A dual-mode chiral sensing platform for identifying amino acid enantiomers, its preparation method and its application

Abstract

This invention relates to a dual-mode chiral sensing platform, its preparation method, and its application for identifying amino acid enantiomers, belonging to the field of electrochemical sensing technology. The preparation method includes the following steps: preparing an MXene-gold nanoparticle-N-acetyl-L-cysteine ​​chiral solution; preparing an MXene-gold nanoparticle-N-acetyl-L-cysteine / L(D)-amino acid solution; preparing an MXene-gold nanoparticle-N-acetyl-L-cysteine ​​modified electrode; electrochemical chiral recognition of amino acid enantiomers; and temperature-based chiral recognition of amino acid enantiomers. This invention utilizes MXene, a two-dimensional nanomaterial with excellent conductivity and photothermal conversion capabilities, as a carrier to in-situ load gold nanoparticles. N-acetyl-L-cysteine ​​containing a thiol group at the end is captured through Au-S bonds. This chiral material can achieve chiral recognition of amino acid enantiomers through both electrochemical and temperature-based chiral sensing modes.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical sensing technology, specifically relating to a dual-mode chiral sensing platform for identifying amino acid enantiomers, its preparation method, and its application. Technical Background

[0002] Chirality is a common phenomenon in nature; enantiomers with different configurations generally exhibit completely different biological activities. Amino acids are an important class of chiral molecules, serving as the basic building blocks of proteins and important bioactive substances. For example, tryptophan, one of the eight essential amino acids for humans, plays a crucial role in living systems. L-tryptophan is a precursor to neurotransmitters and neurohormones; it can improve sleep and immunity and is widely used in the treatment of Parkinson's disease and pellagra. D-tryptophan, however, is a non-protein amino acid and does not participate in the metabolic processes of living systems. Therefore, establishing a simple method for efficient chiral recognition of amino acid enantiomers is of great significance.

[0003] Electrochemical methods have attracted widespread attention from scientists due to their outstanding advantages such as simple operation, low cost, high sensitivity, and broad application prospects. However, low stability has always been a major problem for electrochemical researchers. Therefore, as a single recognition mode, electrochemical chiral recognition still faces significant challenges in improving accuracy.

[0004] To improve the accuracy of electrochemical sensing systems, researchers have designed dual-mode sensing platforms. Temperature sensing technology is of great significance in scientific research, agricultural production, and industrial production. Therefore, a dual-mode sensing platform, which combines electrochemical sensing and temperature sensing, can provide more diverse information and higher accuracy, improving the accuracy and reliability of analysis compared to a single-response system. Two-dimensional transition metal carbides (MXenes) have great application value in the fields of electrochemical and temperature sensing due to their excellent conductivity and high photothermal conversion ability.

[0005] This invention uses MXene, which has excellent electrical conductivity and photothermal conversion capabilities, to load gold nanoparticles in situ. It captures N-acetyl-L-cysteine ​​containing a thiol group at the end through Au-S bonds. The resulting chiral material can realize the chiral recognition of amino acid enantiomers through two chiral sensing modes: electrochemical and temperature. Summary of the Invention

[0006] To address the problems existing in the prior art, the present invention aims to design and provide a dual-mode chiral sensing platform, preparation method, and application that can be used to identify amino acid enantiomers.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] On one hand, the present invention provides a method for preparing a dual-mode chiral sensing platform that can be used to identify amino acid enantiomers, comprising the following steps:

[0009] (1) Weigh lithium fluoride and dissolve it in concentrated hydrochloric acid. Add titanium aluminum carbide and carry out an etching reaction. The product is washed with water several times by centrifugation until the pH of the supernatant is 6.0-7.0. The precipitate is obtained. Water is added and bubbled with N2. After ultrasonic treatment, the supernatant is obtained by centrifugation and freeze-drying to obtain MXene powder.

[0010] (2) Weigh MXene powder, add water, stir at room temperature, add 25mM chloroauric acid trihydrate to carry out in-situ reduction reaction, centrifuge to obtain precipitate and freeze dry to obtain MXene-gold nanoparticle powder.

[0011] (3) Weigh out MXene-gold nanoparticle powder and disperse it in water, perform ultrasonic reaction, add N-acetyl-L-cysteine, stir, and obtain MXene-gold nanoparticle-N-acetyl-L-cysteine ​​chiral solution;

[0012] (4) Take a chiral solution of MXene-gold nanoparticles-N-acetyl-L-cysteine ​​and drop it onto the electrode surface. The solvent evaporates under infrared light to obtain the MXene-gold nanoparticles-N-acetyl-L-cysteine ​​modified electrode.

[0013] In the preparation method described above, the mass and volume ratio of lithium fluoride, concentrated hydrochloric acid and titanium aluminum carbide in step (1) is 1-2g:10-20mL:0.5-1g; the etching reaction conditions are: temperature 25-45℃, time 24-48h; the N2 bubbling time is 10-30min; and the ultrasonic treatment time is 0.5-2h.

[0014] In the preparation method described above, the mass-to-volume ratio of MXene powder, water, and chloroauric acid trihydrate in step (2) is 1-10 mg: 20-30 mL: 1-2 mL; and the in-situ reduction reaction time is 5-20 min.

[0015] In the preparation method described above, the mass-to-volume ratio of MXene-gold nanoparticle powder, water, and N-acetyl-L-cysteine ​​in step (3) is 1-6 mg: 2-12 mL: 1-6 mg; the ultrasonic reaction time is 5-10 min; and the stirring time is 6-12 h.

[0016] Secondly, the present invention provides a dual-mode chiral sensing platform for identifying amino acid enantiomers, obtained by any of the preparation methods described herein.

[0017] Thirdly, the present invention provides a method for identifying amino acid enantiomers using the aforementioned dual-mode chiral sensing platform, comprising the following steps:

[0018] (a) Electrochemical chiral recognition of amino acid enantiomers: The MXene-gold nanoparticle-N-acetyl-L-cysteine ​​modified electrode was placed in L-amino acid and D-amino acid solutions, respectively, and differential pulse voltammetry data were recorded within the electrochemical window range of 0.3 to 1.2 V.

[0019] Alternatively, (b) temperature-chiral recognition of amino acid enantiomers: MXene-gold nanoparticle-N-acetyl-L-cysteine / L-amino acid solution and MXene-gold nanoparticle-N-acetyl-L-cysteine / D-amino acid solution were placed in centrifuge tubes, thermometers were inserted, and the solutions in the centrifuge tubes were irradiated with a near-infrared laser. Starting from 0s, the thermometer readings were observed and recorded every 1min.

[0020] In the identification method described above, the concentrations of the L-amino acid and D-amino acid solutions in step (a) are both 0.1–1 mM, the volumes of the L-amino acid and D-amino acid solutions are both 20–30 mL, and the standing time is 10–60 s.

[0021] The near-infrared laser in step (b) has a power of 1W and a wavelength of 808nm; the irradiation time is 5 to 25 minutes.

[0022] The identification method described herein includes the following steps in preparing the MXene-gold nanoparticle-N-acetyl-L-cysteine / L-amino acid solution and the MXene-gold nanoparticle-N-acetyl-L-cysteine / D-amino acid solution: adding 5 mM amino acid enantiomer solution to the chiral solution of MXene-gold nanoparticle-N-acetyl-L-cysteine, stirring, and obtaining the MXene-gold nanoparticle-N-acetyl-L-cysteine / L-amino acid solution and the MXene-gold nanoparticle-N-acetyl-L-cysteine / D-amino acid solution, respectively.

[0023] In the aforementioned identification method, the volume ratio of the MXene-gold nanoparticle-N-acetyl-L-cysteine ​​chiral solution to the amino acid enantiomer solution is 2–6:1; and the stirring time is 6–12 h.

[0024] The application of the dual-mode chiral sensing platform in the identification of amino acid enantiomers.

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

[0026] This invention utilizes MXene, a two-dimensional nanomaterial with excellent electrical conductivity and photothermal conversion capabilities, as a carrier to in-situ load gold nanoparticles. N-acetyl-L-cysteine ​​containing a thiol group at the terminal end is captured via Au-S bonds. This chiral material can achieve chiral recognition of amino acid enantiomers through both electrochemical and temperature-based chiral sensing modes. Compared to conventional single-mode chiral recognition, this dual-mode chiral recognition strategy improves the accuracy and reliability of chiral recognition through mutual verification of the two methods. Therefore, this dual-mode chiral recognition strategy has potential application prospects for rapid and accurate identification of amino acid enantiomers. Attached Figure Description

[0027] Figure 1 Transmission electron microscopy images of MXene (A) and MXene-gold nanoparticles (B) prepared in Example 1;

[0028] Figure 2 X-ray powder diffraction patterns of MXene and MXene-gold nanoparticles prepared in Example 1;

[0029] Figure 3 The Au 4f(A) and S2p(B) high-resolution XPS spectra of MXene-gold nanoparticles-N-acetyl-L-cysteine ​​prepared in Example 1 are shown.

[0030] Figure 4 Cyclic voltammetry plots of the MXene-gold nanoparticle-N-acetyl-L-cysteine ​​modified electrode in Example 4 and the glassy carbon electrode, MXene modified electrode, and MXene-gold nanoparticle modified electrode in Comparative Example 1 in a 0.1 M potassium chloride solution containing 5 mM potassium ferrocyanide / potassium ferrocyanide.

[0031] Figure 5 The differential pulse voltammogram of the MXene-gold nanoparticle-N-acetyl-L-cysteine ​​modified electrode in Example 5, used to identify 1 mM tryptophan enantiomers in 0.1 M phosphate buffer solution at pH 7.0;

[0032] Figure 6 The temperature-time curves of MXene-gold nanoparticles-N-acetyl-L-cysteine ​​and MXene-gold nanoparticles-N-acetyl-L-cysteine / L(D)-tryptophan solutions after near-infrared light irradiation are shown in Example 6.

[0033] Figure 7The bar graph shows the recognition performance of the MXene-gold nanoparticle-N-acetyl-L-cysteine ​​modified electrode in Example 4 and the MXene-gold nanoparticle modified electrode and N-acetyl-L-cysteine ​​modified electrode in Comparative Example 1 when electrochemically recognizing 1 mM tryptophan enantiomers in 0.1 M phosphate buffer solution at pH 7.0. Detailed Implementation

[0034] The present invention will be further described in conjunction with the accompanying drawings and embodiments. The following embodiments are intended to illustrate the present invention and not to further limit the present invention.

[0035] The MXene-gold nanoparticle-N-acetyl-L-cysteine ​​modified electrode of this invention identifies amino acid enantiomers using the following method:

[0036] R L / D =I L / I D

[0037] In the formula, R L / D I represents the ratio of the enantiomeric oxidation peak currents of amino acids. L and I D The values ​​represent the oxidation peak currents of L-amino acids and D-amino acids on the differential pulse voltammogram, respectively.

[0038] Example 1:

[0039] The preparation of MXene-gold nanoparticle-N-acetyl-L-cysteine ​​modified electrodes includes the following steps:

[0040] (1) Weigh 1.6g of lithium fluoride and dissolve it in 20mL of concentrated hydrochloric acid. Add 1g of titanium aluminum carbide and etch at 45℃ for 24h. After the reaction, wash the product with water by centrifugation several times until the pH of the supernatant is about 6. Add water to the washed precipitate and bubble with N2 for 20min, then sonicate for 1h. Freeze-dry the dark green supernatant obtained by centrifugation to obtain MXene powder. Weigh 1mg of MXene powder into a beaker, add 25mL of water, add 2mL of 25mM chloroauric acid trihydrate under stirring at room temperature, reduce in situ for 15min, and freeze-dry the solid obtained by centrifugation to obtain MXene-gold nanoparticle powder. Weigh 1mg of MXene-gold nanoparticle powder and add it to 2mL of water, sonicate for 5min, then add 1mg of N-acetyl-L-cysteine ​​and stir for 6h to obtain MXene-gold nanoparticle-N-acetyl-L-cysteine ​​chiral solution.

[0041] (2) Use a pipette to transfer 5 μL of the chiral solution of MXene-gold nanoparticles-N-acetyl-L-cysteine ​​prepared in step (1) and drop it onto the surface of the glassy carbon electrode. Evaporate the solvent under infrared light to obtain the MXene-gold nanoparticles-N-acetyl-L-cysteine ​​modified electrode.

[0042] like Figure 1 Transmission electron microscopy images of MXene and MXene-gold nanoparticles. Figure 1 A reveals that MXene exhibits a thin, sheet-like structure similar to graphene. After in-situ reduction, uniformly sized AuNPs (with an average particle size of approximately 15 nm) are loaded onto the MXene sheets. Figure 1 As shown in B. Figure 2 The X-ray powder diffraction pattern of MXene-gold nanoparticles is shown. From the XRD pattern of aluminum titanium carbide, 2θ = 9.5° and 39.0° correspond to the (002) and (104) crystal planes of aluminum titanium carbide, respectively. The diffraction peak of MXene generated from aluminum titanium carbide shifts to lower angles on the (002) crystal plane, which is due to the substitution of Al by OH and F groups. The diffraction peak at 39.0° corresponding to the (104) crystal plane disappears, indicating the successful preparation of MXene. The diffraction peaks of MXene-gold nanoparticles at 2θ = 38.9°, 44.3°, 64.5°, and 77.5° correspond to the (111), (200), (220), and (311) crystal planes of Au, respectively. This indicates that gold nanoparticles have been successfully loaded onto the MXene surface through in-situ reduction of MXene. Figure 3 High-resolution XPS spectra of Au 4f (A) and S 2p (B) of MXene-gold nanoparticles-N-acetyl-L-cysteine. Au 4f can be separated into two peaks, with the peak at 86.30 eV attributed to Au 4f. 5 / 2 The peak at 82.67 eV is attributed to Au 4f 7 / 2 The S2p peaks can be divided into two peaks with binding energies of 161.9 eV and 163.0 eV, belonging to Au-S and CS respectively.

[0043] Example 2:

[0044] The preparation of MXene-gold nanoparticle-N-acetyl-L-cysteine ​​modified electrode-1 includes the following steps:

[0045] (1) Weigh 1g of lithium fluoride and dissolve it in 10mL of concentrated hydrochloric acid. Add 0.5g of titanium aluminum carbide and etch at 25℃ for 30h. After the reaction, wash the product with water by centrifugation several times until the pH of the supernatant is about 6. Add water to the washed precipitate and bubble with N2 for 10min, then sonicate for 0.5h. Freeze-dry the dark green supernatant obtained by centrifugation to obtain MXene powder. Weigh 5mg of MXene powder into a beaker, add 20mL of water, add 1mL of 25mM chloroauric acid trihydrate under stirring at room temperature, reduce in situ for 5min, and freeze-dry the solid obtained by centrifugation to obtain MXene-gold nanoparticle powder. Weigh 3mg of MXene-gold nanoparticle powder and add it to 8mL of water. Sonicate for 7min, then add 3mg of N-acetyl-L-cysteine ​​and stir for 8h to obtain MXene-gold nanoparticle-N-acetyl-L-cysteine ​​chiral solution.

[0046] (2) Use a pipette to transfer 5 μL of the chiral solution of MXene-gold nanoparticles-N-acetyl-L-cysteine ​​prepared in step (1) and drop it onto the surface of the glassy carbon electrode. Evaporate the solvent under infrared light to obtain MXene-gold nanoparticles-N-acetyl-L-cysteine ​​modified electrode-1.

[0047] Example 3:

[0048] The preparation of MXene-gold nanoparticle-N-acetyl-L-cysteine ​​modified electrode-2 includes the following steps:

[0049] (1) Weigh 2g of lithium fluoride and dissolve it in 15mL of concentrated hydrochloric acid. Add 0.7g of titanium aluminum carbide and etch at 30℃ for 48h. After the reaction, wash the product with water by centrifugation several times until the pH of the supernatant is about 6. Add water to the washed precipitate and bubble with N2 for 30min, then sonicate for 2h. Freeze-dry the dark green supernatant obtained by centrifugation to obtain MXene powder. Weigh 10mg of MXene powder into a beaker, add 30mL of water, add 1.5mL of 25mM chloroauric acid trihydrate under stirring at room temperature, reduce in situ for 20min, and freeze-dry the solid obtained by centrifugation to obtain MXene-gold nanoparticle powder. Weigh 6mg of MXene-gold nanoparticle powder and add it to 12mL of water. Sonicate for 10min, then add 6mg of N-acetyl-L-cysteine ​​and stir for 12h to obtain MXene-gold nanoparticle-N-acetyl-L-cysteine ​​chiral solution.

[0050] (2) Use a pipette to transfer 5 μL of the chiral solution of MXene-gold nanoparticles-N-acetyl-L-cysteine ​​prepared in step (1) onto the surface of the glassy carbon electrode. Evaporate the solvent under infrared light to obtain MXene-gold nanoparticles-N-acetyl-L-cysteine ​​modified electrode-2.

[0051] Example 4:

[0052] The MXene-gold nanoparticle-N-acetyl-L-cysteine ​​modified electrode prepared in Example 1, along with the glassy carbon electrode, the MXene-modified electrode, and the MXene-gold nanoparticle modified electrode, were placed in a solution containing 5 mM [Fe(CN)6]. 4- / 3- In a 0.1 MkCl solution, cyclic voltammetry was used for testing within an electrochemical window of –0.2 to 0.6 V. The results are as follows: Figure 4 As shown, the glassy carbon electrode exhibits a pair of distinct redox peaks, which is due to... and This is caused by the interconversion of MXene; due to MXene's good conductivity, The redox peak current increases on the MXene-modified electrode surface. When the glassy carbon electrode surface is modified with MXene-gold nanoparticles, the redox peak current continues to increase. This is because the synergistic effect of MXene and gold nanoparticles effectively promotes electron transfer on the electrode surface. When the glassy carbon electrode surface is modified with MXene-gold nanoparticles-N-acetyl-L-cysteine, the redox peak current decreases. This is because the poorly conductive N-acetyl-L-cysteine ​​binds to the MXene-gold nanoparticles through Au-S bonds, thereby hindering electron transport.

[0053] Example 5:

[0054] The MXene-gold nanoparticle-N-acetyl-L-cysteine ​​modified electrode prepared in Example 1 was placed in 25 mL of 0.1 M phosphate buffer solution (pH 7.0) containing 1 mM L-tryptophan and D-tryptophan, respectively. After standing for 10 s, differential pulse voltammetry was recorded within the electrochemical window of 0.3–1.2 V. The differential pulse voltammetry of the tryptophan enantiomer on the MXene-gold nanoparticle-N-acetyl-L-cysteine ​​modified electrode is shown below. Figure 5 The oxidation peak current of L-tryptophan on the MXene-gold nanoparticle-N-acetyl-L-cysteine ​​modified electrode surface is significantly higher than that of D-tryptophan (R). L / D =1.49), which indicates that MXene-gold nanoparticles-N-acetyl-L-cysteine ​​have a higher affinity for L-tryptophan than for D-tryptophan.

[0055] Example 6:

[0056] Preparation of MXene-gold nanoparticle-N-acetyl-L-cysteine / L(D)-tryptophan solutions: Add 1 mL of 5 mM tryptophan enantiomer to 2 mL of MXene-gold nanoparticle-N-acetyl-L-cysteine ​​chiral solution and stir for 6 h to obtain MXene-gold nanoparticle-N-acetyl-L-cysteine / L(D)-tryptophan solutions. Place the solutions in 5 mL centrifuge tubes and insert a thermometer. Irradiate the solutions in the centrifuge tubes using a near-infrared laser. Starting from 0 s, observe and record the thermometer readings every 1 min for 25 min. Figure 6 Temperature-time curves for MXene-gold nanoparticles-N-acetyl-L-cysteine, MXene-gold nanoparticles-N-acetyl-L-cysteine / L-tryptophan, and MXene-gold nanoparticles-N-acetyl-L-cysteine / D-tryptophan. Figure 6 As can be seen, the MXene-gold nanoparticle-N-acetyl-L-cysteine ​​solution heated from 22℃ to 47℃ within 25 min, indicating that the material has good photothermal conversion ability. The MXene-gold nanoparticle-N-acetyl-L-cysteine / L-tryptophan and MXene-gold nanoparticle-N-acetyl-L-cysteine / D-tryptophan solutions heated from 22℃ to 40℃ and 45℃, respectively, within 25 min. The temperature difference before and after the binding of MXene-gold nanoparticle-N-acetyl-L-cysteine ​​with L-tryptophan was 7℃, which is more significant than the temperature difference before and after the binding of MXene-gold nanoparticle-N-acetyl-L-cysteine ​​with D-tryptophan (2℃). Since the photothermal conversion ability of amino acids is much weaker than that of MXene, this result indicates that L-tryptophan has a strong binding ability with MXene-gold nanoparticle-N-acetyl-L-cysteine.

[0057] Comparative Example 1:

[0058] MXene-modified electrodes, MXene-gold nanoparticle-modified electrodes, and N-acetyl-L-cysteine-modified electrodes were prepared. The operation steps were the same as step (2) in Example 1, except that the chiral solution drop-coated onto the glassy carbon electrode surface in step (2) was replaced with MXene-gold nanoparticles and N-acetyl-L-cysteine.

[0059] The prepared MXene-gold nanoparticle modified electrodes and N-acetyl-L-cysteine ​​modified electrodes were placed in 25 mL of 0.1 M phosphate buffer solution (pH 7.0) containing 1 mM L-tryptophan and D-tryptophan, respectively. After standing for 10 s, differential pulse voltammetry was recorded within the electrochemical window of 0.3–1.2 V. The oxidation peak current ratio is shown in the figure. Figure 7As shown, the oxidation peak current ratio of tryptophan enantiomers on the MXene-gold nanoparticle modified electrode is 1.00, indicating that the tryptophan enantiomers cannot be recognized on this modified electrode. This is because there are no chiral sites on the modified electrode surface. However, the oxidation peak current ratio of tryptophan enantiomers on the N-acetyl-L-cysteine ​​modified electrode is 1.11. This is because N-acetyl-L-cysteine ​​has chiral sites, which can electrochemically recognize the tryptophan enantiomers, showing some recognition effect, but the effect is not high. The oxidation peak current ratio of tryptophan enantiomers on the MXene-gold nanoparticle-N-acetyl-L-cysteine ​​modified electrode can reach 1.49, showing a significantly better recognition efficiency than the N-acetyl-L-cysteine ​​modified electrode.

Claims

1. A method for preparing a dual-mode chiral sensing platform for recognizing amino acid enantiomers, characterized in that, Includes the following steps: (1) Weigh lithium fluoride and dissolve it in concentrated hydrochloric acid. Add titanium aluminum carbide and carry out an etching reaction. The product is washed with water several times by centrifugation until the pH of the supernatant is 6.0-7.

0. The precipitate is obtained. Water is added and bubbled with N2. After ultrasonic treatment, the supernatant is obtained by centrifugation and freeze-drying to obtain MXene powder. (2) Weigh MXene powder, add water, stir at room temperature, add 25mM chloroauric acid trihydrate to carry out in-situ reduction reaction, centrifuge to obtain precipitate and freeze dry to obtain MXene-gold nanoparticle powder. (3) Weigh out MXene-gold nanoparticle powder and disperse it in water, perform ultrasonic reaction, add N-acetyl-L-cysteine, stir, and obtain MXene-gold nanoparticle-N-acetyl-L-cysteine ​​chiral solution; (4) Transfer the chiral solution of MXene-gold nanoparticles-N-acetyl-L-cysteine ​​and drop it onto the electrode surface. The solvent evaporates under infrared light to obtain the MXene-gold nanoparticles-N-acetyl-L-cysteine ​​modified electrode. The dual-mode refers to both electrochemical and temperature-based modes.

2. The preparation method according to claim 1, characterized in that, In step (1), the mass and volume ratio of lithium fluoride, concentrated hydrochloric acid and titanium aluminum carbide is 1-2 g : 10-20 mL : 0.5-1 g; the etching reaction conditions are: temperature 25-45℃, time 24-48 h; the N2 bubbling time is 10-30 min; and the ultrasonic treatment time is 0.5-2 h.

3. The preparation method according to claim 1, characterized in that, In step (2), the mass-to-volume ratio of MXene powder, water, and chloroauric acid trihydrate is 1-10 mg: 20-30 mL: 1-2 mL; the in-situ reduction reaction time is 5-20 min.

4. The preparation method according to claim 1, characterized in that, In step (3), the mass-to-volume ratio of MXene-gold nanoparticle powder, water, and N-acetyl-L-cysteine ​​is 1-6 mg : 2-12 mL : 1-6 mg; the ultrasonic reaction time is 5-10 min; and the stirring time is 6-12 h.

5. A dual-mode chiral sensing platform for identifying amino acid enantiomers, characterized in that, It is obtained by the preparation method according to any one of claims 1-4.

6. The method for identifying amino acid enantiomers using the dual-mode chiral sensing platform as described in claim 5, characterized in that, Includes the following steps: (a) Electrochemical chiral recognition of amino acid enantiomers: The MXene-gold nanoparticle-N-acetyl-L-cysteine ​​modified electrode was placed in L-amino acid and D-amino acid solutions, respectively, and differential pulse voltammetry data were recorded within the electrochemical window range of 0.3 to 1.2 V. Alternatively, (b) temperature-chiral recognition of amino acid enantiomers: MXene-gold nanoparticle-N-acetyl-L-cysteine / L-amino acid solution and MXene-gold nanoparticle-N-acetyl-L-cysteine / D-amino acid solution were placed in centrifuge tubes, thermometers were inserted, and the solutions in the centrifuge tubes were irradiated with a near-infrared laser. Starting from 0s, the thermometer readings were observed and recorded every 1min.

7. The identification method as described in claim 6, characterized in that, In step (a), the concentrations of the L-amino acid and D-amino acid solutions are both 0.1–1 mM, the volumes of the L-amino acid and D-amino acid solutions are both 20–30 mL, and the standing time is 10–60 s. The near-infrared laser in step (b) has a power of 1W and a wavelength of 808nm; the irradiation time is 5 to 25 minutes.

8. The identification method as described in claim 6, characterized in that, The preparation process of the MXene-gold nanoparticle-N-acetyl-L-cysteine / L-amino acid solution and the MXene-gold nanoparticle-N-acetyl-L-cysteine / D-amino acid solution includes: adding 5 mM amino acid enantiomer solution to the chiral solution of MXene-gold nanoparticle-N-acetyl-L-cysteine, stirring, and obtaining the MXene-gold nanoparticle-N-acetyl-L-cysteine / L-amino acid solution and the MXene-gold nanoparticle-N-acetyl-L-cysteine / D-amino acid solution, respectively.

9. The identification method as described in claim 8, characterized in that, The volume ratio of the MXene-gold nanoparticle-N-acetyl-L-cysteine ​​chiral solution to the amino acid enantiomer solution is 2–6:1; the stirring time is 6–12 h.

10. The application of the dual-mode chiral sensing platform as described in claim 5 in the identification of amino acid enantiomers.

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