A method for preparing chiral silver nanoclusters using chiral cysteine and silver nitrate
Chiral silver nanoclusters were prepared by magnetic stirring under mild conditions using chiral cysteine and silver nitrate, and multiple ultrasonic centrifugal cleaning and vacuum freeze-drying, the problems of uneven particle size, easy agglomeration and low yield in the prior art were solved, and chiral silver nanocluster preparation with high yield and uniform morphology were achieved.
Patent Information
- Application Number
- CN202211566436.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-12-07
- Publication Date
- 2025-04-08
- Estimated Expiration
- 2042-12-07
AI Technical Summary
The method for preparing chiral silver nanoclusters in the prior art has problems such as uneven particle size, easy agglomeration, low yield, and unstable reactions, making it difficult to achieve high yield and rapid preparation.
Chiral cysteine and silver nitrate were used as the main reactants, and the reaction was carried out under a 37°C water bath for 2 hours by magnetic stirring, followed by multiple ultrasonic centrifugal cleaning and vacuum freeze-drying to prepare chiral silver nanoclusters.
The high yield and rapid preparation of chiral silver nanoclusters are achieved, and the morphology of the products is uniform and has strong chiral optical rotation, breaking the limitations of harsh reaction conditions and low yield in traditional methods.
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Figure CN116021027B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of nano material preparation, and in particular relates to a method for preparing chiral silver nanoclusters by using chiral cysteine and silver nitrate. Background Art
[0002] With the widespread application of nanomaterials and the deepening of research related to nanomaterials, nanomaterials with single functions can no longer meet people's needs, and people have gradually paid attention to chiral nanomaterials with enantioselective properties. The term chirality refers to the inability of an object to overlap with its mirror image. Chirality refers to the phenomenon that an object cannot overlap with its mirror image, which exists at all scales from microscopic to macroscopic. Chirality is widely present in nature. Since the discovery of chiral optical activity in the early 19th century, chiral materials have been continuously developed. They are of great significance in promoting the development of biomarkers, chiral analysis and detection, enantiomer selective separation, polarization-related photonics and optoelectronics. Chirality is of great significance to the origin of life and life systems. It is well known that life chooses small molecules such as left-handed amino acids and right-handed sugars to construct biological macromolecules such as proteins and nucleic acids. There are also very interesting single chirality phenomena in living organisms. For example, almost all amino acids are left-handed, while all nucleic acids, starch and other polysaccharides are right-handed. Therefore, the development of chiral materials is also crucial to understanding the origin of life. At present, enantioselective chiral nanomaterials have been used in enantioselective catalysis, sensing, biomedicine and chiral optical devices. Metal nanoclusters are represented by gold, silver, copper and platinum nanoclusters (Au, Ag, Cu, Pt NCs). Some noble metal nanoparticles, such as gold nanoparticles and silver nanoparticles, have great potential in cancer diagnosis and treatment due to their surface properties, especially enantioselective silver nanoclusters, which have been applied in sensing and biomedicine. Among them, silver nanoclusters (Ag NCs) have excellent properties such as good photostability, large Stocks shift, and wavelength-tunable fluorescence, so they have attracted attention, especially in the field of analytical sensing, becoming a research hotspot.
[0003] In the prior art, there are several methods for preparing chiral silver nanoclusters:
[0004] Ultrasonic preparation: silver nitrate solution and chiral amino acid solution are mixed and then ultrasonically reacted. In the actual operation process, it was found that the nanosilver particles prepared by this method are uneven in size and easy to agglomerate.
[0005] The high temperature stirring method is to use ascorbic acid as a reducing agent, mix the chiral amino acid solution and the silver nitrate solution, and stir in a 70°C water bath for a period of time to obtain the desired product, but this method has a low yield and an unstable reaction.
[0006] Therefore, a rapid method for preparing chiral silver nanoclusters with high yield is urgently needed. Summary of the invention
[0007] The purpose of the present invention is to provide a method for preparing chiral silver nanoclusters by using chiral cysteine and silver nitrate in view of the shortcomings of the prior art, which has high yield and fast preparation.
[0008] To achieve the above purpose, the technical solution adopted by the present invention to solve the technical problem is:
[0009] A method for preparing chiral silver nanoclusters using chiral cysteine and silver nitrate comprises the following steps:
[0010] S1, preparing a 55 mM chiral cysteine solution: 199.9 mg chiral cysteine is dispersed in 30 mL ultrapure water, and ultrasonically accelerated to dissolve to obtain a 55 mM chiral cysteine solution;
[0011] S2, preparing a 50 mM silver nitrate solution: dispersing 254.8 mg of silver nitrate in 30 mL of ultrapure water, and dissolving by ultrasonication to obtain a 50 mM silver nitrate solution;
[0012] S3, preparation of chiral silver nanoclusters: 30 mL of 50 mM silver nitrate solution was placed in a conical flask, the conical flask was placed in a 37°C water bath and magnetically stirred for 5 minutes, 30 mL of 55 mM chiral cysteine solution (L-cysteine or D-cysteine) was added at one time, and the reaction was continued for 2 hours under magnetic stirring to obtain a white suspension;
[0013] S4, product washing: after ultrasonication, the white suspension was centrifuged at 9384g for 10min to separate the solid and liquid, the clear liquid was discarded and the white precipitate was retained, 25g of ultrapure water was added to the white precipitate, ultrasonication was performed, centrifuged at 9384g again and the solid and liquid were separated, and the washing was repeated 3 times;
[0014] S5, product drying: the washed white precipitate is placed in a vacuum freeze dryer for drying.
[0015] While adopting the above technical solutions, the present invention may also adopt or combine the following technical solutions:
[0016] As a preferred technical solution of the present invention: in step S1, the chiral cysteine is selected from L-cysteine powder or D-cysteine powder to prepare 55 mM L-cysteine or 55 mM D-cysteine solution.
[0017] As a preferred technical solution of the present invention: in step S2, ultrasound is used for 1 min to accelerate the complete dissolution of chiral cysteine.
[0018] As a preferred technical solution of the present invention: in step S3, the reaction temperature for preparing the chiral silver nanoclusters is 37°C, and the heating temperature of the water bath is maintained at 37°C.
[0019] As a preferred technical solution of the present invention: in step S5, the washed white precipitate is frozen and placed in a vacuum freeze dryer for 12 hours, and then ground and stored.
[0020] Compared with the prior art, the method for preparing chiral silver nanoclusters using chiral cysteine and silver nitrate of the present invention uses silver nitrate and chiral amino acids (L-cysteine or D-cysteine) as main reactants, no longer needs to add other auxiliary reagents, the reaction conditions are mild and easy to control, the operation is simple, the reaction process is green and environmentally friendly, the reaction conditions are simple, the reaction product amount is large and stable, and it has the potential to be applied to large-scale preparation of chiral silver nanoclusters. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 The ultraviolet absorption spectra of left-handed silver nanoclusters and right-handed silver nanoclusters prepared by the method of the present invention;
[0022] Figure 2 The original dichroic spectra of left-handed silver nanoclusters and right-handed silver nanoclusters prepared by the method of the present invention;
[0023] Figure 3 High-resolution electron microscopy images of left-handed silver nanoclusters and right-handed silver nanoclusters prepared by the method of the present invention. 3 (a) L-silver nanocluster, 3 (b) D-silver nanocluster;
[0024] Figure 4 The size distribution diagram of left-handed silver nanoclusters and right-handed silver nanoclusters prepared by the method of the present invention, 4 (a) L-silver nanoclusters, 4 (b) D-silver nanoclusters. DETAILED DESCRIPTION
[0025] The present invention is further described in detail below with reference to the accompanying drawings and embodiments:
[0026] A method for preparing chiral silver nanoclusters by using chiral cysteine and silver nitrate of the present invention comprises the following steps:
[0027] S1, 55 mM L-cysteine or D-cysteine solution preparation,
[0028] 199.9 mg of L-cysteine powder or D-cysteine powder was dispersed in 30 mL of ultrapure water, and ultrasonicated for 1 min to accelerate its complete dissolution, thereby obtaining a 55 mM L-cysteine solution or D-cysteine solution.
[0029] S2, 50 mM silver nitrate solution preparation,
[0030] 254.8 mg of silver nitrate was dissolved in 30 mL of ultrapure water to obtain a 50 mM silver nitrate solution.
[0031] S3, Preparation of chiral silver nanoclusters,
[0032] 30 mL of 50 mM silver nitrate solution was magnetically stirred in a 37°C water bath for 5 min. After the solution temperature reached 37°C, 30 mL of 55 mM L-cysteine solution or D-cysteine solution was added at once. After stirring for 5 min to mix well, the reaction was continued at 37°C for 2 h to obtain a white suspension.
[0033] S4, product cleaning,
[0034] The white suspension obtained by the reaction was placed in a centrifuge tube. After centrifugation at 9384g for 10 min, the supernatant was discarded and the white precipitate was retained. Ultrapure water was added and ultrasonic cleaning was performed for 1 min. After centrifugation at 9384g for 10 min again, the supernatant was discarded and the white precipitate was retained. The above cleaning cycle was continued for 2 more times.
[0035] S5, product drying,
[0036] The washed precipitate was placed in a vacuum freeze dryer for 12 hours for drying, and then ground for storage. The product of using 55 mM L-cysteine solution in the preparation process was L-silver nanoclusters, while the product of using 55 mM D-cysteine solution was D-silver nanoclusters.
[0037] When characterizing the chiral silver nanoclusters prepared by the method for preparing chiral silver nanoclusters using chiral cysteine and silver nitrate of the present invention, a UV-visible spectrum is obtained by scanning a wavelength of 200nm to 600nm using a UV-visible spectrophotometer to determine that the prepared product is a silver nanocluster. The particle size and lattice spacing are measured using a high-resolution transmission electron microscope to determine that the product is a silver nanocluster with a size of 1.8-4.6nm. The chiral optical rotation is examined using circular dichroism to determine that the prepared product has chiral characteristics.
[0038] The method for preparing chiral silver nanoclusters using chiral cysteine and silver nitrate of the present invention provides a simple and efficient method for preparing chiral silver nanoclusters, and the chiral silver nanoclusters are finally obtained by stirring the reactants in a water bath at a specific temperature. Compared with the existing preparation method, the preparation method of the chiral silver nanoclusters of the present invention has the advantages of being simple and rapid, high yield, and uniform morphology of the prepared chiral silver nanoclusters, breaking the limitations of the traditional preparation method of chiral silver nanoclusters, which has harsh reaction conditions and low yield, and provides a basis for efficiently preparing chiral silver nanoclusters with good configuration.
[0039] Example 1
[0040] Other preparation methods of chiral silver nanoclusters are as follows:
[0041] (1) Prepare 30 mL of 50 mM silver nitrate solution and 30 mL of 55 mM L-cysteine or D-cysteine solution, and sonicate to fully dissolve them.
[0042] (2) The silver nitrate solution and the L-cysteine solution or the D-cysteine solution prepared above were mixed at once, magnetically stirred for 5 minutes, and then placed in a water bath ultrasonic cleaning apparatus with a power of 120 W.
[0043] (3) The water bath temperature of the ultrasonic cleaning apparatus was 37°C, and the ultrasonic reaction was performed for 2 h.
[0044] After the reaction, a large amount of white precipitate was found at the bottom of the container, and the solution was almost transparent, indicating that the chiral silver nanoclusters prepared by this method had poor dispersion and were very easy to agglomerate and settle, so this method was not considered.
[0045] Example 2
[0046] Since the product in Example 1 has poor dispersibility, it may be because the yield of the obtained chiral silver nanoclusters is large, resulting in the inability to effectively disperse them by ultrasound. Therefore, the concentration of the reactants was reduced to further explore the feasibility of the ultrasonic method.
[0047] (1) Prepare 30 mL of 20 mM silver nitrate solution and 30 mL of 22 mM L-cysteine or D-cysteine solution, and sonicate to fully dissolve them.
[0048] (2) The silver nitrate solution and the L-cysteine solution or the D-cysteine solution prepared above were mixed at once, magnetically stirred for 5 minutes, and then placed in a water bath ultrasonic cleaning apparatus with a power of 120 W.
[0049] (3) The water bath temperature of the ultrasonic cleaning apparatus was 37°C, and the ultrasonic reaction was performed for 2 h.
[0050] After the reaction, a large amount of white precipitate was still accumulated at the bottom of the container, and the solution was almost transparent, indicating that even if the concentration of the reactants was reduced, the dispersion of the chiral silver nanoclusters prepared by this method was still poor and they were very easy to agglomerate and precipitate, so the ultrasonic preparation method was not considered.
[0051] Example 3
[0052] It can be seen from Examples 1 and 2 that the ultrasonic method cannot prepare chiral silver nanoclusters with good dispersibility, so the fixed preparation method is magnetic stirring, and the molar concentration ratio of the two reactants is explored.
[0053] (1) Prepare 30 mL of 50 mM silver nitrate solution and 30 mL of 50 mM L-cysteine or D-cysteine solution.
[0054] (2) The silver nitrate solution and the chiral cysteine solution were mixed at once, and reacted at 37° C. for 2 h under magnetic stirring in a water bath to obtain a milky white suspension.
[0055] (3) The solution was centrifuged at 9384 g for 10 min, the supernatant was discarded, the precipitate was collected, and ultrapure water was added for ultrasonic cleaning, and then the supernatant was discarded. The cleaning was continued for 2 more times, and the final precipitate was placed in a vacuum freeze dryer for drying, and the powder was ground and stored.
[0056] After the reaction, it was found that the circular dichroism spectrum of the chiral silver nanoclusters prepared by this method showed a certain chiral optical rotation, but its chiral optical rotation was weaker than that of the method of this patent, indicating that the concentration of 50mM L-cysteine or D-cysteine is still insufficient for preparing silver nanoclusters with strong chiral optical rotation.
[0057] Example 4
[0058] It can be seen from Example 3 that the result under the condition of a molar concentration ratio of silver nitrate to chiral cysteine of 1:1 is not ideal, so the molar concentration ratio of silver nitrate to chiral cysteine of 1:1.5 was explored to investigate the resulting product.
[0059] (1) Prepare 30 mL of 50 mM silver nitrate solution and 30 mL of 75 mM L-cysteine or D-cysteine solution.
[0060] (2) The silver nitrate solution and the chiral cysteine solution were mixed at once, and reacted under magnetic stirring in a water bath at 37° C. for 2 h to obtain a milky white suspension.
[0061] (3) The solution was centrifuged at 9384 g for 10 min, the supernatant was discarded, and the precipitate was collected. Ultrapure water was added for ultrasonic cleaning, and then the solution was centrifuged at 9384 g for 10 min and the supernatant was discarded. The cleaning was continued for two more times, and the obtained precipitate was finally placed in a vacuum freeze dryer and dried to obtain a powder for grinding and storage.
[0062] After the reaction, it was found that the chiral silver nanoclusters prepared by the method of the present invention:
[0063] (1) A significant improvement in the reaction yield is achieved. The existing chiral silver nanocluster preparation methods have low reactant concentrations, and the yield of the prepared chiral silver nanocluster is low, usually a few to tens of milligrams, and lack a yield of several hundred milligrams in a single synthesis. The overall preparation yield is low, while the method of the present invention can finally obtain 320 mg of left-handed silver nanocluster or right-handed silver nanocluster powder in a single preparation, with a yield of more than 70%.
[0064] (2) Figure 1-Figure 4 As shown, the left-handed silver nanoclusters and the right-handed silver nanoclusters prepared by the method of the present invention both have strong chiral optical rotation, and the nanoclusters have stable morphology and uniform size distribution.
[0065] The above-mentioned specific implementation methods are used to explain the present invention and are only preferred embodiments of the present invention, rather than limiting the present invention. Any modifications, equivalent substitutions, improvements, etc. made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.
Claims
1. A method for preparing chiral silver nanoclusters using chiral cysteine and silver nitrate, comprising the following steps: S1, preparing a 55 mM chiral cysteine solution: 199.9 mg chiral cysteine is dispersed in 30 mL ultrapure water, and ultrasonically accelerated to dissolve to obtain a 55 mM chiral cysteine solution; S2, prepare 50 mM silver nitrate solution: 254.8 mg silver nitrate is dispersed in 30 mL ultrapure water, and ultrasonic accelerated dissolution is performed to obtain 50 mM silver nitrate solution; S3, preparation of chiral silver nanoclusters: 30 mL of 50 mM silver nitrate solution was placed in a conical flask, the conical flask was placed in a 37°C water bath with magnetic stirring for 5 minutes, and 30 mL of 55 mM chiral cysteine solution was added at once, wherein: The chiral cysteine is L-cysteine or D-cysteine, and the reaction is continued for 2 h with magnetic stirring to obtain a white suspension; S4, product washing: after ultrasonication, the white suspension was centrifuged at 9384 g for 10 min to separate the solid and liquid, the clear liquid was discarded and the white precipitate was retained, 25 g of ultrapure water was added to the white precipitate, ultrasonication was performed, and the suspension was centrifuged at 9384 g again to separate the solid and liquid, and the washing was repeated 3 times; S5, product drying: placing the washed white precipitate into a vacuum freeze dryer for drying; Wherein, in step S3, the reaction temperature for preparing the chiral silver nanoclusters is 37°C, and the heating temperature of the water bath is maintained at 37°C.
2. The method for preparing chiral silver nanoclusters using chiral cysteine and silver nitrate as claimed in claim 1, characterized in that: In step S1, the chiral cysteine is selected from L-cysteine powder or D-cysteine powder to prepare a 55 mM L-cysteine or 55 mM D-cysteine solution.
3. The method for preparing chiral silver nanoclusters using chiral cysteine and silver nitrate as claimed in claim 1, characterized in that: In step S2, ultrasound is used for 1 min to accelerate the complete dissolution of chiral cysteine.
4. The method for preparing chiral silver nanoclusters using chiral cysteine and silver nitrate as claimed in claim 1, characterized in that: In step S5, the washed white precipitate is frozen and placed in a vacuum freeze dryer for 12 h, and then ground and stored.