A metal nanomaterial doped with a second metal, its preparation method and its application in chiral recognition

Abstract

This invention relates to a second metal-doped metal nanomaterial, its preparation method, and its application in chiral recognition, belonging to the field of chiral recognition technology. The preparation method of the second metal-doped metal nanomaterial includes the following steps: weighing L-ascorbic acid solution, a first metal solution, and a second metal solution, mixing them, and incubating to obtain the second metal-doped metal nanomaterial; when the first and second metals are different, the concentrations of the first and second metal solutions are different. The second metal-doped metal nanomaterials of this invention, such as AuAu and CuCu, exhibit high affinity for D-tryptophan, while those formed by doping with two metals, such as AuCu, exhibit the opposite recognition effect. This invention achieves the regulation of chiral recognition effects through metal doping, realizing the goal of on-demand control of the chiral recognition ability of metal nanomaterials.

Description

Technical Field

[0001] This invention belongs to the field of chiral recognition technology, specifically relating to a method for regulating the chiral recognition ability of metal nanomaterials by doping with metals. Background Technology

[0002] Chirality is a universal phenomenon in nature and a fundamental attribute of living systems. If an object is different from its mirror image, and the mirror image cannot be superimposed on the original object (like the left and right hands being mirror images that cannot be superimposed), it is called "chiral." Chirality is an essential property of nature, and chiral enantiomers are widely found in medicine, pesticides, food, and the human body. Generally, chiral enantiomers have similar chemical and physical properties, while different enantiomers exhibit different or even opposite pharmacological and biological activities. Therefore, it is necessary to develop chiral recognition strategies to distinguish enantiomers. Since chiral isomers of the same configuration exhibit different affinities when combined with different chiral materials, it is particularly important to regulate the chirality of materials according to the chiral requirements of the target substance. Current methods for material chirality recognition include chromatography, spectroscopy, and electrochemical methods. Optical instruments are expensive, chromatographic methods are too complex, while electrochemical methods are widely used for chiral recognition due to their low cost, high speed, and high sensitivity.

[0003] In the past decade, the chirality of nanomaterials has been a relatively new field, and significant progress has been made in the synthesis of chiral nanomaterials. Common chiral recognition materials include polysaccharide-based materials, chiral cavity-based materials, carbon-based materials, and metallic nanomaterials. Compared with other chiral materials, metallic nanomaterials have advantages such as large specific surface area, good stability, and easy surface modification, thus the field of chiral recognition based on metallic nanomaterials has developed rapidly. Alloy-type metallic nanomaterials are more likely to be anisotropic than single-element metallic nanomaterials, and therefore may have unique chiral recognition advantages. Research exploring the relationship between the chiral recognition capabilities of pure metals and alloy-type metallic nanomaterials is of great value, providing more design inspiration for the development of chiral recognition and separation, physicochemical property analysis of drugs, and cancer diagnosis and treatment. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention aims to provide a metal nanomaterial doped with a second metal, its preparation method, and its application in chiral recognition. The preparation method of the metal nanomaterial doped with a second metal (such as AuAu, CuCu, and AuCu metal nanomaterials) is simple, easy to implement, and highly reproducible. Single metal nanomaterials like AuAu and CuCu exhibit high affinity for D-tryptophan, while AuCu, formed by doping with two metals, exhibits the opposite recognition effect. By controlling the chiral recognition effect through metal doping, the chiral recognition capability of metal nanomaterials can be adjusted as needed, which has significant application value in the fields of chiral recognition and electrochemistry.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] On the one hand, the present invention provides a metal nanomaterial doped with a second metal, wherein the metal nanomaterial doped with a second metal uses a first metal solution and a second metal solution as metal sources, and L-ascorbic acid as a reducing agent to reduce positively charged metal ions to zero-valent metal atoms, thereby forming a metal nanomaterial;

[0007] The second metal may have the same or different metal composition as the metal nanomaterial.

[0008] The aforementioned metal nanomaterial doped with a second metal, wherein the metal component in the metal nanomaterial is one of copper, gold, or platinum, and the second metal is one of copper, gold, or platinum.

[0009] Secondly, the present invention provides a method for preparing a metal nanomaterial doped with a second metal, comprising the following steps:

[0010] Weigh out L-ascorbic acid solution, first metal solution, and second metal solution, mix them, and incubate them to obtain metal nanomaterials doped with the second metal;

[0011] When the first metal and the second metal are different, the concentrations of the first metal solution and the second metal solution are different.

[0012] In the preparation method described above, the first metal solution is one of an acid solution of gold, a salt solution of copper, or an acid solution of platinum; the second metal solution is one of an acid solution of gold, a salt solution of copper, or an acid solution of platinum. The first metal and the second metal have similar atomic radii, making it easy to form an alloy nanomaterial with a substitutional solid solution.

[0013] In the preparation method described above, the acid solution for gold is a chloroauric acid solution; the salt solution for copper is a copper chloride solution; and the acid solution for platinum is a chloroplatinic acid solution.

[0014] In the preparation method described above, the concentration of the L-ascorbic acid solution is 10-50 mmol / L; the concentration of the first metal solution is 1-5 mmol / L; the concentration of the second metal solution is 1-5 mmol / L; and the volume ratio of the L-ascorbic acid solution, the first metal solution, and the second metal solution is (1-5):(1-5):(1-5).

[0015] The preparation method described herein, wherein the incubation conditions are: temperature 30-80℃, time 1-4h.

[0016] Thirdly, the present invention provides the application of the metal nanomaterials doped with a second metal in the electrochemical method for chiral recognition of amino acids.

[0017] In the aforementioned application, the amino acid includes tryptophan.

[0018] The application in question includes the electrochemical method of differential pulse voltammetry.

[0019] The method for electrochemical chiral recognition of the metal nanomaterials in amino acid enantiomers is as follows: using AuAu, CuCu, or AuCu-modified glassy carbon electrodes as working electrodes, platinum sheet electrodes as counter electrodes, and calomel electrodes as reference electrodes, the working electrodes, counter electrodes, and reference electrodes are respectively placed in phosphate buffer solutions of L-tryptophan and D-tryptophan for incubation, and then the differential pulse voltammetry is used for testing and recognition under an electrochemical window.

[0020] The concentrations of both L-tryptophan and D-tryptophan solutions were 0.1-1 mmol / L, and the volumes were both 20-30 mL.

[0021] The concentration of the phosphate buffer solution is 0.1-1 mol / L, and the pH is 6.0-8.0; the voltage of the electrochemical window is 0.4-1.4 V.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. This invention utilizes the doping of pure metals with other metals to facilitate the formation of anisotropic morphologies in the materials, resulting in unique chiral recognition capabilities. The method proposed in this invention for controlling the chiral recognition capabilities of metal nanomaterials based on metal doping is a novel and efficient control method.

[0024] 2. This invention employs sensitive electrochemical techniques to identify tryptophan enantiomers and investigates the differences in their recognition abilities. The results show that AuAu, CuCu, and AuCu metal nanomaterials all exhibit significant recognition effects on tryptophan enantiomers. AuAu and CuCu demonstrate superior chiral recognition of D-tryptophan; while AuCu, formed through metal doping, exhibits the opposite chiral recognition effect, showing better recognition of L-tryptophan than D-tryptophan. The formation process of substitutional alloy solid solutions such as AuCu is prone to lattice defects, thus allowing for effective control of chiral recognition effects through metal doping. The excellent chiral recognition capabilities of AuAu, CuCu, and AuCu metal nanomaterials lay the foundation for constructing a controllable process.

[0025] 3. This invention achieves precise control over the chiral recognition ability of metal nanomaterials based on metal doping, thereby obtaining an excellent chiral recognition sensing platform and realizing the goal of on-demand control over the chiral recognition ability of metal nanomaterials. Metal nanomaterials with chiral recognition capabilities have significant application value in areas such as cancer synergistic therapy and control of enantiomeric enzymatic reactions, expanding the application of metal nanomaterials in the field of electrochemical chiral regulation. This on-demand regulation of chiral recognition is beneficial for enhancing the biocompatibility of materials, facilitating their entry into cells for disease detection and treatment, and providing new hope for drug delivery and cancer treatment. It can provide a reference for the on-demand regulation of chiral materials and open up new avenues for constructing intelligent and convenient chiral sensing platforms with variable enantioselectivity. Attached Figure Description

[0026] Figure 1 The extinction spectrum of AuAu prepared in Example 1;

[0027] Figure 2 Images showing the solution colors of the three metal nanomaterials (AuCu, AuAu, CuCu) prepared in this invention;

[0028] Figure 3 This is a transmission electron microscope image of AuAu prepared in Example 1;

[0029] Figure 4 The extinction spectrum of CuCu prepared in Example 2;

[0030] Figure 5 The extinction spectrum of AuCu prepared in Example 3;

[0031] Figure 6 This is a transmission electron microscope image of AuCu prepared in Example 3;

[0032] Figure 7The X-ray diffraction pattern of AuCu prepared in Example 3;

[0033] Figure 8 The differential pulse voltammogram for AuAu / GCE recognition of tryptophan enantiomers prepared in this invention;

[0034] Figure 9 The differential pulse voltammogram of CuCu / GCE recognizing tryptophan enantiomers prepared in this invention;

[0035] Figure 10 The differential pulse voltammogram of AuCu / GCE recognizing tryptophan enantiomers prepared in this invention;

[0036] Figure 11 Differential pulse voltammetry for recognizing tryptophan enantiomers using the bare glassy carbon electrode (GCE) of the present invention. Detailed Implementation

[0037] The present invention will now 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.

[0038] Unless otherwise specified, the experimental methods described in the embodiments are conventional methods; unless otherwise specified, the reagents and materials can be obtained commercially or through simple preparation using existing technologies.

[0039] The bare GCE, AuAu-modified electrode, CuCu-modified electrode, and AuCu-modified electrode of this invention identify tryptophan enantiomers using the following method: recognition efficiency = ID / IL; ID represents the oxidation peak current of the modified electrode in D-tryptophan solution; IL represents the oxidation peak current of the modified electrode in L-tryptophan solution.

[0040] Example 1: Preparation of AuAu solution

[0041] Includes the following steps:

[0042] Synthesis of AuAu: 800 μL of 40 mmol / L L-ascorbic acid solution was mixed with 1600 μL of 1.5 mmol / L chloroauric acid solution and 1600 μL of 1.25 mmol / L chloroauric acid solution, and incubated at 60 °C for 2 h.

[0043] like Figure 1 The image shows the extinction spectrum of AuAu, revealing a distinct extinction peak around 580 nm, which corresponds to the plasmon resonance peak of gold nanomaterials. Figure 2 Images showing the solution colors of three metallic nanomaterials (AuCu, AuAu, CuCu), and... Figure 2 The purple-red solution in the image corresponds to the color of the solution, thus proving the successful synthesis of AuAu. For example... Figure 3 The image shown is a transmission electron microscope (TEM) image of Au, indicating that the material is a uniform, symmetrical sphere.

[0044] Example 2: Preparation of CuCu solution

[0045] Synthesis of CuCu: 800 μL of 40 mmol / L L-ascorbic acid solution was mixed with 1600 μL of 1.5 mmol / L copper chloride solution and 1600 μL of 1.25 mmol / L copper chloride solution, and incubated at 60 °C for 2 h.

[0046] like Figure 2 As shown, since the CuCu solution is approximately colorless, it corresponds to... Figure 4 CuCu itself does not have a significant extinction peak.

[0047] Example 3: Preparation of AuCu solution

[0048] Mix 800 μL of 40 mmol / L L-ascorbic acid solution with 1600 μL of 1.5 mmol / L chloroauric acid solution and 1600 μL of 1.25 mmol / L copper chloride solution, and incubate at 60 °C for 2 h.

[0049] like Figure 5 The extinction spectrum of AuCu shows that the extinction peak of the formed AuCu alloy nanomaterial is located at around 620 nm, which is different from the extinction peak of AuAu at 580 nm. This proves that the introduction of copper causes a red shift in the extinction spectrum of the gold nanomaterial, and further indicates that the morphology of AuCu material is different from that of AuAu. Figure 2 The blue-purple solution of AuCu differs from the purplish-red of AuAu, which proves that copper is involved in the synthesis of gold nanomaterials and forms AuCu alloy nanomaterials that are different from AuAu.

[0050] like Figure 6 The transmission electron microscopy (TEM) images show the asymmetry of the AuCu morphology, indicating that AuCu is anisotropic, urchin-like nanocrystals. The morphological differences between AuAu and AuCu are consistent with the redshift results of their extinction spectra. Compared to the single metallic nanomaterial AuAu, AuCu alloy nanomaterials are more easily grown anisotropically. This anisotropy makes the material potentially chiral, thus contributing to its unique chiral recognition ability.

[0051] like Figure 7As shown, the five diffraction peaks in the X-ray diffraction pattern of AuCu are 38.35°, 44.49°, 63.71°, 77.70°, and 81.87°, corresponding to the standard card for gold (JCPDS 65-2870), and shifting towards higher angles, proving that the bulk material corresponds to the crystal structure of gold and exhibits cell shrinkage. Since the atomic radii of gold and copper are not significantly different, it is proven that the cell shrinkage is caused by a substitutional solid solution formed by copper atoms replacing gold atoms. This substitutional solid solution leading to cell shrinkage may cause lattice mismatch, thereby inducing a reversal of chiral recognition. The structural defects in the AuCu alloy solid solution result in a higher affinity for L-tryptophan, making AuCu / GCE's recognition of L-tryptophan superior to D-tryptophan, thus leading to a reversal of AuCu's chiral recognition effect. Therefore, this chiral recognition ability mainly originates from the intrinsic chirality of the alloy, with AuCu playing a dominant role. In summary, this demonstrates the reliability of the method of controlling the chiral recognition ability of metal nanomaterials by doping with metals.

[0052] Example 4:

[0053] Preparation of AuAu-modified electrode: 800 μL of 40 mmol / L L-ascorbic acid solution was mixed with 1600 μL of 1.5 mmol / L chloroauric acid solution and 1600 μL of 1.25 mmol / L chloroauric acid solution, and incubated at 60 °C for 2 h to obtain AuAu solution. Then, 5 μL of AuAu solution was drop-coated onto the electrode surface and allowed to air dry to obtain AuAu-modified electrode.

[0054] The AuAu-modified electrode was used as the working electrode, the platinum sheet electrode as the counter electrode, and the calomel electrode as the reference electrode. They were placed in 25 mL of 0.1 M phosphate buffer solution with pH 7.0 containing 1 mL of M-tryptophan and D-tryptophan, respectively, and the differential pulse voltammetry was used for testing within an electrochemical window of 0.4–1.2 V.

[0055] like Figure 8 As shown, when AuAu is modified on the GCE surface, AuAu / GCE exhibits a significant recognition effect on tryptophan enantiomers. For AuAu / GCE, D-tryptophan has a better adsorption effect compared to its isomorphic L-tryptophan, leading to the oxidation of more D-tryptophan on the electrode surface. The oxidation peak current signal of AuAu in the D-tryptophan solution is significantly higher than that in the L-tryptophan solution, and the recognition efficiency (ID / IL) of AuAu for tryptophan enantiomers is 1.14. Furthermore, thanks to the excellent conductivity of gold nanomaterials, the overall current signal of AuAu / GCE is high.

[0056] Example 5:

[0057] Preparation of CuCu-modified electrode: 800 μL of 40 mmol / L L-ascorbic acid solution was mixed with 1600 μL of 1.5 mmol / L copper chloride solution and 1600 μL of 1.25 mmol / L copper chloride solution, and incubated at 60 °C for 2 h to obtain CuCu solution. Then, 5 μL of CuCu solution was drop-coated onto the electrode surface and allowed to air dry to obtain CuCu-modified electrode.

[0058] The CuCu-modified electrode was used as the working electrode, the platinum sheet electrode as the counter electrode, and the calomel electrode as the reference electrode. They were placed in 25 mL of 0.1 M phosphate buffer solution with pH 7.0 containing 1 mL of M-tryptophan and D-tryptophan, respectively, and the differential pulse voltammetry was used for testing within an electrochemical window of 0.4–1.2 V.

[0059] like Figure 9 As shown, although CuCu has weaker conductivity than AuAu, it exhibits better recognition of tryptophan enantiomers. Similarly, CuCu / GCE shows better recognition of D-tryptophan than L-tryptophan, and the oxidation peak current ratio (ID / IL) of CuCu / GCE for tryptophan enantiomers is as high as 1.73, which is superior to the recognition effect of AuAu / GCE for tryptophan enantiomers (ID / IL = 1.14). In the above single-metal nanomaterials AuAu and CuCu, the oxidation peak current for D-tryptophan is significantly higher than that for L-tryptophan, indicating that both metal nanomaterials have a stronger affinity for D-tryptophan. It is speculated that this recognition ability originates from their common reactant, L-ascorbic acid, and the chiral recognition ability may be dominated by L-ascorbic acid.

[0060] Example 6:

[0061] Preparation of AuCu-modified electrode: 800 μL of 40 mmol / L L-ascorbic acid solution was mixed with 1600 μL of 1.5 mmol / L chloroauric acid solution and 1600 μL of 1.25 mmol / L copper chloride solution, and incubated at 60 °C for 2 h to obtain AuCu solution. Then, 5 μL of AuCu solution was drop-coated onto the electrode surface and allowed to air dry to obtain AuCu-modified electrode.

[0062] The AuCu-modified electrode was used as the working electrode, the platinum sheet electrode as the counter electrode, and the calomel electrode as the reference electrode. They were placed in 25 mL of 0.1 M phosphate buffer solution with pH 7.0 containing 1 mL of M-tryptophan and D-tryptophan, respectively, and the differential pulse voltammetry was used for testing within an electrochemical window of 0.4–1.2 V.

[0063] like Figure 10As shown, AuCu / GCE also exhibits a significant recognition effect on tryptophan enantiomers for AuCu, but this recognition effect is completely different from that of single-metal nanomaterials (AuAu, CuCu), showing the opposite recognition effect. Specifically, the oxidation peak current signal of L-tryptophan is significantly higher than that of D-tryptophan, with an oxidation peak current ratio (ID / IL) of only 0.84. Notably, the oxidation peak current value of AuCu / GCE is higher than that of CuCu / GCE but weaker than that of AuAu / GCE, confirming that gold and copper elements simultaneously participated in the synthesis of the AuCu alloy, resulting in a current signal between that of the two pure metal nanomaterials. Furthermore, this further demonstrates the successful synthesis of AuCu. This reversal phenomenon is beneficial for the subsequent controllable adjustment and application of chiral recognition materials.

[0064] Comparative Example 1:

[0065] A bare glassy carbon electrode (GCE) was used as the working electrode, a platinum sheet electrode as the counter electrode, and a calomel electrode as the reference electrode. The electrodes were placed in 25 mL of 0.1 M phosphate buffer solution with pH 7.0 containing 1 mL of M-tryptophan and D-tryptophan, respectively, and the differential pulse voltammetry was used for testing within an electrochemical window of 0.4–1.2 V.

[0066] like Figure 11 As shown, after the naked GCE was placed in L-tryptophan and D-tryptophan solutions, an oxidation peak current of tryptophan was observed at approximately 0.74 V, proving that tryptophan was oxidized on the surface of the naked GCE electrode. However, since there are no chiral sites on the GCE surface, it is impossible to effectively distinguish the enantiomers of tryptophan. Figure 11 The oxidation peak currents of L-tryptophan and D-tryptophan are almost equal, and their differential pulse voltammetric curves almost completely overlap, indicating that the bare GCE cannot recognize the tryptophan enantiomer. This proves that the subsequent signal difference originates solely from the material, rather than from interference from the bare GCE.

Claims

1. The application of a metal nanomaterial doped with a second metal in the chiral recognition of amino acids using an electrochemical method, characterized in that, The metal nanomaterial doped with the second metal uses a first metal solution and a second metal solution as metal sources, and L-ascorbic acid as a reducing agent to reduce positively charged metal ions to zero-valent metal atoms, thereby forming metal nanomaterials. The first metal solution is one of an acid solution of gold and a salt solution of copper; the second metal solution is one of an acid solution of gold and a salt solution of copper. The metal components in the first metal solution and the second metal solution may be the same or different; the metal nanomaterial is AuAu, CuCu, or AuCu; the amino acid is L-tryptophan or D-tryptophan; the metal nanomaterials AuAu and CuCu have a better recognition effect on D-tryptophan than L-tryptophan; the metal nanomaterial AuCu has a better recognition effect on L-tryptophan than D-tryptophan.

2. The application as described in claim 1, characterized in that, The preparation method of the metal nanomaterial doped with the second metal includes the following steps: Weigh out L-ascorbic acid solution, first metal solution, and second metal solution, mix them, and incubate them to obtain metal nanomaterials doped with the second metal; When the first metal and the second metal are different, the concentrations of the first metal solution and the second metal solution are different.

3. The application as described in claim 1, characterized in that, The acid solution for gold is chloroauric acid solution; the salt solution for copper is copper chloride solution.

4. The application as described in claim 2, characterized in that, The concentration of the L-ascorbic acid solution is 10-50 mmol / L; the concentration of the first metal solution is 1-5 mmol / L; the concentration of the second metal solution is 1-5 mmol / L; and the volume ratio of the L-ascorbic acid solution, the first metal solution, and the second metal solution is (1-5): (1-5): (1-5).

5. The application as described in claim 2, characterized in that, The incubation conditions are: temperature 30-80℃, time 1-4h.

6. The application as described in claim 1, characterized in that, The electrochemical method includes differential pulse voltammetry.

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