KR101927715B1 - Gold multipod nanoparticle core - Silica shell nanoparticles and synthetic method thereof - Google Patents

Abstract

The gold nanoparticles having a high surface energy have a problem that when the surfactant is removed, the nanoparticles partially flocculate in the aqueous solution and the catalytic activity decreases. The present invention solves the problem and provides a more stable functional nanoparticle . In order to protect the surface of multiple gold nanoparticles, a particle of a core-shell structure with an inorganic oxide shell such as silicon dioxide has been synthesized for use as a catalyst in a wider and diverse field. In the case of silica nanoparticles, it is possible to synthesize nanoparticles having various surface properties because the surface can be easily functionalized. Since it is well known as being non-toxic and suitable for living body, gold nanoparticles, which exhibit the plasmons in the near- Can be applied to.

Description

[0001] The present invention relates to gold nanoparticle core nanoparticles, and more particularly to gold nanoparticle core nanoparticles and synthetic methods thereof.

The present invention relates to multiple gold nanoparticle core silica shell nanoparticles, gold nanoparticle core-silica intermediate layer-gold nanoparticles having multiple branches, and methods for their synthesis.

There is a growing interest in synthesizing nanoparticle assemblies of controlled size and shape because of the unique nature of such materials and the variety of potential applications (El-Sayed MA; Acc . Chem . Res. 2001 , 34 , 257-264, Xia, Y .; Xiong , Y .; Lim, B .; Skrabalak, SE Angew. Chem. Int. Ed. 2009, 48, 60-103, Hu, M .; Chen, J .; Li , Z.-Y .; Au, L .; Hartland, GV;.. Li, X .; Marquez, M .; Xia, Y. Chem Soc Rev. 2006, 35, 1084-1094).. Colloidal gold nanoparticles exhibit complex optical and stereoscopic properties at wavelengths that span the visible and far infrared spectra. In addition, this is generally considered to be of low toxicity is a surface functional group can be easily screen (Jain, PK; Huang, X .; El-Sayed, IH;.. El-Sayed, MA Acc.Chem Res 2008, 41, 1578 -1586, Eustis, S., El-Sayed, MA Chem . Soc Rev. 2006 , 35 , 209-217). In particular, the properties of gold nanoparticles are significantly influenced by the presence of other metallic nanoparticles in close proximity (Huang, H.-Y .; Chen, W.-F .; Kuo, P.-L. J. Phys . Chem B 2005, 109, 24288-24294 , Hu, H .; Duan, H .; Yang, JKW;. Shen, ZX ACS Nano 2012, 6, 10147-10155). For example, the plasmon resonance of gold nanoparticles can be matched when the particles are very close, and the coupling between the particles is highly dependent on the distance between each particle (Huang, H.-Y .; Chen , W.-F .; Kuo, P.-L. J. Phys. Chem. B 2005, 109, 24288-24294). In order to utilize the paired interactions between gold nanoparticles in a variety of applications, research is being actively conducted on constructing assembly structures that allow small gaps between gold nanoparticles. However, the distance and interaction control between gold nanoparticles in gold nanoparticle assembly structures is still a tremendous challenge.

One useful technique for assembling gold nanoparticles is to wrap them in silica (Liz-Marzan, LM; Correa-Duarte, MA; Pastoriza-Santos, I .; Mulvaney, P.; Ung, T .; Giersig, M .; ; Kotov, NAHandbook of Surfaces and Interfaces ofMaterials, (Ed: HS Nalwa), Academic Press, San Diego, USA 2001; Fan, H.; Yang, K .; Boye, , H .; Brinker, CJ Science 2004 , 304 , 567-571). Nanoparticles composed of gold core and silica shells are attracting much attention because they can be used to enhance the stability of gold nanoparticles, especially in water-soluble solvents, as the silica shell is used as a coating material (Guerrero-Martinez, A .; Perez -Juste, J .; Liz-Marzan, LM Adv .Mater. 2010, 22, 1182-1195.and references therein). The silica is chemically stable as well as optically opaque and does not have a significant effect on the optical properties of the encapsulated gold nanoparticles. In addition, the surface of a porous, biocompatible, non-toxic silica layer can be easily modified with simple techniques, which allows nanoparticles with modified silica shells to be used in a variety of biological applications (Avnir, D., et al. ; Coradin, T .; Lev, O .; Livage, J. J. Mater. Chem . , 2006 , 16 , 1013-1030). Several synthetic methods have been developed to directly coat silica with gold nanoparticles. The first method is to use a coupling agent or a polymer stabilizer to grow the silica outer surface on the surface of gold nanoparticles pre-synthesized by the Stober method (Liz-Marzan, LM; Giersig, M .; Mulvaney, P. Langmuir 1996 , 12 , 4329-4335, Graf, C .; Vossen, DLJ, Imhof, A .; van Blaaderen, A. Langmuir 2003 , 19 , 6693-6700, Pastoriza-Santos, I .; Perez-Juste, J .; Liz-Marzan, LM Chem . Mater. 2006 , 18 , 2465-2467, Lu, Y .; Yin, Y .; Li, Z.-Y .; Xia, Y. Nano Lett . 2002 , 2 , 785-788, Pastoriza-Santos, I .; Perez-Juste, J .; Liz-Marzan, LM Chem . Mater. 2006 , 18 , 2465-2467, Stober, W .; Fink, A .; Bohn, E .; J. Colloid Interface Sci . 1968 , 26 , 62-69). Another method of coating silica on gold nanoparticles involves the use of reverse microemulsion (water / micellar solution), which enables the silica coating of small gold nanoparticles (<20 nm) Ying, JY Langmuir 2008, 24, 5842-5848, Earhart, C .; Jana, NR; Erathodiyil, N .; Ying, JY Langmuir 2008 , 24 , 6215-6219 , Thakur, R .; Gupta, RB Ind . Eng . Chem. Res., 2005 , 44 , 3086-3090). In the microemulsion phase, water droplets are formed in the surface reverse micelle. The silicon precursor can be polymerized on the surface of gold nanoparticles by hydrolysis and condensation in water to form gold core-silica outer nanoparticles.

M. Moeller and colleagues have fabricated gold nanoparticles in a water-in-water microemulsion and fused silica matrices in a microemulsion to form silica nanoparticles containing gold nanoparticle dimers (Wang, H., Schaefer, K .; Moeller , J. Phys. Chem . C 2008 , 112 , 3175-3178). The silica coating of multi-nanoparticles using already synthesized iron nanoparticles or quantum dots has also been reported (Stjerndahl, M .; Andersson, M .; Hall, HE; Pajerowski, DM; Meisel, MW; Duran, RS Langmuir 2008 , 24 , 3532-3536, Vestal, CR; Zhang, ZJ Nano Lett 2003 , 3 , 1739-1743, Yang, Y.; Gao M. Adv . Mater ., 2005 , 17 , 2354-2357).

Korean Patent Laid-Open Publication No. 10-2009-77530 discloses a gold nanoparticle which controls the shape of gold nanoparticles by mixing a gold salt aqueous solution with a nonionic surfactant to change the concentration of the gold salt aqueous solution and the nonionic surfactant, A method for producing particles is disclosed. However, this invention is not stable because no outer angle is formed, and the shape of the composite is also various, such as triangular, square, pentagonal, circular, etc., and is not uniform in size.

Korean Patent Laid-Open Publication No. 10-2007-68871 discloses mesoporous silica nanoparticles encapsulating inorganic nanoparticles and i) dispersing hydrophobic inorganic nanoparticles dispersed in an organic solvent in an aqueous solution in which a surfactant is dissolved to form a surfactant Preparing an aqueous dispersion of the inorganic nanoparticles surrounded by the inorganic nanoparticles; And ii) adding a silica precursor to the prepared aqueous dispersion to form an outer layer made of mesoporous silica in the inorganic nanoparticles. The mesoporous silica nanoparticle-containing mesoporous silica nanoparticle- Lt; / RTI &gt; However, these nanoparticles have pores on the surface, which may leak nested nanoparticles.

The gold nanoparticles having a high surface energy have a problem that when the surfactant is removed, the nanoparticles partially flocculate in the aqueous solution and the catalytic activity decreases. The present invention solves the problem and provides a more stable functional nanoparticle .

Since nanoparticles with large surface area and many defects have high surface energies, removal of the surfactant partially agglomerates in the aqueous solution and reduces catalytic activity. In order to alleviate this disadvantage, an inorganic oxide shell such as silicon dioxide (SiO ₂ ) or titanium dioxide (TiO ₂ ) may be synthesized on the Au surface to improve stability. In addition, the functionality of the inorganic oxide itself can be utilized in the hybrid nanostructure, and the functionality of the inorganic oxide can be dramatically improved due to the unique properties of the core metal nanoparticles.

Gold multipod nanoparticles (GMN) synthesized by the seed mediated method maintain stable morphology in acidic, basic and neutral conditions but can be used as catalysts for use as catalysts in a wider, And a core-shell structure in which an inorganic oxide such as titanium dioxide is used as a shell. In the case of silica nanoparticles, it is possible to synthesize nanoparticles having various surface properties because the surface can be easily functionalized. Since it is well known as being non-toxic and suitable for living body, gold nanoparticles, which exhibit the plasmons in the near- Can be applied to.

In general, the stover method is widely known as a method for synthesizing silica nanoparticles, and this method is easy to synthesize silica nanoparticles by a sol-gel process. Metals, especially gold, exhibit accurate optical properties depending on the structure of the gold nanoparticles. When the thickness of the surrounding shell is increased, it becomes difficult to utilize the properties of gold nanoparticles. Since TEOS (tetraethylorthosilicate), which is a widely used silica precursor, is hydrolyzed by a basic catalyst and then condensed to form silica (SiO ₂ ) particles. When water is used as a solvent, .

Therefore, MPTMS {3- (mercaptopropyl) trimethoxysilane} was used as a silica precursor to maintain the morphology of gold nanoparticles and to form silica even in aqueous solution, and MPTMS was hydrolyzed in aqueous solution pre-hydrolysis precursor was used to synthesize a silica shell using water as a reaction solvent. Metallic nanoparticles such as gold and silver can be easily attached to various organosilanes terminated with thiols and amino. Therefore, it is necessary to use a silane precursor containing a thiol group to synthesize a silica shell with a thin thickness while maintaining the shape of the gold nanoparticles using this method. Therefore, by using MPTMS, which can be used in an aqueous solution containing a thiol group and metallic nanoparticles dispersed, a condensation reaction occurs selectively from the surface of the nanoparticles to synthesize core-shell type particles having a uniform size and shape have. In addition, it was possible to control the thickness of silica by controlling the amount of basic catalyst used in the process of synthesizing silica shell, and it was possible to grow gold nanoparticles by functionalizing the surface of silica.

The present invention

a) suspending star-shaped gold nanoparticles having multiple branches in an aqueous solution of a cationic surfactant to produce a star-shaped gold nanoparticle solution having multiple branches;

b) preparing a 3-mercapto-propylethyldimethoxysilane (MPTMS) hydrolyzate; And

c) synthesizing gold nanoparticle core-silica nanoparticles having multiple branches by adding the star-shaped gold nanoparticle solution having the multiple branches, the base catalyst, and the MPTMS hydrolyzate prepared in the step The present invention relates to a gold nanoparticle core-silica outer nanoparticle synthesis method having multiple branches.

Further, the present invention relates to a method for producing a nanoparticle,

and d) separating and washing the synthesized nanoparticles. The present invention also relates to a method for synthesizing nanoparticles.

The present invention also relates to a method for synthesizing nanoparticles, wherein the step b) of producing the MPTMS hydrolyzate is carried out by adding water to the MPTMS and stirring the mixture.

The present invention also relates to a method of preparing a gold nanoparticle core-silica nanoparticle having multiple branches by adding a base catalyst to a star-shaped gold nanoparticle solution having multiple branches in step c), stirring and adding MPTMS hydrolyzate, And a method for synthesizing nanoparticles.

The present invention also relates to a method for synthesizing nanoparticles, wherein the base catalyst is NH ₄ OH.

The present invention also relates to a method for synthesizing nanoparticles, characterized in that the thickness of the silica shell is controlled by adjusting the amount of the base catalyst in the same reaction time.

The present invention also relates to gold nanoparticle core-silica outer shell nanoparticles having 5 to 10 branches prepared by the above method and having a silica outer shell thickness of more than 0 and less than 50 nm.

The present invention also relates to a method for preparing a nanoparticle nanoparticle, comprising the steps of: forming a -NH ₂ group on the nanoparticle surface by adding APTES {3- (aminopropyl) triethoxysilane} and a base catalyst to a gold nanoparticle core- silica outer nanoparticle solution having multiple branches;

Dispersing the nanoparticles formed on the surface of the -NH ₂ group into water or a water-soluble solvent; And

Adding a cationic gold precursor aqueous solution or gold nanoparticles to the nanoparticles dispersed in the solvent to conduct a reaction to synthesize gold nanoparticle core-silica intermediate layer-gold nanoparticles having multiple branches. The present invention relates to a gold nanoparticle core-silica intermediate layer-gold outer nanoparticle synthesis method.

In addition, the present invention is the cationic gold precursor is Keumsan potassium chloride (KAuCl _4), chloroauric acid sodium (NaAuCl _4), chloroauric acid (HAuCl _4), brominated Keumsan sodium (NaAuBr _4), yeomhwageum (AuCl), yeomhwageum (Ⅲ ) (it relates to AuCl ₃₎ and gold bromide (AuBr ₃₎ nano-particles synthesis method characterized in that selected.

The present invention also relates to gold nanoparticle core-silica intermediate layer-gold nanoparticles having multiple branches of gold reduced on the surface of gold nanoparticle core-silica outer nanoparticles produced by the above method. The nanoparticles are characterized in that the length from the intersection of the branches to the apex of the branches is 50 to 150 nm.

The present invention also relates to a catalyst comprising the gold nanoparticle core-silica outer nanoparticle or the gold nanoparticle core-silica middle layer-gold outer nanoparticle having multiple branches.

According to the present invention, nanoparticles having a silica outer surface grown on the surface of gold nanoparticles having multiple branches are formed. In the case of silica nanoparticles, it is possible to synthesize nanoparticles having various surface properties because the surface can be easily functionalized. Since it is well known as being non-toxic and suitable for living body, gold nanoparticles, which exhibit the plasmons in the near- Can be applied to.

In addition, according to the present invention, gold nanoparticle core-silica intermediate layer-gold outer nanoparticles having multiple branches are formed, and the particles can also be applied to various applications such as catalysts and biomedical applications.

1 is a scanning electron microscope (SEM) image of GMN @ SiO ₂ NPs synthesized on ethanol using TEOS.
FIG. 2 is a scanning electron microscope (SEM) image of GMN @ SiO ₂ NPs synthesized by directly adding MPTMS without hydrolysis.
3 is a schematic diagram of GMN @ SiO ₂ NPs synthesized by adding MPTMS hydrolyzate.
4 is a transmission electron microscope (TEM) image and (b) scanning electron microscope (SEM) image of GMN @ SiO 2 synthesized by adding MPTMS hydrolyzate.
FIG. 5 is a scanning electron microscope image of GMN @ SiO ₂ NPs (28% NH ₄ OH) synthesized by adjusting the SiO ₂ thickness by adding NH ₄ OH as a base catalyst of the condensation reaction. (a), (b) 20 μl, (c) 100 μl, and (d) 200 μl.
6 is a scanning electron microscope image of GMN @ SiO ₂ @ Au NPs synthesized on (a) methanol and (b) distilled water.

Hereinafter, the configuration of the present invention will be described in more detail with reference to specific embodiments. However, it is apparent to those skilled in the art that the scope of the present invention is not limited by the descriptions of the embodiments.

reagent

(Cetyltrimethylammonium bromide, CH ₃ (CH ₂ ) ₁₅ N (CH ₃ ) ₃ Br, hereinafter abbreviated as "CTAB", 99 +%, Acros organic), Polyoxyethylene glycol Acro Organics), Hydrogen tetrachloroauratetrihydrate (HAuCl ₄ .3H ₂ O, 99.9%, Sigma-Aldrich), dodecyl ether, (C ₂ H ₄ O) ₂₃ C ₁₂ H ₂₅ OH, hereinafter abbreviated as "Brij 35" silver nitrate _{(silver nitrate, AgNO 3, 99} +%, Sigma-Aldrich), sodium borohydride _{(sodium borohydride, NaBH 4, 99.995} %, Sigma-Aldrich), ascorbic acid (L-ascorbic acid, 99% , Sigma-Aldrich) salicylic acid sodium (sodium salicylate, NaSal, 99.5% , Sigma-Aldrich), 3- mercapto-propyl ethyl dimethoxy silane (3-mercapto-propylethyldimethoxysilane, MPTS , CH 3 Si (OCH 3) 2 CH 2 H ₂ H ₂ SH, 95%, Alfa Aesar), APTES {3- (aminopropyl) triethoxysilane, 98%, Sigma-Aldrich}, polyvinylpyrolidone (C ₆ H ₉ NO) _n , PVP 10, molecular weight 10,000, Sigma-Aldrich), ammonium hydroxide _{(ammonium hydroxide, NH 4 OH,} 28 ~ 30 wt%, Sigma-Aldrich), tetraethyl ortho silicate _{(tetraethylorthosilicate, (Si (OC 2} H 5) 4, TEOS, 98% , Sigma-Aldrich), citric acid trisodium (trisodium citrate, 99%, Sigma -Aldrich), sodium oleate (sodium oleate, 99 +%, Sigma-Aldrich), hydrochloric acid (HCl), nitric acid (HNO _3), acetone and ethyl All glassware was rinsed with aqua regia (hydrochloric acid: nitric acid = 3: 1 (v / v)) and rinsed thoroughly with tertiary distilled water prior to use.

Synthesis of gold nanoparticles with multiple branches

Gold nanoparticles (GMNs) with multiple branches are synthesized using a seeded mediated method. Two step growth solutions are needed to synthesize GMN by seed mediator. The first growth solution (A) was prepared by mixing 200 μl of 50 mM sodium salicylate solution with 1 ml of 200 mM brij35 aqueous solution and 1 ml of 100 mM CTAB aqueous solution, followed by mixing for 5 minutes using an ultrasonic mill do. Next, prepare 10 μl of 5 mM AgNO ₃ aqueous solution, 80 μl of 10 mM HAuCl ₄ aqueous solution, and 20 μl of 100 mM aqueous ascorbic acid solution in this order.

The second growth solution (B) is composed of the same components as the growth solution (A) and is prepared by increasing the volume by 10 times. (10 ml of 200 mM brij35 aqueous solution, 10 ml of 100 mM CTAB aqueous solution, 2 ml of 50 mM sodium salicylate, 100 μl of 5 mM aqueous AgNO ₃ solution, 800 μl of 10 mM HAuCl ₄ aqueous solution and 200 μl of 100 mM ascorbic acid aqueous solution). 100 μl of the synthesized gold nanoside solution was added to the prepared growth solution (A), and the mixture was shaken vigorously. 100 μl of the mixture was added to the growth solution (B), and the mixture was evenly mixed. Store at room temperature. The color of the reaction solution changes from pale yellow to clear color during the reaction and turns dark blue when the reaction is complete.

After completion of the reaction, the GMNs were centrifuged at 6000 rpm for 10 minutes to remove the supernatant. The solvent was replaced with distilled water and the supernatant was washed with an ultrasonic disintegrator. The same procedure was repeated three times to remove residual surfactant Remove it and use it as a seed.

Gold nanoparticle core with multiple branches - Outer silica nanoparticle synthesis

MPTMS was hydrolyzed before addition of MPTMS (3-mercapto-propylethyldimethoxysilane) to multi-branched gold nanoparticles (GMNs). After the -SH group of MPTMS was attached to the surface of GMNs, Gold nanoparticle core-silica outer nanoparticles (hereinafter referred to as " GMN @ SiO ₂ NPs &quot;). MPTMS hydrolyzate was prepared by adding 100 μl of MPTMS to 30 ml of distilled water and stirring for 1 hour.

10 ml of the previously prepared GMNs growth solution (B) was centrifuged at 6000 rpm for 10 minutes to remove the supernatant and redispersed in 10 ml of distilled water. NH ₄ OH used as a base catalyst is added to the above solution, which is then stirred for 5 minutes, and 2.5 ml of MPTMS hydrolyzate solution is added thereto. The reaction mixture was stirred at room temperature for 5 hours. After completion of the reaction, the reaction mixture was centrifuged at 6000 rpm for 10 minutes to collect GMN @ SiO ₂ NPs and then washed twice with distilled water. For characterization, the obtained GMN @ SiO ₂ NPs are dispersed in 1 ml of distilled water.

For the synthesis of GMN @ SiO ₂ NPs using TEOS, 3.448 mM GMNs were washed once with distilled water, PVP10 (200 [mu] l) is added to the above solution and stirred for 12 hours. The GMNs surface-treated with PVP10 are centrifuged (6000 rpm, 10 minutes) and dispersed in 7 ml of ethanol. 30 μl of TEOS, which is a silica precursor, and 200 μl of NH ₄ OH are added and reacted for 4 hours.

GMN @ SiO ₂ @Au Of NPs  synthesis

By using the GMN @ SiO ₂ NPs synthesized using MPTMS hydrolyzate was synthesized GMN @ SiO ₂ @Au NPs. FIG. 6 (a) shows GMN @ SiO ₂ NPs synthesized by centrifugation after the reaction, and FIG. 6 (b) shows APTES added to the reaction solution immediately after the reaction. In each case, 30 μl of APTES and 100 μl of NH ₄ OH were added and stirred for 12 hours or longer to allow the -NH ₂ group to be formed on the surface of the nanoparticles. After the reaction, (a) and (b) (A) was dispersed in methanol, and (b) was dispersed in 2 ml of distilled water. 300 μl of 0.01 M HAuCl ₄ aqueous solution is added to the above solution, and 500 μl of NaBH ₄ 0.1 M is added for reduction of Au ^{3 +} . After stirring for 1 hour, the reaction proceeded, and the GMN @ SiO ₂ @ Au NPs synthesized by centrifugation were collected and redispersed in 1 ml of distilled water for characterization.

Character analysis

The nanoparticles were photographed using a Hitachi S-4800 scanning electron microscope (SEM) and a JEOL JEM-2010 Luminography (Fuji FDL-5000) Ultramicrotome (CRX) transmission electron microscopy (TEM). High-resolution transmission electron microscopy (HRTEM) analysis and energy dispersive X-ray (EDX) and selected-area electron diffraction (SAED) pattern analysis were performed using a JEOL JEM-2100F transmission electron microscope Respectively. Sample preparation for TEM was performed by centrifugation at 6000 rpm for 10 minutes, redispersing in 100 mL of tertiary distilled water, and fixing 10 mL of the solution on a TEM grid (Ted Pella, Inc. Formvar / Carbon 400 mesh, copper coated). The pH of the solution was measured using an Orion 420 A + pH meter.

A SiO ₂ shell was synthesized by using MPTMS, an organosilane precursor containing a thiol group (- SH), in the form of GMNs having multiple branches and large surface area. We successfully synthesized GMN @ SiO ₂ NPs without any alcohol or organic solvent by hydrolysis in water without using MPTMS directly and using hydrolyzed MPTMS. Before the addition of MPTMS, GMNs were used without removing any surfactant remaining after synthesis to keep the GMNs stable without aggregation.

FIG. 1 is a scanning electron microscope image of TEOS as a silica precursor, in which GMN @ SiO ₂ NPs are formed but retains the original shape of the GMNs and no silica shell is formed. It is also difficult to control the shape and thickness of the silica shell even by controlling the amount of the precursor, and SiO ₂ NPs are formed separately from the GMN surface as shown in FIG. 1 (b). It is believed that this is because the structure of TEOS used as a precursor has no functional groups with affinity to the surface of gold nanoparticles. Also, when MPTMS, a silane precursor containing a thiol group having affinity with the surface of gold nanoparticles, was directly added to the reaction solution without hydrolysis, GMN @ SiO ₂ NPs were not formed properly as shown in FIG. 2 . This shows that the silica shell is formed uniformly when a precursor of the hydrolyzed form is used before the addition of the thiol group of MPTMS to the surface of gold nanoparticles to form a silica shell. When the base catalyst was added without hydrolysis, it was confirmed that MPTMS was not formed from the surface of the gold nanoparticles, and the aggregated silica shell was formed.

FIG. 3 shows a schematic diagram of synthesis of GMN @ SiO ₂ NPs by adding hydrolyzed MPTMS. (--SH) group of hydrolyzed MPTMS is bonded to the surface of GMNs, and after the base catalyst is added thereto, the condensation reaction proceeds to synthesize GMN @ SiO ₂ NPs. Due to the thiol group of MPTMS, silica shell could be easily and efficiently synthesized along the shape of GMNs, unlike the case of using TEOS. Transmission electron microscopy (TEM) images and scanning electron microscope (SEM) images of GMN @ SiO ₂ synthesized in this manner are shown in FIG. 4, respectively. As compared with FIG. 1, it is possible to maintain the original shape of gold nanoparticles having multiple branches, and no separate SiO ₂ NPs are produced on the outside.

In general, the thickness of the silica shell can be controlled by adjusting the reaction time or controlling the amount of the base catalyst. In the case of GMN @ SiO ₂ NPs, the silica shell thickness can be efficiently controlled by controlling the amount of the base catalyst ( 5). When no base catalyst is added, a silica shell is not formed on the surface of the GMNs (FIG. 5 (a)), and even when a small amount of NH ₄ OH is added, the silica shell is uniformly formed (FIG. When the amount of NH ₄ OH is gradually increased, the thickness of the silica shell becomes thicker. (Fig. 5 (c) - (d))

Thus the synthesized GMN @ SiO ₂ NPs with APTES containing an amino (-NH ₂₎ group by treating the surface by adding an aqueous solution of HAuCl ₄ was able to synthesize GMN @ SiO ₂ @Au NPs. When GMN @ SiO ₂ NPs were synthesized and the surface was washed and HAuCl ₄ aqueous solution was added on methanol, gold nanoparticles having an irregular size and shape were observed on the surface of GMN @ SiO ₂ NP as shown in FIG. 6 (a) When synthesized on distilled water after synthesizing GMN @ SiO ₂ NPs (FIG. 6 (b)), the size of gold particles formed on the surface was relatively small and uniformly synthesized. Recently, Paulina and his team have synthesized gold nanoparticles as shells on silica or titanium dioxide surfaces. The surface of silica and titanium dioxide particles used as core in the same way as in this study was surface treated with APTES and the experiment was carried out using two methods; 1) synthesis of gold nanoparticles on the silica surface by adding HAuCl ₄ aqueous solution, and 2) synthesis of core-shell nanoparticles by adding gold nanoparticles synthesized in a uniform size. When HAuCl ₄ aqueous solution was added, gold nanoparticles were not formed uniformly. However, when gold nanoparticles were synthesized, gold nanoparticles on the silica surface were uniformly formed. Thus, it can be seen that the solvent used in the synthesis of GMN @ SiO ₂ @ Au NPs can affect the rate and selectivity of the reduction of gold ions.

GMN @ SiO ₂ NPs were synthesized with hydrolyzed MPTMS while maintaining the unique structure of GMN with multiple branches. Condensation reaction occurred from the surface of gold nanoparticles by using MPTMS, which is a silane precursor having a thiol (-SH) group among many kinds of silanes. By controlling the amount of NH ₄ OH as a base catalyst, the SiO ₂ shell thickness I was able to control it successfully. In addition, amino (-NH ₂₎ After processing the GMN @ SiO ₂ NPs synthesized using APTES containing surface groups, again by the addition of gold ions on the surface and reduced using NaBH ₄ GMN @ SiO ₂ @ Au NPs could be synthesized.

Claims (11)

a) preparing a star-shaped gold nanoparticle solution having multiple branches;
b) preparing a 3-mercapto-propylethyldimethoxysilane (MPTMS) hydrolyzate; And
c) stirring the spherical gold nanoparticle solution having the multiple branches without adding polyvinylpyrrolidone, adding a base catalyst, stirring the mixture at MPTMS hydrolyzate, and stirring at room temperature to prepare gold nanoparticle core-silica And synthesizing the outer nanoparticles. The method of synthesizing gold nanoparticle core-silica outer nanoparticles having multiple branches.
The method according to claim 1,
Wherein the step b) of preparing the MPTMS hydrolyzate is carried out by adding water to MPTMS and agitating the core.
delete The method according to claim 1,
Wherein the base catalyst is NH4OH. &Lt; RTI ID = _0.0 &gt; 8. &lt; / RTI &gt;
The method according to claim 1,
Wherein the amount of the base catalyst is controlled in the same reaction time to adjust the thickness of the silica outer shell. &Lt; RTI ID = 0.0 &gt; 8. &lt; / RTI &gt;
delete delete a) preparing a star-shaped gold nanoparticle solution having multiple branches;
b) preparing a 3-mercapto-propylethyldimethoxysilane (MPTMS) hydrolyzate;
c) stirring the spherical gold nanoparticle solution having the multiple branches without adding polyvinylpyrrolidone, adding a base catalyst, stirring the mixture at MPTMS hydrolyzate, and stirring at room temperature to prepare gold nanoparticle core-silica Synthesizing outer nanoparticles;
d) A gold nanoparticle core having multiple branches. A gold nanoparticle core having multiple branches by adding APTES {3- (aminopropyl) triethoxysilane} and a base catalyst to the outer surface of the nanoparticles of silica. ₂ group;
e) dispersing the gold nanoparticle core-silica nanoparticles having multiple branches formed on the surface of the -NH ₂ group into water or a water-soluble solvent; And
f) a gold nanoparticle core-silica intermediate nanoparticle having multiple branches dispersed in the water or a water-soluble solvent, and a cationic gold precursor aqueous solution or gold nanoparticles are added to the reaction, Synthesizing gold nanoparticle core-silica intermediate layer-gold nanoparticle nanoparticles having multiple branches, comprising: synthesizing gold nanoparticles.
delete delete delete

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