Method for regulating chiral response of chiral nanoparticles

Abstract

The invention discloses a method for regulating and controlling chiral response of chiral nanoparticles, which comprises the following steps: providing a circular gold nano-plate; cetyltrimethylammonium bromide, chloroauric acid and a reducing agent are sequentially added into water to be evenly mixed, and an overgrowth solution is obtained; uniformly mixing the circular gold nano-plate with the overgrowth solution, and standing for reaction to obtain a hexagonal gold nano-plate; sequentially adding hexadecyl trimethyl ammonium bromide, chloroauric acid, a chiral inducer and a reducing agent into water, and uniformly mixing to obtain a chiral growth solution; uniformly mixing a hexagonal gold nano-plate with the chiral growth solution, and standing for reaction to obtain chiral nano-particles; wherein the chiral response of the chiral nanoparticles is regulated and controlled by adjusting the concentration of hexadecyl trimethyl ammonium bromide in the chiral growth solution. By adopting the method disclosed by the invention, two chiral nanoparticles with inverted optical signals can be synthesized in the presence of a single chiral inducer by adjusting the concentration of cetyltrimethylammonium bromide.

Description

Technical Field

[0001] The present invention relates to the technical field of optical materials, and particularly to a method for regulating the chiral response of chiral nanoparticles. Background Art

[0002] Due to plasmonic and chiral properties, chiral nanoparticles have shown great application potential in the fields of optics, electronics, biomedicine, etc.

[0003] Currently, the methods for chemically synthesizing chiral nanoparticles are constantly improved and innovated. The wet chemical synthesis strategy of seed-mediated growth can prepare chiral nanoparticles with uniform size and good dispersibility on a large scale, and thus is widely used in the preparation of chiral nanoparticles with various shapes (such as spherical, rod-shaped, helical, etc.). At the same time, through surface ligand modification and functionalization, the optical properties and stability of chiral nanoparticles can be further regulated.

[0004] However, the seed-mediated chemical synthesis method still has some disadvantages. For example: ① High complexity: The process of chemically synthesizing chiral nanoparticles is usually relatively complex and requires designing appropriate reaction routes and conditions, which may increase the complexity and time cost of the synthesis process; ② Unknown reaction selectivity: In the process of chemically synthesizing chiral nanoparticles, it is often necessary to use molecular induction for chiral growth of particles. The selection of chiral reagents and the control of reaction conditions are crucial for obtaining highly selective reaction products; ③ Low uniformity of synthesized particles: In the seed-mediated chemical synthesis method, a high requirement is imposed on the uniformity of seeds. The high consistency of seeds in morphology, lattice orientation, etc. can ensure the repeatability and practicality of the final chiral nanoparticles.

[0005] Therefore, the existing technology still needs to be improved and developed. Summary of the Invention

[0006] In view of the above deficiencies of the prior art, the purpose of the present invention is to provide a method for regulating the chiral response of chiral nanoparticles, aiming to solve the problems of complex operation and difficult chiral regulation in the preparation process of existing chiral nanoparticles.

[0007] The technical solution of the present invention is as follows:

[0008] In the first aspect, a method for regulating the chiral response of chiral nanoparticles is provided, including:

[0009] Providing circular gold nanoplates;

[0010] Adding cetyltrimethylammonium bromide, chloroauric acid, and a reducing agent into water in sequence and mixing evenly to obtain an overgrowth solution;

[0011] Mixing the circular gold nanoplates with the overgrowth solution evenly, standing for reaction, and obtaining hexagonal gold nanoplates;

[0012] Cetyltrimethylammonium bromide, chloroauric acid, chiral inducer and reducing agent are successively added to water and mixed evenly to obtain a chiral growth solution;

[0013] The hexagonal gold nanoplates are mixed evenly with the chiral growth solution, and left standing for reaction to obtain chiral nanoparticles;

[0014] Among them, by adjusting the concentration of cetyltrimethylammonium bromide in the chiral growth solution, the chiral response of the chiral nanoparticles is regulated.

[0015] In a preferred technical solution, in the overgrowth solution, the concentration of cetyltrimethylammonium bromide is 5-15 mmol / L, the concentration of chloroauric acid is 0.1-0.5 mmol / L, and the concentration of the reducing agent is 0.5-2.5 mmol / L.

[0016] In a preferred technical solution, in the chiral growth solution, the concentration of cetyltrimethylammonium bromide is 4-24 mmol / L, the concentration of chloroauric acid is 0.1-3 mmol / L, the concentration of the chiral inducer is 0.01-0.6 mmol / L, and the concentration of the reducing agent is 0.4-30 mmol / L.

[0017] In a preferred technical solution, the reducing agent is ascorbic acid.

[0018] In a preferred technical solution, the chiral inducer is a chiral polypeptide molecule.

[0019] In a preferred technical solution, during the standing reaction, the reaction temperature is 25-35 °C and the reaction time is 2-72 h.

[0020] In a preferred technical solution, the preparation method of the circular gold nanoplates includes the steps of:

[0021] Providing a mixed solution of chloroauric acid and a surfactant;

[0022] Sodium borohydride is added to the mixed solution of chloroauric acid and the surfactant and mixed evenly, and left standing for reaction until sodium borohydride is completely decomposed to obtain a seed solution;

[0023] Cetyltrimethylammonium bromide, chloroauric acid, sodium hydroxide, potassium iodide and a reducing agent are successively added to water and mixed evenly to obtain a growth solution;

[0024] The seed solution is mixed evenly with the growth solution, and left standing for reaction to obtain triangular gold nanoplates;

[0025] The triangular gold nanoplates are dispersed in water or a cetyltrimethylammonium bromide solution, and left standing for oxidation to obtain circular gold nanoplates.

[0026] In a preferred technical solution, in the mixed solution of chloroauric acid and surfactant, the concentration of chloroauric acid is 0.1 - 0.5 mmol / L, and the concentration of surfactant is 0.1 - 0.5 mmol / L.

[0027] In a preferred technical solution, the surfactant is sodium citrate.

[0028] In a preferred technical solution, in the growth solution, the concentration of cetyltrimethylammonium bromide is 10 - 100 mmol / L, the concentration of chloroauric acid is 0.1 - 0.5 mmol / L, the concentration of sodium hydroxide is 0.3 - 0.8 mmol / L, the concentration of potassium iodide is 0.03 - 0.08 mmol / L, and the concentration of reducing agent is 0.3 - 0.8 mmol / L.

[0029] In a preferred technical solution, the cetyltrimethylammonium bromide solution is prepared with water and cetyltrimethylammonium bromide; wherein, the concentration of cetyltrimethylammonium bromide is 1 - 100 mmol / L.

[0030] In a second aspect, chiral nanoparticles are provided, and the chiral nanoparticles are prepared by regulating the chiral response of chiral nanoparticles through the method described above.

[0031] Beneficial effects: The present invention uses hexagonal gold nanoplates with strong anisotropy as seeds to synthesize chiral nanoparticles. Compared with the prior art that uses isotropic gold octahedrons or gold spheres as seeds to synthesize chiral nanoparticles, the hexagonal gold nanoplates of the present invention can enable chiral inductors to preferentially aggregate on the high-energy surface exposed by the reducing agent, thereby regulating the aggregation of reduced gold, and further regulating the rotation angle of the ridges or branch-like structures protruding on the particle morphology, and improving the signal in chiral optical response. By using the method of the present invention, the operation is simple and easy to control, and chiral nanoparticles with uniform size and good dispersibility can be prepared on a large scale; and by adjusting the concentration of cetyltrimethylammonium bromide in the chiral growth solution, two kinds of chiral nanoparticles with reversed optical signals can be synthesized in the presence of a single chiral inductor. Description of the Drawings

[0032] Figure 1 is the synthesis flow chart of chiral nanoparticles.

[0033] Figure 2 is the synthesis schematic diagram of chiral nanoparticles. Detailed Embodiments

[0034] The present invention provides a method for regulating the chiral response of chiral nanoparticles. To make the purpose, technical solution and effects of the present invention clearer and more definite, the present invention is further described in detail below.

[0035] An embodiment of the present invention provides a method for regulating the chiral response of chiral nanoparticles, including the steps:

[0036] Provide circular gold nanoplates;

[0037] Add cetyltrimethylammonium bromide, chloroauric acid, and a reducing agent into water in sequence and mix evenly to obtain an overgrowth solution;

[0038] Mix the circular gold nanoplates with the overgrowth solution evenly, and let it stand for reaction to obtain hexagonal gold nanoplates;

[0039] Add cetyltrimethylammonium bromide, chloroauric acid, a chiral inducer, and a reducing agent into water in sequence and mix evenly to obtain a chiral growth solution;

[0040] Mix the hexagonal gold nanoplates with the chiral growth solution evenly, and let it stand for reaction to obtain chiral nanoparticles;

[0041] Among them, by adjusting the concentration of cetyltrimethylammonium bromide in the chiral growth solution, the chiral response of the chiral nanoparticles is regulated.

[0042] Specifically, the flowchart of this embodiment is as Figure 1 shown. First, circular gold nanoplates are used to synthesize hexagonal gold nanoplates, and then chiral nanoparticles, such as chiral gold nanoparticles, are synthesized from the hexagonal gold nanoplates. Among them, the crystal plane structure of the hexagonal gold nanoplates is an anisotropic structure with <111> planes on the upper and lower surfaces and alternating <111> and <100> planes on the side surfaces. Most of the chiral nanoparticles synthesized by the prior art are isotropic gold octahedrons or gold spheres composed of <111> crystal planes. Compared with the prior art, in the step of synthesizing chiral nanoparticles in this embodiment, affected by anisotropy, the chiral inducer preferentially aggregates on the high-energy surface of the hexagonal gold nanoplates exposed by the reducing agent, thereby regulating the aggregation of reducing gold, and further regulating the rotation angle of the ridges or branch-like structures protruding on the particle morphology, and finally regulating the chirality of the particles.

[0043] In the method of this embodiment, chiral nanoparticles with morphological differences and optical response inversion can be produced by adjusting the content of cetyltrimethylammonium bromide, and its synthesis schematic diagram is as Figure 2 shown. The principle lies in the different affinities of halogen ions (Cl - , Br - , I - ) for crystal planes. In this embodiment, cetyltrimethylammonium bromide is used as a surfactant, which contains bromide ions (Br - ), and the binding order of Br - to the two crystal planes of the hexagonal gold nanoplates is <111>-<100>. When the concentration of cetyltrimethylammonium bromide is low, Br -Preferentially combined with the <111> plane, with more edges exposed to the reduced gold, resulting in more chiral structures growing into curved branches at the edges. When the concentration of cetyltrimethylammonium bromide is high, Br - Combined with the <111> and <100> planes, with less edges exposed to the reduced gold, the competitive growth between the <111> plane and the edges is reduced, resulting in the chiral structure showing a convex ridge. Therefore, by using the method of this embodiment, it is possible to synthesize two kinds of chiral nanoparticles with reversed optical signals in the presence of a single chiral inducer by adjusting the concentration of cetyltrimethylammonium bromide.

[0044] In one embodiment, in the overgrowth solution, the concentration of cetyltrimethylammonium bromide is 5-15 mmol / L, preferably 10 mmol / L; the concentration of chloroauric acid is 0.1-0.5 mmol / L, preferably 0.12 mmol / L; the concentration of the reducing agent is 0.5-2.5 mmol / L, preferably 0.6 mmol / L; but not limited thereto. Among them, the molar ratio of cetyltrimethylammonium bromide, chloroauric acid and the reducing agent is (5-15):(0.1-0.5):(0.5-2.5), preferably 10:0.12:0.6, but not limited thereto. Specifically, by regulating the concentration and ratio of cetyltrimethylammonium bromide, chloroauric acid and the reducing agent in the overgrowth solution, the reaction degree and reaction rate can be controlled, so as to form hexagonal gold nanoplates with uniform size and regular shape.

[0045] In one embodiment, in the chiral growth solution, the concentration of cetyltrimethylammonium bromide is 4-24 mmol / L; the concentration of chloroauric acid is 0.1-3 mmol / L, preferably 0.2 mmol / L; the concentration of the chiral inducer is 0.01-0.6 mmol / L; the concentration of the reducing agent is 0.4-30 mmol / L; but not limited thereto. Among them, the molar ratio of cetyltrimethylammonium bromide, chloroauric acid, the chiral inducer and the reducing agent is (4-24):(0.1-3):(0.01-0.6):(0.4-30), preferably (4-24):0.2:(0.01-0.6):(0.4-30), but not limited thereto. Specifically, by regulating the concentration and ratio of cetyltrimethylammonium bromide, chloroauric acid, the chiral inducer and the reducing agent in the chiral growth solution, the reaction degree and reaction rate can be controlled, so as to form chiral nanoparticles with different morphologies.

[0046] In one embodiment, the reducing agent is ascorbic acid.

[0047] In one embodiment, the chiral inducer is a chiral polypeptide molecule; preferably, the chiral polypeptide molecule is L-glutathione, D-glutathione, but not limited thereto, and other substances capable of inducing the deposition of elemental gold in a solution to form chiral nanoparticles can also be used. Currently, the commonly used chiral inducers in the seed-mediated chemical synthesis method are glutathione (GSH) and cysteine (Cys). The chiral inducer needs to have a functional group that can combine with the target nanoparticle element. For example, the sulfhydryl group (-SH) in glutathione can form an Au-S chemical bond with the gold atoms on the particle surface, which has a relatively high chemical bond energy and can form a stable interfacial layer on the surface of gold nanoparticles. For noble metal nanoparticles, when selecting a chiral inducer, in addition to biological toxicity, the most important thing is whether there is a functional group that can form a strong chemical bond with the surface atoms. In addition to the sulfhydryl group, functional groups that can form strong chemical bonds with noble metal atoms also include carboxyl group (-COOH), amino group (-NH 2 ), phosphate group (-PO 4 2- ), etc.

[0048] In one embodiment, during the static reaction, the reaction temperature is 25-35°C and the reaction time is 2-72 h, but not limited thereto, and can be adjusted according to actual needs. Specifically, an increase in temperature usually accelerates the nucleation rate. At a higher temperature, the reactant molecules have higher kinetic energy, and both the collision frequency and energy between molecules increase, making it easier for the atoms on the seed surface to aggregate and form new nuclei. Different temperature conditions may lead to different dominant nucleation mechanisms. At a lower temperature, homogeneous nucleation may be dominant, that is, nuclei form uniformly in the solution; while at a higher temperature, heterogeneous nucleation may be more likely, that is, nuclei preferentially form on the seed surface or other impurity surfaces. This change in the nucleation mechanism will affect the size distribution and morphology of the nanoparticles. In this embodiment, controlling the reaction temperature and time within a suitable range is to control the reaction degree and reaction rate, so as to form nanostructures with uniform size and regular shape.

[0049] In one embodiment, after mixing the hexagonal gold nanoplates with the chiral growth solution, the pH value of the resulting mixed solution is 2-5, preferably 3.5, but not limited thereto. Specifically, the acidity and alkalinity will affect the existence form of the reactants. Many metal ions exist in different ionic forms at different pH values, and the activities and reaction mechanisms of these different ionic forms in the reaction may be different. The pH value also affects the reaction activity of the reactants. In some reactions, the reactants have higher activity under specific pH value conditions, and the reaction is easier to proceed. In this embodiment, controlling the pH value of the mixed solution within a suitable range is to control the reaction degree and reaction rate, so as to form nanostructures with uniform size and regular shape.

[0050] In one embodiment, the method for preparing the circular gold nanoplates includes the steps of:

[0051] Providing a mixed solution of chloroauric acid and a surfactant;

[0052] Adding sodium borohydride to the mixed solution of chloroauric acid and the surfactant, mixing evenly, and allowing to stand and react until sodium borohydride is completely decomposed to obtain a seed solution;

[0053] Adding cetyltrimethylammonium bromide, chloroauric acid, sodium hydroxide, potassium iodide, and a reducing agent to water in sequence and mixing evenly to obtain a growth solution;

[0054] Mixing the seed solution and the growth solution evenly, allowing to stand and react to obtain triangular gold nanoplates;

[0055] Dispersing the triangular gold nanoplates in water or a cetyltrimethylammonium bromide solution, allowing to stand and oxidize to obtain circular gold nanoplates.

[0056] Specifically, in this embodiment, triangular gold nanoplates were first synthesized, and then the triangular gold nanoplates were oxidized to circular gold nanoplates. The diameter of the triangular gold nanoplates is about 177 nm, the thickness is about 8 nm, and the main surface plasmon peak is beyond 1200 nm. The diameter of the circular gold nanoplates is about 110 nm, the thickness is about 10 nm, and the main surface plasmon peak is around 800 nm. Compared with the triangular gold nanoplates, the advantages of the circular gold nanoplates are as follows: ① The anisotropy is weaker than that of the triangular gold nanoplates. For the seed-mediated chemical growth method, the circular plates are easier to be customized for growth; ② The observability is stronger. Since the circularization reduces the diameter of the plates (177→110 nm) and slightly increases the thickness of the plates (8→10 nm), its main surface plasmon peak blue-shifts from infrared 1200+ nm to around 800 nm, which is convenient for measurement and observation.

[0057] Further, in a more specific embodiment, in the mixed solution of chloroauric acid and the surfactant, the concentration of chloroauric acid is 0.1 - 0.5 mmol / L, preferably 0.2 - 0.3 mmol / L, more preferably 0.25 mmol / L; the concentration of the surfactant is 0.1 - 0.5 mmol / L, preferably 0.2 - 0.3 mmol / L, more preferably 0.25 mmol / L; but not limited thereto. The molar ratio of chloroauric acid to the surfactant is 1:1, but not limited thereto. Specifically, by regulating the concentration and ratio of chloroauric acid and the surfactant, the reaction degree and reaction rate can be controlled, thereby forming a seed solution with uniform particles.

[0058] Further, in a more specific embodiment, the surfactant is trisodium citrate, but is not limited thereto, and can be selected according to actual needs. The role of the surfactant is to adsorb on the surface of gold nanoparticles, change the surface energy of the particles, and thus affect the reduction and deposition rates of gold ions. By adjusting the concentration and type of the surfactant, the nucleation and growth processes of chiral nanoparticles can be controlled, and the regulation of the particle size and shape can be achieved.

[0059] Further, in a more specific embodiment, in the growth solution, the concentration of cetyltrimethylammonium bromide is 10 - 100 mmol / L, preferably 40 - 60 mmol / L, more preferably 45 mmol / L; the concentration of chloroauric acid is 0.1 - 0.5 mmol / L, preferably 0.2 - 0.3 mmol, more preferably 0.25 mmol / L; the concentration of sodium hydroxide is 0.3 - 0.8 mmol / L, preferably 0.5 - 0.6 mmol / L, more preferably 0.5 mmol / L; the concentration of potassium iodide is 0.03 - 0.08 mmol / L, preferably 0.05 - 0.06 mmol / L, more preferably 0.05 mmol / L; the concentration of the reducing agent is 0.3 - 0.8 mmol / L, preferably 0.5 - 0.6 mmol / L, more preferably 0.5 mmol / L; but is not limited thereto. Among them, the molar ratio of cetyltrimethylammonium bromide, chloroauric acid, sodium hydroxide, potassium iodide and the reducing agent is (50 - 500) : (0.5 - 2.5) : (1.5 - 4) : (0.15 - 0.4) : (1.5 - 4); preferably (150 - 300) : (0.8 - 1.2) : (1.6 - 2.4) : (0.08 - 0.12) : (1.6 - 2.4), more preferably 180 : 1 : 2 : 0.2 : 2; but is not limited thereto. Specifically, by regulating the concentration and ratio of cetyltrimethylammonium bromide, chloroauric acid, sodium hydroxide, potassium iodide and the reducing agent in the growth solution, the reaction degree and reaction rate can be controlled, so as to form triangular gold nanoplates and circular gold nanoplates with uniform size and regular shape.

[0060] Further, in a more specific embodiment, the cetyltrimethylammonium bromide solution is prepared with water and cetyltrimethylammonium bromide; among them, the concentration of cetyltrimethylammonium bromide is 1 - 100 mmol / L, preferably 50 mmol / L, but is not limited thereto.

[0061] Further, in a more specific embodiment, in the step of mixing the seed solution and the growth solution, the seed solution and the growth solution are mixed step by step. Mixing step by step can control the reaction rate, so as to form nanostructures with uniform size and regular shape.

[0062] In one embodiment, the chiral nanoparticles are chiral gold nanoparticles.

[0063] The embodiments of the present invention also provide chiral nanoparticles, which are prepared by regulating the chiral response of chiral nanoparticles through the method described above.

[0064] The embodiments of the present invention also provide the applications of the chiral nanoparticles described above in chiral molecule detection, fabricating chiral devices for regulating the polarization state of light, chiral chemical catalysis, highly targeted imaging of chiral plasmons, quantum superposition, and quantum entanglement.

[0065] The present invention will be further described below through specific embodiments.

[0066] In the following specific embodiments, unless otherwise specified, D-glutathione (D-GSH), chloroauric acid (HAuCl 4 ), ascorbic acid (AA), cetyltrimethylammonium bromide (CTAB), trisodium citrate (TSC), sodium borohydride (NaBH 4 ), potassium iodide (KI), sodium hydroxide (NaOH), etc. are all commercially available products.

[0067] Example 1

[0068] This example provides a kind of chiral gold nanoparticles, and the preparation steps are as follows:

[0069] (1) Synthesis of circular gold nanoplates

[0070] Add chloroauric acid solution (0.01M, 1 mL) and trisodium citrate solution (0.01M, 1 mL) into water (36 mL) and mix well to obtain a mixed solution of chloroauric acid and trisodium citrate; then quickly inject the freshly prepared ice-cold sodium borohydride solution (0.1M, 1 mL) into the mixed solution of chloroauric acid and trisodium citrate, mix well and let it stand and react at 35 °C for 2 - 4 hours to completely decompose the unreacted sodium borohydride, obtaining a seed solution containing spherical gold nanoparticles.

[0071] Prepare three tubes of solutions, where solution ① and solution ② are the same: Mix cetyltrimethylammonium bromide solution (0.5M, 9 mL), chloroauric acid solution (0.01M, 0.25 mL), sodium hydroxide solution (0.1M, 0.05 mL), and potassium iodide solution (0.01M, 0.05 mL) to obtain solution ① or solution ②.

[0072] The preparation of solution ③ is as follows: Mix cetyltrimethylammonium bromide solution (0.5M, 90 mL), chloroauric acid solution (0.01M, 2.5 mL), sodium hydroxide solution (0.1M, 0.5 mL), and potassium iodide solution (0.01M, 0.5 mL) to obtain solution ③.

[0073] In the preparation step of the circular gold nanoplates, ascorbic acid solution (0.1 M, 0.05 mL) was injected into Solution ① and mixed evenly to obtain the first growth solution. After the first growth solution became colorless, 1 mL of the seed solution was taken and injected into the first growth solution and mixed evenly to obtain the first intermediate solution. Ascorbic acid solution (0.1 M, 0.05 mL) was injected into Solution ② and mixed evenly to obtain the second growth solution. After the second growth solution became colorless, 1 mL of the first intermediate solution was taken and injected into the second growth solution and mixed evenly to obtain the second intermediate solution. Ascorbic acid solution (0.1 M, 0.5 mL) was injected into Solution ③ and mixed evenly to obtain the third growth solution. After the third growth solution became colorless, the second intermediate solution was all injected into the third growth solution and mixed evenly, and then left standing at 35 °C for 24 h. Then the supernatant was sucked off with a dropper, and water (40 mL) was added to the container to disperse the precipitate, obtaining triangular gold nanoplates. The triangular gold nanoplates were left standing at room temperature for 12 hours to be automatically oxidized into circular gold nanoplates.

[0074] (2) Synthesis of hexagonal gold nanoplates

[0075] Cetyltrimethylammonium bromide solution (0.1 M, 5 mL), chloroauric acid solution (0.01 M, 0.6 mL) and ascorbic acid solution (0.1 M, 0.3 mL) were mixed evenly in sequence, and water was added to adjust the total volume to 40 mL to obtain the overgrowth solution.

[0076] The circular gold nanoplate solution obtained in step (1) was adjusted with water so that the extinction at the main surface plasmon peak (around 800 nm) was 3. The adjusted circular gold nanoplate solution (10 mL) was mixed evenly with the overgrowth solution (40 mL), and left standing and reacting in a constant temperature oven at 30 °C for 10 hours to obtain hexagonal gold nanoplates. Subsequently, it was centrifuged at a speed of 4000 revolutions per minute for 12 minutes, and after removing the supernatant, the particles were dispersed in cetyltrimethylammonium bromide solution (0.01 M) for storage.

[0077] (3) Synthesis of chiral gold nanoparticles

[0078] Cetyltrimethylammonium bromide solution (0.1 M, 0.2 mL), chloroauric acid solution (0.01 M, 0.1 mL), D - glutathione solution (1 mM, 0.5 mL) and ascorbic acid solution (0.1 M, 0.5 mL) were mixed evenly in sequence, and water was added to adjust the total volume to 4 mL to obtain the chiral growth solution.

[0079] Adjust the hexagon-shaped gold nanoplate solution obtained in step (2) with water to make the extinction coefficient of its main plasmon peak (around 820 nm) equal to 1. Take 1 mL of the adjusted hexagon-shaped gold nanoplate solution and mix it with 4 mL of the chiral growth solution to make the total volume of the reaction solution 5 mL, that is, the concentration of cetyltrimethylammonium bromide therein is 4 mM. Then, let it stand and react at room temperature for 2 hours to obtain chiral gold nanoparticles.

[0080] Example 2

[0081] This example provides a kind of chiral gold nanoparticles. The difference in the preparation steps from Example 1 is only that the synthesis of chiral gold nanoparticles in step (3) is different.

[0082] The synthesis steps of the chiral gold nanoparticles in this example are as follows:

[0083] Mix the cetyltrimethylammonium bromide solution (0.1 M, 0.4 mL), chloroauric acid solution (0.01 M, 0.1 mL), D-glutathione solution (1 mM, 0.5 mL), and ascorbic acid solution (0.1 M, 0.5 mL) in sequence, and adjust the total volume to 4 mL with water to obtain the chiral growth solution.

[0084] Adjust the hexagon-shaped gold nanoplate solution obtained in step (2) with water to make the extinction coefficient of its main plasmon peak (around 820 nm) equal to 1. Take 1 mL of the adjusted hexagon-shaped gold nanoplate solution and mix it with 4 mL of the chiral growth solution to make the total volume of the reaction solution 5 mL, that is, the concentration of cetyltrimethylammonium bromide therein is 8 mM. Then, let it stand and react at room temperature for 2 hours to obtain chiral gold nanoparticles.

[0085] Example 3

[0086] This example provides a kind of chiral gold nanoparticles. The difference in the preparation steps from Example 1 is only that the synthesis of chiral gold nanoparticles in step (3) is different.

[0087] The synthesis steps of the chiral gold nanoparticles in this example are as follows:

[0088] Mix the cetyltrimethylammonium bromide solution (0.1 M, 0.6 mL), chloroauric acid solution (0.01 M, 0.1 mL), D-glutathione solution (1 mM, 0.5 mL), and ascorbic acid solution (0.1 M, 0.5 mL) in sequence, and adjust the total volume to 4 mL with water to obtain the chiral growth solution.

[0089] Adjust the hexagon-shaped gold nanoplate solution obtained in step (2) with water to make the extinction coefficient of its main plasmon peak (around 820 nm) equal to 1. Take 1 mL of the adjusted hexagon-shaped gold nanoplate solution and mix it with 4 mL of the chiral growth solution to make the total volume of the reaction solution 5 mL, that is, the cetyltrimethylammonium bromide concentration therein is 12 mM. Then, let it stand and react at room temperature for 2 hours to obtain chiral gold nanoparticles.

[0090] Example 4

[0091] This example provides a kind of chiral gold nanoparticles. The difference in the preparation steps from Example 1 is only that the synthesis of chiral gold nanoparticles in step (3) is different.

[0092] The synthesis steps of the chiral gold nanoparticles in this example are as follows:

[0093] Mix the cetyltrimethylammonium bromide solution (0.1 M, 0.8 mL), chloroauric acid solution (0.01 M, 0.1 mL), D-glutathione solution (1 mM, 0.5 mL), and ascorbic acid solution (0.1 M, 0.5 mL) in sequence, and adjust the total volume to 4 mL with water to obtain the chiral growth solution.

[0094] Adjust the hexagon-shaped gold nanoplate solution obtained in step (2) with water to make the extinction coefficient of its main plasmon peak (around 820 nm) equal to 1. Take 1 mL of the adjusted hexagon-shaped gold nanoplate solution and mix it with 4 mL of the chiral growth solution to make the total volume of the reaction solution 5 mL, that is, the cetyltrimethylammonium bromide concentration therein is 16 mM. Then, let it stand and react at room temperature for 2 hours to obtain chiral gold nanoparticles.

[0095] Example 5

[0096] This example provides a kind of chiral gold nanoparticles. The difference in the preparation steps from Example 1 is only that the synthesis of chiral gold nanoparticles in step (3) is different.

[0097] The synthesis steps of the chiral gold nanoparticles in this example are as follows:

[0098] Mix the cetyltrimethylammonium bromide solution (0.1 M, 1.0 mL), chloroauric acid solution (0.01 M, 0.1 mL), D-glutathione solution (1 mM, 0.5 mL), and ascorbic acid solution (0.1 M, 0.5 mL) in sequence, and adjust the total volume to 4 mL with water to obtain the chiral growth solution.

[0099] Adjust the hexagon-shaped gold nanoplates solution obtained in step (2) with water to make the extinction coefficient of its main surface plasmon peak (around 820 nm) equal to 1. Take 1 mL of the adjusted hexagon-shaped gold nanoplates solution and mix it with 4 mL of the chiral growth solution to make the total volume of the reaction solution 5 mL, that is, the concentration of cetyltrimethylammonium bromide therein is 20 mM, and then let it stand and react at room temperature for 2 hours to obtain chiral gold nanoparticles.

[0100] Example 6

[0101] This example provides a kind of chiral gold nanoparticles. The difference in the preparation steps from Example 1 is only that the synthesis of chiral gold nanoparticles in step (3) is different.

[0102] The synthesis steps of the chiral gold nanoparticles in this example are as follows:

[0103] Mix the cetyltrimethylammonium bromide solution (0.1 M, 1.2 mL), chloroauric acid solution (0.01 M, 0.1 mL), D-glutathione solution (1 mM, 0.5 mL) and ascorbic acid solution (0.1 M, 0.5 mL) in sequence, and adjust the total volume to 4 mL with water to obtain the chiral growth solution.

[0104] Adjust the hexagon-shaped gold nanoplates solution obtained in step (2) with water to make the extinction coefficient of its main surface plasmon peak (around 820 nm) equal to 1. Take 1 mL of the adjusted hexagon-shaped gold nanoplates solution and mix it with 4 mL of the chiral growth solution to make the total volume of the reaction solution 5 mL, that is, the concentration of cetyltrimethylammonium bromide therein is 24 mM, and then let it stand and react at room temperature for 2 hours to obtain chiral gold nanoparticles.

[0105] Example 7

[0106] This example provides a kind of chiral gold nanoparticles. The difference in the preparation steps from Example 1 is only that the synthesis of chiral gold nanoparticles in step (3) is different.

[0107] The synthesis steps of the chiral gold nanoparticles in this example are as follows:

[0108] Mix the cetyltrimethylammonium bromide solution (0.1 M, 0.2 mL), chloroauric acid solution (0.01 M, 0.1 mL), D-glutathione solution (1 mM, 0.25 mL) and ascorbic acid solution (0.1 M, 1.0 mL) in sequence, and adjust the total volume to 4 mL with water to obtain the chiral growth solution.

[0109] Adjust the hexagon-shaped gold nanoplate solution obtained in step (2) with water to make the extinction of its main plasmon peak (around 820 nm) equal to 1. Take the adjusted hexagon-shaped gold nanoplate solution (1 mL) and mix it with the chiral growth solution (4 mL) to make the total volume of the reaction solution 5 mL, that is, the concentration of cetyltrimethylammonium bromide in it is 4 mM, and then let it stand and react at room temperature for 2 hours to obtain chiral gold nanoparticles.

[0110] Example 8

[0111] This example provides a kind of chiral gold nanoparticles. The difference in the preparation steps from Example 1 is only that the synthesis of chiral gold nanoparticles in step (3) is different.

[0112] The synthesis steps of the chiral gold nanoparticles in this example are as follows:

[0113] Mix the cetyltrimethylammonium bromide solution (0.1 M, 1.2 mL), chloroauric acid solution (0.01 M, 0.1 mL), D-glutathione solution (1 mM, 0.25 mL) and ascorbic acid solution (0.1 M, 0.08 mL) in sequence, and adjust the total volume to 4 mL with water to obtain the chiral growth solution.

[0114] Adjust the hexagon-shaped gold nanoplate solution obtained in step (2) with water to make the extinction of its main plasmon peak (around 820 nm) equal to 1. Take the adjusted hexagon-shaped gold nanoplate solution (1 mL) and mix it with the chiral growth solution (4 mL) to make the total volume of the reaction solution 5 mL, that is, the concentration of cetyltrimethylammonium bromide in it is 24 mM, and then let it stand and react at room temperature for 2 hours to obtain chiral gold nanoparticles.

[0115] Characterization and analysis

[0116] Use circular dichroism spectroscopy (CD), ultraviolet-visible spectroscopy (UV-Vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and other means to characterize the synthesis products of the above examples.

[0117] The main plasmon peak of the hexagon-shaped gold nanoplate is around 820 nm, its average diameter is 146.9 ± 7.33 nm, and its average thickness is 14.13 ± 1.7 nm.

[0118] The optical signals of the chiral gold nanoparticles in Examples 1-6 change with the change of the cetyltrimethylammonium bromide concentration. When only D-glutathione is present as a chiral inducer in the solution, in the range of 550-650 nm, as the cetyltrimethylammonium bromide concentration increases, the chiral signal that dominates the optical response changes from positive to negative, and the inversion of the chiral signal is achieved in this wavelength band. The nanoparticle morphology shows that as the cetyltrimethylammonium bromide concentration increases, the diameter of the nanoparticles decreases, the branched structure disappears, and curved ridges grow on the particle surface.

[0119] Example 7 is the experimental formula with the strongest g-factor found by adjusting the concentrations of ascorbic acid and D-glutathione under the condition of low cetyltrimethylammonium bromide concentration. Its scanning electron micrograph and g-factor spectrogram are as Figure 2 shown. Example 8 is the experimental formula with the strongest g-factor found by adjusting the concentrations of ascorbic acid and D-glutathione under the condition of high cetyltrimethylammonium bromide concentration. Its scanning electron micrograph and g-factor spectrogram are as Figure 2 shown. It can be Figure 2 seen that the chiral nanoparticles prepared in Example 7 and Example 8 have opposite results in the circular dichroism spectral response at a wavelength of 600 nm, and there are significant differences in morphology.

[0120] The significant differences in the morphology of the chiral gold nanoparticles are as follows:

[0121] (1) Macroscopic differences in diameter and thickness

[0122] ① For the chiral gold nanoparticles grown in an environment with low cetyltrimethylammonium bromide concentration, the branches are long, and both the branches and the protrusions on the surface have tips. For the chiral gold nanoparticles in an environment with high cetyltrimethylammonium bromide concentration, the protrusions on the surface are relatively flat ridges, and their tip effect is weaker than that of the branched structure.

[0123] ② As the cetyltrimethylammonium bromide concentration increases, the chiral gold nanoparticles gradually become thicker, the flatness increases, and the stacking effect weakens. For the manufacture of optical polarization elements formed by flat particles, the chiral gold nanoparticles prepared in an environment with high cetyltrimethylammonium bromide concentration are more suitable.

[0124] ③ Role of the tip effect in plasmon enhancement: The sharp branched structure greatly increases the surface curvature of chiral gold nanoparticles. According to classical electromagnetic theory, at the tip positions with larger curvature, the charge density will increase significantly. When excited by external light, these high charge density regions can more effectively excite surface plasmons, thereby generating a stronger local surface plasmon resonance effect. In terms of applications, a stronger surface plasmon enhanced Raman effect can greatly enhance the Raman signals of molecules adsorbed on the surface of gold nanoparticles.

[0125] (2) Crystal plane structure differences

[0126] ① For chiral gold nanoparticles synthesized under low concentration of cetyltrimethylammonium bromide, the long branched crystal plane is the <311> high Miller index plane, indicating that the particles preferentially grow under the exposure of this crystal plane; the short branched crystal plane is the <110> low Miller index plane, with slow growth. For nanoparticles with a high Miller crystal plane structure, the high Miller plane usually has more low-coordinated atoms. These atoms have a higher surface energy and more vacant bonds, making the nanoparticles more likely to interact with surrounding substances, thus showing a higher chemical reaction activity.

[0127] ② For chiral gold nanoparticles synthesized under high concentration of cetyltrimethylammonium bromide, the crystal planes between adjacent corners and between corners are all <111>, indicating that the lateral and longitudinal growth differences of the particles are small. The atomic arrangement of the low Miller plane is relatively regular and close, and the surface energy is relatively low, making the nanoparticles have good thermodynamic stability. They can maintain a relatively stable structure and performance under different environmental conditions, and are not prone to agglomeration or structural changes. When applied in the biomedical field, nanoparticles with a low Miller plane structure can remain stable in blood circulation, reducing the probability of being cleared by the immune system, which is beneficial to achieving long-term drug delivery.

[0128] It should be understood that the applications of the present invention are not limited to the above examples. For those of ordinary skill in the art, improvements or transformations can be made according to the above description. All such improvements and transformations should fall within the protection scope of the appended claims of the present invention.

Claims

1. A method for regulating the chiral response of chiral nanoparticles, characterized in that: include: Provide circular gold nanoplates; adding hexadecyltrimethylammonium bromide, chloroauric acid and a reducing agent into water in sequence and mixing well to obtain an overgrowth solution; Mixing the circular gold nanoplate and the overgrowth solution, and allowing to react, to obtain a hexagonal gold nanoplate; adding hexadecyltrimethylammonium bromide, chloroauric acid, a chiral inducing agent and a reducing agent into water in sequence and mixing them evenly to obtain a chiral growth solution; Mixing the hexagonal gold nanoplate and the chiral growth solution, and allowing to react to obtain chiral nanoparticles; The chiral response of the chiral nanoparticles is regulated by adjusting the concentration of hexadecyltrimethylammonium bromide in the chiral growth solution.

2. The method according to claim 1, characterized in that In the overgrowth solution, the concentration of hexadecyltrimethylammonium bromide is 5-15 mmol / L, the concentration of chloroauric acid is 0.1-0.5 mmol / L, and the concentration of the reducing agent is 0.5-2.5 mmol / L.

3. The method according to claim 1, characterized in that In the chiral growth solution, the concentration of hexadecyltrimethylammonium bromide is 4-24 mmol / L, the concentration of chloroauric acid is 0.1-3 mmol / L, the concentration of the chiral inducing agent is 0.01-0.6 mmol / L, and the concentration of the reducing agent is 0.4-30 mmol / L.

4. The method according to claim 1, characterized in that: The reducing agent is ascorbic acid.

5. The method according to claim 1, characterized in that The chiral inducing agent is a chiral polypeptide molecule.

6. The method according to claim 1, characterized in that During the static reaction, the reaction temperature is 25-35° C. and the reaction time is 2-72 hours.

7. The method according to claim 1, characterized in that The method for preparing the circular gold nanoplate comprises the steps of: providing a mixed solution of chloroauric acid and a surfactant; Adding sodium borohydride to the mixed solution of chloroauric acid and surfactant, mixing well, and standing to react until the sodium borohydride is completely decomposed to obtain a seed solution; Hexadecyltrimethylammonium bromide, chloroauric acid, sodium hydroxide, potassium iodide and a reducing agent are sequentially added into water and mixed to obtain a growth solution; The seed solution and the growth solution are mixed and allowed to stand for reaction to obtain a triangular gold nanoplate; The triangular gold nanoplates are dispersed in water or a hexadecyltrimethylammonium bromide solution and allowed to stand for oxidation to obtain circular gold nanoplates.

8. The method according to claim 7, characterized in that In the mixed solution of chloroauric acid and surfactant, the concentration of chloroauric acid is 0.1-0.5 mmol / L, and the concentration of surfactant is 0.1-0.5 mmol / L; And / or, the surfactant is trisodium citrate; And / or, in the growth solution, the concentration of hexadecyltrimethylammonium bromide is 10-100 mmol / L, the concentration of chloroauric acid is 0.1-0.5 mmol / L, the concentration of sodium hydroxide is 0.3-0.8 mmol / L, the concentration of potassium iodide is 0.03-0.08 mmol / L, and the concentration of the reducing agent is 0.3-0.8 mmol / L.

9. The method according to claim 7, characterized in that: The cetyltrimethylammonium bromide solution is prepared with water and cetyltrimethylammonium bromide; wherein the concentration of cetyltrimethylammonium bromide is 1-100 mmol / L.

10. Chiral nanoparticles, characterized in that The chiral nanoparticles are prepared by regulating the chiral response of the chiral nanoparticles according to the method described in any one of claims 1 to 9.

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