CN112823978A - Preparation method of silver-coated gold nano-star - Google Patents
Preparation method of silver-coated gold nano-star Download PDFInfo
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- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 title claims abstract description 96
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 title claims abstract description 60
- 229910052709 silver Inorganic materials 0.000 title claims abstract description 60
- 239000004332 silver Substances 0.000 title claims abstract description 60
- 238000002360 preparation method Methods 0.000 title claims abstract description 7
- 229910004042 HAuCl4 Inorganic materials 0.000 claims abstract description 12
- 239000011248 coating agent Substances 0.000 claims abstract description 11
- 238000000576 coating method Methods 0.000 claims abstract description 11
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 claims description 26
- 238000000034 method Methods 0.000 claims description 17
- 239000011668 ascorbic acid Substances 0.000 claims description 15
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(I) nitrate Inorganic materials [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 claims description 14
- 229960005070 ascorbic acid Drugs 0.000 claims description 13
- 235000010323 ascorbic acid Nutrition 0.000 claims description 13
- 101710134784 Agnoprotein Proteins 0.000 claims description 10
- KRKNYBCHXYNGOX-UHFFFAOYSA-K Citrate Chemical compound [O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O KRKNYBCHXYNGOX-UHFFFAOYSA-K 0.000 claims description 8
- 238000003756 stirring Methods 0.000 claims description 8
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 7
- 150000002500 ions Chemical class 0.000 claims description 7
- 229910021642 ultra pure water Inorganic materials 0.000 claims description 7
- 239000012498 ultrapure water Substances 0.000 claims description 7
- 238000009835 boiling Methods 0.000 claims description 6
- 239000002253 acid Substances 0.000 claims description 5
- 238000007792 addition Methods 0.000 claims description 5
- 239000003638 chemical reducing agent Substances 0.000 claims description 5
- 238000013019 agitation Methods 0.000 claims description 4
- 239000000203 mixture Substances 0.000 claims description 4
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 3
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 3
- 230000008859 change Effects 0.000 claims description 3
- 230000009467 reduction Effects 0.000 claims description 3
- 229910001961 silver nitrate Inorganic materials 0.000 claims description 3
- 238000003260 vortexing Methods 0.000 claims description 3
- 238000002156 mixing Methods 0.000 claims description 2
- 238000012546 transfer Methods 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims 1
- 238000004416 surface enhanced Raman spectroscopy Methods 0.000 description 23
- 239000002105 nanoparticle Substances 0.000 description 8
- 239000010931 gold Substances 0.000 description 7
- 229910052737 gold Inorganic materials 0.000 description 7
- 239000000758 substrate Substances 0.000 description 7
- 238000001514 detection method Methods 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 238000001069 Raman spectroscopy Methods 0.000 description 4
- 238000003917 TEM image Methods 0.000 description 4
- VYXSBFYARXAAKO-WTKGSRSZSA-N chembl402140 Chemical compound Cl.C1=2C=C(C)C(NCC)=CC=2OC2=C\C(=N/CC)C(C)=CC2=C1C1=CC=CC=C1C(=O)OCC VYXSBFYARXAAKO-WTKGSRSZSA-N 0.000 description 4
- 239000011521 glass Substances 0.000 description 4
- 229910000510 noble metal Inorganic materials 0.000 description 4
- 230000005672 electromagnetic field Effects 0.000 description 3
- 239000010410 layer Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000002082 metal nanoparticle Substances 0.000 description 3
- 239000004094 surface-active agent Substances 0.000 description 3
- 238000000479 surface-enhanced Raman spectrum Methods 0.000 description 3
- 230000002194 synthesizing effect Effects 0.000 description 3
- 238000004627 transmission electron microscopy Methods 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 229910003771 Gold(I) chloride Inorganic materials 0.000 description 2
- 238000000862 absorption spectrum Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000005284 excitation Effects 0.000 description 2
- FDWREHZXQUYJFJ-UHFFFAOYSA-M gold monochloride Chemical compound [Cl-].[Au+] FDWREHZXQUYJFJ-UHFFFAOYSA-M 0.000 description 2
- 238000003384 imaging method Methods 0.000 description 2
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- 125000003118 aryl group Chemical group 0.000 description 1
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- 239000013626 chemical specie Substances 0.000 description 1
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- 239000000084 colloidal system Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
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- 238000004519 manufacturing process Methods 0.000 description 1
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- 108090000623 proteins and genes Proteins 0.000 description 1
- 102000004169 proteins and genes Human genes 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000001509 sodium citrate Substances 0.000 description 1
- NLJMYIDDQXHKNR-UHFFFAOYSA-K sodium citrate Chemical compound O.O.[Na+].[Na+].[Na+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O NLJMYIDDQXHKNR-UHFFFAOYSA-K 0.000 description 1
- 238000002198 surface plasmon resonance spectroscopy Methods 0.000 description 1
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- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/16—Making metallic powder or suspensions thereof using chemical processes
- B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
- B22F9/24—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from liquid metal compounds, e.g. solutions
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Abstract
The invention discloses a preparation method of silver-coated gold nano-star, which comprises the following steps: preparing a seed solution; adding seed solution to HAuCl4Preparing a gold nano star solution by using the solution; and forming a silver coating on the surface of the gold nano-star.
Description
Technical Field
The invention relates to the technical field of preparation of nano biological materials. Specifically, the invention relates to a preparation method of silver-coated gold nano-star.
Background
The development of active substrates for Surface Enhanced Raman Spectroscopy (SERS) using noble metal Nanoparticles (NPs) is an important topic for the detection and characterization of chemical species at the single molecule level. Currently, the main applications of SERS substrates are focused in the fields of medicine, biology, homeland security, environmental pollution and food pollution.
In recent years, much effort has been put into developing nanoparticles with a stronger surface raman enhancement (SERS) effect. Noble metal Nanoparticles (NPs) have great advantages in developing novel biosensors for biochemical analysis of biomolecules such as proteins due to their good biocompatibility, excellent optical and electrical properties, extremely large specific surface area, and surface modification easiness. The electric field enhancement of local incident light caused by the resonance excitation of local surface plasmon polaritons (LSPR) of noble metal Nanoparticles (NPs) such as gold and silver is a main contribution mechanism of Surface Enhanced Raman Scattering (SERS) induction. Furthermore, it has now been determined that the LSPR morphology of NPs is tunable, allowing for an increase in the effect of noble metal components on SERS intensity. Although spherical gold and silver colloids have long been used in SERS studies, focusing is often required to create "hot spots" of electromagnetic fields, thereby increasing the strength of SERS. Although this may provide a very low detection limit, reproducibility becomes an issue when relying on aggregation. To overcome this problem, nanoparticles having inherent hot spots, such as nanorods and gold nanostars, may be used. The gold nanostars have tunable plasmons, can match excitation wavelengths, and have a plurality of distinct branches, each having an enhanced electromagnetic field (EM) at their tip, and thus have superior SERS characteristics.
Compared with the metallographic phase, silver has a larger surface plasmon resonance adjustable range, higher plasmon intensity and lower manufacturing cost. The silver-coated gold nano-star can obviously improve the local field of the nano-particles by covering the silver layer while keeping the hot spot of the gold nano-star, thereby improving the detection sensitivity. The enhancement has wide application prospect for detecting molecules by using surface enhanced Raman scattering.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a preparation method of silver-coated gold nano-star, which comprises the following steps:
preparing a seed solution;
adding the seed solution to HAuCl4Preparing a gold nano star solution by using the solution; and
and forming a silver coating on the surface of the gold nano-star.
In one embodiment of the invention, the citrate solution is added to the boiling HAuCl4To prepare a seed solution.
In one embodiment of the invention, 1.5mL of a 1% citrate solution is added to 10mL of boiling 0.001M HAuCl with stirring at 700rpm4To prepare a seed solution, and after 15 minutes the solution was cooled.
In one embodiment of the present invention, preparing the gold nanostar solution comprises adding a seed solution to HAuCl4Adding acid to adjust the pH value of the solution to acidity, adding a reducing agent and an Ag + ion solution into the solution, centrifuging the obtained solution in a centrifuge, and dispersing the solution in ultrapure water.
In one embodiment of the present invention, the acid is hydrochloric acid, and the Ag + ion solution is AgNO3And (3) solution.
In one embodiment of the invention, 2mL of seed solution is added to 200mL of 2.5X 10-4M HAuCl4To the solution, 200. mu.L of 1M HCl was added, and then 400. mu.L of 0.01M AgNO was added while vigorously stirring for 30 seconds3The solution and 1mL ascorbic acid solution, and finally, the solution is centrifuged at 4000rpm for 1.5h at 4 ℃ and then redispersed in ultrapure water, wherein vigorous stirring is selected at a stirring speed of about 1200 rpm.
In one embodiment of the invention, the forming of the silver coating on the surface of the gold nano-star comprises adding silver nitrate and ascorbic acid solutions with different concentrations into the gold nano-star solution, then adding ammonia water, and uniformly mixing until the color does not change any more, so that the surface of the gold nano-star is coated with the silver layer.
In one embodiment of the invention, the transfer is to a 2mL centrifuge tube. To 0.5mL of the prepared gold nanostar solution was added 7.5. mu.L of 0.1M AgNO3And 0.1M ascorbic acid, then 3. mu.L NH was added4OH, AgNO reduction by ascorbic acid3The mixture turned black and the solution was centrifuged 10 at 4000rpm at 4 DEG CFor a minute, and then redispersed in ultrapure water.
In one embodiment of the invention, 7.5. mu.L of 0.1M AgNO was added3And 0.1M ascorbic acid can be added in multiple portions, with 10s vortexing after each addition.
In one embodiment of the present invention, the core and tips of the gold nanostars are completely covered with silver.
The embodiment of the invention discloses a method for synthesizing silver-coated gold nano-star. The gold nano-star has stronger SERS characteristic through silver coating, and meanwhile, the gold nano-star particles have better biocompatibility through silver coating, and the stability of the gold nano-star is maintained without using a surfactant, so that the silver-coated gold nano-star is applied to biomedicine, such as biosensors, biomedical imaging, medical rapid detection and the like, and a larger space is obtained.
Drawings
To further clarify the above and other advantages and features of embodiments of the present invention, a more particular description of embodiments of the invention will be rendered by reference to the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. In the drawings, the same or corresponding parts will be denoted by the same or similar reference numerals for clarity.
Fig. 1 illustrates a method for preparing silver-coated gold nano-star according to an embodiment of the present invention.
Fig. 2 shows a transmission electron microscopy TEM image of gold nanostars formed by an embodiment of the present invention.
Fig. 3 shows a transmission electron microscope TEM image of silver-coated gold nanostars formed by an embodiment of the present invention.
Fig. 4 shows ultraviolet-visible (UV-Vis) absorption spectra of gold nano-star and silver-coated gold nano-star formed by an embodiment of the present invention.
Fig. 5 shows a Surface Enhanced Raman Spectroscopy (SERS) of a 1 μ M gold nanostar solution formed by an embodiment of the present invention dropped on a glass slide.
Fig. 6 shows a Surface Enhanced Raman Spectroscopy (SERS) of a 1 μ M silver-coated gold nanostar solution formed by an embodiment of the present invention dropped on a glass slide.
Detailed Description
In the following description, the invention is described with reference to various embodiments. One skilled in the relevant art will recognize, however, that the embodiments may be practiced without one or more of the specific details, or with other alternative and/or additional methods, materials, or components. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of embodiments of the invention. Similarly, for purposes of explanation, specific numbers, materials and configurations are set forth in order to provide a thorough understanding of the embodiments of the invention. However, the invention may be practiced without specific details. Further, it should be understood that the embodiments shown in the figures are illustrative representations and are not necessarily drawn to scale.
Reference in the specification to "one embodiment" or "the embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment.
The embodiment of the invention provides a method for synthesizing silver-coated gold nano-star. The silver-coated gold nano star has stronger SERS performance. In the synthesis method of the silver-coated gold nano-star disclosed by the embodiment of the invention, a surfactant is not used, the biocompatibility is strong, and the method has the advantages of simplicity in operation, rapidness, strong repeatability, low cost and the like.
Fig. 1 illustrates a method for preparing silver-coated gold nano-star according to an embodiment of the present invention.
As shown in fig. 1, first, at step 110, a seed solution is prepared. In one embodiment of the invention, the citrate solution may be added to the boiling HAuCl4To prepare a seed solution.
For example, in one example, 1.5mL of a 1% citrate solution is added to 10mL of boiling 0.001M (mol/L) HAu with stirring at 700rpmCl4To prepare a seed solution, and after 15 minutes the solution was cooled. The citrate can be sodium citrate or the like.
In this step, AuCl in solution4 -The ions are reduced under the action of citrate radicals to generate gold nanospheres with the diameter of about 5nm, and the gold nanospheres are used as seeds for the growth of the gold nanostars.
Next, at step 120, the seed solution is added to HAuCl4And (4) preparing a gold nano star solution. In one embodiment of the invention, the seed solution is the core of the growth of gold nanostars. Adding seed solution to HAuCl4Adding acid to adjust pH of the solution to acidity, adding reducing agent and AgNO to the solution3And (3) solution. Reducing agent to reduce AuCl in solution4 -The ions are reduced and grow on the surface of the gold nano in the seed solution to form the gold nano star, and the Ag + ions have a catalytic action and regulate and control the number and the size of the surface branches of the gold nano star.
For example, in one example, 2mL of seed solution is added to 200mL of 2.5X 10-4M HAuCl4To the solution, 200. mu.L of 1M HCl was added. Thereafter, 400. mu.L of 0.01M AgNO was added thereto while vigorously stirring for 30 seconds3Solution and 1mL ascorbic acid solution. Ascorbic acid acts as a reducing agent. Finally, the solution was centrifuged at 4000rpm for 1.5h at 4 ℃ and then redispersed in ultrapure water to form a gold nanostar solution. The agitation speed for vigorous agitation was about 1200 rpm.
At step 130, a silver coating is formed on the surface of the gold nano-star. Specifically, silver nitrate and ascorbic acid solutions with different concentrations are added into a gold nano-star solution, then ammonia water is added, and the mixture is uniformly mixed until the color does not change any more, so that the surface of the gold nano-star is coated with a silver layer, and the silver-coated gold nano-star solution is obtained.
For example, in one example, 0.5mL of a previously prepared gold nanostar solution was transferred to a 2mL centrifuge tube. Add 7.5. mu.L of 0.1M AgNO to the tube3And 0.1M Ascorbic Acid (AA). Multiple additions were made, with 10s vortexing after each addition. Then 3. mu.L NH was added4OH due to reduction of AgNO by AA3The mixture turns black. The solution will stabilize in about 5 minutes. Finally, the solution was centrifuged at 4000rpm for 10 minutes at 4 ℃ and then redispersed in ultrapure water.
Next, the silver coating layer of the gold nanostar was studied by using ultraviolet-visible light (UV-Vis) absorption spectroscopy and TEM transmission electron microscopy.
Fig. 2 shows a transmission electron microscopy TEM image of gold nanostars formed by an embodiment of the present invention. As shown in FIG. 2, the diameter of the gold nanostar core formed by the method of the embodiment of the present invention is 38. + -.4 nm, the length of the branch structure is in the range of 7. + -.3 nm, and the number of branches is in the range of 8. + -.4. The zeta potential of the gold nanostar particles was in the range-41.8 ± 0.98mV, due to the electronegativity of the surface for the citrate ion coverage.
Fig. 3 shows a transmission electron microscope TEM image of silver-coated gold nanostars formed by an embodiment of the present invention. As shown in fig. 3, the core and tips of the gold nano-star are completely covered with silver.
Fig. 4 shows ultraviolet-visible (UV-Vis) absorption spectra of gold nano-star and silver-coated gold nano-star formed by an embodiment of the present invention. Fig. 4 shows the optical density of gold nano-star and silver-coated gold nano-star, the plasmonic peak having a blue shift from 732nm to 574nm after the gold nano-star is coated with silver, since the silver of the surface of the gold nano-star is coated.
Rhodamine 6G (R6G) was used as a model analyte to test the surface raman enhancement performance of gold and silver-coated gold nanostars. Fig. 5 shows a Surface Enhanced Raman Spectrum (SERS) of a 1 μ M solution of gold nanostars formed by an embodiment of the present invention dropped on a glass slide. Fig. 6 shows a Surface Enhanced Raman Spectrum (SERS) of a 1 μ M solution of silver-coated gold nano-star formed by an embodiment of the present invention dropped on a glass slide. As can be seen from fig. 5 and 6, the signal intensity from the silver-coated gold nano-star is an order of magnitude higher than that of the gold nano-star. 612cm-1The peak at (A) is due to the in-plane vibration of the C-C deformation, and 772cm-1The peak at (a) is associated with the out-of-plane curvature of the C-H deformation. 1184cm-1The peak at corresponds to the C-C tensile vibration, and 1312, 1362. 1511, 1573 and 1650cm-1The peak at (a) is assigned to the aromatic C-C stretching vibration. In addition, SERS Enhancement Factors (EF) of the gold nanostars and silver-coated gold nanostars were determined using 1 μ M R6G in ethanol as raman standard. Reference 1511cm-1The EF is calculated using the following formula:
wherein, ISERSAnd IRSRespectively represents the Raman signal intensity of the same peak in the SERS spectrum on the gold nanoparticle substrate and the initial Raman spectrum of the blank substrate. N is a radical ofSERSAnd NRSIndicating the number of R6G molecules attached to the substrate in the area of the laser spot. For gold nanostar substrate, EF is 4.6 × 105(ii) a For silver coated gold nanostar substrate, EF is 9.0 × 105. The EF of silver-coated gold nanostars is higher due to hot spots at the tips, silver coating and inter-particle hot spots between different particles.
The embodiment of the invention discloses a method for synthesizing silver-coated gold nano-star. The gold nano-star has stronger SERS characteristic through silver coating, and meanwhile, the gold nano-star particles have better biocompatibility through silver coating, and the stability of the gold nano-star is maintained without using a surfactant, so that the silver-coated gold nano-star is applied to biomedicine, such as biosensors, biomedical imaging, medical rapid detection and the like, and a larger space is obtained.
While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. It will be apparent to persons skilled in the relevant art that various combinations, modifications, and changes can be made thereto without departing from the spirit and scope of the invention. Thus, the breadth and scope of the present invention disclosed herein should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.
Claims (10)
1. A preparation method of silver-coated gold nano-star comprises the following steps:
preparing a seed solution;
adding seed solution to HAuCl4Preparing a gold nano star solution by using the solution; and
and forming a silver coating on the surface of the gold nano-star.
2. The method of preparing silver-coated gold nanostars as claimed in claim 1, wherein the addition of citrate solution to the boiling HAuCl is performed4To prepare a seed solution.
3. The method of preparing silver-coated gold nanostars as claimed in claim 2, wherein 1.5mL of 1% citrate solution is added to 10mL of boiling 0.001M HAuCl with stirring at 700rpm4To prepare a seed solution, and after 15 minutes the solution was cooled.
4. The method of preparing silver-coated gold nanostars as claimed in any one of claims 1 to 3, wherein preparing the gold nanostars solution comprises adding a seed solution to HAuCl4Adding acid to adjust the pH value of the solution to acidity, adding a reducing agent and an Ag + ion solution into the solution, centrifuging the obtained solution in a centrifuge, and dispersing the solution in ultrapure water.
5. The method of claim 4, wherein the acid is hydrochloric acid and the Ag + ion solution is AgNO3And (3) solution.
6. The method of preparing silver-coated gold nanostars as claimed in any one of claims 1 to 3, wherein 2mL of the seed solution is added to 200mL of 2.5X 10-4M HAuCl4To the solution, 200. mu.L of 1M HCl was added, and then 400. mu.L of 0.01M AgNO was added while vigorously stirring for 30 seconds3The solution and 1mL ascorbic acid solution, and finally, the solution was centrifuged at 4000rpm for 1.5h at 4 ℃ and then redispersed inUltra pure water, wherein the agitation speed selected for vigorous agitation is about 1200 rpm.
7. The method of claim 1, wherein the forming of the silver coating on the surface of the gold nano-star comprises adding silver nitrate and ascorbic acid solutions with different concentrations into the gold nano-star solution, adding ammonia water, and mixing until the color does not change any more, so that the surface of the gold nano-star is coated with the silver layer.
8. The method of preparing silver-coated gold nanostars as claimed in claim 1, wherein the transfer into a 2mL centrifuge tube is performed. To 0.5mL of the prepared gold nanostar solution was added 7.5. mu.L of 0.1M AgNO3And 0.1M ascorbic acid, then 3. mu.L NH was added4OH, AgNO reduction by ascorbic acid3The mixture was blackened, and the solution was centrifuged at 4000rpm for 10 minutes at 4 ℃ and then redispersed in ultrapure water.
9. The method of preparing silver-coated gold nanostars of claim 1, wherein 7.5 μ L of 0.1M AgNO is added3And 0.1M ascorbic acid can be added in multiple portions, with 10s vortexing after each addition.
10. The method of preparing silver-coated gold nano-star of claim 1, wherein the core and the tip of the gold nano-star are completely covered with silver.
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| CN114178541A (en) * | 2021-10-18 | 2022-03-15 | 温州医科大学 | Preparation method of yolk eggshell type gold nanostructure with built-in LSPR coupling |
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| CN113510239B (en) * | 2021-07-07 | 2022-12-09 | 黄河科技学院 | Gold nanorod based on silver coating, and preparation method and application thereof |
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