Chiral silver nanoparticles and preparation method thereof

Abstract

The invention discloses chiral silver nanoparticles and a preparation method thereof, relates to the technical field of nano materials, and solves the problems that in the prior art, the preparation operation of silver nanoparticles is complicated, the cost is high, and a controllable chiral structure cannot be introduced. The preparation method comprises the following steps: adding secondary water into a centrifugal tube, continuously and sequentially adding a dispersing agent, a precursor, a chiral reagent, an oxidizing agent, a reducing agent, anionic salt and a buffer solution, stirring until the solution is uniformly mixed, putting the mixed solution into a constant-temperature water bath kettle for reaction, and performing centrifugal separation and washing on the mixed solution after the reaction to obtain the chiral silver nanoparticles. The chiral silver nanoparticles synthesized by a one-step method not only keep excellent optical, electrical and catalytic properties of the silver nano-material, but also have chiral optical properties, the chiral optical response position of the silver nanoparticles can be accurately controlled, the chiral optical properties of the silver nanoparticles can be regulated and controlled, the production process is simple, and the method is suitable for industrial production. And the production cost is reduced.

Description

Technical Field

[0001] The 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 catalysis, sensing, optical imaging, antibacterial and biomedicine due to their unique physical and chemical properties. The special properties of silver nanoparticles mainly come from their surface plasmon resonance (SPR) effect, quantum size effect and large surface energy, which give silver nanoparticles excellent functional performance in many application fields. In particular, the wide application of silver nanoparticles in the optical field, such as surface enhanced Raman scattering (SERS) and optical sensing, depends 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] At present, the methods for preparing silver nanoparticles mainly include traditional methods such as physical deposition, self-assembly, hard template and chemical reduction. Physical deposition methods such as evaporation and sputtering can usually control the size and morphology of silver nanoparticles more accurately, and can obtain high-purity silver nanoparticles; however, these methods rely on high-precision equipment and complex process flows, with high production costs and cumbersome operations. They are usually only suitable for small-scale laboratory preparation and are difficult to achieve large-scale production. At the same time, these methods are difficult to introduce chiral structures during the preparation process, and most of the prepared silver nanoparticles lack obvious chiral characteristics, which is difficult to meet the needs of some specific applications. The self-assembly method induces the spontaneous arrangement of silver nanoparticles through intermolecular interactions (such as van der Waals forces, hydrogen bonds, electrostatic forces, etc.), which has the advantages of simple process and low cost; however, the self-assembly method has certain limitations in achieving high-precision and high-consistency preparation, especially when giving silver nanoparticles chiral structures, it lacks sufficient controllability. Although the self-assembly method can generate certain chiral nanostructures under certain conditions, its repeatability is poor and its stability is insufficient. It is usually difficult to ensure the consistency of particle morphology, and the chiral characteristics of the silver nanoparticles obtained in the end are not obvious, which cannot meet the needs of high-performance applications. The hard template method usually constrains the shape and size of silver nanoparticles through prefabricated templates to obtain silver nanoparticles with high precision and high symmetry; this method can achieve obvious chiral structures to a certain extent, but the selection of template materials, template preparation, and template removal process are complicated and time-consuming, especially during the removal process, it may affect the purity of silver nanoparticles and even introduce unnecessary impurities.

[0004] In summary, although the existing preparation methods of various silver nanoparticles have achieved certain results, there are still certain technical bottlenecks in the precise control of particle morphology and size and the introduction of specific chiral structures. Therefore, the development of a new and simple preparation method can solve the shortcomings of the existing technology, especially in giving silver nanoparticles chiral structures, which has important scientific significance and application value. Summary of the invention

[0005] In order to solve the problems of complicated preparation operation, high cost and inability to introduce controllable chiral structure of silver nanoparticles in the prior art, the present invention proposes a chiral silver nanoparticle and a preparation method thereof. The technical solution of the present invention is as follows:

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

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

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

[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, and has the following specific beneficial effects:

[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 the traditional synthesis method, the one-step method has mild and simple reaction conditions, is fast and simple, and does not require a template, which greatly reduces the current technical procedures and difficulty, saves the amount of raw materials, and further reduces the production cost.

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

[0023] 3. Promote the research progress in the field of chiral silver nanomaterials: The present invention not only provides a new 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, which lays a 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 microscope 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 a limitation to 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 evenly mixed, wherein the stirring speed was 1000 r / m; the mixed solution was placed in a 15° C. constant temperature water bath for reaction for 60 min, the mixed solution after the reaction was centrifuged, wherein the centrifugal speed was 12000 r / m, and L-chiral silver nanoparticles were obtained by washing.

[0034] like Figure 1 The scanning electron microscope image of the L-chiral silver nanostructure shows that these nanoparticles have a distinct polyhedral structure, and the carriers are mainly divided into triangular and hexalobular geometric forms. This structural feature proves that the 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 evenly mixed, wherein the stirring speed was 1000 r / m; the mixed solution was placed in a 15° C. constant temperature water bath for reaction for 60 min, the mixed solution after the reaction was centrifuged, wherein the centrifugal speed was 12000 r / m, and L-chiral silver nanoparticles were obtained by washing.

[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 evenly mixed, wherein the stirring speed was 1000 r / m; the mixed solution was placed in a 15° C. constant temperature water bath to react for 60 min, the mixed solution after the reaction was centrifuged, wherein the centrifugal speed was 12000 r / m, and L-chiral silver nanoparticles were obtained by washing.

[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 evenly mixed, wherein the stirring speed was 1000 r / m; the mixed solution was placed in a 15° C. constant temperature water bath for reaction for 60 min, the mixed solution after the reaction was centrifuged, wherein the centrifugal speed was 12000 r / m, and L-chiral silver nanoparticles were obtained by washing.

[0041] like Figure 3The circular dichroism spectra of L-chiral silver nanostructures at different L-cysteine ​​concentrations are shown in the figure. It can be seen from the figure that by adjusting the concentration of L-cysteine, the position of the chiral optical response of the nanoparticles can be precisely controlled. The peak wavelength of the circular dichroism spectrum is adjustable in the range of 445 to 520nm; the peak intensity of the circular dichroism spectrum (g-factor) is adjustable in the range of 0.002 to 0.01, which proves that the chiral optical properties of L-chiral silver nanoparticles have certain continuity and adjustability. This method realizes the control of 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 evenly mixed, wherein the stirring speed was 1000 r / m; the mixed solution was placed in a 15° C. constant temperature water bath to react for 60 min, and the mixed solution after the reaction was centrifuged, wherein the centrifugal speed was 12000 r / m, and D-chiral silver nanoparticles were obtained by washing.

[0044] like Figure 4 This is a scanning electron microscope image of D-chiral silver nanostructure. It can be seen from the figure that these nanoparticles have a distinct polyhedral structure, and the carriers are mainly divided into triangular and hexapetal geometric forms. This structural feature proves that the silver nanoparticles show 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 can achieve 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 20 mM 50% L-cysteine ​​and 50% L-cysteine ​​mixed 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 evenly mixed, wherein the stirring speed was 1000 r / m; the mixed solution was placed in a 15° C. constant temperature water bath for reaction for 60 min, and the mixed solution after the reaction was centrifuged, wherein the centrifugal speed was 12000 r / m, and non-chiral silver nanoparticles were obtained by washing.

[0047] like Figure 6 This is a scanning electron microscope image of achiral silver nanostructures. It can be seen from the figure that these nanoparticles have a distinct 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 property characteristics of the silver nanoparticles during the synthesis process.

[0048] The chiral silver nanoparticles synthesized by the one-step method of the present invention retain the excellent optical, electrical and catalytic properties of the silver nanomaterial itself, and also have chiral optical properties, can accurately control the position of the chiral optical response of the silver nanoparticles, and realize the regulation of the chiral optical properties of the silver nanoparticles. The present invention not only provides a new synthesis route for silver nanoparticles, but also provides a new direction for the research of chiral nanomaterials, greatly reduces the current technical procedures and difficulties, saves the amount of raw materials, further reduces the production cost, and lays a foundation for the application of silver nanoparticles in the fields of chiral chemistry, chiral optics, chiral catalysis, etc.

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 adding dispersant, precursor, chiral reagent, oxidant, reductant, anion salt and buffer solution in sequence, stirring until the solution is evenly mixed, placing the mixed solution in a constant temperature water bath for reaction, centrifuging the mixed solution after the reaction, and washing to obtain chiral silver nanoparticles; The precursor includes one or a combination of at least two of silver nitrate, silver acetate, silver fluoride, amino complex silver, and 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 oxidant 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, characterized in that: The stirring speed is 0-2000r / m.

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

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

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

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

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