An Fe for serum creatinine detection 3 O 4 -V 2 O 5 Ultra-small composite foam nanozyme and its preparation method and application

Abstract

The present invention discloses an Fe3O4-V2O5 ultrafine composite foam nanozyme for serum creatinine detection, its preparation method and application, belonging to the technical fields of serum creatinine detection and nanozyme preparation. The method comprises the following steps: (1) Dissolve vanadium dichloride, ferric trichloride hexahydrate and sucrose in an ethanol solution, then add an aqueous solution of phytic acid, and dry to obtain a first solid; (2) Place the first solid on the graphite sample stage of a Joule heating device, and perform rapid Joule heat shock in an air atmosphere to obtain the Fe3O4-V2O5 ultrafine composite foam nanozyme. Sucrose acts as a template agent, promoting the formation of an ultrafine composite foam structure, significantly increasing the specific surface area of the material, and providing more active sites. The synergistic effect between Fe3O4 and V2O5 enhances the catalytic activity of the active sites. This porous structure effectively prevents the aggregation of nanozymes and provides more channels for the rapid recognition and reaction of serum creatinine.

Description

Technical Field

[0001] The present invention relates to the technical fields of serum creatinine detection and nanozyme preparation, and particularly to an Fe 3 O 4 -V 2 O 5 ultra-micro composite foam nanozyme for serum creatinine detection, and its preparation method and application. Background Art

[0002] Serum creatinine is a metabolite of human muscle metabolism and is often used as an important biomarker for evaluating renal function. As renal function is impaired, the serum creatinine level will increase significantly. Therefore, the accurate detection of serum creatinine is crucial for clinical diagnosis of kidney diseases, assessment of patient conditions, and formulation of treatment plans. Traditional methods for serum creatinine detection mainly rely on the picric acid method, which is easily interfered by non-creatinine substances (such as glucose, uric acid, ketone bodies, etc.) in serum, resulting in false positive or false negative results and affecting the accuracy of detection. Compared with the picric acid method, the enzyme colorimetric method can utilize the high specificity of creatinine enzyme and only react with creatinine through an enzyme-catalyzed reaction, greatly reducing non-specific interference during the detection process and significantly improving the specificity and accuracy of detection. At the same time, the enzyme colorimetric method has a lower detection limit and can more precisely detect low-concentration serum creatinine. This is particularly important for evaluating early renal function damage and can help detect slight renal function decline, thereby improving the sensitivity of early screening and diagnosis. However, the enzyme colorimetric method is often limited by problems such as enzyme stability and high cost.

[0003] In recent years, the emergence of nanozymes has provided new possibilities for serum creatinine detection. Nanozymes are nanomaterials with enzyme catalytic activity and have gradually attracted wide attention due to their high stability and adjustable catalytic performance. The application of nanozymes in serum creatinine detection can provide higher sensitivity, better stability, and lower cost, becoming a research hotspot. However, the current design and preparation methods of nanozymes for serum creatinine detection are not yet mature. Currently, the preparation process of most nanozymes is relatively complex, costly, and prone to problems such as uneven particle size and aggregation during the preparation process, which in turn affect their catalytic performance and stability, limiting their application in clinical diagnosis. Therefore, researching and developing an efficient and stable nanozyme for serum creatinine detection has important scientific significance and application value. Summary of the Invention

[0004] The object of the present invention is to provide an Fe 3 O 4 -V 2 O 5Ultramicrocomposite foam nanozyme, its preparation method and application, to solve the problems in the above-mentioned existing technologies, such as relatively complex preparation process, high cost, easy agglomeration, low catalytic efficiency, etc.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] One of the technical solutions of the present invention is a method for preparing Fe 3 O 4 -V 2 O 5 ultramicrocomposite foam nanozyme for serum creatinine detection, including the following steps:

[0007] (1) Dissolve vanadium dichloride, ferric trichloride hexahydrate and sucrose in an ethanol solution, then add an aqueous solution of phytic acid, and dry to obtain a first solid;

[0008] (2) Place the first solid on the graphite sample stage of a Joule heating device, and perform rapid Joule heating shock in an air atmosphere to obtain the Fe 3 O 4 -V 2 O 5 ultramicrocomposite foam nanozyme.

[0009] Another technical solution of the present invention is the Fe 3 O 4 -V 2 O 5 ultramicrocomposite foam nanozyme prepared by the above preparation method.

[0010] Another technical solution of the present invention is the application of the Fe 3 O 4 -V 2 O 5 ultramicrocomposite foam nanozyme in the preparation of products for detecting serum creatinine.

[0011] Another technical solution of the present invention is a product for detecting serum creatinine, including the Fe 3 O 4 -V 2 O 5 ultramicrocomposite foam nanozyme.

[0012] The sucrose-assisted Joule heat calcination method proposed by the present invention can quickly and efficiently prepare Fe 3 O 4 -V 2 O 5 ultramicrocomposite foam nanozyme. This kind of Fe 3 O 4 -V 2 O 5The ultra-fine composite foam structure has a large specific surface area, which can provide more active sites. The synergistic effect between multiple components inside enhances the catalytic activity of single sites, thus significantly improving the catalytic efficiency of nanozymes. Secondly, this porous structure can effectively prevent the aggregation of nanozymes and maintain their good dispersibility and stability. In addition, the porous characteristics of the ultra-fine composite foam structure can provide more channels for the rapid recognition and reaction of serum creatinine, effectively shortening the detection time. Based on this ultra-fine composite foam nanozyme, a colorimetric sensor for serum creatinine detection has a low detection limit (LOD) as low as 0.179 µM and high stability, providing new ideas and methods for the efficient and accurate detection of serum creatinine.

[0013] Based on the above technical solutions, the present invention has the following technical effects:

[0014] 1. The present invention proposes a sucrose-assisted Joule heating calcination method, which can rapidly and efficiently prepare Fe 3 O 4 -V 2 O 5 ultra-fine composite foam nanozymes. Sucrose, as a templating agent, promotes the formation of the ultra-fine composite foam structure, significantly increases the specific surface area of the material, and provides more active sites. The synergistic effect between Fe 3 O 4 and V 2 O 5 enhances the catalytic activity of the active sites. In addition, this porous structure effectively prevents the aggregation of nanozymes, maintains good dispersibility and stability, and provides more channels for the rapid recognition and reaction of serum creatinine, shortening the detection time.

[0015] 2. The Joule heating calcination method utilizes the Joule heat generated by the current passing through the material, which has the characteristics of rapidity, high efficiency, and energy conservation, and can achieve high-temperature treatment in a short time to promote the formation of nanozymes.

[0016] 3. The ultra-fine composite foam nanozymes prepared based on this method, when used to construct a colorimetric sensor for serum creatinine, exhibit a low detection limit (LOD) and high stability, providing new ideas and methods for the efficient and accurate detection of serum creatinine. This method is simple, rapid, and low-cost, and has good application and popularization value. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0018] Figure 1 X-ray powder diffraction pattern of Example 1.

[0019] Figure 2 Scanning electron microscopy image and elemental distribution map of Example 1.

[0020] Figure 3 Scanning electron microscopy image of Comparative Example 1.

[0021] Figure 4 Scanning electron microscopy image of Comparative Example 2.

[0022] Figure 5 Nitrogen adsorption-desorption isotherm curve of Example 1.

[0023] Figure 6 X-ray photoelectron spectroscopy (XPS) images of Example 1, Comparative Example 3, and Comparative Example 4. Among them, a is the V 2p XPS spectrum of Example 1 and Comparative Example 3, and b is the Fe 2p XPS spectrum of Example 1 and Comparative Example 4.

[0024] Figure 7 Comparison chart of peroxidase-like activity of samples of Example 1 and Comparative Examples 1-4.

[0025] Figure 8 UV absorption spectra of CR / TMB / H 2 O 2 / Fe 3 O 4 -V 2 O 5 -1 nanozyme system with different creatinine (CR) concentrations.

[0026] Figure 9 Graph of the relationship between UV absorption value and creatinine concentration.

[0027] Figure 10 Peroxidase-like activity graph of Example 1 after 9 cycles of creatinine detection.

[0028] Figure 11 Scanning electron microscopy image of Example 1 after 9 cycles of creatinine detection. Detailed implementation manners

[0029] Now, various exemplary implementation manners of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0030] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. In addition, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0031] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0032] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of this application are merely exemplary.

[0033] Regarding the use of "comprising", "including", "having", "containing", etc. herein, they are all open-ended terms, meaning including but not limited to.

[0034] The technical solutions described in the present invention, unless otherwise specified, are all conventional solutions in the art, and the reagents or raw materials used, unless otherwise specified, are all purchased from commercial channels or have been made public.

[0035] An embodiment of the present invention provides a preparation method of Fe 3 O 4 -V 2 O 5 ultra-small composite foam nanozyme for serum creatinine detection, comprising the following steps:

[0036] (1) Dissolve vanadium dichloride, ferric trichloride hexahydrate and sucrose in an ethanol solution, then add an aqueous solution of phytic acid, and dry to obtain a first solid;

[0037] (2) Place the first solid on a graphite sample stage of a Joule heating device, and perform rapid Joule heat shock in an air atmosphere to obtain the Fe 3 O 4 -V 2 O 5 ultra-small composite foam nanozyme.

[0038] In some specific embodiments, the mass ratio of vanadium dichloride, ferric chloride hexahydrate, sucrose and phytic acid is 1:(1 - 3):(10 - 20):(8 - 12).

[0039] In some specific embodiments, the mass concentration of the ethanol solution is 40%; the mass concentration of the phytic acid aqueous solution is 50%.

[0040] In some specific embodiments, the drying conditions are: heat preservation at 90 °C for 24 h.

[0041] In some specific embodiments, the temperature of the rapid Joule heat shock is 550 - 900 °C, the heating rate is 1000 - 2000 °C / s, and the number of times is 1 - 10 times.

[0042] In the present invention, the Joule heat shock is from room temperature to the target temperature and then naturally cooled to room temperature, which is regarded as one time.

[0043] The embodiment of the present invention also provides Fe 3 O 4 -V 2 O 5 ultra - micro composite foam nanozyme.

[0044] The embodiment of the present invention also provides the application of the Fe 3 O 4 -V 2 O 5 ultra - micro composite foam nanozyme in the preparation of a product for detecting serum creatinine.

[0045] The embodiment of the present invention also provides a product for detecting serum creatinine, including the Fe 3 O 4 -V 2 O 5 ultra - micro composite foam nanozyme.

[0046] The present invention provides a preparation method of Fe 3 O 4 -V 2 O 5 ultra - micro composite foam nanozyme for serum creatinine detection, which can solve the problems of the nanozyme prepared by the traditional method, such as relatively complex process, high cost, easy agglomeration, low catalytic efficiency, etc. The sucrose - assisted Joule heat calcination method proposed by the present invention can promote the rapid nucleation and growth of crystals, inhibit the agglomeration of crystals, and at the same time, sucrose as a pore - forming agent can promote the formation of a rich pore structure, thereby rapidly and efficiently preparing Fe 3 O 4 -V 2 O 5 ultra - micro composite foam nanozyme. This kind of Fe3 O 4 -V 2 O 5 The ultrafine composite foam structure has a large specific surface area, which can provide more active sites. The synergistic effect between internal Fe 3 O 4 and V 2 O 5 enhances the catalytic activity of the active sites, thus significantly improving the catalytic efficiency of the nanozyme. Secondly, this porous structure can effectively prevent the aggregation of nanozymes and maintain their good dispersibility and stability. In addition, the porous characteristics of the ultrafine composite foam structure can provide more channels for the rapid recognition and reaction of serum creatinine, effectively shortening the detection time. Based on this ultrafine composite foam nanozyme, a colorimetric sensor for serum creatinine detection has a low detection limit (LOD) as low as 0.179 μM and high stability, and can be used repeatedly, which is of great significance for the trace determination of creatinine in actual samples.

[0047] Example 1

[0048] Step S1: Dissolve 5 mg of vanadium dichloride, 10 mg of ferric trichloride hexahydrate, and 70 mg of sucrose in 100 mL of an ethanol solution with a mass fraction of 40%. Then, add 50 mg of an aqueous solution of phytic acid with a mass fraction of 50% under stirring, and place it in a forced-air drying oven at 90 °C for 24 h to obtain a first solid.

[0049] Step S2: Place 50 mg of the first solid on the graphite sample stage of the Joule heating device, and perform rapid Joule heating shock in an air atmosphere. The rapid Joule heating shock temperature is 650 °C, the heating rate of Joule heating shock is 1500 °C / s, and the number of Joule heating shocks is 5 times. An ultrafine composite foam nanozyme is obtained and named Fe 3 O 4 -V 2 O 5 -1.

[0050] Step S3: Add 10 μL of a 2 mg / mL Fe 3 O 4 -V 2 O 5 -1 ultrafine composite foam nanozyme suspension, 10 μL of 10 mM H 2 O 2 and 10 μL of 1 mM TMB to 2970 μL of a 0.2 M sodium acetate - acetic acid (NaAc - HAc, pH = 4.5) buffer solution. After incubating at room temperature for 20 min, measure the absorbance of the reaction solution at 652 nm using a UV - visible spectrophotometer to detect Fe 3 O 4 -V2 O 5 Activity of the ultra - fine composite foam nanozyme.

[0051] Step S4: Mix 80 μL of 0.015 M phosphate - buffered saline (PBS, pH = 7.5) with 10 μL of 0.1 mg / mL creatinase solution, 10 μL of 0.2 mg / mL creatininease solution, 10 μL of 0.2 mg / mL sarcosine oxidase solution, and 20 μL of creatinine solution (0 - 82.5 mM), and incubate at 37 °C for 30 min. Then, add 2850 μL of 0.2 M NaAc - HAc buffer (pH = 4.5), 10 μL of 2 mg / mL Fe 3 O 4 -V 2 O 5 -1 ultra - fine composite foam nanozyme suspension and 10 μL of 1 mM TMB, and incubate at room temperature for 5 min. Finally, measure the absorbance of the reaction solution at 652 nm using a UV - visible spectrophotometer to detect the creatinine content in the solution, and further evaluate the detection sensitivity of creatinine by the colorimetric sensing method based on this nanozyme.

[0052] Example 2

[0053] The difference from Example 1 is only that 70 mg of sucrose in Step S1 is replaced by 50 mg of sucrose. The remaining methods are exactly the same as those in Example 1, denoted as Fe 3 O 4 -V 2 O 5 -2.

[0054] Example 3

[0055] The difference from Example 1 is only that 70 mg of sucrose in Step S1 is replaced by 100 mg of sucrose. The remaining methods are exactly the same as those in Example 1, denoted as Fe 3 O 4 -V 2 O 5 -3.

[0056] Example 4

[0057] The difference from Example 1 is only that 50 mg of 50% aqueous phytic acid solution in Step S1 is replaced by 40 mg of 50% aqueous phytic acid solution. The remaining methods are exactly the same as those in Example 1, denoted as Fe 3 O 4 -V 2 O 5 -4.

[0058] Example 5

[0059] The difference from Example 1 is only that in step S1, 50 mg of an aqueous solution of phytic acid with a mass fraction of 50% is replaced by 60 mg of an aqueous solution of phytic acid with a mass fraction of 50%. The remaining methods are exactly the same as those in Example 1, denoted as Fe 3 O 4 -V 2 O 5 -5.

[0060] Example 6

[0061] The difference from Example 1 is only that in step S2, the rapid Joule heating calcination conditions are changed to: the Joule heat shock temperature is 550 °C, the Joule heat shock heating rate is 1000 °C / s, and the number of Joule heat shocks is 10 times. The remaining methods are exactly the same as those in Example 1, denoted as Fe 3 O 4 -V 2 O 5 -6.

[0062] Example 7

[0063] The difference from Example 1 is only that in step S2, the rapid Joule heating calcination conditions are changed to: the Joule heat shock temperature is 900 °C, the Joule heat shock heating rate is 2000 °C / s, and the number of Joule heat shocks is 1 time. The remaining methods are exactly the same as those in Example 1, denoted as Fe 3 O 4 -V 2 O 5 -7.

[0064] Comparative Example 1

[0065] The difference from Example 1 is only that sucrose is not added in step S1. The remaining methods are exactly the same as those in Example 1, denoted as Fe 3 O 4 -V 2 O 5 -a.

[0066] Comparative Example 2

[0067] The difference from Example 1 is only that in step S1, the Joule heating method is replaced by muffle furnace heating. The specific implementation steps are: placing 50 mg of the first solid substance in a muffle furnace. Under an air atmosphere, the heating rate is 10 °C / min, heating to 650 °C, and holding for 0.5 h. The remaining methods are exactly the same as those in Example 1, denoted as Fe 3 O 4 -V 2 O 5 -b.

[0068] Comparative Example 3

[0069] The difference from Example 1 is only that in step S1, 5 mg of vanadium dichloride is changed to 15 mg of vanadium dichloride, and 10 mg of ferric chloride hexahydrate is changed to 0 mg of ferric chloride hexahydrate. The remaining methods are exactly the same as those in Example 1, denoted as V 2 O 5 -c.

[0070] Comparative Example 4

[0071] The difference from Example 1 is only that in step S1, 5 mg of vanadium dichloride is changed to 0 mg of vanadium dichloride, and 10 mg of ferric chloride hexahydrate is changed to 15 mg of ferric chloride hexahydrate. The remaining methods are exactly the same as those in Example 1, denoted as Fe 3 O 4 -d.

[0072] Experimental results

[0073] Figure 1 The X-ray powder diffraction pattern of Example 1 is shown. The results show that Fe 3 O 4 -V 2 O 5 -1 prepared in Example 1 is composed of two phases of Fe 3 O 4 and V 2 O 5 The synergistic effect between different components can optimize the intrinsic nanozyme activity of the active substance, thereby improving the creatinine detection performance.

[0074] Figure 2 The scanning electron microscope image and element distribution map of Example 1 are shown. The results show that Example 1 is a superfine composite nano-foam structure composed of nanoparticles, and the particle size of a single nanoparticle is about 100 nm. In addition, Fe and V elements are evenly distributed in the superfine nano-composite foam, indicating that Fe 3 O 4 and V 2 O 5 two phases have good dispersibility in Fe 3 O 4 -V 2 O 5 -1, which is beneficial to the synergistic effect between different phases. At the same time, this superfine composite nano-foam structure can effectively prevent the aggregation of nanozymes and maintain its good dispersibility and stability. In addition, the porous characteristics of the superfine composite foam structure can provide more channels for the rapid recognition and reaction of serum creatinine, effectively shortening the detection time.

[0075] Figure 3The scanning electron microscope image of Comparative Example 1 is shown. The main difference between Comparative Example 1 and Example 1 is that sucrose was not added during the preparation process of the nanozyme. The results showed that Comparative Example 1 presented a blocky structure with mutual adhesion, rather than the ultrafine nano-composite foam structure of Example 1. It was shown that sucrose was beneficial to the formation of the ultrafine composite nano-structure. The main reason was that during the calcination process, sucrose was oxidized by oxygen in the air to form a large amount of carbon dioxide, which could be used as a pore-forming agent to promote the formation of the ultrafine nano-composite foam structure.

[0076] Figure 4 The scanning electron microscope image of Comparative Example 2 is shown. The main difference between Comparative Example 2 and Example 1 is that Joule heating was not used during the preparation process of the nanozyme, but heating was carried out by a muffle furnace. It can be seen from Figure 4 that the nanozyme prepared by the muffle furnace heating method had fewer foamy structures and more massive materials. The main reason was that the heating and cooling rates of the muffle furnace were slower, and the crystal nucleation and growth time were longer, which was easy to agglomerate and form large massive materials. While the Joule heating method had an ultra-fast heating rate and cooling rate, which could inhibit the agglomeration during the crystal growth process and the formation of large particles, and thus was more conducive to the formation of the ultrafine nano-composite foam structure.

[0077] To further analyze the pore structure of Fe 3 O 4 -V 2 O 5 -1, N 2 adsorption-desorption tests were carried out. Figure 5 And Table 1 shows the N 2 adsorption-desorption test results of Example 1, Comparative Example 1 and Comparative Example 2. Figure 5 It can be seen from that the adsorption-desorption curve of Example 1 presented an H3-type special hysteresis loop, indicating that the material had a rich mesoporous structure. The Barrett-Joyner-Halenda (BJH) analysis results in the inset showed a wide pore size distribution, further proving that the material was mainly mesoporous structure. It can be seen from Table 1 that the specific surface areas from large to small were: Example 1 (45.23 m 2 / g) > Comparative Example 2 (18.65 m 2 / g) > Comparative Example 1 (8.69 m 2 / g). It was shown that during the synthesis process of the nanozyme, sucrose and Joule heat acted together to promote the formation of the ultrafine nano-foam structure, and the contribution of sucrose was better than that of Joule heat. This rich pore structure was helpful for the dispersion of active substances, exposing more enzyme active sites, effectively preventing the agglomeration of nanozymes, maintaining good dispersion and stability, and providing more channels for the rapid recognition and reaction of serum creatinine, shortening the detection time.

[0078] Table 1 N 2Adsorption-desorption test results

[0079] Title Example 1 Comparative Example 1 Comparative Example 2 <![CDATA[Specific surface area (m 2 / g)]]> 45.23 8.69 18.65

[0080] Figure 6 For the XPS spectra of Example 1, Comparative Example 3 and Comparative Example 4, from Figure 6 It can be seen that, compared with Comparative Example 3 and Comparative Example 4, the binding energies of V and Fe elements in Example 1 shift towards lower binding energy and higher binding energy respectively, indicating that there is a synergistic effect between Fe 3 O 4 and V 2 O 5 which optimizes the electronic structures of Fe and V elements, can reduce the adsorption, activation and conversion energy barriers of reactants in the enzyme-catalyzed reaction, and thus significantly enhance the catalytic activity of the enzyme active site.

[0081] Figure 7 The peroxidase-like activities of the samples of Example 1 and Comparative Examples 1-4 were compared. The intensity of the absorption peak at 652 nm in the example is proportional to the enzyme activity. It can be seen from the figure that the material of Example 1 exhibits the highest nanozyme activity, far superior to the nanozyme activities of the comparative examples. In addition, the order of the nanozyme activities of the comparative examples is Comparative Example 2 > Comparative Example 4 > Comparative Example 3 > Comparative Example 1. It shows that sucrose, Joule heat, and multi-metal elements are all essential for enhancing the nanozyme activity, and the synergistic effect of multiple factors significantly enhances the activity of the nanozyme in Example 1.

[0082] Figure 8 Shows the ultraviolet absorption spectra of the Fe 3 O 4 -V 2 O 5 -1 system at different creatinine (CR) concentrations. The results show that as the creatinine concentration in the solution increases from 0.4~550 µM, the absorbance value of the TMB solution increases steadily, indicating that the absorbance value of the TMB solution can be used to quantify the concentration of the creatinine solution.

[0083] According to the Lambert-Beer law, the absorbance data of the Fe 3 O 4 -V 2 O 5 -1 system at different creatinine (CR) concentrations were converted to obtain the relationship diagram between the ultraviolet absorption value and the creatinine concentration in Figure 9 . In the range of 0.4 - 250 µM, the ultraviolet absorption intensity has a good linear relationship with the creatinine concentration (see Figure 9 inset), and the linear equation is: y = 0.00339x + 0.00407 (R 2= 0.996), the limit of detection (LOD) was calculated to be 0.179 µM using the calculation method of LOD = 3σ / K, where σ is the standard deviation of the blank sample and K is the slope of the linear equation. Therefore, this Fe 3 O 4 -V 2 O 5 The limit of detection (LOD) of the ultrafine composite foam nanozyme material is as low as 0.179 µM, indicating that the colorimetric sensing method based on this material has excellent detection limit and high sensitivity for creatinine.

[0084] Figure 10 Figure for the active peroxidase-like activity of Example 1 after 9 cycles of creatinine detection. It can be seen from the figure that Example 1 still exhibits excellent enzyme activity after 9 cycles of creatinine detection, indicating that Example 1 has excellent enzyme activity stability and can be reused multiple times.

[0085] Figure 11 Scanning electron microscopy image of Example 1 after 9 cycles of creatinine detection. The results show that the microstructure of Example 1 did not change significantly after 9 cycles of creatinine detection and still maintained the ultrafine composite foam nanostructure, indicating that Example 1 has excellent structural stability, which is beneficial to the stability of its enzyme activity.

[0086] In the embodiments of the present invention, the rapid Joule heat shock technology comes from a Joule heat rapid heating device, which consists of electrodes, a 316L vacuum chamber, a gas path device, a vacuum pump, a graphite sample stage, a temperature measurement module, and a data collection system; the output voltage is 0 - 40V, the output current is 0 - 375A, the current ramp time is 1000 ms, the model is JH3.2, and the power supply is single-phase 220V / 40A.

[0087] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A method for preparing Fe3O4-V2O5 ultrafine composite foam nanozyme for serum creatinine detection, characterized in that: The following steps are involved: (1) dissolving vanadium dichloride, ferric chloride hexahydrate and sucrose in an ethanol solution, then adding a phytic acid aqueous solution, and drying to obtain a first solid; (2) Placing the first solid object in a graphite sample stage of a Joule heat device and subjecting it to rapid Joule heat shock in an air atmosphere to obtain the Fe3O4-V2O5 ultrafine composite foam nanozyme.

2. The preparation method according to claim 1, characterized in that: The mass ratio of the vanadium dichloride, ferric chloride hexahydrate, sucrose and phytic acid is 1:(1-3):(10-20):(8-12).

3. The preparation method according to claim 1, characterized in that: The mass concentration of the ethanol solution is 40%; the mass concentration of the phytic acid aqueous solution is 50%.

4. The preparation method according to claim 1, characterized in that: The drying conditions are: keeping warm at 90° C. for 24 hours.

5. The preparation method according to claim 1, characterized in that: The temperature of the rapid Joule thermal shock is 550-900°C, the heating rate is 1000-2000°C / s, and the number of times is 1-10 times.

6. The Fe3O4-V2O5 ultrafine composite foam nanozyme prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the Fe3O4-V2O5 ultrafine composite foam nanozyme as described in claim 6 in the preparation of a product for detecting serum creatinine.

8. A product for detecting serum creatinine, characterized in that: Including the Fe3O4-V2O5 ultrafine composite foam nanozyme as described in claim 6.

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