Chiral silver nanoparticles and preparation method thereof

Abstract

Chiral silver nanoparticles and their preparation method relate to the field of nanomaterial technology and address the complex preparation procedures, high costs, and inability to introduce controllable chiral structures in existing silver nanoparticle preparation techniques. The preparation steps are as follows: adding secondary water to a centrifuge tube, sequentially adding a dispersant, a precursor, a chiral reagent, an oxidant, a reducing agent, an anionic salt, and a buffer solution, stirring until the solution is uniformly mixed, placing the mixed solution in a constant-temperature water bath for reaction, and centrifuging and washing the mixed solution after the reaction to obtain chiral silver nanoparticles. The chiral silver nanoparticles synthesized in this invention via a one-step method not only retain the excellent optical, electrical, and catalytic properties of silver nanomaterials, but also possess chiral optical properties. The position of the chiral optical response of the silver nanoparticles can be precisely controlled, enabling the regulation of the chiral optical properties of the silver nanoparticles. The production process is simple and reduces production costs.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterials, and in particular to chiral silver nanoparticles and a preparation method thereof. Background Art

[0002] In the field of modern nanotechnology, silver nanoparticles are widely used in a variety of fields, including catalysis, sensing, optical imaging, antibacterial, and biomedicine, due to their unique physicochemical properties. The special properties of silver nanoparticles are mainly derived from their surface plasmon resonance (SPR) effect, quantum size effect, and large surface energy, which endow silver nanoparticles with outstanding functional performance in various application fields. In particular, the widespread application of silver nanoparticles in the optical field, such as surface-enhanced Raman scattering (SERS) and optical sensing, relies on the precise control of their morphology, size, and surface structure. Therefore, the preparation of silver nanoparticles with specific structures and functions has always been a research focus in the field of nanotechnology.

[0003] Currently, methods for preparing silver nanoparticles mainly include traditional methods such as physical deposition, self-assembly, hard templates, and chemical reduction. Physical deposition methods such as evaporation and sputtering can generally accurately control the size and morphology of silver nanoparticles and can produce high-purity silver nanoparticles. However, these methods rely on high-precision equipment and complex process flows, resulting in high production costs and cumbersome operations. They are generally only suitable for small-scale laboratory preparation and are difficult to achieve large-scale production. Furthermore, these methods have difficulty in introducing chiral structures during the preparation process, and the resulting silver nanoparticles mostly lack distinct chiral characteristics, making them difficult to meet the needs of some specific applications. Self-assembly methods, which induce the spontaneous arrangement of silver nanoparticles through intermolecular interactions (such as van der Waals forces, hydrogen bonds, and electrostatic forces), have the advantages of simple processes and low costs. However, self-assembly methods have certain limitations in achieving high-precision and high-consistency preparation, especially when imparting chiral structures to silver nanoparticles, due to the lack of sufficient controllability. While self-assembly methods can generate certain chiral nanostructures under certain conditions, they suffer from poor reproducibility and instability, making it difficult to ensure consistent particle morphology. The resulting silver nanoparticles also lack distinct chiral characteristics, failing to meet the demands of high-performance applications. The hard template method typically uses a prefabricated template to constrain the shape and size of silver nanoparticles, resulting in highly precise and symmetrical silver nanoparticles. While this method can achieve distinct chiral structures to a certain extent, the selection of template materials, template preparation, and template removal are complex and time-consuming. The removal process, in particular, can affect the purity of the silver nanoparticles and even introduce unnecessary impurities.

[0004] In summary, while various existing methods for preparing silver nanoparticles have achieved some success, certain technical bottlenecks remain in precisely controlling particle morphology and size, as well as introducing specific chiral structures. Therefore, developing a novel, simpler preparation method that can address the shortcomings of existing technologies, particularly in imparting chiral structures to silver nanoparticles, has significant scientific significance and application value. Summary of the Invention

[0005] To address the problems of complex preparation operations, high costs, and the inability to introduce controllable chiral structures in the prior art silver nanoparticles, the present invention provides chiral silver nanoparticles and a method for preparing the same. The technical solutions of the present invention are as follows:

[0006] A method for preparing chiral silver nanoparticles comprises the following steps:

[0007] Adding secondary water to the centrifuge tube, and then sequentially adding a dispersant, a precursor, a chiral reagent, an oxidant, a reducing agent, an anion salt, and a buffer solution, stirring until the solution is uniformly mixed, placing the mixed solution in a constant temperature water bath for reaction, and after the reaction, centrifuging the mixed solution and washing to obtain chiral silver nanoparticles;

[0008] The precursor includes silver nitrate, silver acetate, silver fluoride, amino complex silver, and one or a combination of at least two of silver chloride, silver bromide and silver iodide;

[0009] The dispersant comprises one or a combination of at least two of citric acid, tartaric acid, fumaric acid, succinic acid, malic acid, oxalic acid and oxalic acid derivatives;

[0010] The chiral reagent includes one or a combination of at least two of chiral amino acids, chiral polypeptides and chiral amines;

[0011] The oxidizing agent comprises one or a combination of peroxide and peroxyacid;

[0012] The reducing agent comprises one or a combination of at least two of ascorbic acid, sodium borohydride, sulfite, hydrazine, glucose and hydroxylamine hydrochloride water-soluble reducing agents;

[0013] The anion salt includes one or a combination of at least two of fluoride ion salt, chloride ion salt, bromide ion salt, phosphate ion salt and carbonate ion salt;

[0014] The buffer salt includes one or a combination of at least two of hydroxide, carbonate, phosphate, and acetate;

[0015] Furthermore, the stirring speed is 0 to 2000 r / m;

[0016] Furthermore, the temperature of the constant temperature water bath is 0-60°C;

[0017] Furthermore, the reaction time is 2 to 720 minutes;

[0018] Furthermore, the centrifugal rotation speed is 2000-15000 r / m.

[0019] A chiral nanoparticle is prepared by the above-mentioned preparation method.

[0020] Compared with the prior art, the present invention solves the problems of complex preparation operation, high cost and inability to introduce controllable chiral structure of silver nanoparticles. The specific beneficial effects are:

[0021] 1. Simplify the synthesis process and reduce production costs: The present invention adopts a one-step method to synthesize chiral silver nanoparticles. Compared with traditional synthesis methods, the one-step method has mild and simple reaction conditions, is fast and simple, and does not require a template. It greatly reduces the current technical process and difficulty, saves the amount of raw materials, and further reduces production costs.

[0022] 2. Enhance the function and performance of the material: The chiral silver nanoparticles synthesized by the one-step method not only retain the excellent optical, electrical and catalytic properties of the silver nanomaterial itself, but also have chiral optical properties. The position of the chiral optical response of the silver nanoparticles can be precisely controlled, and the chiral optical properties of the silver nanoparticles can be regulated.

[0023] 3. Promote research progress in the field of chiral silver nanomaterials: The present invention not only provides a novel synthesis route for silver nanoparticles, but also provides a new direction for the research of chiral nanomaterials. Traditional chiral nanomaterials usually rely on complex synthesis routes, such as template method, physical deposition method, self-assembly method, etc. The present invention provides a one-step preparation of chiral silver nanoparticles, laying the foundation for the application of silver nanoparticles in the fields of chiral chemistry, chiral optics, chiral catalysis, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a scanning electron micrograph of L-chiral silver nanoparticles;

[0025] Figure 2 is the circular dichroism spectrum of L-chiral silver nanoparticles;

[0026] Figure 3 Circular dichroism spectra of L-chiral silver nanoparticles at different L-cysteine ​​concentrations;

[0027] Figure 4 is a scanning electron microscopy image of D-chiral silver nanoparticles;

[0028] Figure 5 is the circular dichroism spectrum of D-chiral silver nanoparticles;

[0029] Figure 6 is a scanning electron micrograph of achiral silver nanoparticles;

[0030] Figure 7 Circular dichroism spectrum of achiral silver nanoparticles. DETAILED DESCRIPTION

[0031] In order to make the technical solution of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the specification of the present invention. It should be noted that the following embodiments are only used to better understand the technical solution of the present invention and should not be understood as limiting the present invention.

[0032] Example 1.

[0033] 1 mL of 0.02 M citric acid solution was added to 3.6 mL of secondary water, placed in a 25 mL centrifuge tube, and gently shaken to disperse it evenly; 134 μL of 20 mM L-cysteine ​​solution, 1 mL of 3 mM silver nitrate solution, 100 μL of 0.2 M hydrogen peroxide solution, 3.5 mL of 3.5 mM potassium chloride solution, 320 μL of 75 mM sodium borohydride solution and 880 μL of 0.1 M potassium hydroxide solution were added thereto and stirred until the solution was uniformly mixed, wherein the stirring speed was 1000 r / m; the mixed solution was placed in a constant temperature water bath at 15°C for 60 min, and the reacted mixed solution was centrifuged at a centrifugal speed of 12000 r / m, and L-chiral silver nanoparticles were obtained by washing.

[0034] like Figure 1 The scanning electron microscope image of L-chiral silver nanostructures shows that these nanoparticles have a distinct polyhedral structure, and the carriers are mainly divided into triangular and hexagonal geometric forms. This structural feature proves that silver nanoparticles have obvious chiral characteristics under the action of L-cysteine. Figure 2 This is the circular dichroism spectrum of the L-chiral silver nanostructure. It can be seen from the figure that the L-chiral silver nanoparticles have a certain uniformity and dispersion, which proves that this method can achieve the control of the chiral morphology and chiral optical properties of silver nanoparticles during the synthesis process.

[0035] Example 2.

[0036] 1 mL of 0.02 M citric acid solution was added to 3.6 mL of secondary water, placed in a 25 mL centrifuge tube, and gently shaken to disperse it evenly; 134 μL of 10 mM L-cysteine ​​solution, 1 mL of 3 mM silver nitrate solution, 100 μL of 0.2 M hydrogen peroxide solution, 3.5 mL of 3.5 mM potassium chloride solution, 320 μL of 75 mM sodium borohydride solution and 880 μL of 0.1 M potassium hydroxide solution were added thereto and stirred until the solution was uniformly mixed, wherein the stirring speed was 1000 r / m; the mixed solution was placed in a constant temperature water bath at 15°C for 60 min, and the reacted mixed solution was centrifuged at a centrifugal speed of 12000 r / m, and washed to obtain L-chiral silver nanoparticles.

[0037] Example 3.

[0038] 1 mL of 0.02 M citric acid solution was added to 3.6 mL of secondary water, placed in a 25 mL centrifuge tube, and gently shaken to disperse it evenly; 134 μL of 30 mM L-cysteine ​​solution, 1 mL of 3 mM silver nitrate solution, 100 μL of 0.2 M hydrogen peroxide solution, 3.5 mL of 3.5 mM potassium chloride solution, 320 μL of 75 mM sodium borohydride solution and 880 μL of 0.1 M potassium hydroxide solution were added thereto and stirred until the solution was uniformly mixed, wherein the stirring speed was 1000 r / m; the mixed solution was placed in a constant temperature water bath at 15°C for 60 min, and the reacted mixed solution was centrifuged at a centrifugal speed of 12000 r / m, and washed to obtain L-chiral silver nanoparticles.

[0039] Example 4.

[0040] 1 mL of 0.02 M citric acid solution was added to 3.6 mL of secondary water, placed in a 25 mL centrifuge tube, and gently shaken to disperse it evenly; 134 μL of 40 mM L-cysteine ​​solution, 1 mL of 3 mM silver nitrate solution, 100 μL of 0.2 M hydrogen peroxide solution, 3.5 mL of 3.5 mM potassium chloride solution, 320 μL of 75 mM sodium borohydride solution and 880 μL of 0.1 M potassium hydroxide solution were added thereto and stirred until the solution was uniformly mixed, wherein the stirring speed was 1000 r / m; the mixed solution was placed in a constant temperature water bath at 15°C for 60 min, and the reacted mixed solution was centrifuged at a centrifugal speed of 12000 r / m, and washed to obtain L-chiral silver nanoparticles.

[0041] like Figure 3The circular dichroism spectra of L-chiral silver nanostructures at different L-cysteine ​​concentrations show that the position of the nanoparticle's chiral optical response can be precisely controlled by adjusting the L-cysteine ​​concentration. The circular dichroism peak wavelength is adjustable within the range of 445 to 520 nm, and the circular dichroism peak intensity (g-factor) is adjustable within the range of 0.002 to 0.01, demonstrating the continuity and tunability of the chiral optical properties of L-chiral silver nanoparticles. This method achieves control over the chiral optical properties of silver nanoparticles during the synthesis process.

[0042] Example 5.

[0043] 1 mL of 0.02 M citric acid solution was added to 3.6 mL of secondary water, placed in a 25 mL centrifuge tube, and gently shaken to disperse it evenly; 134 μL of 20 mM D-cysteine ​​solution, 1 mL of 3 mM silver nitrate solution, 100 μL of 0.2 M hydrogen peroxide solution, 880 μL of 0.1 M potassium hydroxide solution, 3.5 mL of 3.5 mM potassium chloride solution and 320 μL of 75 mM sodium borohydride solution were added in sequence and stirred until the solution was uniformly mixed, wherein the stirring speed was 1000 r / m; the mixed solution was placed in a constant temperature water bath at 15°C for 60 min, and the mixed solution after the reaction was centrifuged at a centrifugal speed of 12000 r / m, and washed to obtain D-chiral silver nanoparticles.

[0044] like Figure 4 This is a scanning electron microscope image of D-chiral silver nanostructures. It can be seen from the figure that these nanoparticles have a clear polyhedral structure, and the carriers are mainly divided into triangular and hexagonal geometric forms. This structural feature proves that silver nanoparticles have obvious chiral characteristics under the action of D-cysteine. Figure 5 This is the circular dichroism spectrum of the D-chiral silver nanostructure. It can be seen from the figure that the D-chiral silver nanoparticles have a certain uniformity and dispersion, indicating that this method achieves the control of the chiral morphology and chiral optical properties of silver nanoparticles during the synthesis process.

[0045] Comparative Example 1.

[0046] 1 mL of 0.02 M citric acid solution was added to 3.6 mL of secondary water, placed in a 25 mL centrifuge tube, and gently shaken to disperse it evenly; 134 μL of a 20 mM mixed solution of 50% L-cysteine ​​and 50% L-cysteine, 1 mL of a 3 mM silver nitrate solution, 100 μL of a 0.2 M hydrogen peroxide solution, 880 μL of a 0.1 M potassium hydroxide solution, 3.5 mL of a 3.5 mM potassium chloride solution, and 320 μL of a 75 mM sodium borohydride solution were added in sequence and stirred until the solution was uniformly mixed, wherein the stirring speed was 1000 r / m; the mixed solution was placed in a constant temperature water bath at 15° C. and reacted for 60 min. The reacted mixed solution was centrifuged at a centrifugal speed of 12000 r / m, and washed to obtain achiral silver nanoparticles.

[0047] like Figure 6 This is a scanning electron microscope image of achiral silver nanostructures. It can be seen from the image that these nanoparticles have a clear polyhedral structure, and the carriers are mainly triangular in geometry and have no chiral rotation characteristics. Figure 7 The circular dichroism spectrum of the achiral silver nanostructure is compared with the chiral silver nanoparticles prepared in Examples 1-5, which shows that the above method can achieve control of the chiral morphology and chiral optical properties of silver nanoparticles during the synthesis process.

[0048] The chiral silver nanoparticles synthesized in this invention using a one-step method retain the excellent optical, electrical, and catalytic properties inherent to silver nanomaterials while also possessing chiral optical properties. This allows for precise control of the location of the chiral optical response of the silver nanoparticles, enabling regulation of the chiral optical properties of the silver nanoparticles. This invention not only provides a novel synthesis pathway for silver nanoparticles but also offers a new direction for the research of chiral nanomaterials, significantly reducing current technical processes and difficulties, conserving raw materials, and further lowering production costs. This paves the way for the application of silver nanoparticles in fields such as chiral chemistry, chiral optics, and chiral catalysis.

Claims

1. A method for preparing chiral silver nanoparticles, characterized in that: The following steps are involved: Adding secondary water to the centrifuge tube, and then sequentially adding a dispersant, a precursor, a chiral reagent, an oxidant, a reducing agent, an anion salt, and a buffer solution, stirring until the solution is uniformly mixed, placing the mixed solution in a constant temperature water bath for reaction, and after the reaction, centrifuging the mixed solution and washing to obtain chiral silver nanoparticles; The precursor includes silver nitrate, silver acetate, silver fluoride, amino complex silver, and one or a combination of at least two of silver chloride, silver bromide and silver iodide; The dispersant comprises one or a combination of at least two of citric acid, tartaric acid, fumaric acid, succinic acid, malic acid, oxalic acid and oxalic acid derivatives; The chiral reagent includes one or a combination of at least two of chiral amino acids, chiral polypeptides and chiral amines; The oxidizing agent comprises one or a combination of peroxide and peroxyacid; The reducing agent comprises one or a combination of at least two of ascorbic acid, sodium borohydride, sulfite, hydrazine, glucose and hydroxylamine hydrochloride water-soluble reducing agents; The anion salt includes one or a combination of at least two of fluoride ion salt, chloride ion salt, bromide ion salt, phosphate ion salt and carbonate ion salt; The buffer salt includes one or a combination of at least two of hydroxide, carbonate, phosphate, and acetate.

2. The method for preparing chiral nanoparticles according to claim 1, wherein: The stirring speed is 0 to 2000 r / m.

3. The method for preparing chiral nanoparticles according to claim 1, wherein: The temperature of the constant temperature water bath is 0-60°C.

4. The method for preparing chiral nanoparticles according to claim 1, wherein: The reaction time is 2 to 720 minutes.

5. The method for preparing chiral nanoparticles according to claim 1, wherein: The centrifugal speed is 2000-15000 r / m.

6. A chiral nanoparticle, characterized in that: The method is prepared by the method according to any one of claims 1 to 5.

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