An electrochemical sensor for detecting uric acid and a preparation method thereof

Abstract

The application discloses an electrochemical sensor for uric acid detection and a preparation method thereof, which comprises an electrode sensing layer, a polymer layer and a porous aromatic framework layer which are sequentially stacked, wherein the electrode sensing layer adopts a glassy carbon electrode; the polymer layer is made of a crosslinking agent and comprises at least one of glutaraldehyde, perfluorosulfonic acid-based polymer, polyaniline and polyvinylidene fluoride; and the porous aromatic framework layer is made of porous PAF-5 material. The electrochemical sensor for uric acid detection provided by the application is composed of only the electrode sensing layer, the polymer layer and the porous aromatic framework layer, has a simple and clear structure and is easy to prepare. In the sensor, polyvinylidene fluoride is added to the polymer layer and porous PAF-5 material is added to the porous aromatic framework layer, so that the amplification of the uric acid detection signal is realized, the selectivity, sensitivity and stability of the sensing platform are improved, the detection limit is reduced, and the electrochemical sensor has a good clinical diagnosis application prospect.

Description

Technical Field

[0001] This application relates to the field of electrochemical sensing, and more particularly to an electrochemical sensor for uric acid detection and its preparation method. Background Technology

[0002] Uric acid is a byproduct of purine metabolism in the human body. When the body is healthy, uric acid levels fluctuate within the normal range. Uric acid is a biomarker for many diseases. In clinical diagnosis, abnormal uric acid levels in blood, urine, or cerebrospinal fluid indicate the occurrence of disease. Uric acid crystals in the joints can cause gout, while crystals in the kidneys can lead to kidney stones. High uric acid levels cause hyperuricemia, which is related to insulin levels, indirectly leading to diabetes. Besides the diseases directly caused by abnormal uric acid levels mentioned above, neurological disorders, certain cancers, obesity, and gestational hypertension are also closely related to abnormal uric acid levels.

[0003] Currently, commonly used methods for uric acid detection include colorimetry, mass spectrometry, fluorescence spectroscopy, and electrochemical sensing technology. Colorimetry suffers from many similar colors, which can lead to difficulty in distinguishing between them in clinical diagnosis, and the instability of color reactions reduces measurement accuracy. Mass spectrometry and fluorescence spectroscopy involve expensive instruments, high maintenance costs, require specialized personnel, have complex sample preparation, and long analysis times, making them unsuitable for widespread clinical application. Electrochemical sensing technology, on the other hand, offers advantages such as high cost-effectiveness, short detection time, no need for complex analyte preparation, less demanding experimental environment requirements, and high portability. Therefore, applying electrochemical sensing technology to clinical diagnosis is highly suitable. However, current electrochemical sensing technologies for uric acid still have some challenges, requiring modifications to materials to capture more uric acid molecules, improve the stability and selectivity of the sensing platform, and lower the detection limit.

[0004] Therefore, there is an urgent need to develop an electrochemical sensor for uric acid with advantages such as high selectivity, high stability, low detection limit, strong anti-interference ability and repeatability. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide an electrochemical sensor for uric acid detection and its preparation method.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: In a first aspect, the present invention provides an electrochemical sensor for uric acid detection, comprising: [the following components are stacked sequentially:] The electrode sensing layer uses glassy carbon electrodes; The polymer layer is made of a crosslinking agent, including at least one of glutaraldehyde, perfluorosulfonic acid polymer, polyaniline, and polyvinylidene fluoride; The porous aromatic framework layer is made of porous PAF-5 material.

[0007] In a preferred embodiment of the present invention, the thickness of the electrode sensing layer is 1000 nanometers, and the diameter of the electrode core of the electrode sensing layer is 2000-4000 micrometers.

[0008] In a preferred embodiment of the present invention, the thickness of the polymer layer is 400-600 nanometers.

[0009] In a preferred embodiment of the present invention, the thickness of the porous aromatic framework layer is 1000-3000 nanometers.

[0010] In a preferred embodiment of the present invention, the polymer layer is made of polyvinylidene fluoride, and the weight-average molecular weight of the polyvinylidene fluoride is approximately 400,000 Da.

[0011] In a preferred embodiment of the present invention, the porous PAF-5 material is polymerized from 1,3,5-tris(4-bromophenyl)benzene monomer, the average particle size of the porous PAF-5 material is 200 nanometers, and the mass fraction of the porous PAF-5 material in the porous aromatic framework layer is greater than 95%.

[0012] Secondly, the present invention also provides a method for preparing the electrochemical sensor for uric acid detection as described above, comprising the following steps: S1: A polymer layer is formed on one side of the electrode sensing layer; S2: A porous aromatic framework layer is formed on the side of the polymer layer away from the electrode sensing layer.

[0013] In a preferred embodiment of the present invention, step S1 includes: S101: The electrode sensing layer is polished using Al2O3 powder, ultrasonically cleaned in ethanol and deionized water respectively, and finally activated in dilute sulfuric acid. S102: At room temperature, a crosslinking agent is loaded onto the surface of the treated electrode sensing layer and dried under infrared light to form a polymer layer.

[0014] In a preferred embodiment of the present invention, step S2 includes: loading porous PAF-5 material onto the side of the polymer layer away from the electrode sensing layer at room temperature, and drying it under infrared light to form a porous aromatic framework layer.

[0015] In a preferred embodiment of the present invention, the porous PAF-5 material used to form the porous aromatic framework is prepared by the following steps: Step 1: Under nitrogen atmosphere, dissolve bis(1,5-cyclooctadiene)nickel(0), 2,2'-bipyridine and 1,5-cyclooctadiene in anhydrous N,N-dimethylformamide and react at 60-80℃ for 1-3 h to obtain the first mixed solution. Step 2: Add 1,3,5-tris(4-bromophenyl)benzene to the first mixed solution, react at 60-80℃ for 24 hours, wash and vacuum dry to obtain the final product.

[0016] Compared with the prior art, the electrochemical sensor for uric acid detection and its preparation method provided by the present invention have the following beneficial effects after adopting the above technical solution: The electrochemical sensor for uric acid detection provided by this invention consists of only an electrode sensing layer, a polymer layer, and a porous aromatic framework layer, exhibiting a simple and clear structure that is easy to fabricate. In this sensor, by adding polyvinylidene fluoride to the polymer layer and porous PAF-5 material to the porous aromatic framework layer, the uric acid detection signal is amplified, improving the selectivity, sensitivity, and stability of the sensing platform, and lowering the detection limit, thus demonstrating promising prospects for clinical diagnostic applications. Attached Figure Description

[0017] The accompanying drawings, as part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention, but do not constitute an undue limitation of the invention. Obviously, the drawings described below are merely some embodiments, and those skilled in the art can obtain other drawings based on these drawings without creative effort. In the drawings: Figure 1 A schematic diagram of the electrochemical sensor provided in an embodiment of the present invention is shown; Figure 2 The electrochemical characterization diagrams provided in the embodiments of the present invention are shown; Figure 3 The SEM image of the porous aromatic framework layer provided in the embodiment of the present invention is shown. Figure 4 The cyclic voltammetry scan rate diagram provided in the embodiment of the present invention is shown; Figure 5 The linear relationship between the electrochemical sensor provided in the embodiments of the present invention and different uric acid concentrations is shown in the figure. Figure 6 The graph shows the linear relationship between the glassy carbon sheet provided in the embodiment of the present invention and different uric acid concentrations.

[0018] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0020] like Figure 1 As shown, this application provides an electrochemical sensor for uric acid detection, comprising an electrode sensing layer, a polymer layer, and a porous aromatic framework layer stacked sequentially. The sensor has a simple and clear structure and is easy to fabricate.

[0021] Specifically, the electrode sensing layer uses a glassy carbon electrode with a thickness of 1000 nanometers, and the electrode core diameter of the electrode sensing layer is 2000-4000 micrometers. Preferably, the electrode core diameter of the electrode sensing layer is 3000 micrometers. If the electrode core diameter is too small, it will result in a low electrochemical active area of ​​the sensor; if the electrode core diameter is too large, it will result in excessive cost and reduce cost-effectiveness.

[0022] Furthermore, the polymer layer is made of a crosslinking agent. The crosslinking agent has high electrochemical stability, does not affect the overall performance of the electrochemical sensor, and has a stable structure. The thickness of the polymer layer is 400-600 nanometers, preferably 500 nanometers. Excessive thickness of the polymer layer reduces the material's permeability, hindering the binding of uric acid to the sensor; insufficient thickness affects the bonding between the porous aromatic framework layer and the sensor surface, and may even lead to detachment.

[0023] The crosslinking agent used to prepare the polymer layer is at least one of glutaraldehyde, perfluorosulfonic acid-based polymer, polyaniline, and polyvinylidene fluoride (PVDF), with PVDF being particularly preferred. After contacting the porous aromatic framework layer material, PVDF can firmly fix it to the sensor surface, further improving the overall material stability. Simultaneously, PVDF has excellent antioxidant properties, making the sensing platform voltage more stable and reducing data errors. In a preferred embodiment, the weight-average molecular weight of the PVDF crosslinking agent used to prepare the polymer layer is approximately 400,000 Da.

[0024] Furthermore, the porous aromatic framework layer is made of porous PAF-5 material with a thickness of 1000-3000 nanometers, preferably 2000 nanometers. If the porous aromatic framework layer is too thin, it will affect the signal amplification factor; if the porous aromatic framework layer is too thick, it will hinder the contact between uric acid and the sensor surface.

[0025] Preferably, the porous PAF-5 material is polymerized from 1,3,5-tris(4-bromophenyl)benzene monomers, the average particle size of the porous PAF-5 material is 200 nanometers, and the mass fraction of the porous PAF-5 material in the porous aromatic framework layer is greater than 95%.

[0026] Porous aromatic frameworks are a novel type of porous organic material. Traditional diamond materials are typically linked by C-C covalent bonds, which, while producing a significantly stable structure, result in reduced porosity due to overly tight connections. Porous aromatic frameworks, on the other hand, use aromatic building blocks as monomers and, through different polymerization reactions, generate various porous materials while maintaining excellent structural stability. Because they allow for greater exposure of the aromatic structure, they significantly increase the effective specific surface area. Porous PAF-5 material is a porous organic polymer containing only benzene rings after polymerization. Its high porosity, large specific surface area, and high stability greatly increase the sensitivity of sensors for uric acid detection, lower the detection limit, and improve experimental repeatability.

[0027] In this electrochemical sensor, the uric acid detection signal is amplified by adding polyvinylidene fluoride to the polymer layer and porous PAF-5 material to the porous aromatic framework layer, thereby improving the selectivity, sensitivity, and stability of the sensing platform and reducing the detection limit.

[0028] This specification also provides a method for preparing porous PAF-5 materials for preparing porous aromatic framework layers, specifically including the following steps: Step 1: Under nitrogen atmosphere, dissolve bis(1,5-cyclooctadiene)nickel(0), 2,2'-bipyridine and 1,5-cyclooctadiene in anhydrous N,N-dimethylformamide and react at 60-80°C (preferably 70°C) for 1-3 hours (preferably 2 hours) to obtain a first mixed solution; Step 2: Add 1,3,5-tris(4-bromophenyl)benzene to the first mixed solution, react at 60-80℃ (preferably 70℃) for 24 h, wash and vacuum dry to obtain the final product.

[0029] Preferably, the porous PAF-5 material used in subsequent embodiments of this application is obtained through the following steps: In a nitrogen atmosphere, 1 g of bis(1,5-cyclooctadiene)nickel (0), 0.3 g of 2,2'-bipyridine, and 100 μL of 1,5-cyclooctadiene were added to 40 mL of anhydrous N,N-dimethylformamide. The mixture was then stirred at 70 °C for 2 h. After the reaction was complete, 0.5 g of 1,3,5-tris(4-bromophenyl)benzene was added, and the mixture was stirred at 70 °C for 24 h to obtain the crude product. The PAF-5 product was separated by acidification and repeatedly washed with deionized water, tetrahydrofuran, and chloroform. The product was then dried in a vacuum drying oven to obtain pure PAF-5.

[0030] The present invention also provides a method for preparing an electrochemical sensor for uric acid detection as described above, comprising at least the following steps: S1: Provide an electrode sensing layer, and form a polymer layer on one side of the electrode sensing layer; S2: A porous aromatic framework layer is formed on the side of the polymer layer away from the electrode sensing layer; Specifically, in the fabrication process of the aforementioned sensor, step S1 further includes: S101: The electrode sensing layer was polished using Al2O3 powder, and then ultrasonically cleaned in ethanol and deionized water, followed by activation treatment in dilute sulfuric acid. Physical polishing removes impurities or oxide layers from the electrode surface, reducing experimental errors.

[0031] S102: At room temperature, a crosslinking agent (preferably polyvinylidene fluoride) is loaded onto the surface of the electrode sensing layer and dried under infrared light to form a polymer layer.

[0032] Furthermore, step S2 also includes: loading the porous PAF-5 material onto the side of the polymer layer away from the electrode sensing layer at room temperature, and drying it under infrared light to form a porous aromatic framework layer.

[0033] The electrochemical sensor for uric acid detection in this application will be further described below with reference to embodiments: Example 1: A glassy carbon electrode was provided and mechanically polished. A suitable amount of large-diameter Al₂O₃ powder was added to an electric polisher, followed by deionized water to create a slurry. After polishing for 1 minute, the electrode was ultrasonically cleaned in ethanol and then in deionized water. This process was repeated, but with smaller-diameter Al₂O₃ powder replaced with larger-diameter powder. After ultrasonic cleaning, the electrode surface was dried with nitrogen gas and activated using 0.5 M dilute sulfuric acid via cyclic voltammetry. Electrochemical workstation parameters were set as follows: initial potential: -1 V; final potential: 1 V; scan rate: 50 mV / s; sampling interval: 5 mV; number of scan segments: 50; initial scan direction: forward. These operations remove impurities or oxide layers from the glassy carbon electrode surface, reducing experimental error.

[0034] After treating the glassy carbon electrode, a polyvinylidene fluoride solution is loaded onto the surface of the glassy carbon electrode and dried under infrared light to form a polymer layer. Subsequently, porous PAF-5 material is loaded onto the side of the polymer layer away from the electrode sensing layer and dried under infrared light to form a porous aromatic framework layer.

[0035] Example 2: The only difference between this embodiment and Embodiment 1 is that the glassy carbon electrode is replaced with a glassy carbon sheet.

[0036] Comparative example: The only difference between this comparative example and the embodiment is whether or not polyvinylidene fluoride and PAF-5 are added.

[0037] The electrochemical response of uric acid was tested in phosphate buffer using the electrochemical sensors obtained in Examples 1, 2, and the comparative examples, respectively. pass Figure 2 In the electrochemical characterization curves of Example 1 and the comparative example, it can be seen that when the electrode surface is modified with crosslinking agent polyvinylidene fluoride and porous PAF-5 material, the current response signal for the same concentration of uric acid is amplified by about 4.5 times. This indicates that the addition of the polymer layer and the porous aromatic framework layer greatly improves the performance of the sensor in detecting uric acid.

[0038] refer to Figure 3 As can be seen, the PAF-5 material used in Examples 1 and 2 exhibits a large number of porous structures under a scanning electron microscope. The structure is compact and stable, and the specific surface area is increased due to the porous structure.

[0039] refer to Figure 4 The electrode from Example 1 was immersed in 5 mL of phosphate buffer. Cyclic voltammetry was used. Electrochemical workstation parameters were set as follows: initial potential: -1 V; final potential: 1 V; sampling interval: 5 mV; number of scan segments: 50; initial scan direction: forward. Scan rates were 30, 50, 70, 90, 110, 130, 150, 170, 190, and 210 mV / s. Figure 4 The results showed that the scan rate to the power of 1 / 2 was proportional to the current response value, indicating that the uric acid sensing process was a diffusion-controlled process on the sensor. Therefore, increasing the active sites on the sensor could amplify the current signal.

[0040] Different concentrations of uric acid were prepared using phosphate buffer: 1, 2, 5, 10, 50, 100, 500, and 1000 μM. The electrochemical method employed was the current-time method. Electrochemical workstation parameters were set as follows: running time: 4000 s; operating voltage: 0.2 V; sampling interval: 0.1 mV; pause time: 2 s. Initially, 20 mL of phosphate buffer was added to the electrolytic cell. After the current stabilized, different concentrations of uric acid were added dropwise after the current corresponding to each concentration stabilized, thus altering the uric acid concentration in the electrolytic cell.

[0041] refer to Figure 5 As can be seen, the linear regression equation obtained by electrochemical testing of uric acid using Example 1 is: I = 7.17E-8 + 6.09E-9 [uric acid concentration] (μM) (R) 2=0.99716), the detection limit is 15.5 nM (SNR = 3), and the linear range is 0.186 ~ 46.055 μM. This indicates that the sensor has excellent linearity in the range of 0.186 ~ 46.055 μM and a low detection limit.

[0042] refer to Figure 6 As can be seen, the linear regression equation obtained by electrochemical testing of uric acid using Example 2 is: I = 2.59E-6 + 8.20-8 [uric acid concentration] (μM) (R) 2 =0.99478), the detection limit is 0.59 μM (SNR = 3), and the linear range is 1.766 ~ 46.055 μM. This indicates that the sensor has excellent linearity in the 1.766 ~ 46.055 μM range, but the detection limit is not as good as in Example 1. The success of Example 2 demonstrates the potential of this invention to further develop portable sensing platforms.

[0043] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. The implementation schemes in the above embodiments can also be further combined or replaced. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

[0044] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0045] In the description of this invention, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0046] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0047] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

Claims

1. An electrochemical sensor for uric acid detection, characterized in that, Including those set up in a stacked manner: The electrode sensing layer uses glassy carbon electrodes; The polymer layer is made of a crosslinking agent, including at least one of glutaraldehyde, perfluorosulfonic acid polymer, polyaniline, and polyvinylidene fluoride; The porous aromatic framework layer is made of porous PAF-5 material; The electrode sensing layer has a thickness of 1000 nanometers and the electrode core diameter of the electrode sensing layer is 2000-4000 micrometers. The thickness of the polymer layer is 400-600 nanometers; The thickness of the porous aromatic framework layer is 1000-3000 nanometers.

2. The electrochemical sensor for uric acid detection as described in claim 1, characterized in that: The polymer layer is made of polyvinylidene fluoride.

3. The electrochemical sensor for uric acid detection as described in claim 1, characterized in that, The porous PAF-5 material is polymerized from 1,3,5-tris(4-bromophenyl)benzene monomers. The average particle size of the porous PAF-5 material is 200 nanometers, and the mass fraction of the porous PAF-5 material in the porous aromatic framework layer is greater than 95%.

4. A method for preparing an electrochemical sensor for uric acid detection as described in any one of claims 1-3, characterized in that, Includes the following steps: S1: A polymer layer is formed on one side of the electrode sensing layer; S2: A porous aromatic framework layer is formed on the side of the polymer layer away from the electrode sensing layer.

5. The preparation method according to claim 4, characterized in that, Step S1 includes: S101: The electrode sensing layer is polished using Al2O3 powder, ultrasonically cleaned in ethanol and deionized water respectively, and finally activated in dilute sulfuric acid. S102: At room temperature, a crosslinking agent is loaded onto the surface of the treated electrode sensing layer and dried under infrared light to form a polymer layer.

6. The preparation method according to claim 4, characterized in that, Step S2 includes: loading porous PAF-5 material onto the side of the polymer layer away from the electrode sensing layer at room temperature, and drying it under infrared light to form a porous aromatic framework layer.

7. The preparation method according to claim 4, characterized in that, The porous PAF-5 material used to form the porous aromatic framework is prepared by the following steps: Step 1: Under nitrogen atmosphere, dissolve bis(1,5-cyclooctadiene)nickel(0), 2,2'-bipyridine and 1,5-cyclooctadiene in anhydrous N,N-dimethylformamide and react at 60-80℃ for 1-3 h to obtain the first mixed solution. Step 2: Add 1,3,5-tris(4-bromophenyl)benzene to the first mixed solution, react at 60-80℃ for 24 hours, wash and vacuum dry to obtain the final product.

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