10. F represents the absorbance change of substrate TMB at 652 nm after sodium hyaluronate (HA) was coated onto the surface of cerium oxide nanozymes at mass ratios of 10:1, 5:1, 1:1, 1:5, and 1:10.
[0029] Figure 4These are graphs showing the enhanced enzyme activity of cerium oxide nanozymes modified with different polymers obtained in Examples 11-13. A represents the absorbance change of substrate TMB in the 400-800 nm range after polyvinyl alcohol (PVA, Mw20500) was coated onto the surface of cerium oxide nanozymes at mass ratios of 10:1, 5:1, 1:1, 1:5, and 1:10. B represents the absorbance change of substrate TMB in the 400-800 nm range after chitosan (CS) was coated onto the surface of cerium oxide nanozymes at mass ratios of 10:1, 5:1, 1:1, 1:5, and 1:10. C represents the absorbance change of substrate TMB in the 400-800 nm range after dextran (Dex) was coated onto the surface of cerium oxide nanozymes at mass ratios of 10:1, 5:1, 1:1, 1:5, and 1:10. D represents the absorbance change of substrate TMB at 652 nm after polyvinyl alcohol (PVA, Mw20500) was coated onto the surface of cerium oxide nanozymes at mass ratios of 10:1, 5:1, 1:1, 1:5, and 1:10. E represents the absorbance change of substrate TMB at 652 nm after chitosan (CS) was coated onto the surface of cerium oxide nanozymes at mass ratios of 10:1, 5:1, 1:1, 1:5, and 1:10. F represents the absorbance change of substrate TMB at 652 nm after dextran (Dex) was coated onto the surface of cerium oxide nanozymes at mass ratios of 10:1, 5:1, 1:1, 1:5, and 1:10.
[0030] Figure 5 This describes the mechanism by which catalytic efficiency is enhanced by cerium oxide nanoparticles prepared in Example 6 and polyacrylamide-modified cerium oxide nanozymes. A represents the Michaelis-Menten equation fitting with different concentrations of TMB at fixed H2O2 and CeO2NPs concentrations. B represents the linear equation fitting of the reaction rate with different concentrations of TMB at fixed H2O2 and CeO2NPs concentrations. C represents the Kt of CeO2NPs and PAA-CeO2 on TMB. m and V max D represents the Michaelis-Menten equation fitting with different concentrations of H2O2 at fixed TMB and CeO2NPs concentrations. E represents the linear equation fitting the reaction rate with different concentrations of H2O2 at fixed TMB and CeO2NPs concentrations. F represents the effect of H2O2 K on the reaction rate before and after encapsulation. m and V max The changes. Detailed Implementation
[0031] The following examples are further illustrations of the present invention, but not limitations thereof. The hydrothermal time for achieving high surface area can be 6h, 8h, 10h, or 12h; the polymer is one of polypropylene, polyvinylpyrrolidone, sodium polystyrene sulfonate, polyvinyl alcohol, sodium dodecyl sulfate, sodium hyaluronate, chitosan, and dextran.
[0032] Example 1:
[0033] (1) Weigh 1.736 g of cerium nitrate hexahydrate and 19.2 g of sodium hydroxide and dissolve them in 10 mL and 70 mL of deionized water, respectively. After complete dissolution, mix the solutions and stir at room temperature for 30 min. Then transfer the solutions to an oil bath at 100 °C, condense and reflux for 24 h. Cool to room temperature and wash three times each with deionized water and anhydrous ethanol, alternating between the two. The resulting yellow solution is dried in an oven at 80 °C for 12 h to obtain the desired cerium oxide nanorod precursor.
[0034] (2) The above-mentioned cerium oxide nanorod precursor (200 mg) was dispersed in 100 mL of deionized water by ultrasonic oscillation at 30 Hz for 15 min. The yellow solution was transferred to a 150 mL hydrothermal reactor lined with polytetrafluoroethylene and reacted at 160 °C for 6 h. After cooling to room temperature, the solution was washed three times each with deionized water and anhydrous ethanol, respectively. The resulting solution was dried in an oven at 80 °C to obtain the desired cerium oxide nanoparticles (CeO2NPs).
[0035] (3) Particle size analysis: The nanorod precursor was prepared into a pure aqueous dispersion with a concentration of 1 mg / mL, and its morphology was characterized using transmission electron microscopy. The results are as follows: Figure 1 As shown.
[0036] Example 2:
[0037] (1) Weigh 1.736 g of cerium nitrate hexahydrate and 19.2 g of sodium hydroxide and dissolve them in 10 mL and 70 mL of deionized water, respectively. After complete dissolution, mix the solutions and stir at room temperature for 30 min. Then transfer the solutions to an oil bath at 100 °C, condense and reflux for 24 h. Cool to room temperature and wash three times each with deionized water and anhydrous ethanol, alternating between the two. The resulting yellow solution is dried in an oven at 80 °C for 12 h to obtain the desired cerium oxide nanorod precursor.
[0038] (2) The above-mentioned cerium oxide nanorod precursor (200 mg) was dispersed in 100 mL of deionized water by ultrasonic oscillation at 30 Hz for 15 min. The yellow solution was transferred to a 150 mL hydrothermal reactor lined with polytetrafluoroethylene and reacted at 160 °C for 8 h. After cooling to room temperature, the solution was washed three times each with deionized water and anhydrous ethanol, respectively. The resulting solution was dried in an oven at 80 °C to obtain the desired cerium oxide nanoparticles (CeO2NPs).
[0039] Example 3:
[0040] (1) Weigh 1.736 g of cerium nitrate hexahydrate and 19.2 g of sodium hydroxide and dissolve them in 10 mL and 70 mL of deionized water, respectively. After complete dissolution, mix the solutions and stir at room temperature for 30 min. Then transfer the solutions to an oil bath at 100 °C, condense and reflux for 24 h. Cool to room temperature and wash three times each with deionized water and anhydrous ethanol, alternating between the two. The resulting yellow solution is dried in an oven at 80 °C for 12 h to obtain the desired cerium oxide nanorod precursor.
[0041] (2) The above-mentioned cerium oxide nanorod precursor (200 mg) was dispersed in 100 mL of deionized water by ultrasonic oscillation at 30 Hz for 15 min. The yellow solution was transferred to a 150 mL hydrothermal reactor lined with polytetrafluoroethylene and reacted at 160 °C for 10 h. After cooling to room temperature, the solution was washed three times each with deionized water and anhydrous ethanol. The resulting solution was dried in an oven at 80 °C to obtain the desired cerium oxide nanoparticles (CeO2NPs).
[0042] Example 4:
[0043] (1) Weigh 1.736 g of cerium nitrate hexahydrate and 19.2 g of sodium hydroxide and dissolve them in 10 mL and 70 mL of deionized water, respectively. After complete dissolution, mix the solutions and stir at room temperature for 30 min. Then transfer the solutions to an oil bath at 100 °C, condense and reflux for 24 h. Cool to room temperature and wash three times each with deionized water and anhydrous ethanol, alternating between the two. The resulting yellow solution is dried in an oven at 80 °C for 12 h to obtain the desired cerium oxide nanorod precursor.
[0044] (2) The above-mentioned cerium oxide nanorod precursor (200 mg) was dispersed in 100 mL of deionized water by ultrasonic oscillation at 30 Hz for 15 min. The yellow solution was transferred to a 150 mL hydrothermal reactor lined with polytetrafluoroethylene and reacted at 160 °C for 12 h. After cooling to room temperature, the solution was washed three times each with deionized water and anhydrous ethanol, respectively. The resulting solution was dried in an oven at 80 °C to obtain the desired cerium oxide nanoparticles (CeO2NPs).
[0045] Experimental Example: Changes in specific surface area of cerium oxide nanoparticles prepared in Examples 1-4 under different hydrothermal treatment times.
[0046] The cerium oxide nanozymes after hydrothermal reaction were tested using a JW-BK112 surface area and pore size analyzer from China Precision Microelectronics. The test samples were cerium oxide nanoparticle powders prepared in Examples 1-4. The test temperature was room temperature (25℃), the pressure was set to mesoporous integrated standard, and the environment was high-purity nitrogen, high-purity argon, and liquid nitrogen (-196℃). The BET curve selection range was 0.05-0.3, the T curve selection range was 0.37-0.5, and the maximum P / P0 ratio was 0.993. The results are shown in Table 1. The cerium oxide nanoparticles exhibited the largest specific surface area after 10 hours of hydrothermal treatment.
[0047] Table 1 shows the changes in specific surface area of cerium oxide nanoparticles prepared in Examples 1-4 under different hydrothermal treatment times.
[0048]
[0049] Example 5:
[0050] (1) Weigh 1.736 g of cerium nitrate hexahydrate and 19.2 g of sodium hydroxide and dissolve them in 10 mL and 70 mL of deionized water, respectively. After complete dissolution, mix the solutions and stir at room temperature for 30 min. Then transfer the solutions to an oil bath at 100 °C, condense and reflux for 24 h. Cool to room temperature and wash three times each with deionized water and anhydrous ethanol, alternating between the two. The resulting yellow solution is dried in an oven at 80 °C for 12 h to obtain the desired cerium oxide nanorod precursor.
[0051] (2) The above-mentioned cerium oxide nanorod precursor (200 mg) was dispersed in 100 mL of deionized water by ultrasonic oscillation at 30 Hz for 15 min. The yellow solution was transferred to a 150 mL hydrothermal reactor lined with polytetrafluoroethylene and reacted at 160 °C for 10 h. After cooling to room temperature, the solution was washed three times each with deionized water and anhydrous ethanol. The resulting solution was dried in an oven at 80 °C to obtain the desired cerium oxide nanoparticles (CeO2NPs).
[0052] (3) The obtained cerium oxide nanoparticles and polyvinylpyrrolidone (PVP, Mw3000) were weighed out at mass ratios of 10:1, 5:1, 1:1, 1:5, and 1:10, and dissolved in ultrapure water (the ratio of cerium oxide nanoparticles, PVP, and ultrapure water was 0.5 mg / mL). Then, the cerium oxide nanoparticle solution was added dropwise to the corresponding continuously stirred polyvinylpyrrolidone solution using a rubber-tipped dropper. After stirring at room temperature for 3 hours, the resulting yellow solution was washed three times each with deionized water and anhydrous ethanol to remove excess polymer. The resulting solution was then dried in an oven at 80°C for later use.
[0053] Example 6:
[0054] Steps (1) and (2) are the same as steps (1) and (2) in Example 5.
[0055] Step (3) involves weighing the obtained cerium oxide nanoparticles and polyacrylic acid (PAA, Mw3000) at mass ratios of 10:1, 5:1, 1:1, 1:5, and 1:10, and dissolving them separately in ultrapure water (the ratio of cerium oxide nanoparticles, polyacrylic acid, and ultrapure water is 0.5 mg / mL). Then, using a rubber-tipped dropper, the cerium oxide nanoparticle solution is added dropwise to the corresponding continuously stirred polyacrylic acid solution. After stirring at room temperature for 3 hours, the resulting yellow solution is washed three times each with deionized water and anhydrous ethanol to remove excess polymer. The resulting solution is then dried in an 80°C oven to obtain the cerium oxide nanoenzyme derivative PAA-CeO2 for later use.
[0056] Example 7:
[0057] Steps (1) and (2) are the same as steps (1) and (2) in Example 5.
[0058] Step (3) is as follows: Weigh the obtained cerium oxide nanoparticles and sodium dodecyl sulfate (SDS) at mass ratios of 10:1, 5:1, 1:1, 1:5, and 1:10, and dissolve them separately in ultrapure water (the ratio of cerium oxide nanoparticles, SDS, and ultrapure water is 0.5 mg / mL). Then, use a rubber-tipped dropper to add the cerium oxide nanoparticle solution to the corresponding continuously stirred sodium dodecyl sulfate solution. After stirring at room temperature for 3 hours, wash the resulting yellow solution three times each with deionized water and anhydrous ethanol to remove excess polymer. Dry the resulting solution in an 80°C oven for later use.
[0059] Example 8:
[0060] Steps (1) and (2) are the same as steps (1) and (2) in Example 5.
[0061] Step (3) is as follows: Weigh the obtained cerium oxide nanoparticles and sodium polystyrene sulfonate (PSS, Mw7000) at mass ratios of 10:1, 5:1, 1:1, 1:5, and 1:10 respectively, and dissolve them separately in ultrapure water (the ratio of cerium oxide nanoparticles, sodium polystyrene sulfonate, and ultrapure water is 0.5 mg / mL). Then, use a rubber-tipped dropper to drop the cerium oxide nanoparticle solution into the corresponding continuously stirred sodium polystyrene sulfonate solution. After stirring at room temperature for 3 hours, wash the resulting yellow solution three times each with deionized water and anhydrous ethanol to remove excess polymer. Dry the resulting solution in an 80°C oven for later use.
[0062] Example 9:
[0063] Steps (1) and (2) are the same as steps (1) and (2) in Example 5.
[0064] Step (3) is as follows: Weigh the obtained cerium oxide nanoparticles and polyacrylic acid (PAA, Mw45000) at mass ratios of 10:1, 5:1, 1:1, 1:5, and 1:10 respectively, and dissolve them separately in ultrapure water (the ratio of cerium oxide nanoparticles, polyacrylic acid, and ultrapure water is 0.5 mg / mL). Then, use a rubber-tipped dropper to drop the cerium oxide nanoparticle solution into the corresponding continuously stirred polyacrylic acid solution. After stirring at room temperature for 3 hours, wash the resulting yellow solution three times each with deionized water and anhydrous ethanol to remove excess polymer. Dry the resulting solution in an 80°C oven for later use.
[0065] Example 10:
[0066] Steps (1) and (2) are the same as steps (1) and (2) in Example 5.
[0067] Step (3) is as follows: Weigh the obtained cerium oxide nanoparticles and sodium hyaluronate (HA) at mass ratios of 10:1, 5:1, 1:1, 1:5, and 1:10 respectively, and dissolve them separately in ultrapure water (the ratio of cerium oxide nanoparticles, sodium hyaluronate, and ultrapure water is 0.5 mg / mL). Then, use a rubber-tipped dropper to add the cerium oxide nanoparticle solution to the corresponding continuously stirred sodium hyaluronate (HA) solution. After stirring at room temperature for 3 hours, wash the resulting yellow solution three times each with deionized water and anhydrous ethanol to remove excess polymer. Dry the resulting solution in an 80°C oven for later use.
[0068] Example 11:
[0069] Steps (1) and (2) are the same as steps (1) and (2) in Example 5.
[0070] Step (3) is as follows: Weigh the obtained cerium oxide nanoparticles and polyvinyl alcohol (PVA, Mw20500) at mass ratios of 10:1, 5:1, 1:1, 1:5, and 1:10 respectively, and dissolve them separately in ultrapure water (the ratio of cerium oxide nanoparticles, polyvinyl alcohol, and ultrapure water is 0.5 mg / mL). Then, use a rubber-tipped dropper to drop the cerium oxide nanoparticle solution into the corresponding continuously stirred polyvinyl alcohol solution. After stirring at room temperature for 3 hours, wash the resulting yellow solution three times each with deionized water and anhydrous ethanol to remove excess polymer. Dry the resulting solution in an 80°C oven for later use.
[0071] Example 12:
[0072] Steps (1) and (2) are the same as steps (1) and (2) in Example 5.
[0073] Step (3) involves weighing the obtained cerium oxide nanoparticles and chitosan (CS) at mass ratios of 10:1, 5:1, 1:1, 1:5, and 1:10, and dissolving them separately in ultrapure water (the ratio of cerium oxide nanoparticles, chitosan, and ultrapure water is 0.5 mg / mL). Then, using a rubber-tipped dropper, the cerium oxide nanoparticle solution is added dropwise to the corresponding continuously stirred chitosan solution. After stirring at room temperature for 3 hours, the resulting yellow solution is washed three times each with deionized water and anhydrous ethanol, alternating between the two, to remove excess polymer. The resulting solution is then dried in an 80°C oven for later use.
[0074] Example 13:
[0075] Steps (1) and (2) are the same as steps (1) and (2) in Example 5.
[0076] Step (3) involves weighing the obtained cerium oxide nanoparticles and dextran (Dex) at mass ratios of 10:1, 5:1, 1:1, 1:5, and 1:10, and dissolving them separately in ultrapure water (the ratio of cerium oxide nanoparticles, dextran, and ultrapure water is 0.5 mg / mL). Then, using a rubber-tipped dropper, the cerium oxide nanoparticle solution is added dropwise to the corresponding continuously stirred dextran solution. After stirring at room temperature for 3 hours, the resulting yellow solution is washed three times each with deionized water and anhydrous ethanol to remove excess polymer. The resulting solution is then dried in an 80°C oven for later use.
[0077] Experimental Example: Changes in peroxidase activity of polymer-modified cerium oxide nanoparticles prepared in Examples 5-13 at different proportions.
[0078] TMB (transferase induction) is a commonly used biochemical experimental technique for detecting enzyme activity, protein content, and other parameters. In this experiment, TMB was selected for detecting the activity of polymer-modified artificial nanozymes. It can be catalyzed and oxidized by peroxidase to produce a blue oxidation product. This blue product can be determined by spectroscopic analysis.
[0079] The cerium oxide nanozyme particles encapsulated in polymers obtained in Examples 5-13 were used to determine enzyme activity under the following conditions: 37°C, pH 4, HAc-NaAc concentration of 50 μg / mL, TMB = 0.5 mM, and H2O2 = 10 mM. The cerium oxide nanozyme derivative material was first incubated in HAc-NaAc (pH = 4) at 37°C for 15 min. Then, TMB and H2O2 were added, and the reaction was carried out at 37°C for 5 min. The absorbance of the samples in the 400-800 nm range was collected using UV-Vis, plotted, and the results were statistically analyzed. Figure 2-4As shown, the blank group represents pure cerium oxide nanozymes (CeO2NPs) without polymer encapsulation.
[0080] Experimental Example: Mechanism of Oxidase Enhancement in PAA-Modified Cerium Oxide Nanoparticles Prepared in Example 6
[0081] The absorbance was measured under the following conditions: HAc-NaAc (pH=4) at 37℃, material (CeO2NPs, PAA-CeO2) concentration of 50 μg / mL, TMB concentration fixed at 0.5 mM, and H2O2 concentration fixed at 10 mM. The materials were first incubated in HAc-NaAc (pH=4) at 37℃ for 15 min, then TMB and H2O2 were added, and the reaction was carried out at 37℃ for 5 min. The absorbance (400-800 nm) was recorded using UV-vis, and the level of absorbance was used to determine whether the POD activity of the polymer-modified CeO2 nanoparticles was enhanced.
[0082] The results are as follows Figure 5 As shown, CeO2 or PAA-CeO2 can decompose H2O2 into reactive oxygen species (ROS). The generated ROS can oxidize some chromogenic substrates TMB to blue (oxTMB) in aqueous solution. The signal change is collected by a UV spectrometer (A). The amount of substrate TMB consumed and the amount of product generated per unit time (t) (A) represent the rate of the enzymatic reaction. Therefore, absorbance can indirectly reflect the reaction rate of CeO2 or PAA-CeO2 nanozymes. Km is the concentration of the substrate when the initial reaction rate is half of Vmax.
[0083] At 37℃, with HAc-NaAc (pH=4), a material concentration of 50 μg / mL, and keeping the TMB (0.5 mM) concentration constant, the relationship between absorbance (A) and time (t) was measured by changing the H2O2 concentration (2.5, 5, 10, 20, 40, 80, 160, and 320 mM). Similarly, keeping the H2O2 concentration (10 mM) constant, the relationship between absorbance (A) and time (t) was measured by changing the TMB concentration (0.05, 0.1, 0.15, 0.3, 0.4, 0.6, 0.8, and 1.0 mM). The affinity of CeO2NPs and PAA-CeO2 for TMB and H2O2 was calculated using the Michaelis-Menten equation, as follows:
[0084]
[0085] Where V0 represents the reaction rate, V max V represents the maximum reaction rate. max The larger the value, the faster the reaction rate. m K represents the affinity between the material and the substrate. mThe smaller the value, the better the affinity between the material and the substrate. [S] represents the substrate concentration.
Claims
1. A method for preparing a cerium oxide nanozyme derivative, characterized in that, Cerium oxide nanorod precursors were prepared by precipitation, and then treated with a hydrothermal method to obtain cerium oxide nanozymes. The cerium oxide nanozymes were then surface-modified with polymers to obtain cerium oxide nanozyme derivatives. The preparation method includes the following steps: (1) Mix cerium nitrate hexahydrate solution and sodium hydroxide solution, stir, transfer to an oil bath at 100°C, condense and reflux for 24 h, and then purify to obtain cerium oxide nanorod precursor after cooling to room temperature; (2) The cerium oxide nanorod precursor was dispersed in a solvent by ultrasonic oscillation to obtain a yellow solution. The yellow solution was subjected to hydrothermal reaction for 1-12 h, and then purified after cooling to room temperature to obtain cerium oxide nanozyme. (3) Dissolve the polymer and cerium oxide nanozyme separately, add the cerium oxide nanozyme solution dropwise into the polymer solution under constant stirring, and purify the cerium oxide nanozyme derivative after stirring at room temperature. The polymer is polyacrylic acid, polyvinylpyrrolidone, sodium polystyrene sulfonate, polyvinyl alcohol, sodium hyaluronate, or dextran; Step (1) is as follows: Weigh 1.736 g of cerium nitrate hexahydrate and 19.2 g of sodium hydroxide and dissolve them in 10 mL and 70 mL of deionized water, respectively. After complete dissolution, mix them and stir at room temperature for 30 min. Then transfer them to an oil bath at 100 °C, condense and reflux for 24 h, cool to room temperature, and wash them three times each with deionized water and anhydrous ethanol. The resulting yellow solution is dried in an oven at 80 °C for 12 h to obtain the cerium oxide nanorod precursor. Step (2) is as follows: 200 mg of the above cerium oxide nanorod precursor is dispersed in 100 mL of deionized water under ultrasonic oscillation at 30 Hz for 15 min. The yellow solution is transferred into a 150 mL hydrothermal reactor lined with polytetrafluoroethylene and reacted at 160 °C for 10 h. After cooling to room temperature, it is washed three times each with deionized water and anhydrous ethanol. The resulting solution is dried in an oven at 80 °C to obtain cerium oxide nanoparticles CeO2 NPs. The mass ratio of polymer to cerium oxide nanozyme in step (3) is 1:10-10:
1. The stirring speed at room temperature is 300-800 rpm and the time is 3h. The purification to obtain the cerium oxide nanozyme derivative is to wash the yellow solution three times each with deionized water and ethanol to remove excess polymer, and then dry the solution at 80℃ to obtain the cerium oxide nanozyme derivative.
2. The cerium oxide nanozyme derivative prepared by the preparation method according to claim 1.