Construction and Application of AuNPs@COFs-MWCNTs Composite Modified Electrode

Abstract

The present invention relates to the field of composite materials, and discloses the construction and application of an AuNPs@COFs-MWCNTs composite material modified electrode, including using 1,3,5-tris(4-aminophenyl)benzene and 2,5-dimethoxyterephthalaldehyde as monomers, synthesizing porous spherical COFs by the solvent penetration method, attaching electrocatalytically active AuNPs to the surface of COFs by the hydrothermal method to synthesize AuNPs@COFs, and forming a large conjugated system of AuNPs@COFs-MWCNTs with MWCNTs as a conductive agent through π–π stacking. Using AuNPs@COFs-MWCNTs as an electrode modification material, a glassy carbon electrode is modified by the drop-coating method to obtain AuNPs@COFs-MWCNTs / GCE for the sensitive detection of doxorubicin. This method combines COFs with a variety of electroactive materials, fully leveraging the advantage of the high specific surface area of COFs, and significantly improving the electrocatalytic activity and conductivity of the materials, thereby achieving accurate and highly sensitive detection of doxorubicin, with the detection limit of the composite material modified electrode being 10 nM.

Description

Technical Field

[0001] The present invention relates to the field of composite materials, and specifically to the construction and application of an electrode modified with AuNPs@COFs-MWCNTs composite material. Background Art

[0002] Doxorubicin is an anthracycline antibiotic and an important chemotherapeutic drug in clinical cancer treatment. Due to its broad-spectrum anti-tumor efficacy and excellent anti-tumor activity, doxorubicin has been widely used in chemotherapy for various cancers, including acute leukemia, malignant lymphoma, breast cancer and other malignancies. However, like many chemotherapeutic drugs, doxorubicin is accompanied by dose-dependent cytotoxic effects. Acute or cumulative doses of doxorubicin are associated with irreversible complications such as myelosuppression or cardiomyopathy. Therefore, it is necessary to detect the level of doxorubicin in cancer patients.

[0003] Currently, some traditional methods for detecting doxorubicin include capillary electrophoresis, high-performance liquid chromatography, spectrophotometry, etc. However, considering the common problems of these techniques such as expensive equipment, time-consuming operation and low sensitivity, some novel techniques with high sensitivity, good specificity and simple operation have also been developed, such as fluorescence method and electrochemical method. Among them, electrochemical detection technology has received extensive attention due to its simple instrument, easy miniaturization and application potential in point-of-care testing. More importantly, the quinone and hydroquinone groups of doxorubicin have electrochemical activity, and the electrochemical method can help analyze the reaction mechanism of doxorubicin, providing valuable pharmacological and pharmacokinetic information for clinical research. The performance of the electrochemical sensor is closely related to the modification of the electrode interface. Using nanomaterials as electrode modification materials can significantly improve the accuracy, sensitivity and response speed of the analytical method. Currently, some electroactive nanomaterials have been used as electrode modification materials for the electrochemical detection of doxorubicin, including silver nanoparticles / carbon dots / reduced graphene oxide nanocomposites, 1T-MoS2 nanosheets modified with shape-controlled gold nanoparticles, glutathione and cysteine-functionalized MoS2 core-shell nanoparticles, and silver nanoparticles loaded with chitosan materials, etc. Among these electrode materials, composite electroactive nanomaterials have become increasingly popular electrode modification materials for sensitive detection of doxorubicin due to the improvement of their catalytic activity and conductivity. However, most of them are two-dimensional dense-structured nanocomposites, which will affect the distribution of electroactive sites of the electrode material and the contact area with doxorubicin, resulting in reduced electrocatalytic activity and limited analytical performance. Therefore, there is an urgent need to develop novel electrode modification materials with high specific surface area and electroactive sites for the sensitive determination of doxorubicin. Summary of the Invention

[0004] The present invention aims to provide the construction and application of an electrode modified with AuNPs@COFs-MWCNTs composite materials, so as to solve the problem that most of the existing electrode modification materials for sensitive detection of doxorubicin are two-dimensional dense structure nanocomposite materials, which will affect the distribution of electroactive sites of the electrode materials and the contact area with doxorubicin, resulting in a decrease in electrocatalytic activity and limited analytical performance.

[0005] To achieve the above object, the basic scheme of the present invention is as follows: The construction of an electrode modified with AuNPs@COFs-MWCNTs composite materials includes using 1,3,5-tris(4-aminophenyl)benzene and 2,5-dimethoxyterephthalaldehyde as monomers, synthesizing porous spherical COFs by the solvent infiltration method, attaching electrocatalytically active AuNPs to the surface of COFs by the hydrothermal method to synthesize AuNPs@COFs, using MWCNTs as a conductive agent to form a large conjugate system of AuNPs@COFs-MWCNTs through π–π stacking, using AuNPs@COFs-MWCNTs as an electrode modification material, and modifying a glassy carbon electrode by the drop-casting method to obtain AuNPs@COFs-MWCNTs / GCE.

[0006] Further, the steps for preparing COFs by the solvent infiltration method are as follows:

[0007] (1) Weigh 1,3,5-tris(4-aminophenyl)benzene and 2,5-dimethoxyterephthalaldehyde and place them in a mixed solvent system of 1,4-dioxane-butanol-methanol (v / v / v, 4:4:1), and ultrasonically disperse the mixed solvent system to obtain a homogeneous solution;

[0008] (2) Add acetic acid to the homogeneous solution under stirring;

[0009] (3) Let the stirred solution stand, then add acetic acid and let it stand again;

[0010] (4) Centrifuge to collect the solid obtained after standing, and wash it with tetrahydrofuran and acetone multiple times;

[0011] (5) Dry the washed solid to obtain porous spherical COFs.

[0012] Further, the steps for preparing AuNPs@COFs by the hydrothermal method are as follows:

[0013] (1) Weigh COFs, ultrasonically disperse them in ultrapure water, and gradually add HAuCl4 solution dropwise under ultrasonic treatment to obtain a mixture;

[0014] (2) Transfer the mixture to a reaction kettle and heat it for reaction;

[0015] (3) Cool the mixture to room temperature, then centrifuge to collect the product, and wash the product with ultrapure water multiple times;

[0016] (4) Dry the product to obtain AuNPs@COFs.

[0017] Furthermore, the steps for preparing AuNPs@COFs-MWCNTs by ultrasound are as follows:

[0018] (1) Weigh AuNPs@COFs and MWCNTs and prepare them into an aqueous dispersion, and ultrasonically disperse until the materials are fully and evenly dispersed;

[0019] (2) Collect the composite material by centrifugal separation and drying to obtain AuNPs@COFs-MWCNTs.

[0020] Furthermore, the steps for modifying the electrode are as follows:

[0021] (1) Disperse AuNPs@COFs-MWCNTs in ultrapure water and obtain a uniform aqueous dispersion by ultrasound;

[0022] (2) Polish the bare glassy carbon electrode with polishing powder on suede until the surface is shiny;

[0023] (3) Ultrasonically clean with absolute ethanol and ultrapure water respectively, and then dry with nitrogen;

[0024] (4) Then, evenly drop the dispersion on the surface of the glassy carbon electrode by the drop-casting method and air-dry to obtain AuNPs@COFs-MWCNTs / GCE.

[0025] Furthermore, in the preparation of AuNPs@COFs, the mass ratio of AuNPs to COFs is 1:5.

[0026] Furthermore, in the preparation of AuNPs@COFs-MWCNTs, the mass ratio of AuNPs@COFs to MWCNTs is 1:1.

[0027] Furthermore, in the preparation of the electrode modification material for the electrochemical sensor, the dropping amount of the dispersion (1.0 mg / mL) is 6 μL.

[0028] Furthermore, 0.1 M B-R buffer solution is used as the electrolyte solution, and the B-R buffer solution is prepared from phosphoric acid, acetic acid and boric acid.

[0029] To achieve the above purpose, the basic solution of the present invention is as follows: the application of the AuNPs@COFs-MWCNTs composite material modified electrode for the detection of doxorubicin in biological sample cell lysate and serum:

[0030] Steps for preparing cell lysate:

[0031] (1) Transfer a certain number of cells into an EP tube and then completely dissolve them in Tris-HCl lysis buffer;

[0032] (2) After ice - water bath, ultrasonication is used to break cells;

[0033] (3) The mixture is centrifuged, and the supernatant is collected. The supernatant is filtered through a 0.45 - μm filter membrane to obtain cell lysate.

[0034] Detection steps of doxorubicin:

[0035] (1) Dilute HeLa cell lysate and serum with B - R solution at a dilution factor of 50 times;

[0036] (2) Add different concentrations of doxorubicin to the above - diluted HeLa cell lysate and serum, and use the prepared AuNPs@COFs - MWCNTs / GCE for the detection of doxorubicin.

[0037] Principle and beneficial effects of the present invention: The modification of the electrode sensing interface is crucial for the detection sensitivity. COFs have a high π - electron density, which results in a relatively high affinity between COFs and doxorubicin. At the same time, the porous structure of COFs can effectively promote the mass transfer process during the catalytic reaction of doxorubicin. Loading a large number of AuNPs on the surface of COFs can effectively increase the distribution of active sites and enhance the electrocatalytic activity of the material towards doxorubicin. Further compounding AuNPs@COFs with highly conductive MWCNTs can accelerate the electron transfer rate. The synergistic effect of the three makes AuNPs@COFs - MWCNTs have stronger electrocatalytic activity and conductivity. Using it as an electrode modification material to construct an electrochemical sensing system can significantly amplify the doxorubicin response signal and achieve sensitive detection of doxorubicin. Beneficial effects: The electrochemical sensor based on the AuNPs@COFs - MWCNTs nanocomposite shows good analytical performance for doxorubicin, with a linear range of 0.08 - 25 μM, a detection limit of 10 nM, and a sensitivity as low as 16.93 μA μM -1 cm -2 . In addition, the sensor has good selectivity, repeatability, and stability, and shows good performance in the detection of doxorubicin in serum and cell lysate samples; it solves the problem that most of the existing electrode modification materials for sensitive detection of doxorubicin are two - dimensional dense - structure nanocomposites, which will affect the distribution of electroactive sites of the electrode material and the contact area with doxorubicin, resulting in a decrease in electrocatalytic activity and limited analytical performance.

[0038] Additional aspects and advantages of the present invention will be given in part in the following description, will become apparent in part from the following description, or will be understood through the practice of the present invention. Brief Description of the Drawings

[0039] Figure 1Schematic diagram of the synthesis process of AuNPs@COFs-MWCNTs in the embodiments of the present application and its application in the detection of doxorubicin.

[0040] Figure 2 Influence diagram of the mass ratio of AuNPs to COFs in the embodiments of the present application on the oxidation peak current of doxorubicin (20 μM).

[0041] Figure 3 Influence diagram of the mass ratio of AuNPs@COFs to MWCNTs in the embodiments of the present application on the oxidation peak current of doxorubicin (20 μM).

[0042] Figure 4 Influence diagram of the coating amount of AuNPs@COFs-MWCNTs dispersion (1.0 mg / mL) in the embodiments of the present application on the oxidation peak current of doxorubicin (20 μM).

[0043] Figure 5 Influence diagram of the supporting electrolyte in the embodiments of the present application on the oxidation peak current of doxorubicin (20 μM).

[0044] Figure 6 (A) CV diagrams of GCE, COFs / GCE, AuNPs@COFs / GCE, MWCNTs / GCE, and AuNPs@COFs-MWCNTs / GCE in 0.1 M B-R buffer (pH 4.5) containing 20 μM doxorubicin (scan rate: 100 mV / s). -1 ); (B) Diagram of the relationship between E pa and I pa and the pH value in B-R buffer containing 20 μM doxorubicin; (C) CV diagrams of AuNPs@COFs-MWCNTs / GCE at different scan rates in 0.1 M B-R buffer (pH 4.5) containing 20 μM doxorubicin; (D) Linear relationship diagram between the oxidation-reduction peak current of doxorubicin and the square root of the scan rate.

[0045] Figure 7 (A) DPV response diagrams of AuNPs@COFs-MWCNTs / GCE in 0.1 M B-R buffer solution (pH 4.5) containing different concentrations of doxorubicin (0.08 - 25 μM); (B) Linear relationship diagram between the oxidation peak current of doxorubicin and the concentration.

[0046] Figure 8This is the oxidation peak current response diagram of the AuNPs@COFs-MWCNTs / GCE of the embodiment of this application after adding urea (Urea), glucose (Glu), ascorbic acid (AA), glycine (Gly), threonine (Thr), histidine (His) interferents (the interference concentration is 50 μM for all) and 5.0 μM doxorubicin to the test solution containing 5.0 μM doxorubicin.

[0047] Figure 9 This is the reproducibility test diagram of the doxorubicin sensor.

[0048] Figure 10 This is the long-term stability test diagram of the doxorubicin sensor. Detailed implementation manners

[0049] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation to the present invention.

[0050] The following will be further detailed through specific implementation manners:

[0051] The embodiment is basically as shown in the attached Figure 1 : The construction of the AuNPs@COFs-MWCNTs composite modified electrode includes using 1,3,5-tris(4-aminophenyl)benzene and 2,5-dimethoxyterephthalaldehyde as monomers, synthesizing porous spherical COFs by the solvent infiltration method, attaching electrocatalytically active AuNPs on the surface of COFs by the hydrothermal method to synthesize AuNPs@COFs, using MWCNTs as a conductive agent to form a large conjugated system of AuNPs@COFs-MWCNTs through π–π stacking, using AuNPs@COFs-MWCNTs as an electrode modification material, and modifying the glassy carbon electrode by the drop-coating method to obtain AuNPs@COFs-MWCNTs / GCE.

[0052] The specific construction process of the solvent penetration method is as follows: First, weigh 8.7 mg of 2,5-dimethoxyterephthalaldehyde and 10.5 mg of 1,3,5-tris(4-aminophenyl)benzene in a 4.5 mL mixed solvent system of 1,4-dioxane-butanol-methanol (v / v / v, 4:4:1), and then obtain a homogeneous solution through ultrasonic dispersion for 0.5 hours. Then, add 50 μL of 12 M acetic acid to the system under stirring and stir for 1 hour. After standing for 1 hour, add 450 μL of 12 M acetic acid to the reaction system and stand for 24 hours. Then, collect the obtained solid by centrifugation and wash it with tetrahydrofuran and acetone multiple times to remove unreacted monomers. Finally, vacuum-dry the product at 60 °C for 6 hours to obtain porous spherical COFs.

[0053] The preparation principle is as follows: COFs have a porous structure, a large π-conjugated system, and a high specific surface area, which can effectively enhance the adsorption and contact area with doxorubicin, thus realizing the signal amplification of doxorubicin.

[0054] The specific construction process of the hydrothermal method is as follows: Weigh 5 mg of COFs and ultrasonically disperse them in 10 mL of ultrapure water, and then gradually add 90 μL of 20 mg / mL HAuCl4 solution drop by drop and ultrasonically disperse until it is uniformly dispersed. Then transfer the mixture to a reaction kettle and react at 80 °C for 4 hours. After cooling to room temperature, collect the product by centrifugation, wash it with ultrapure water multiple times, and finally vacuum-dry it at 60 °C for 12 hours to obtain AuNPs@COFs.

[0055] The preparation principle is as follows: The large specific surface area of COFs can load more electroactive AuNPs, increasing the electroactive sites of the AuNPs@COFs nanocomposite, thereby enhancing the electrocatalytic activity towards doxorubicin.

[0056] The specific construction process of AuNPs@COFs-MWCNTs is as follows: Weigh equal masses of AuNPs@COFs and MWCNTs and prepare a 2.0 mg / mL aqueous dispersion, and ultrasonically disperse for 2 hours until the materials are fully and uniformly dispersed. Collect the composite material by centrifugal separation and drying to obtain AuNPs@COFs-MWCNTs.

[0057] The preparation principle is as follows: Composite AuNPs@COFs with highly conductive MWCNTs to ensure conductivity. The obtained AuNPs@COFs-MWCNTs accelerates the electron transfer rate and can significantly amplify the doxorubicin response signal.

[0058] The specific construction process of the electrode modification material for the electrochemical sensor is as follows: Before modifying the electrochemical sensor electrode, the bare GCE is first polished on suede with 1.0, 0.3, and 0.05 μm α-Al2O3 polishing powders until the surface is shiny, then the electrode is ultrasonically treated with absolute ethanol and ultrapure water for 1 minute respectively, and finally dried with nitrogen for electrode modification. When preparing the AuNPs@COFs-MWCNTs modified electrode, 1.0 mg of AuNPs@COFs-MWCNTs is first dispersed in 1 mL of ultrapure water and ultrasonically treated for 0.5 hours to obtain a uniform aqueous dispersion system. Subsequently, 6.0 μL of the AuNPs@COFs-MWCNTs material dispersion is evenly drop-coated on the electrode surface by the drop-coating method and naturally dried to obtain AuNPs@COFs-MWCNTs / GCE. As a control experiment, COFs / GCE, AuNPs@COFs / GCE, and MWCNTs / GCE are prepared by the same method.

[0059] The preparation principle is as follows: The dispersed composite material dispersion after ultrasonic dispersion is drop-coated on the surface of the polished glassy carbon electrode. After drying at room temperature, the composite material can uniformly form a film on the electrode surface, that is, the modified electrode AuNPs@COFs-MWCNTs / GCE is successfully prepared.

[0060] As attached Figure 2 shown: In the preparation of AuNPs@COFs, the mass ratio of AuNPs to COFs is 1:5.

[0061] The preparation principle is as follows: AuNPs have excellent electrocatalytic performance. The increase in the AuNPs loading provides more active sites for the oxidation of doxorubicin, which is more conducive to the electrocatalytic oxidation-reduction of doxorubicin at the electrode interface, and the peak current increases. However, when there are too many AuNPs, it will hinder the mass transfer process of doxorubicin, so the peak current has a decreasing trend.

[0062] As attached Figure 3 shown: In the preparation of AuNPs@COFs-MWCNTs, the mass ratio of AuNPs@COFs to MWCNTs is 1:1.

[0063] The preparation principle is as follows: Since MWCNTs can accelerate the electron transfer rate, but too many MWCNTs will coat AuNPs@COFs, resulting in limited catalytic activity of AuNPs for doxorubicin. Therefore, when the mass ratio of MWCNTs to AuNPs@COFs-MWCNTs is 1:1, the oxidation peak current of the electrocatalytic reaction for doxorubicin is the highest.

[0064] As attached Figure 4 shown: The drop-coating amount of the composite material dispersion (1.0 mg / mL) in the preparation of the modified electrode is 6 μL.

[0065] The preparation principle is as follows: Since the small drop-coating amount is not sensitive enough to the response of doxorubicin, an excessive drop-coating amount will cause the AuNPs@COFs-MWCNTs film formed on the electrode surface to be too thick, increasing the distance for electrons to transfer to the electrode interface, which is not conducive to electron transfer and results in a decrease in peak current.

[0066] As shown in the Figure 5 appendix: Using 0.1M B-R buffer solution as the electrolyte solution, and the B-R buffer solution is prepared from phosphoric acid, acetic acid and boric acid.

[0067] The preparation principle is as follows: When the B-R buffer solution is used as the supporting electrolyte, the oxidation peak current of doxorubicin reaches the maximum response.

[0068] The implementation example is basically as shown in the Figure 1 appendix: The application of the AuNPs@COFs-MWCNTs composite modified electrode, including the detection of doxorubicin in biological sample cell lysates and serum.

[0069] The specific production process of the cell lysate is as follows: Transfer a certain number of cells into an EP tube, and then completely dissolve them in 100 μL of Tris-HCl (10 mM, pH 7.0) lysis buffer. After ice-water bath for 0.5 hours, ultrasonicate to break the cells. Thereafter, centrifuge the mixture (12000 rpm, 4 °C), and collect the supernatant. Finally, filter the supernatant through a 0.45 μm filter membrane to obtain the cell lysate.

[0070] The specific detection process is as follows: First, dilute the HeLa cell lysate and serum with B-R solution at a dilution factor of 50 times. Then, add different concentrations of doxorubicin to the above-diluted HeLa cell lysate and serum, and use the prepared AuNPs@COFs-MWCNTs / GCE for the determination of doxorubicin.

[0071] The electrochemical response of doxorubicin on different modified electrodes. The experiment explores the cyclic voltammetry (CV) response of electrodes modified with different materials in B-R buffer solution (pH 4.5) containing 20 μM doxorubicin. By Figure 6It can be seen that a pair of significant doxorubicin redox peaks appear on each electrode. The glassy carbon electrode modified with COFs obtains a higher doxorubicin response signal, which is mainly due to the fact that COFs have a high π electron density, enabling the material to have a high affinity with doxorubicin, and the porous structure accelerating the mass transfer process. At the same time, the peak current of doxorubicin on AuNPs@COFs / GCE further increases, indicating that the COFs loaded with AuNPs obtain more active sites, further improving the catalytic activity of the electrode. In addition, the current response of MWCNTs / GCE is much higher than that of the bare GCE, indicating that MWCNTs with excellent conductivity greatly improve the electron transfer efficiency of the doxorubicin oxidation reaction. Obviously, the oxidation peak current of doxorubicin on AuNPs@COFs-MWCNTs / GCE is higher, which is 1.62 times that of GCE. The above results show that based on the structural characteristics of the high specific surface area of COFs, loading electroactive AuNPs on its surface and compounding with conductive MWCNTs can effectively improve the sensitivity of doxorubicin detection.

[0072] Investigation of the interfacial reaction mechanism of doxorubicin on AuNPs@COFs-MWCNTs / GCE. In order to obtain the optimal pH value of the B-R buffer solution for the quantitative determination of doxorubicin and evaluate the electrocatalytic oxidation-reduction mechanism of doxorubicin, the CV responses of the sensor to 20 μM doxorubicin at different pH values (2.5 - 8.5) were tested. From Figure 6 It can be seen from B that the maximum response current was observed when the pH value of the buffer solution was 4.5. Considering the detection sensitivity, 4.5 was selected as the optimal pH value of the B-R buffer solution for subsequent experiments. At the same time, the peak potential (E pa ) shifts negatively with the increase of the pH value. E pa shows a good linear relationship with pH, and the linear relationship can be expressed as: E pa (V) = -0.068pH + 0.9595 (R 2 = 0.9937). The absolute value of the slope is close to the Nernst theoretical value of 0.059 V / pH, indicating that the number of electrons and protons involved in the electrocatalytic oxidation-reduction process of doxorubicin on the composite modified electrode is equal. Therefore, the electrocatalytic reaction mechanism of doxorubicin on AuNPs@COFs-MWCNTs / GCE can be obtained:

[0073]

[0074] Finally, in order to study the influence of the scan rate on oxidation-reduction and clarify the electron transfer mechanism in the kinetic process, the CV responses of doxorubicin on AuNPs@COFs-MWCNTs / GCE were measured in the scan rate range of 10 - 200 mV s 1 . As Figure 6As shown in Fig. C, with the increase of the scanning rate, the oxidation peak current of doxorubicin gradually increases, and the oxidation peak potential gradually shifts towards the positive potential direction. In addition, the oxidation peak current (I pa ) and the reduction peak current (I pc ) have good linear relationships with the square root (ν 1 / 2 ) of different scanning rates respectively. The corresponding linear regression equations can be expressed as: I pa = 2.864 – 6.702ν 1 / 2 (R 2 = 0.9981) and I pc = -3.685 + 10.704ν 1 / 2 (R 2 = 0.9963) ( Figure 6 Fig. D). Therefore, it can be concluded that the electrocatalytic oxidation-reduction of doxorubicin on AuNPs@COFs-MWCNTs / GCE is a typical diffusion-controlled process. Considering the stability and sensitivity of the sensor, a scanning rate of 100 mV s -1 was selected for subsequent experiments.

[0075] Quantitative detection of doxorubicin. To evaluate the detection and analysis performance of the constructed doxorubicin electrochemical sensor, differential pulse voltammetry (DPV) was used to measure the electrochemical responses of different concentrations of doxorubicin under the optimal conditions. As Figure 7 shown in Fig. A, in the range of 0.08 - 25 μM, with the increase of the doxorubicin concentration, its oxidation peak current gradually increases, and two good linear relationships are presented in the ranges of 0.08 - 3.0 μM and 3.0 - 25 μM. The equations are I = 1.185c - 0.0696 (R 2 = 0.996) and I = 0.402c + 2.507 (R 2 = 0.998) ( Figure 7 Fig. B). The sensitivity was calculated to be 16.93 μA μM -1 cm -2 , and the detection limit (LOD) was 10 nM (S / N = 3).

[0076] The performance of the electrochemistry sensor constructed in this experiment exhibits superior or comparable linear range and detection limit. The excellent performance of the sensor may be attributed to the following reasons: (1) The π-π interaction between the aromatic rings of COFs and DOX can effectively increase the affinity between DOX and the modified electrode; (2) The porous structure of COFs can effectively promote the mass transfer process during the catalytic reaction of doxorubicin; (3) The electroactive AuNPs uniformly grown on the surface of COFs with a high specific surface area provide more catalytically active sites for the electrocatalytic oxidation and reduction of doxorubicin; (4) The large conjugated system formed by COFs and MWCNTs with excellent electrical conductivity accelerates the electron transfer rate. In summary, through the synergistic interaction among the three materials, the formed AuNPs@COFs-MWCNTs composite material has excellent electrochemical performance and is an ideal electrode modification material with high sensitivity.

[0077] The selectivity, reproducibility and stability of the electrochemistry sensor. In addition to sensitivity, the selectivity of the sensing platform is also an important parameter for evaluating its analytical performance. Various potential interfering substances coexisting in biological samples were successively added to the electrochemistry cell containing 5.0 μM doxorubicin, including urea (Urea), glucose (Glu), ascorbic acid (AA), glycine (Gly), threonine (Thr) and histidine (His). As Figure 8 shown, 10-fold of the above electroactive interfering substances did not significantly interfere with the detection of doxorubicin, while the current increased significantly after adding another 5.0 μM doxorubicin, indicating that the sensor has good selectivity for doxorubicin.

[0078] As attached Figure 9 shown, under the same conditions, the responses of 5 parallel electrodes to 20 μM doxorubicin were measured respectively, and the results showed almost the same DPV response current with an RSD of 4.1%, indicating that the doxorubicin electrochemistry sensor has good reproducibility.

[0079] As attached Figure 10 shown, meanwhile, the long-term stability was also evaluated by measuring the response current of 20 μM doxorubicin every five days. Even after 25 days, the response current still maintained 96% of its initial current response. These results indicate that the prepared doxorubicin sensor has good stability.

[0080] Determination of doxorubicin in actual samples. The fundamental purpose of developing a simple and sensitive electrochemical sensor is to be able to directly analyze doxorubicin in real samples without separation. To verify the practical application of the sensor, a standard addition experiment was conducted to determine doxorubicin in serum and cell lysate samples. Briefly, different concentrations of doxorubicin (1.0, 5.0, 10 μM) were added to the B-R buffer of diluted serum and cell lysate, and then the prepared sensor was used to determine the doxorubicin concentration in these samples. As shown in the table, the recovery rates were between 96.4% and 102.0%, and the RSDs were between 1.1% and 4.0%, indicating that the constructed AuNPs@COFs-MWCNTs electrochemical sensor can be used as an important tool for the analysis and determination of doxorubicin.

[0081] Table Detection of doxorubicin in actual samples by AuNPs@COFs-MWCNTs / GCE (n = 3)

[0082]

[0083] In summary, we designed a novel electrode material based on AuNPs@COFs-MWCNTs for the quantitative determination of doxorubicin. By combining porous spherical COFs with electroactive materials such as AuNPs and MWCNTs, the prepared AuNPs@COFs-MWCNTs nanocomposite has a large specific surface area and high electrocatalytic activity. The results show that the doxorubicin electrochemical sensor has good analytical performance, including a wide linear range, a low detection limit, and high sensitivity. In addition, due to its good selectivity, reproducibility, and stability, the constructed doxorubicin sensor has good analytical performance in serum and cell lysate samples and has potential application value in clinical monitoring of doxorubicin drug levels. Moreover, all these characteristics indicate that the COF-based electrochemical sensor has broad application prospects in clinical practice and will greatly expand the application scope of COF-based composites.

[0084] The above are only examples of the present invention, and common knowledge such as specific structures and / or characteristics well known in the art are not described in detail herein. It should be noted that for those skilled in the art, without departing from the structure of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope required by this application should be subject to the content of its claims, and the specific implementation manners described in the specification can be used to interpret the content of the claims.

Claims

1. A method for constructing a modified electrode of AuNPs@COFs-MWCNTs composite material, characterized in that: It includes using 1,3,5-tris(4-aminophenyl)benzene and 2,5-dimethoxyterephthalaldehyde as monomers, synthesizing porous spherical COFs by the solvent infiltration method, attaching electrocatalytically active AuNPs to the surface of COFs by the hydrothermal method to synthesize AuNPs@COFs, forming a large conjugated system of AuNPs@COFs-MWCNTs with MWCNTs as the conductive agent through π–π stacking, using AuNPs@COFs-MWCNTs as the electrode modification material, and modifying the glassy carbon electrode by the drop-coating method to obtain AuNP@COFs-MWCNTs / GCE; The steps of the solvent infiltration method are as follows: (1) Weigh 1,3,5-tris(4-aminophenyl)benzene and 2,5-dimethoxyterephthalaldehyde and place them in a mixed solvent system of 1,4-dioxane-butanol-methanol (v / v / v, 4:4:1), and ultrasonically disperse the mixed solvent system to obtain a homogeneous solution; (2) Add acetic acid to the homogeneous solution under stirring; (3) Let the stirred solution stand and then add acetic acid, and then let it stand again; (4) Centrifuge to collect the solid obtained after standing, and wash it with tetrahydrofuran and acetone multiple times; (5) Dry the washed solid to obtain porous spherical COFs; The steps of the hydrothermal method are as follows: (1) Weigh COFs and ultrasonically disperse them in ultrapure water, and dropwise add HAuCl4 solution drop by drop under ultrasonic conditions to obtain a mixture; (2) Transfer the mixture to a reaction kettle and heat it for reaction; (3) Cool the mixture to room temperature and then centrifuge to collect the product, and wash the product with ultrapure water multiple times; (4) Dry the product to obtain AuNPs@COFs; The preparation steps of AuNPs@COFs-MWCNTs are as follows: (1) Weigh AuNPs@COFs and MWCNTs and prepare an aqueous dispersion, and ultrasonically disperse it until the materials are fully dispersed and uniform; (2) Collect the composite material by centrifugal separation and drying to obtain AuNPs@COFs-MWCNTs; The modification steps of the electrode are as follows: (1) Disperse AuNPs@COFs-MWCNTs in ultrapure water and ultrasonically obtain a uniform aqueous dispersion; (2) Polish the bare glassy carbon electrode with polishing powder on suede until the surface is bright; (3) Ultrasonically clean it with absolute ethanol and ultrapure water respectively, and then dry it with nitrogen; (4) Then use the drop-coating method to uniformly drop the dispersion on the surface of the glassy carbon electrode and dry it to obtain AuNPs@COFs-MWCNTs / GCE.

2. The construction method of the AuNPs@COFs-MWCNTs composite material modified electrode according to claim 1, wherein: In the preparation of AuNPs@COFs, the mass ratio of AuNPs to COFs is 1:

5.

3. The construction method of the AuNPs@COFs-MWCNTs composite modified electrode according to claim 1, characterized in that: In the preparation of AuNPs@COFs-MWCNTs, the mass ratio of AuNPs@COFs to MWCNTs is 1:

1.

4. The construction method of the AuNPs@COFs-MWCNTs composite modified electrode according to claim 1, characterized in that: In the preparation of the electrode modification material for the electrochemical sensor, the drop-coating amount of the dispersion at 1.0 mg / mL is 6 μL.

5. The construction method of the AuNPs@COFs-MWCNTs composite material modified electrode according to claim 1, characterized in that: Using 0.1 M B-R buffer solution as the electrolyte solution, and the B-R buffer solution is prepared from phosphoric acid, acetic acid and boric acid.

6. The application of the AuNPs@COFs-MWCNTs composite modified electrode according to claim 1, characterized in that: For the detection of doxorubicin in biological sample cell lysate and serum: The preparation steps of the cell lysate: (1) Transfer a certain number of cells into an EP tube and then dissolve them completely in Tris-HCl lysis buffer; (2) After ice-water bath, sonicate to break the cells; (3) Centrifuge the mixture and collect the supernatant. Filter the supernatant through a 0.45 μm filter membrane to obtain the cell lysate; Detection steps for doxorubicin: (1) Dilute the HeLa cell lysate and serum with B-R solution at a dilution factor of 50 times; (2) Add different concentrations of doxorubicin to the above-diluted HeLa cell lysate and serum, and use the prepared AuNPs@COFs-MWCNTs / GCE for the detection of doxorubicin.

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