Biosensor based on mxene-rare earth oxide hybrid composite and preparation and application thereof

Abstract

The application discloses a biosensor based on an MXene-rare earth oxide hybrid compound and preparation and application thereof, and belongs to the technical field of electrochemical biosensors.The rare earth oxide is dispersed on the surface of Mxene molecules through ultrasonic dispersion and electrostatic action to obtain an MXene-rare earth oxide hybrid compound, the compound solution and an enzyme solution are sequentially constructed on the surface of a platinum disc electrode, and a polyphenol oxidase biosensor is prepared through a phase transfer process.The sensor has the advantages of simple preparation, small size, fast response time, good selectivity, high sensitivity (2394 mA / M), extremely low detection lower limit (7 nM) and the like, is suitable for rapidly and accurately detecting trace concentration of catechol, and is applied to rapid determination of trace catechol in common environmental water bodies such as river water, river water and seawater.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical biosensor technology, specifically relating to a biosensor based on MXene-rare earth oxide hybrid complex and its preparation and application. Background Technology

[0002] Catechol, also known as catechol, is an important chemical intermediate used as a rubber hardener, electroplating additive, skin antiseptic, hair dye, photographic developer, and color photography antioxidant. While cadmium is typically present in low concentrations in environmental water bodies, its concentration has gradually exceeded safety thresholds due to the development of the chemical industry. Furthermore, even at low concentrations, cadmium poses a threat to environmental ecosystems, the natural environment, and human health. Phenolic compounds have irreversible toxic effects on organisms, and the cumulative effect of cadmium on organisms poses a serious threat to human health. Its accumulation in phytoplankton and zooplankton has a profound impact on marine food webs and biogeochemical cycles. Therefore, the determination of these phenolic compounds in environmental matrices and biological metabolites is of great significance. Currently, the detection methods for low concentrations of cadmium mainly utilize techniques such as high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). The aforementioned methods suffer from drawbacks such as long detection times, expensive instruments, and complex sample pretreatment, and cannot perform in-situ online detection. Therefore, developing a simple, highly sensitive method with a low detection limit suitable for trace amounts of catechol is crucial for protecting the aquatic environment and maintaining safe drinking water. Electrochemical methods offer advantages such as simple preparation, low cost, and convenient detection, making them particularly suitable for online in-situ detection. While there is considerable research on electrochemical biosensors based on polyphenol oxidases, achieving high sensitivity, low detection limits, and excellent anti-interference capabilities for phenolic biosensors remains a challenge.

[0003] MXene is a two-dimensional layered material with graphene-like properties, and its general structural formula is M. n+1 X n T xIn this model, M represents a transition metal element; X represents C or N; and Tx represents surface functional groups such as -OH, -COOH, or -F. Compared to other two-dimensional materials, MXene possesses excellent conductivity, hydrophilicity, tunable surface chemistry, and biocompatibility, giving it a unique advantage in the field of biosensors. A Chinese invention patent (201910268734.0) describes a tyrosinase biosensor using phosphorus-doped MXene-modified electrodes, which exhibits a low detection limit, but the sensitivity still falls short of the expected target. To improve the electron transfer capability of the modified electrodes, MXene can be combined with rare earth oxides to construct hybrid complexes, suitable for immobilizing the biomolecule polyphenol oxidase on its surface, thus preparing novel electrochemical biosensors with broad application prospects in environmental analysis. Summary of the Invention

[0004] The purpose of this invention is to provide a biosensor based on an MXene-rare earth oxide hybrid complex, its preparation, and its application. This invention overcomes the shortcomings of existing polyphenol oxidase biosensors, such as low sensitivity and difficulty in lowering the detection limit, and provides a rapid, simple, low-cost, and highly selective biosensor for detecting catechol in water, which can also be used for online detection.

[0005] The specific technical solution adopted in this invention is as follows:

[0006] In a first aspect, the present invention provides a method for preparing a biosensor based on an MXene-rare earth oxide hybrid complex, as detailed below:

[0007] (1) A certain amount of rare earth oxide is added to an MXene solution with a concentration of 1 to 10 mg / mL to obtain a mixed solution. At the same time, the concentration of rare earth oxide in the mixed solution is 1 to 20 mg / mL. After ultrasonic dispersion, an MXene-rare earth oxide hybrid complex is obtained.

[0008] In practice, the ultrasonic dispersion time can be 5 to 30 minutes.

[0009] (2) Prepare a 0.5 wt% chitosan solution using 0.05 M acetic acid solution as solvent;

[0010] In the actual preparation process, acetic acid solution and chitosan can be mixed using a vortex mixer and then left to stand overnight at room temperature.

[0011] (3) Mix the phosphate buffer solution with the chitosan solution described in step (2) at a volume ratio of 1:1, then add an appropriate amount of polyphenol oxidase, mix evenly to obtain a polyphenol oxidase solution with a concentration of 3 to 10 mg / mL.

[0012] In practice, a vortex mixer can be used to mix the materials evenly.

[0013] (4) The MXene-rare earth oxide hybrid complex described in step (1) and the polyphenol oxidase solution described in step (3) are sequentially constructed onto the surface of a platinum disk electrode, and a biosensor based on the MXene-rare earth oxide hybrid complex is prepared by a phase transfer process.

[0014] Preferably, the MXene is a two-dimensional layered structure material with graphene-like properties, obtained by reacting MAX phase material with HF solution, and is a single-layer Ti3C2 colloidal solution.

[0015] Preferably, the rare earth oxide is one of yttrium oxide, praseodymium oxide, lanthanum oxide, or samarium oxide.

[0016] Preferably, in the mixed solution of step (1), the mass ratio of rare earth oxide to MXene is 1:1 to 1:20.

[0017] Preferably, the concentration of the phosphate buffer solution is 0.02M.

[0018] Preferably, in step (4), the volume ratio of the MXene-rare earth oxide hybrid complex and the polyphenol oxidase solution constructed on the surface of the platinum disk electrode is 1:1 to 1:3.

[0019] In a second aspect, the present invention provides a biosensor based on an MXene-rare earth oxide hybrid complex obtained by any of the preparation methods described in the first aspect.

[0020] Thirdly, the present invention provides an application of the biosensor based on the MXene-rare earth oxide hybrid complex described in the second aspect for detecting trace amounts of catechol in common environmental water bodies (such as river water, lake water, and seawater), and the detection does not require pretreatment.

[0021] Preferably, the biosensor has a sensitivity to catechol up to 2394 mA / M.

[0022] As a preferred embodiment, the linear regression equation for the change in catechol concentration and reduction current during the detection process is as follows:

[0023] I = 0.1154 - 2.3949C

[0024] Where I is the change in current during catechol detection, in μA; C is the concentration of catechol in the test solution, in μmol / L; the linear detection range of catechol in the test solution is 0.04–2.84 μM, the detection limit is 7 nM, and the correlation coefficient R0 is [missing value]. 2 =0.9985.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] The biosensor prepared by loading polyphenol oxidase using the method of this invention through a hybrid complex of MXene and rare earth oxides significantly improves the conductivity of the electrode, promotes electron transfer on the electrode surface, and enhances the sensor's sensitivity to 2394 mA / M. Furthermore, the electrostatic interaction enhances the adsorption of polyphenol oxidase, substantially improving the sensor's stability and selectivity. It also exhibits an extremely low detection limit (7 nM) and can be used to detect trace amounts of catechol in common environmental water bodies, such as river water, lake water, and seawater, without requiring pretreatment. It has broad application prospects in the field of environmental pollution and detection. Attached Figure Description

[0027] Figure 1 This is a surface electron microscope image of the MXene-yttrium oxide hybrid complex. Detailed Implementation

[0028] The present invention will be further described below with reference to specific embodiments, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solutions of the present invention that do not depart from the scope of the technical solutions of the present invention should be covered within the protection scope of the present invention.

[0029] Example 1

[0030] This embodiment prepares a biosensor based on an MXene-rare earth oxide hybrid complex. The specific steps of the preparation method are as follows:

[0031] (1) Preparation of MXene-yttrium oxide hybrid complex: Using MXene colloidal solution as solvent, 20 mg of yttrium oxide was added to MXene colloidal solution with a concentration of 10 mg / mL, and then ultrasonicated for 30 min with an ultrasonic cleaner to obtain MXene-yttrium oxide hybrid complex.

[0032] The surface electron microscopy image of the MXene-yttrium oxide hybrid complex obtained in this embodiment is as follows: Figure 1 As shown, MXene and yttrium oxide are hybridized to achieve good dispersion, which improves the conductivity of the electrode and increases its specific surface area.

[0033] (2) Preparation of biosensor: A 0.5 wt% chitosan solution was prepared using 0.05 M acetic acid solution as solvent and mixed evenly with a vortex mixer. The mixture was left to stand overnight at room temperature. The prepared chitosan solution was mixed with 0.02 M phosphate buffer at a volume ratio of 1:1. Polyphenol oxidase was added to make the final polyphenol oxidase concentration 5 mg / mL. The mixture was then mixed evenly with a vortex mixer to prepare a polyphenol oxidase-chitosan mixture. The platinum disk electrode was polished sequentially on a polishing cloth loaded with 1.5 μm, 0.5 μm, and 0.05 nm alumina powder. Then, it was sonicated for 3 min in ultrapure water, ethanol, and ultrapure water, respectively. Finally, the electrode was dried with purified nitrogen gas to obtain a clean platinum disk electrode. The MXene-yttrium oxide hybrid complex solution and the polyphenol oxidase-chitosan solution were sequentially constructed on the surface of the clean platinum disk electrode. The biosensor based on the MXene-rare earth oxide hybrid complex was prepared by phase transfer process and sealed and stored in a refrigerator at 4 °C for later use.

[0034] (3) Detection of catechol concentration: A three-electrode system was established using the prepared biosensor as the working electrode, a calomel electrode as the reference electrode, and a platinum disk electrode as the counter electrode. The three-electrode system was placed in the test solution containing catechol. The results showed that the linear regression equation of the biosensor for catechol was: I = 0.1154 - 2.3949C, the detection range was 0.04–2.84 μM, the sensitivity was 2394 mA / M, the detection limit was 7 nM, and the correlation coefficient R was [missing value]. 2 =0.9985.

[0035] Example 2

[0036] This embodiment prepares a biosensor based on an MXene-rare earth oxide hybrid complex. The specific steps of the preparation method are as follows:

[0037] (1) Preparation of MXene-praseodymium oxide hybrid complex: Using MXene colloidal solution as solvent, 1 mg of praseodymium oxide was added to MXene colloidal solution with a concentration of 5 mg / mL. The mixed solution was then ultrasonicated for 5 min using an ultrasonic cleaner to obtain MXene-praseodymium oxide hybrid complex.

[0038] (2) Preparation of biosensors: The process is carried out in accordance with step (2) of Example 1, except that the concentration of polyphenol oxidase in the polyphenol oxidase-chitosan mixture is 3 mg / mL by controlling the amount of polyphenol oxidase added.

[0039] (3) Detection of catechol concentration: A three-electrode system was established using the prepared biosensor as the working electrode, a calomel electrode as the reference electrode, and a platinum disk electrode as the counter electrode. The three-electrode system was placed in the test solution containing catechol. The results showed that the detection range of the biosensor for catechol was 0.2–3 μM, the sensitivity was 1247 mA / M, and the correlation coefficient R was [missing value]. 2 =0.9982.

[0040] Example 3

[0041] This embodiment prepares a biosensor based on an MXene-rare earth oxide hybrid complex. The specific steps of the preparation method are as follows:

[0042] (1) Preparation of MXene-lanthanum oxide hybrid complex: Using MXene colloidal solution as solvent, 4 mg of lanthanum oxide was added to MXene colloidal solution with a concentration of 5 mg / mL. The mixture was then ultrasonicated for 30 min using an ultrasonic cleaner to obtain MXene-lanthanum oxide hybrid complex.

[0043] (2) The preparation process of the biosensor was carried out in accordance with step (2) of Example 1;

[0044] (3) Detection of catechol concentration: A three-electrode system was established using the prepared biosensor as the working electrode, a calomel electrode as the reference electrode, and a platinum disk electrode as the counter electrode. The three-electrode system was placed in the test solution containing catechol. The results showed that the detection range of the biosensor for catechol was 0.2–3 μM, the sensitivity was 1458 mA / M, and the correlation coefficient R was [missing value]. 2 =0.9985.

[0045] Example 4

[0046] This embodiment prepares a biosensor based on an MXene-rare earth oxide hybrid complex. The specific steps of the preparation method are as follows:

[0047] (1) Preparation of MXene-samarium oxide hybrid complex: Using MXene colloidal solution as solvent, 4 mg of samarium oxide was added to MXene colloidal solution with a concentration of 1 mg / mL. The mixture was then ultrasonicated for 15 min using an ultrasonic cleaner to obtain MXene-samarium oxide hybrid complex.

[0048] (2) The preparation process of the biosensor is carried out in accordance with step (2) of Example 1, except that the concentration of polyphenol oxidase in the polyphenol oxidase-chitosan mixture is 10 mg / mL by controlling the amount of polyphenol oxidase added.

[0049] (3) Detection of catechol concentration: A three-electrode system was established using the prepared biosensor as the working electrode, a calomel electrode as the reference electrode, and a platinum disk electrode as the counter electrode. The three-electrode system was placed in the test solution containing catechol. The results showed that the detection range of the biosensor for catechol was 0.2–3 μM, the sensitivity was 1138 mA / M, and the correlation coefficient R was [missing value]. 2 =0.9980.

[0050] Example 5

[0051] Based on the biosensor prepared in Example 1, this example demonstrates the detection of catechol concentration, as detailed below:

[0052] Phosphate buffer solution at pH 6.0, river water, and seawater were used as test water bodies. Under constant potential (-0.1V vs. SCE) and rapid stirring conditions, 20 μL of 1.0 mM catechol was added dropwise to 20 mL of the test water solution every 100 s. The performance of the biosensor in different water bodies was obtained, as shown in Table 1.

[0053] Table 1 Performance of biosensors modified with MXene-yttrium oxide hybrid complexes

[0054]

[0055] Example 6

[0056] Based on the biosensor prepared in Example 1, this example conducted an anti-interference experiment, as detailed below:

[0057] In 20 mL of phosphate buffer (pH 6.0, concentration 0.02 mol / L), at a constant potential (-0.1 V vs. SCE), 20 μL each of 0.2 mM catechol and 1.0 mM catechol were added sequentially. Then, 20 μL of a 0.1 M inorganic mixed salt (FeCl3, CaCl2, MgSO4, ZnSO4, CuSO4) and 20 μL of 2 mM ascorbic acid and aniline were added dropwise. The results showed that the added interfering substances had no significant response to the detection performance of the biosensor, indicating that the biosensor has good anti-interference performance.

[0058] This invention disperses rare earth oxides on the surface of Mxene molecules through ultrasonic dispersion and electrostatic interaction to obtain an MXene-rare earth oxide hybrid complex. The complex solution and enzyme solution are then sequentially constructed onto the surface of a platinum disk electrode, and a biosensor is prepared through a phase transfer process. This biosensor is simple to prepare, compact, and possesses advantages such as fast response time, good selectivity, high sensitivity (2394 mA / M), and extremely low detection limit (7 nM). It is suitable for the rapid and accurate detection of trace concentrations of catechol and can be applied to the rapid determination of trace catechol in common environmental water bodies such as river water, lake water, and seawater.

[0059] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained through equivalent substitution or transformation fall within the protection scope of the present invention.

Claims

1. A method for fabricating a biosensor based on an MXene-rare earth oxide hybrid complex, characterized in that, Specifically as follows: (1) Rare earth oxide is added to an MXene solution with a concentration of 1~10 mg / mL to make the rare earth oxide dispersion concentration in the mixed solution 1~20 mg / mL, and the MXene-rare earth oxide hybrid complex is obtained after ultrasonic dispersion; the rare earth oxide is one of yttrium oxide, praseodymium oxide, lanthanum oxide or samarium oxide; the mass ratio of rare earth oxide to MXene in the mixed solution is 1:1 to 20:1; (2) Prepare a 0.5 wt% chitosan solution using a 0.05 M acetic acid solution as a solvent; (3) Mix the phosphate buffer solution with the chitosan solution described in step (2) at a volume ratio of 1:1, then add polyphenol oxidase and mix well to obtain a polyphenol oxidase solution with a concentration of 3~10 mg / mL. (4) The MXene-rare earth oxide hybrid complex described in step (1) and the polyphenol oxidase solution described in step (3) are sequentially constructed onto the surface of a platinum disk electrode, and a biosensor based on the MXene-rare earth oxide hybrid complex is prepared by a phase transfer process.

2. The method for preparing the biosensor based on the MXene-rare earth oxide hybrid complex according to claim 1, characterized in that, The MXene is a two-dimensional layered structure material with graphene-like properties, obtained by reacting MAX phase material with HF solution.

3. The method for preparing the biosensor based on the MXene-rare earth oxide hybrid complex according to claim 1, characterized in that, The concentration of the phosphate buffer solution is 0.02 mol / L.

4. The method for preparing the biosensor based on the MXene-rare earth oxide hybrid complex according to claim 1, characterized in that, In step (4), the volume ratio of the MXene-rare earth oxide hybrid complex and the polyphenol oxidase solution constructed on the surface of the platinum disk electrode is 1:1 to 1:

3.

5. A biosensor based on an MXene-rare earth oxide hybrid complex obtained by any of the preparation methods described in claims 1 to 4.

6. An application of the biosensor based on the MXene-rare earth oxide hybrid complex as described in claim 5 for detecting trace amounts of catechol in environmental water.

7. The application of the biosensor according to claim 6 in detecting trace amounts of catechol in environmental water, characterized in that, The biosensor has a sensitivity of up to 2394 mA / M to catechol.

8. The application of the biosensor according to claim 6 in detecting trace amounts of catechol in environmental water, characterized in that, During the detection process, the linear regression equation for the change in catechol concentration and reduction current is as follows: I = 0.1154-2.3949C; Where I is the change in current during catechol detection, in μA; C is the concentration of catechol in the test solution, in μmol / L; the linear detection range of catechol in the test solution is 0.04~2.84μM, the detection limit is 7nM, and the correlation coefficient R0 is [missing value]. 2 =0.9985.

Images