JP2011093013A - Surface modifying agent for nanoparticle, metallic nanoparticle, and method of manufacturing surface modifying agent for nanoparticle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface modifying agent for nanoparticles which prevents coagulation of the nanoparticles and also gives functionality, and to provide gold nanoparticles, and a manufacturing method of the surface modifying agent of the nanoparticles. <P>SOLUTION: First hydroxy fatty acid is amide-coupled with cysteamide to form into thiol. The thiol compound is ester-coupled by means of the first hydroxy fatty acid or second hydroxy fatty acid different from the first hydroxy fatty acid. A dendritic molecule having a surface densely covered with a highly hydrophilic hydroxyl group and having a structure in which highly hydrophobic alkyl chains are scarcely arranged is generated. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a nanoparticle surface modifier, a metal nanoparticle, and a method for producing a nanoparticle surface modifier.

  Conventionally, it has become possible to synthesize nanoparticles from various raw materials such as metals and polymers, and development of practical nanomaterials has been actively conducted. For example, microsensors that can be used in vivo with DNA molecules and sugar chains bonded to metal nanoparticles, and methods for detecting influenza viruses with ultrasensitivity using nanoparticles have been developed. It is also applied to pharmaceuticals and printing toners. Moreover, the technique which solders gold nanowire with the fine particle of tin as a conductive nanoparticle is also disclosed (for example, refer nonpatent literature 1).

  In general, since nanoscale particles easily aggregate, a dispersion stabilizer is added when the nanoparticles are synthesized or stored. For example, in the case of metal nanoparticles, a method of covering the surface of the nanoparticles by adding a cetyltrimethylammonium bromide (CTAB) surfactant as a dispersion stabilizer during synthesis is often used (for example, patent documents). 1).

JP 2005-68447 A

Peng, Y.; Cullis, T.; Inkson, B.; Bottom-up Nanoconstruction by the Welding of Individual Metallic Nanoobjects Using Nanoscale Solder.Nano Lett. 2009, 9 (1), 91-96.

  However, since the CTAB described above is mainly composed of an alkyl chain and has a simple structure, it is difficult to react with other compounds to impart functionality, and even if functionality is imparted, Physical property control is difficult. In addition, it is bonded to the nanoparticles by interaction with a highly hydrophobic alkyl chain, and has a structure that is easily detached. Furthermore, CTAB has cytotoxicity and is difficult to use as a biomaterial.

  Therefore, when the surface of a nanoparticle is covered using this method, when the produced nanoparticle is applied as a functional substance, the surfactant must be removed and then the metal surface must be re-modified. For this reason, there is a problem that the efficiency is not good when the nanoparticles are applied.

  In view of the above-described problems, the present invention provides a nanoparticle surface modifier, a metal nanoparticle, and a method for producing a nanoparticle surface modifier that prevent the nanoparticles from aggregating and provide functionality. It is an object.

  The nanoparticle surface modifier of the present invention has a structure represented by Chemical Formula 1.

（式中、ｘ，ｚ≧２、かつｙ，ｗ≧１であり、ｘ＋ｙ≧３、ｚ＋ｗ≧３）

(Wherein, x, z ≧ 2, and y, w ≧ 1, x + y ≧ 3, z + w ≧ 3)

  Another feature of the nanoparticle surface modifier of the present invention is that it has a structure represented by Chemical Formula 2.

（式中、ｘ，ｚ，ｕ≧２、かつｙ，ｗ，ｖ≧１であり、ｘ＋ｙ≧３、ｚ＋ｗ≧３、ｕ＋ｖ≧３）

(Wherein, x, z, u ≧ 2 and y, w, v ≧ 1, x + y ≧ 3, z + w ≧ 3, u + v ≧ 3)

The metal nanoparticle of the present invention is characterized in that the thiol group of the surface modifier of the nanoparticle described above and gold or silver are adsorbed.
In addition, another feature of the metal nanoparticles of the present invention is that the thiol group of the surface modifier of the nanoparticles according to any one of the above and gold are adsorbed, and further the surface of the nanoparticles. Pyrene is encapsulated between the modifier and the gold.

  The method for producing a nanoparticle surface modifier of the present invention includes a step of thiolating a first dihydroxy fatty acid with an amide bond with cysteamide, the thiolated compound, and the first dihydroxy fatty acid or the first dihydroxy fatty acid. And a step of producing a dendritic compound by ester bonding using a second dihydroxy fatty acid different from the dihydroxy fatty acid.

  According to the present invention, by adsorbing a surface modifier to nanoparticles such as gold, a surface that is densely covered with hydroxyl groups having high hydrophilicity and an interior in which large hydrophobic alkyl chains are sparsely arranged. Therefore, the surface modifier which provides various functionality can be provided.

It is a figure which shows the structural example of the surface part of the modified gold nanoparticle. It is a figure which shows the state which pyrene is solubilizing in the hydrophobic space formed by the dendritic molecule. It is a figure which shows the analysis result of the spectrum by FTIR of the gold nanoparticle in the Example of this invention. It is a figure which shows an example of the absorption peak of the gold nanorod by the absorption spectrophotometer in the Example of this invention. It is a SEM photograph which shows the gold | metal | money nanorod with a density | concentration of 1.0 * 10 < ^-5 > mol / l produced in the Example of this invention. It is a figure which shows the analysis result of the spectrum by FTIR of the silver nanoparticle in the Example of this invention. It is a figure which shows the relationship between the density | concentration of the gold nanoparticle solution and the fluorescence intensity of pyrene in the Example of this invention.

  As a result of intensive studies, the present inventors have found that a surface modifier having a thiol group introduced on the carboxylic acid terminal side of a dendritic molecule derived from dihydroxy fatty acid is effective for synthesizing or storing nanoparticles as a dispersion stabilizer. I found something. By adding this surface modifier, the thiol group is fixed as a stable root on the surface of the nanoparticle, and since there are many hydroxyl groups on the outside, it is highly hydrophilic and prevents aggregation between the nanoparticles. can do. Furthermore, when this surface modifier is fixed to the nanoparticles, a large void is formed inside the dendritic molecule, and there are hydrophobic sites such as alkyl groups. It can be applied as a functional substance such as a delivery system.

  Here, the nanoparticle radius has a particle diameter of about 10 nm at the minimum and about 300 nm at the maximum. Although the particle radius depends on experimental conditions such as temperature, concentration, and reaction time during preparation, there is an advantage that nanoparticles having a particle size of several tens of nanometers can be produced relatively easily.

The dihydroxy fatty acid used in the present invention is a saturated fatty acid having a molecular formula of C _n H _2n-1 (OH) ₂ COOH. This dihydroxy fatty acid usually has a linear structure, but when dissolved in an aqueous solution, the dihydroxy fatty acid is bent into a U shape at the carboxyl group side and the alkyl group side at the hydroxyl group boundary. This is because a hydroxyl group having high hydrophilicity faces outward due to a hydrogen bond with a water molecule, and an alkyl chain portion having high hydrophobicity folds inward to avoid interaction with the water molecule. Thus, when a dendritic molecule is synthesized using a dihydroxy fatty acid having a U-shaped structure, a structure having both a hydrophilic portion and a hydrophobic portion is obtained as described above.

  Here, as an example of the dihydroxy fatty acid, anything may be used as long as n is 5 or more. When n is 4 or less, since the hydroxyl group is located at the β-position of the carbonyl group, it becomes a relatively unstable compound, and a surface modifier cannot be stably obtained. Therefore, it is necessary that n ≧ 5. is there. However, when n is 24 or more, fatty acids are generally difficult to obtain, and more labor and cost are required to synthesize dihydroxy fatty acids with two hydroxyl groups added. For this reason, it is preferable that 5 ≦ n ≦ 23. The dihydroxy fatty acid used in the present invention has a structure represented by the following chemical formula 3.

（式中、ｘ＋ｙ＝ｎ−２）

(Where x + y = n−2)

  Thus, x and y in the formula vary depending on the position of the hydroxyl group of the dihydroxy fatty acid. As described above, when a hydroxyl group is located at the β-position of the carbonyl group, the compound becomes unstable. On the other hand, when the two hydroxyl groups are adjacent secondary hydroxyl groups, the hydroxyl groups that are hydrophilic groups are arranged side by side and are located outside, resulting in a stable structure. Based on the above, in order to form a U-shaped structure in an aqueous solution, it is necessary that x ≧ 2, y ≧ 1, and two hydroxyl groups be adjacent to each other.

  In addition, since it synthesize | combines by oxidizing a monovalent | monohydric unsaturated fatty acid when synthesize | combining the fatty acid in which two hydroxyl groups arranged, what is easy to synthesize | combine and obtain is more preferable as dihydroxy fatty acid used by this invention. That is, unsaturated fatty acids that are easily available as raw materials are myristoleic acid, palmitoleic acid, oleic acid, vaccenic acid, gadoleic acid, eicosenoic acid, erucic acid, and nervic acid, and therefore as dihydroxy fatty acids used in the present invention 9,10-dihydroxytetradecanoic acid, 9,10-dihydroxyhexadecanoic acid, 9,10-dihydroxyoctadecanoic acid, 11,12-dihydroxyoctadecanoic acid, 9,10-dihydroxyicosanoic acid, 11,12-dihydroxyicosane More preferably, it is an acid, 13,14-dihydroxydocosanoic acid, or 15,16-dihydroxytetracosanoic acid. In addition, since these listed dihydroxy fatty acids are all produced in the human body during the fatty acid metabolism process, they do not exhibit strong toxicity.

  The nanoparticle surface modifier of the present invention can be prepared, for example, by the following procedure.

  First, the dihydroxy fatty acid represented by Chemical Formula 3 is amide-bonded with cysteamine to convert it to a thiol group to produce a first generation dihydroxy fatty acid stabilizer represented by Chemical Formula 4 below.

  Next, the compound represented by Chemical Formula 4 is ester-bonded using two molecules of the compound represented by Chemical Formula 3 to produce a second generation dendritic molecule stabilizer represented by Chemical Formula 5 below. . At this time, the dihydroxy fatty acid for two molecules is not directly ester-bonded, but the ester bond is made after converting the hydroxyl group of the dihydroxy fatty acid for two molecules into a t-butyldimethylsilyl group (TBS group).

（式中、ＲはＴＢＳ基）

(Wherein R is a TBS group)

  Then, methanol or the like is added to the compound represented by Chemical Formula 5 to form a dendritic molecule represented by Chemical Formula 6 below by changing the branch tip portion (TBS group portion) to a hydroxyl group.

  A dendritic molecule surface modifier can be produced by the above procedure. In order to increase the number of hydrophilic hydroxyl groups and hydrophobic alkyl groups, the following procedure can be used. A third generation dendritic molecule stabilizer as shown in

  Here, when the second generation type or the third generation type dendritic molecule stabilizer is produced, it is not always necessary to use the same dihydroxy fatty acid for ester bonding. For example, after thiolation with 9,10-dihydroxyoctadecanoic acid, 11,12-dihydroxyicosanoic acid may be used to produce a second generation dendritic molecular stabilizer, and 9,10-dihydroxy After generating the second generation dendritic molecule stabilizer using octadecanoic acid, the third generation dendritic molecule stabilizer may be generated using 11,12-dihydroxyicosanoic acid. However, in each generation, when different dihydroxy fatty acids are used, the balance of the structure of the dendritic molecule is lost, and therefore it is necessary to use the same dihydroxy fatty acid.

FIG. 1 is a view showing a structural example of a surface portion of a modified gold nanoparticle.
When acetic acid is added to the dendritic molecule represented by Chemical Formula 6 or Chemical Formula 7, and then a gold (III) salt and a reducing agent are added, the thiol group at the end of the dendritic molecule reacts with the surface of the metal nanoparticle. As shown in FIG. 1, the end of the dendritic molecule 2 is bonded to the surface of the gold nanoparticle 1 to generate a gold nanoparticle modified with the dendritic molecule. Further, when gold colloid solution is added to a gold nanoparticle solution in which a dendritic molecule prepared in advance is modified to grow gold nanoparticles, gold nanorods are obtained. As shown in FIG. 1, this modified gold nanoparticle has a structure that is greatly different between a surface that is densely covered with a highly hydrophilic hydroxyl group and an interior in which highly hydrophobic alkyl groups are sparsely arranged. ing. When silver is used instead of gold, silver nanoparticles modified with dendritic molecules are generated.

FIG. 2 is a diagram showing a state where pyrene is solubilized in a hydrophobic space formed by dendritic molecules.
As shown in FIG. 2, since pyrene is a hydrophobic aromatic hydrocarbon, when pyrene is added to the modified gold nanoparticles, pyrene is included in the space where alkyl groups formed by adjacent dendritic molecules are arranged. And form an aggregate.

  Moreover, since the dihydroxy fatty acid used as a material of a dendritic molecule is one of the metabolites of a fatty acid, its toxicity is low. Gold used as nanoparticles is also a metal with low reactivity and does not have toxicity as heavy metal. Therefore, taking advantage of this property, it can be expected to be used as a solubilizing agent for pharmaceuticals that incorporates water-insoluble pharmaceuticals into hydrophobic spaces, and as functional materials for drug delivery.

Examples of the present invention will be described below.
(First embodiment)
First, 10 g of 9,10-dihydroxyoctadecanoic acid represented by the following chemical formula 8 was dissolved in 64 ml of dichloromethane, and 7.8 g of dicyclohexylcarbodiimide (DCC) and 3.0 g of cysteamine were mixed and left at room temperature for 6 hours. And after filtering the produced | generated precipitation, 100 ml of water was added to the obtained filtrate, and it extracted 3 times with 100 ml of dichloromethane. All the organic layers were mixed, dried with about 10 g of magnesium sulfate and concentrated. The obtained product was purified by silica gel column chromatography to obtain a compound represented by the following chemical formula 9. At this time, the yield was 90%.

  Next, 10 g of 9,10-dihydroxyoctadecanoic acid represented by Chemical Formula 8 is dissolved in 64 ml of N, N-dimethylformamide (DMF), and 5 g of potassium carbonate and 6.5 g of benzyl bromide are mixed with this solution at room temperature. Left for 12 hours. Thereafter, 100 ml of a 5% aqueous phosphoric acid solution was added to the reaction vessel, and extracted three times with 100 ml of dichloromethane. All the organic layers were mixed, dried with about 10 g of magnesium sulfate and concentrated. The obtained product was purified by silica gel column chromatography to obtain a compound represented by the following chemical formula 10. At this time, the yield was 86%.

（式中、Ｂｎはベンジル基）

(Wherein Bn is a benzyl group)

  Furthermore, 4 g of imidazole, 8 g of t-butyldimethylsilyl chloride and 50 ml of DMF were mixed with 10 g of the compound represented by the chemical formula 10 obtained, and the mixture was allowed to stand for 24 hours while maintaining at 50 ° C. Thereafter, 100 ml of a 5% aqueous phosphoric acid solution was added to the reaction vessel, and extracted three times with 100 ml of dichloromethane. All the organic layers were mixed, dried over about 10 g of magnesium sulfate, concentrated and purified by silica gel column chromatography. Next, 240 ml of methanol and 500 mg of palladium carbon (PD / C) were added to the obtained product, and the mixture was allowed to stand at room temperature for 12 hours in a hydrogen atmosphere. The reaction solution was filtered through Celite to remove palladium on carbon, and then the filtrate was concentrated and purified by silica gel column chromatography to obtain a compound represented by the following chemical formula 11. At this time, the yield was 85%.

（式中、ＲはＴＢＳ基）

(Wherein R is a TBS group)

  Next, 5 g of dicyclohexylcarbodiimide (DCC) was added to a solution obtained by dissolving 12 g of the compound represented by Chemical Formula 11 in 220 ml of dichloromethane, and the mixture was stirred to obtain a suspension. Further, 3.8 g of the compound represented by Chemical Formula 9 and 1 g of dimethylaminopyridine (DMAP) as a catalyst were mixed and allowed to stand at room temperature for 12 hours. And after filtering the produced | generated precipitation, 100 ml of water was added to the obtained filtrate, and it extracted 3 times with 100 ml of dichloromethane. Then, all organic layers were mixed, dried with about 10 g of magnesium sulfate and concentrated, and the resulting product was purified by silica gel column chromatography to obtain a compound represented by the following chemical formula 12. At this time, the yield was 80%.

（式中、ＲはＴＢＳ基）

(Wherein R is a TBS group)

  Furthermore, 11 g of the compound represented by Chemical formula 12 was mixed with 100 ml of acetic acid and allowed to stand for 24 hours while maintaining at 50 ° C. Then, acetic acid was distilled off under reduced pressure, and the resulting product was purified by silica gel column chromatography to obtain a second generation dendritic molecule stabilizer represented by the following chemical formula 13. At this time, the yield was 73%.

Next, 5.0 ml of an aqueous solution of a dendritic molecule represented by chemical formula 6 having a concentration of 1.0 × 10 ⁻² mol / l and 5.0 ml of an aqueous tetrachloroauric (III) acid solution having a concentration of 5.0 × 10 ⁻⁴ mol / l And 0.6 ml of a 1.0 × 10 ⁻² mol / l sodium borohydride aqueous solution as a reducing agent were mixed, cooled to 5 ° C., and left for 1 hour. Then, the absorption peak was measured using a Fourier transform infrared spectrophotometer (FTIR) manufactured by PerkinElmer.

FIG. 3 is a diagram showing a spectrum analysis result by FTIR of the gold nanoparticles in this example.
As shown in FIG. 3, the peak ν (SH) of the thiol group located at the end of the dendritic molecule represented by Chemical formula 13 was not observed. This indicates that the thiol group of the dendritic molecule causes chemical adsorption with the surface of the gold nanoparticle, and the dendritic molecule functions as a stabilizer.

Next, 5.0 ml of an aqueous solution of a dendritic molecule represented by chemical formula 13 of 1.0 × 10 ⁻² mol / l, 5.0 ml of an aqueous solution of tetrachloroauric (III) acid of 5.0 × 10 ⁻⁴ mol / l, and 4.0 × 10 ⁻ Gold nano-adsorbed with 5 kinds of modified stabilizers prepared by the above procedure by mixing 0.2 ml of ³ mol / l silver nitrate aqueous solution and 70 μl of 7.9 × 10 ^-2 mol / l ascorbic acid Each was added to 12 μl of particle solution. And the absorption peak of the gold nanorod was measured using the Hitachi absorption spectrophotometer.

  FIG. 4 is a diagram showing an example of an absorption peak of a gold nanorod by an absorption spectrophotometer in the present example. In FIG. 4, when the concentration of the nanoparticle solution having the highest concentration is 100, the absorption peak 11 when not added to the gold nanoparticle solution, and the absorption peak 12 of the gold nanoparticle solution having a concentration ratio of 20 are shown. 5 types of absorption peak 13 of gold nanoparticle solution having a concentration ratio of 60, absorption peak 14 of gold nanoparticle solution having a concentration ratio of 80, and absorption peak 15 of gold nanoparticle solution having the highest concentration Measurements were made on these samples.

  As shown in FIG. 4, as the concentration of the dendritic molecules increases, the absorption peak shifts to the longer wavelength side, so that gold nanorods with a larger aspect ratio are obtained as the concentration increases.

FIG. 5 is an SEM photograph showing a gold nanorod having a concentration of 1.0 × 10 ⁻⁵ mol / l prepared in this example.
As shown in FIG. 5, the gold nanorods produced in this example had a feature that the lengths in the major axis direction a and the minor axis direction b were different. The absorption band near 520 nm to 530 nm observed in the absorption spectrum of FIG. 4 corresponds to the short axis component of the gold nanorod, and was 10 nm in the case of the gold nanorod shown. On the other hand, the absorption band observed in the region of 780 nm to 800 nm corresponds to the long axis component, and the length of the shown nanorod was 40 nm to 50 nm. It is known that as the aspect ratio (a / b) increases, the long axis becomes longer, and the absorption peak of the absorption spectrum shifts to a longer wavelength region and shifts to a maximum near 1300 nm.

In the above-described example, an example in which gold is used as a nanoparticle has been described. Similarly, an experiment was performed on a silver nanoparticle. 1.0 × 10 ⁻² mol / l of the compound represented by chemical formula 13 (first generation dihydroxy fatty acid stabilizer) 5.0 ml, 5.0 × 10 ⁻⁴ mol / l silver aqueous solution 5.0 ml, reducing agent Was mixed with 0.6 ml of 1.0 × 10 ⁻² mol / l sodium borohydride aqueous solution, cooled to 5 ° C. and left for 1 hour. Similarly, the absorption peak was measured using FTIR manufactured by PerkinElmer.

FIG. 6 is a diagram showing a spectrum analysis result by FTIR of silver nanoparticles in this example.
As shown in FIG. 6, as a result of the measurement, the absorption band of the thiol group in the vicinity of 2550 cm ⁻¹ disappears, which indicates that the dendritic molecule is bound to the surface of the silver nanoparticle. Thus, it was confirmed that these silver nanoparticles were adsorbed on the surface of the silver nanoparticles as a surface modifier.

Next, prepare 5 types of gold nanoparticle solution adsorbed with the surface modifier, prepared in the above procedure, at different concentrations, mix 1.0 × 10 ^-3 g of pyrene to each, and use fluorescence spectroscopy manufactured by PerkinElmer. The fluorescence intensity of pyrene was measured using a photometer.

FIG. 7 is a diagram showing the relationship between the concentration of the gold nanoparticle solution and the fluorescence intensity of pyrene in this example.
As shown in FIG. 7, the fluorescence intensity of pyrene increased as the concentration of gold nanoparticles adsorbed with dendritic molecules increased. As shown in FIG. 2, this indicates that as the dendritic molecule increases, the hydrophobic region in which the alkyl groups are arranged increases, so that pyrene is solubilized to form an aggregate. That is, it shows that a hydrophobic region exists in the surface modifier.

(Second embodiment)
5 g of dicyclohexylcarbodiimide (DCC) was added to a solution obtained by dissolving 12 g of the compound represented by Chemical formula 11 in 220 ml of dichloromethane, and the mixture was stirred to obtain a suspension. Furthermore, 4.1 g of the compound represented by Chemical Formula 10 and 1 g of dimethylaminopyridine (DMAP) as a catalyst were mixed and left at room temperature for 12 hours. And after filtering the produced | generated precipitation, 100 ml of water was added to the obtained filtrate, and it extracted 3 times with 100 ml of dichloromethane. All the organic layers were mixed, dried over about 10 g of magnesium sulfate and concentrated. The resulting product was purified by silica gel column chromatography to obtain the compound represented by the following chemical formula (14). At this time, the yield was 78%.

（式中、ＲはＴＢＳ基であり、Ｂｎはベンジル基）

(Wherein R is a TBS group and Bn is a benzyl group)

  Next, 750 ml of methanol and 750 mg of palladium carbon (Pd / C) were added to 11 g of the compound represented by Chemical formula 14, and left at room temperature for 12 hours in a hydrogen atmosphere. Then, the reaction solution was filtered through Celite to remove palladium on carbon, and then the filtrate was concentrated and purified by silica gel column chromatography to obtain a compound represented by the following chemical formula 15. At this time, the yield was 85%.

（式中、ＲはＴＢＳ基）

(Wherein R is a TBS group)

  Next, 1.4 g of dicyclohexylcarbodiimide (DCC) was added to a solution obtained by dissolving 8.2 g of the compound represented by Chemical formula 15 in 60 ml of dichloromethane, and the mixture was stirred to obtain a suspension. Further, 1.1 g of the compound represented by Chemical Formula 9 and 1 g of dimethylaminopyridine (DMAP) as a catalyst were mixed and allowed to stand at room temperature for 12 hours. And after filtering the produced | generated precipitation, 100 ml of water was added to the obtained filtrate, and it extracted 3 times with 100 ml of dichloromethane. All the organic layers were mixed, dried with about 10 g of magnesium sulfate and concentrated. The obtained product was purified by silica gel column chromatography to obtain a compound represented by the following chemical formula (16). At this time, the yield was 66%.

（式中、ＲはＴＢＳ基）

(Wherein R is a TBS group)

  Next, 20 ml of a 1.0 mol / L tetrahydrofuran (THF) solution of tetrabutylammonium fluoride was added to 6.1 g of the compound represented by Chemical formula 16, and the mixture was allowed to stand for 24 hours while maintaining at 50 ° C. Then, 50 ml of water was added to the reaction solution, and extracted three times with 100 ml of dichloromethane. All the organic layers were mixed, dried with about 10 g of magnesium sulfate and concentrated, and the resulting product was purified by silica gel column chromatography. An agent was obtained. At this time, the yield was 73%.

Next, 5.0 ml of an aqueous solution of a third generation dendritic molecule stabilizer represented by Chemical Formula 17 having a concentration of 1.0 × 10 ⁻² mol / l and tetrachlorogold (III) having a concentration of 5.0 × 10 −4 mol / l ) 5.0 ml of an aqueous acid solution and 0.6 ml of a 1.0 × 10 ⁻² mol / l sodium borohydride aqueous solution as a reducing agent were mixed, cooled to 5 ° C., and left for 1 hour. And the absorption peak of the gold nanoparticle was measured using the absorption spectrophotometer made from Hitachi. As a result of the measurement, as in Example 1, the peak ν (SH) of the thiol group located at the end of the third generation dendritic molecule represented by Chemical Formula 17 was not observed, and the third generation type was also observed. The thiol group of the dendritic molecule causes chemical adsorption with the surface of the gold nanoparticle, and the dendritic molecule functions as a stabilizer.

  As described above, according to the present example, by adsorbing the surface modifier to gold or silver nanoparticles, the surface densely covered with a highly hydrophilic hydroxyl group and a highly hydrophobic alkyl chain are sparse. Therefore, it can be said that a surface modifier imparting various functions can be provided.

1 Gold nanoparticles 2 Dendritic molecules

Claims (10)

A surface modifying agent for nanoparticles having a structure represented by Chemical Formula 1:

(Wherein, x, z ≧ 2, and y, w ≧ 1, x + y ≧ 3, z + w ≧ 3)   2. The nanoparticle surface modifier according to claim 1, wherein x and z have the same value, and y and w have the same value. A nanoparticle surface modifier characterized by having a structure represented by Chemical Formula 2:

(Wherein, x, z, u ≧ 2 and y, w, v ≧ 1, x + y ≧ 3, z + w ≧ 3, u + v ≧ 3)   4. The nanoparticle surface modifier according to claim 3, wherein x, z, and u have the same value, and y, w, and v have the same value.   A metal nanoparticle, wherein the thiol group of the surface modifier of the nanoparticle according to any one of claims 1 to 4 is adsorbed on gold or silver.   The thiol group of the surface modifier of the nanoparticle according to any one of claims 1 to 4 is adsorbed on gold, and further, pyrene is included between the surface modifier of the nanoparticle and the gold. Metal nanoparticles characterized by being made. Thiolating a first dihydroxy fatty acid with an amide bond with cysteamide;
Using the first thiolated compound and the first dihydroxy fatty acid or the second dihydroxy fatty acid different from the first dihydroxy fatty acid to form an ester bond to form a dendritic compound. A method for producing a nanoparticle surface modifier, which is characterized.   The first dihydroxy fatty acid and the second dihydroxy fatty acid are 9,10-dihydroxytetradecanoic acid, 9,10-dihydroxyhexadecanoic acid, 9,10-dihydroxyoctadecanoic acid, 11,12-dihydroxyoctadecanoic acid, 9,10, respectively. The surface of a nanoparticle according to claim 7, characterized in that it is -dihydroxyicosanoic acid, 11,12-dihydroxyicosanoic acid, 13,14-dihydroxydocosanoic acid, or 15,16-dihydroxytetracosanoic acid A method for producing a modifier.   In the step of producing the dendritic compound, the first dihydroxy fatty acid, the second dihydroxy fatty acid, or a third dihydroxy fatty acid different from the first dihydroxy fatty acid and the second hydroxy fatty acid. The method for producing a nanoparticle surface modifier according to claim 7 or 8, wherein an ester bond is used.   The third dihydroxy fatty acid is 9,10-dihydroxytetradecanoic acid, 9,10-dihydroxyhexadecanoic acid, 9,10-dihydroxyoctadecanoic acid, 11,12-dihydroxyoctadecanoic acid, 9,10-dihydroxyicosanoic acid, 11 The method for producing a nanoparticle surface modifier according to claim 9, which is 1,12-dihydroxyicosanoic acid, 13,14-dihydroxydocosanoic acid, or 15,16-dihydroxytetracosanoic acid.

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