Composite material modified electrode based on functionalized single-walled carbon nanotubes and application thereof

Abstract

The invention discloses a composite material modified electrode based on a functionalized single-walled carbon nanotube and application thereof, and belongs to the technical field of electrochemistry, the modified electrode comprises a glassy carbon electrode and a functionalized single-walled carbon nanotube-glucose composite material coating coated on the surface of the glassy carbon electrode; the mass ratio of functionalized single-walled carbon nanotubes to glucose in the coating is (0.2-5): 1, and the functionalized single-walled carbon nanotubes comprise at least one of hydroxylated single-walled carbon nanotubes, carboxylated single-walled carbon nanotubes and aminated single-walled carbon nanotubes, preferably hydroxylated single-walled carbon nanotubes. The composite material modified electrode provided by the invention has a large number of active sites, and by effectively utilizing the synergistic effect of the hydroxylated single-walled carbon nanotubes and glucose, the modified electrode shows excellent selective recognition capability on amino acid enantiomers and also shows good stability; and the method has a good application prospect in quantitative analysis of the amino acid enantiomers.

Description

[0001] This invention relates to the field of electrochemical testing technology, and in particular to composite material modified electrodes based on functionalized single-walled carbon nanotubes and their applications. Background Technology

[0002] Chirality is a crucial characteristic of nature, playing a vital role at the molecular level in biology, medicine, and biotechnology. Most bioactive substances are chiral molecules, such as amino acids, proteins, enzymes, and deoxyribonucleic acid (DNA). Amino acids are the most important and predominant chiral compounds in nature, serving as crucial biomarkers for various metabolic diseases. Developing efficient, rapid, and sensitive methods for the determination of amino acid enantiomers is a pressing challenge.

[0003] Chiral recognition of chiral enantiomers typically employs methods such as high-performance liquid chromatography (HPLC), molecular imprinting (MIP), capillary electrochromatography (CEC), fluorescence (FL) detection, and electrochemical analysis. Electrochemical methods have attracted widespread attention from researchers due to their advantages of low cost, high specificity, high sensitivity, fast detection speed, and ease of regeneration. In recent years, electrochemical sensing techniques based on chiral functional recognition molecules modified with electrodes have also been developed for the determination of chiral enantiomers. A key step in the electrochemical chiral recognition of amino acid enantiomers is the preparation of chiral surfaces with multiple recognition sites to distinguish enantiomers.

[0004] Currently, common chiral selectors used for the chiral electrochemical recognition of amino acid (AA) enantiomers include cyclodextrins (CDs) (such as α-CD, β-CD, and γ-CD) and their derivatives, bovine serum albumin (BSA), chitosan (CS), amino acids (AAs), and sodium alginate (SA). Nanomaterials such as carbon nanotubes, graphene oxide, and reduced graphene oxide, due to their high surface area, high intrinsic mobility, and good conductivity, are used to modify electrodes, significantly enhancing the functional characteristics of chiral electrochemical sensors and are therefore applied in the field of electrochemical chiral recognition. Furthermore, chiral nanocomposites can be synthesized by modifying nanomaterials with conventional optically pure chiral selectors, or nanomaterials can be mixed with optically pure chiral selectors and used as chiral selectors to modify electrodes. This also yields electrode surfaces with chiral recognition sensing functions, and the chiral recognition sensitivity of such electrodes is far higher than that of electrodes directly modified with ordinary selectors. For example, Yu et al. constructed a novel electrochemical sensor based on a glassy carbon electrode modified with a multi-walled carbon nanotube (MWCNT)-chitosan (CS) composite material (MWCNT-CS), which can achieve chiral recognition of tryptophan (Trp) enantiomers, with a peak potential difference of 117 mV using differential pulse voltammetry (DPV). RSC AdvancesFu et al. modified a glassy carbon electrode with acidified multi-walled carbon nanotubes (MWCNTs), dried it under an infrared lamp, then drop-coated hemoglobin (Hb) and dried it in air to form a film. With Cu(II) assistance, this film could be used for the electrochemical analysis of arginine (Arg) enantiomers. Chemical Communications (2012, 48, 2322-2324). However, due to the significant inhomogeneity of the coating on the electrode surface after coupling or mixing of nano-carbon materials with chiral selectors, this method suffers from poor reproducibility and unstable coating that is prone to peeling off during analysis. Solving this problem can better improve the universality and sensitivity of electrochemical chiral recognition, and is of great significance for the reliable identification and detection of chiral enantiomers.

[0005] Single-walled carbon nanotubes (SWCNTs), as a type of carbon nanomaterial, have been widely used in electrochemical sensors due to their large specific surface area and good conductivity. However, the application of raw SWCNTs is somewhat limited by their aggregation effect, while functionalized SWCNTs can reduce this aggregation effect. Furthermore, glucose, a widely distributed monosaccharide in nature, is a chiral molecule with good hydrophilicity. Applying glucose to functionalized SWCNTs can further reduce the aggregation effect, thereby improving the stability of electrochemical chiral sensors. Summary of the Invention

[0006] The purpose of this invention is to provide a composite material modified electrode based on functionalized single-walled carbon nanotubes and its application. By using a self-assembled functionalized single-walled carbon nanotube-glucose composite material to modify the surface of a glassy carbon electrode, the stability, specificity and chiral recognition ability of the modified electrode for amino acid enantiomers are effectively improved.

[0007] To achieve the above objectives, the present invention first provides a composite material modified electrode based on functionalized single-walled carbon nanotubes, including a glassy carbon electrode and a functionalized single-walled carbon nanotube-glucose composite material coating coated on the surface of the glassy carbon electrode.

[0008] Furthermore, the functionalized single-walled carbon nanotubes include, but are not limited to, at least one of hydroxylated single-walled carbon nanotubes, carboxylated single-walled carbon nanotubes, and aminated single-walled carbon nanotubes.

[0009] Preferably, the functionalized single-walled carbon nanotubes include hydroxylated single-walled carbon nanotubes. The composite material electrode assembled from hydroxylated single-walled carbon nanotubes and glucose exhibits better recognition ability for amino acid enantiomers, presumably because: hydroxyl groups are strongly hydrophilic, enabling the composite material to disperse more uniformly and stably in aqueous solution, promoting the formation of a denser and more uniform composite film on the electrode surface, providing a larger effective surface area and more reaction sites, thus giving the electrode a higher current response. Although carboxylated single-walled carbon nanotubes are also hydrophilic, they easily form hydrogen bond aggregations in solution, while aminated single-walled carbon nanotubes are less dispersible in aqueous solution than hydroxyl groups. Secondly, the hydroxylation group modifies the chiral microenvironment of the single-walled carbon nanotubes, enabling it to form multiple, direction-specific hydrogen bonds with the chiral center of glucose and amino, carboxyl, and phenolic hydroxyl groups of amino acids such as tyrosine. This optimizes and stabilizes the hydrogen bond combination between the composite material and specific enantiomers (L-type or D-type), increasing the recognition ability for amino acid enantiomers and exhibiting higher potential difference and current ratio values.

[0010] In a preferred embodiment, the functionalized single-walled carbon nanotube is a hydroxylated single-walled carbon nanotube.

[0011] Furthermore, in the functionalized single-walled carbon nanotube-glucose composite coating, the mass ratio of functionalized single-walled carbon nanotubes to glucose is 0.2-5:1, such as, but not limited to, any one of 0.2:1, 0.3:1, 0.33:1, 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, etc.

[0012] In a preferred embodiment, the mass ratio of functionalized single-walled carbon nanotubes to glucose in the composite coating is 0.3-3:1.

[0013] Furthermore, the present invention also provides a method for preparing the composite material modified electrode, comprising the following steps: dispersing functionalized single-walled carbon nanotubes and glucose in deionized water, preparing a functionalized single-walled carbon nanotube-glucose composite material by hydrothermal reaction, and then drop-coating the composite material onto the surface of a glassy carbon electrode and drying it.

[0014] In one embodiment, the method for preparing the composite material modified electrode includes the following steps: S1: Weigh functionalized single-walled carbon nanotubes and glucose according to the mass ratio and place them in a reaction vessel. Add deionized water to prepare a mixture with a total mass concentration of 2-10 mg / mL. The mixture is then subjected to hydrothermal reaction at 50-180℃ to obtain the functionalized single-walled carbon nanotube-glucose composite material. S2: The functionalized single-walled carbon nanotube-glucose composite material obtained in S1 is drop-coated onto the surface of a glassy carbon electrode and dried to obtain the composite material-modified electrode.

[0015] Further, the hydrothermal reaction temperature in step S1 is 80-160℃, exemplified but not limited to any of the following: 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, 130℃, 135℃, 140℃, 145℃, 150℃, 155℃, and 160℃. During the hydrothermal process, functionalized single-walled carbon nanotubes, especially hydroxylated single-walled carbon nanotubes, can form an effective cross-linking reaction with glucose molecules. When the hydrothermal temperature is too low, the cross-linking of functionalized single-walled carbon nanotubes and glucose is insufficient, resulting in a loose structure or weak specific recognition. Conversely, when the hydrothermal temperature is too high, glucose will generate highly carbonized substances, which will cover the chiral recognition sites of the functionalized single-walled carbon nanotubes, leading to a sharp decrease in the chiral recognition ability of the composite material. This manifests as a reduction in both the potential difference and current ratio of the modified electrode to the amino acid enantiomer. Furthermore, excessively high temperatures can cause the functionalized single-walled carbon nanotubes to become densely packed, increasing the charge transfer resistance of the composite material. This results in a decrease in the response current value of the modified electrode to the amino acid enantiomer and a positive shift in the oxidation potential. Only at a suitable hydrothermal temperature can the two components form a composite structure with an appropriate distribution of pores and active sites through intermolecular interactions such as hydrogen bonding and electrostatic interactions. These distributed pores and active sites can match the size and interaction sites of the amino acid enantiomers, providing the modified electrode with a chiral microenvironment, thereby enriching and recognizing the amino acid enantiomers.

[0016] Further, the hydrothermal reaction time in step S1 is 60-240 min, exemplified but not limited to any one of 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, 130 min, 140 min, 150 min, 160 min, 170 min, 180 min, 190 min, 200 min, 210 min, 220 min, 230 min, and 240 min.

[0017] Furthermore, the total mass concentration of the mixture in S1 is 4-8 mg / mL, and can be any one of 4 mg / mL, 5 mg / mL, 6 mg / mL, 7 mg / mL, 8 mg / mL, etc.

[0018] Further, in step S2, the amount of the functionalized single-walled carbon nanotube-glucose composite material applied is 2-15 μL, exemplified but not limited to any of the following: 2 μL, 3 μL, 4 μL, 5 μL, 6 μL, 7 μL, 8 μL, 9 μL, 10 μL, 11 μL, 12 μL, 13 μL, 14 μL, 15 μL. This invention does not strictly limit the number of applications; the coating can be completed in one application or applied in multiple applications, such as two, three, or four applications, depending on actual needs. If the amount applied is too small, the composite coating thickness is thin. Although the diffusion path of amino acid molecules in the electrolyte to the active sites is short, the electrode surface coverage is insufficient, the density of chiral recognition sites is low, and the selective recognition ability is weak. If the amount applied is too large, the diffusion layer thickness exceeds the penetration depth of amino acids on the electrode surface. Deep active sites become ineffective because amino acid molecules cannot fully reach them, and the effective chiral sites will decrease.

[0019] Furthermore, in step S2, the drying method includes one or more of the following: air drying, infrared lamp heating drying, and nitrogen gas purging drying, with a drying time of 30-360 minutes.

[0020] Furthermore, the present invention also provides the application of the functionalized single-walled carbon nanotube composite material modified electrode in the selective recognition of amino acid enantiomers, specifically: using the functionalized single-walled carbon nanotube composite material modified electrode as the working electrode, constructing a three-electrode system, and placing it in an electrolyte containing amino acid enantiomers for electrochemical scanning.

[0021] Furthermore, the application of the composite material modified electrode in the selective recognition of amino acid enantiomers is specifically as follows: A1. Constructing a three-electrode system: using a composite material modified electrode of functionalized single-walled carbon nanotubes as the working electrode, an Ag / AgCl electrode as the reference electrode, and a platinum wire electrode as the counter electrode; A2. Immersing the above three-electrode system in an electrolyte solution containing amino acid enantiomers for electrochemical scanning to identify and detect amino acid enantiomers.

[0022] Preferably, the electrolyte solution is selected from one or more of inorganic salt buffer solutions and inorganic acid buffer solutions; in one embodiment, the electrolyte solution is a phosphate buffer solution (PBS); in one embodiment, the electrolyte solution is an HAc-NaAc buffer solution; in one embodiment, the electrolyte solution is a Tris-HCl buffer solution; in one embodiment, the electrolyte solution is a BR buffer solution.

[0023] Preferably, the concentration of the electrolyte solution is 0.01-1 mol / L, more preferably 0.01-0.5 mol / L, and even more preferably 0.05-0.2 mol / L.

[0024] Preferably, the electrochemical scanning can be performed using any one of cyclic voltammetry (CV), differential pulse voltammetry (DPV), linear sweep voltammetry (LSV), or square wave voltammetry (SWV); in one embodiment, the electrochemical scanning is performed using square wave voltammetry.

[0025] Preferably, the potential window for electrochemical scanning is 0-1.4V.

[0026] Preferably, the functionalized single-walled carbon nanotube composite modified electrode has a potential difference of ≥18mV with respect to the amino acid enantiomers, more preferably ≥24mV; the potential difference can be interpreted as the peak potential difference between L-type and D-type amino acids, i.e., E L -E D or E D -E L .

[0027] Preferably, the functionalized single-walled carbon nanotube composite modified electrode has a peak current ratio >1.1 for amino acid enantiomers, more preferably a peak current ratio ≥1.5, and even more preferably a peak current ratio ≥1.7. The peak current ratio can be interpreted as: the peak current response value of L-type amino acids (IL). L ) and D-type amino acid peak current response value (I D The ratio of I to 1 L / I D Or the peak current response value of D-type amino acids (I D ) and L-type amino acid peak current response value (I L The ratio of I to 1 D / I L .

[0028] Preferably, the amino acid is tyrosine.

[0029] The beneficial effects of this invention are: (1) The composite material modified electrode of functionalized single-walled carbon nanotubes in this application exhibits excellent selectivity based on the synergistic effect between functionalized single-walled carbon nanotubes and glucose. Functionalized single-walled carbon nanotubes (especially hydroxylated single-walled carbon nanotubes) can form hydrogen bond networks with glucose, enhance the chiral microenvironment, improve the recognition accuracy of amino acid enantiomers, and show high electrochemical signal and chiral recognition specificity.

[0030] (2) This invention utilizes functionalized single-walled carbon nanotubes to increase the density of active sites and stabilizes the composite material structure through glucose; hydrothermal self-assembly of functionalized single-walled carbon nanotubes and glucose with a specific content can not only increase the density of active sites by utilizing the high specific surface area of ​​functionalized single-walled carbon nanotubes and enhance the enrichment of amino acid enantiomers on the electrode surface, but also effectively retain the recognition ability of functionalized single-walled carbon nanotubes-glucose molecules, thereby ensuring good conductivity and recognition molecule characteristics.

[0031] (3) The functionalized single-walled carbon nanotube-glucose composite material prepared by the present invention improves the uniformity and adhesion stability of the coating of the electrode surface, provides a larger effective surface area and more reaction sites for the electrode surface, and gives the latter a higher and more stable current response.

[0032] (4) The method for detecting / identifying amino acid enantiomers by the composite material modified electrode of the functionalized single-walled carbon nanotubes prepared in this invention is efficient and accurate. It can accurately and quickly perform qualitative and quantitative analysis of amino acid enantiomers, with excellent reproducibility, which is conducive to expanding its application range in practical electrochemical detection. Attached Figure Description

[0033] Figure 1 Scanning electron microscope image of hydroxylated single-walled carbon nanotubes.

[0034] Figure 2 Scanning electron microscope image of glucose.

[0035] Figure 3 Scanning electron microscope image of hydroxylated single-walled carbon nanotube-glucose composite material.

[0036] Figure 4 Square wave voltammetry curves for recognizing tyrosine enantiomers using a bare GCE glassy carbon electrode.

[0037] Figure 5 Square wave voltammetry curves of glucose-modified electrode (Glc / GCE) recognizing tyrosine enantiomers.

[0038] Figure 6 Square wave voltammetry curves of hydroxylated single-walled carbon nanotube modified electrode (SWCNT-OH / GCE) recognizing tyrosine enantiomers.

[0039] Figure 7 Square wave voltammetry curves of hydroxylated single-walled carbon nanotube-glucose-modified glassy carbon electrode (SWCNT-OH-Glc / GCE) recognizing tyrosine enantiomers.

[0040] Figure 8Square wave voltammetry curves of L-tyrosine at different concentrations using a hydroxylated single-walled carbon nanotube-glucose-modified glassy carbon electrode (SWCNT-OH-Glc / GCE).

[0041] Figure 9 Square wave voltammetry curves of D-tyrosine at different concentrations using a hydroxylated single-walled carbon nanotube-glucose-modified glassy carbon electrode (SWCNT-OH-Glc / GCE).

[0042] Figure 10 Linear curves of L-tyrosine and D-tyrosine detection at different concentrations using a hydroxylated single-walled carbon nanotube-glucose-modified glassy carbon electrode (SWCNT-OH-Glc / GCE).

[0043] Figure 11 Comparison of recognition efficiency of hydroxylated single-walled carbon nanotube-glucose-modified glassy carbon electrode (SWCNT-OH-Glc / GCE) for enantiomers of tryptophan (Trp), histidine (His), tyrosine (Tyr), and phenylalanine (Phe).

[0044] Figure 12 Square wave voltammetry curves of tryptophan enantiomer (Trp) recognized by hydroxylated single-walled carbon nanotube-glucose modified glassy carbon electrode (SWCNT-OH-Glc / GCE).

[0045] Figure 13 Square wave voltammetry curves of histidine enantiomer (His) recognized by hydroxylated single-walled carbon nanotube-glucose modified glassy carbon electrode (SWCNT-OH-Glc / GCE).

[0046] Figure 14 Square wave voltammetry curves of hydroxylated single-walled carbon nanotube-glucose-modified glassy carbon electrode (SWCNT-OH-Glc / GCE) recognizing tyrosine enantiomers (Tyr).

[0047] Figure 15 Square wave voltammetry curves of hydroxylated single-walled carbon nanotube-glucose-modified glassy carbon electrode (SWCNT-OH-Glc / GCE) recognizing phenylalanine enantiomer (Phe).

[0048] Appendix Figure 4-7 In the diagram, curve a corresponds to L-tyrosine (L-Tyr), and curve b corresponds to D-tyrosine (D-Tyr). The current separation between curves a and b (using IL) is analyzed. L / I D The difference in recognition ability can be seen from the expression (representation) and the potential difference (ΔEp). Detailed Implementation

[0049] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0050] In the following examples, the hydroxylated single-walled carbon nanotubes were purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd., with the following specifications: purity >95%, diameter 1-2 nm, and length 5-30 μm.

[0051] Example 1 This embodiment provides a composite material modified electrode based on functionalized single-walled carbon nanotubes, specifically: a hydroxylated single-walled carbon nanotube-glucose modified electrode, prepared by the following method: S1: Weigh 24 mg of hydroxylated single-walled carbon nanotubes and 8 mg of glucose and place them in a reaction vessel and mix them. Add 4 mL of deionized water and perform hydrothermal treatment at 100 °C for 240 min. After the reaction is completed, cool the mixture to room temperature and pour out the reaction solution to obtain the hydroxylated single-walled carbon nanotube-glucose composite material. S2: Use a pipette to transfer 5 μL of the hydroxylated single-walled carbon nanotube-glucose composite material and drop it onto the surface of a clean glassy carbon electrode. Dry it in an infrared drying oven for 30 min to obtain the hydroxylated single-walled carbon nanotube-glucose modified electrode.

[0052] Example 2 This embodiment provides a composite material modified electrode based on functionalized single-walled carbon nanotubes, specifically: a hydroxylated single-walled carbon nanotube-glucose modified electrode, prepared by the following method: S1: Weigh 8 mg of hydroxylated single-walled carbon nanotubes and 16 mg of glucose and place them in a reaction vessel and mix them. Add 4 mL of deionized water and perform hydrothermal treatment at 130 °C for 100 min. After the reaction is completed, cool the mixture to room temperature and pour out the reaction solution to obtain the hydroxylated single-walled carbon nanotube-glucose composite material. S2: Use a pipette to transfer 10 μL of the hydroxylated single-walled carbon nanotube-glucose composite material and drop it onto the surface of a clean glassy carbon electrode. Let it air dry for 360 min to obtain the hydroxylated single-walled carbon nanotube-glucose modified glassy carbon electrode.

[0053] Example 3 This embodiment provides a composite material modified electrode based on functionalized single-walled carbon nanotubes, specifically: a hydroxylated single-walled carbon nanotube-glucose modified electrode, prepared by the following method: S1: Weigh 8 mg of hydroxylated single-walled carbon nanotubes and 24 mg of glucose and place them in a reaction vessel and mix them. Add 4 mL of deionized water and perform hydrothermal treatment at 140 °C for 100 min. After the reaction is completed, cool the mixture to room temperature and pour out the reaction solution to obtain the hydroxylated single-walled carbon nanotube-glucose composite material. S2: Use a pipette to transfer 10 μL of the hydroxylated single-walled carbon nanotube-glucose composite material and drop it onto the clean glassy carbon electrode surface. Dry it in a nitrogen stream for 100 min to obtain the hydroxylated single-walled carbon nanotube-glucose modified glassy carbon electrode.

[0054] Example 4 This embodiment provides a composite material modified electrode based on functionalized single-walled carbon nanotubes, specifically: a hydroxylated single-walled carbon nanotube-glucose modified electrode, prepared by the following method: S1: Weigh 8 mg of hydroxylated single-walled carbon nanotubes and 8 mg of glucose and place them in a reaction vessel and mix them. Add 4 mL of deionized water and perform hydrothermal treatment at 120 °C for 120 min. After the reaction is completed, cool the mixture to room temperature and pour out the reaction solution to obtain the hydroxylated single-walled carbon nanotube-glucose composite material. S2: Use a pipette to transfer 8 μL of the hydroxylated single-walled carbon nanotube-glucose composite material and drop it onto the surface of a clean glassy carbon electrode. Let it air dry for 300 min to obtain the hydroxylated single-walled carbon nanotube-glucose modified glassy carbon electrode.

[0055] Appendix Figure 1-3 The images show scanning electron microscope (SEM) images of hydroxylated single-walled carbon nanotubes, glucose, and a hydroxylated single-walled carbon nanotube-glucose composite material (Example 1), respectively. (See attached image.) Figure 1 It can be seen that the hydroxylated single-walled carbon nanotubes exhibit a slender tubular structure, with slightly rough or locally irregular protrusions on the tube wall surface, and a small amount of aggregation. (From the attached...) Figure 2 It can be seen that glucose exhibits a wrinkled, sheet-like structure. From the appendix... Figure 3 It can be seen that the hydroxylated single-walled carbon nanotube-glucose composite material has a loose, elongated tubular structure with a large specific surface area, exposing more active sites, which is beneficial for the chiral recognition of amino acid enantiomers. The structure of the hydroxylated single-walled carbon nanotube-glucose composite material is slightly different from that of individual hydroxylated single-walled carbon nanotubes and glucose, indicating that the composite material has been successfully assembled.

[0056] Example 5 This embodiment provides an application of a hydroxylated single-walled carbon nanotube-glucose modified electrode in the selective recognition of amino acid enantiomers, specifically: A1. Constructing a three-electrode system: The hydroxylated single-walled carbon nanotube-glucose-modified glassy carbon electrode prepared in Example 4 was used as the working electrode, the Ag / AgCl electrode as the reference electrode, and the platinum wire electrode as the counter electrode. A2. The above three-electrode system was immersed in a PBS buffer solution (0.1M, pH 7.0) containing amino acid enantiomers for square wave voltammetry electrochemical scanning to identify and detect amino acid enantiomers. The electrochemical scanning potential window for tyrosine (Tyr) enantiomers, phenylalanine (Phe) enantiomers, tryptophan (Trp) enantiomers, and histidine (His) enantiomers was 0-1.4 V; the SWV frequency was 15 Hz.

[0057] The analysis of the material characterization diagram and the detection results of the modified electrode for amino acid enantiomers is as follows: Appendix Figure 4 Square wave voltammetry (SWV) curves for identifying Tyr enantiomers using a bare GCE (glassy carbon electrode) are shown in the figure. As can be seen, the SWV peak potential and peak current almost overlap, indicating that the bare GCE lacks the ability to identify Tyr enantiomers due to the absence of a chiral selector. (See attached figure...) Figure 7 It can be seen that the peak current response ratio of the hydroxylated single-walled carbon nanotube-glucose modified glassy carbon electrode (SWCNT-OH-Glc / GCE) to L-Tyr and D-Tyr is (I L / I D =1.79) is the highest, and the peak potential difference is large (ΔEp=24mV), which means its recognition efficiency is much higher than that of glucose-modified glassy carbon electrode (Glc / GCE, I L / I D = 1.15, ΔEp = 8mV, Appendix Figure 5 ) and hydroxylated single-walled carbon nanotube modified glassy carbon electrode (SWCNT-OH / GCE, I L / I D =1.26, ΔEp=12mV, Appendix Figure 7 These results indicate that the hydroxylated single-walled carbon nanotube-glucose composite material assembled by the synergistic effect of hydroxylated single-walled carbon nanotubes and glucose has a loose, elongated tubular structure with abundant active sites, enabling it to efficiently capture and recognize Tyr enantiomers, and exhibiting high electrochemical signals and chiral recognition specificity.

[0058] Appendix Figure 8-9 Square wave voltammetry curves of L-tyrosine and D-tyrosine at different concentrations were obtained using a hydroxylated single-walled carbon nanotube-glucose-modified glassy carbon electrode (SWCNT-OH-Glc / GCE) as described in Example 4 of this application, as shown in the attached graph. Figure 10Linear curves for the detection of L-tyrosine and D-tyrosine at different concentrations using a glassy carbon electrode (SWCNT-OH-Glc / GCE) modified with hydroxylated single-walled carbon nanotubes and glucose at different concentrations are shown in the figure. Within the concentration range of 0.05-1.0 mM, the peak current of SWCNT-OH-Glc / GCE increases with increasing Tyr enantiomer concentration, exhibiting a good linear relationship. R 2 L-Tyr = 0.9997 and R 2 D-Tyr =0.97332).

[0059] Appendix Figure 12-15 The figures show square-wave voltammetry curves of Trp, Phe, His, and Tyr at the same concentration (1.0 mM) using a hydroxylated single-walled carbon nanotube-glucose-modified glassy carbon electrode (SWCNT-OH-Glc / GCE) as described in Example 4 of this application. Figure 11 The graph shows a comparison of the recognition efficiency of hydroxylated single-walled carbon nanotube-glucose-modified glassy carbon electrode (SWCNT-OH-Glc / GCE) for the enantiomers of tryptophan (Trp), histidine (His), tyrosine (Tyr), and phenylalanine (Phe). It can be seen that SWCNT-OH-Glc / GCE exhibits excellent stereospecificity for the Tyr enantiomer, mainly due to the differences in the stereospecificity of hydrogen bonds caused by the structural differences of the four amino acids. Specifically, the amino / carboxyl / phenolic hydroxyl groups of the Tyr enantiomer can form hydrogen bonds with the hydroxyl groups of SWCNT-OH-Glc / GCE, while Trp, Phe, and His lack phenolic hydroxyl groups, leading to weakened intermolecular interactions and even reducing the chiral recognition efficiency to below 1.10.

[0060] Stability test: (1) Electrode stability: Following the method in Example 5, the electrode was used for five parallel tests within one day, and the relative standard deviations of the L-Tyr and D-Tyr current response results were calculated ( RSD The figures are 0.64% and 3.65%, respectively.

[0061] (2) Composite Material Stability: The SWCNT-OH-Glc composite material prepared in Example 4 was stored at 4-8℃ for 6 months. Then, following the electrode preparation method, the SWCNT-OH-Glc composite material was used to modify a glassy carbon electrode. Five parallel tests were conducted on L-Tyr and D-Tyr. The current response of L-Tyr was calculated. RSD The current response of D-Tyr is 1.17%. RSD It is 0.71%.

[0062] The above results indicate that the designed composite material and its modified electrode SWCNT-OH-Glc / GCE have good stability and can be used for the detection and identification of Tyr enantiomers.

[0063] The method for detecting / identifying amino acid enantiomers using a composite material modified electrode based on functionalized single-walled carbon nanotubes prepared in this invention is efficient and accurate, and can accurately and rapidly perform qualitative and quantitative analysis of amino acid enantiomers, showing good application prospects.

[0064] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0065] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A composite material modified electrode based on functionalized single-walled carbon nanotubes, characterized in that, Including glassy carbon electrodes and functionalized single-walled carbon nanotube-glucose composite material coatings applied to the surface of glassy carbon electrodes; In the functionalized single-walled carbon nanotube-glucose composite coating, the mass ratio of functionalized single-walled carbon nanotubes to glucose is 0.2-5:

1. The functionalized single-walled carbon nanotubes include at least one of hydroxylated single-walled carbon nanotubes, carboxylated single-walled carbon nanotubes, and aminated single-walled carbon nanotubes.

2. The composite material modified electrode according to claim 1, characterized in that, The functionalized single-walled carbon nanotubes include hydroxylated single-walled carbon nanotubes; the mass ratio of functionalized single-walled carbon nanotubes to glucose is 0.3-3:

1.

3. The composite material modified electrode according to any one of claims 1-2, characterized in that, The preparation method of the composite material modified electrode includes the following steps: functionalized single-walled carbon nanotubes and glucose are dispersed in deionized water, and a hydrothermal reaction is carried out to prepare a functionalized single-walled carbon nanotube-glucose composite material. The composite material is then drop-coated onto the surface of a glassy carbon electrode and dried.

4. The composite material modified electrode according to claim 3, characterized in that, Includes the following steps: The method for preparing the composite material modified electrode includes the following steps: S1: Weigh functionalized single-walled carbon nanotubes and glucose according to the mass ratio and place them in a reaction vessel. Add deionized water to prepare a mixture with a total mass concentration of 2-10 mg / mL. The mixture is then subjected to hydrothermal reaction at 50-180℃ to obtain the functionalized single-walled carbon nanotube-glucose composite material. S2: The functionalized single-walled carbon nanotube-glucose composite material obtained in S1 is drop-coated onto the surface of a glassy carbon electrode and dried to obtain the composite material-modified electrode.

5. The composite material modified electrode according to claim 3 or 4, characterized in that, The hydrothermal reaction temperature is 80-160℃, and the hydrothermal reaction time is 60-240 min.

6. The composite material modified electrode according to claim 4, characterized in that, The amount of the functionalized single-walled carbon nanotube-glucose composite material is 5-10 μL.

7. The application of the composite material modified electrode according to claim 1 or 2 in the selective recognition of amino acid enantiomers, characterized in that, Specifically: A1. Construct a three-electrode system: use a composite material modified electrode with functionalized single-walled carbon nanotubes as the working electrode, use an Ag / AgCl electrode as the reference electrode, and use a platinum wire electrode as the counter electrode. A2. The above three-electrode system was immersed in an electrolyte solution containing amino acid enantiomers for electrochemical scanning to identify and detect amino acid enantiomers.

8. The application according to claim 7, characterized in that, The electrolyte solution is selected from phosphate buffer solution, HAc-NaAc buffer solution, Tris-HCl buffer solution or BR buffer solution; and / or, the concentration of the electrolyte solution is 0.01-1 mol / L; and / or, the electrochemical scan is performed using any one of cyclic voltammetry, differential pulse voltammetry, linear scan voltammetry, square wave voltammetry; and / or, the potential window for the electrochemical scan is 0-1.4 V.

9. The application according to claim 7, characterized in that, The functionalized single-walled carbon nanotube composite modified electrode has a potential difference of ≥18mV to the amino acid enantiomer and a peak current ratio of >1.

1.

10. The application according to any one of claims 7-9, characterized in that, The amino acid in question is tyrosine.

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