JP2011080137A - Blue coloring agent made of gold fine particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a blue coloring agent by gold nano fine particles of the quality same as that of a gold hydrosol (gold colloid) widely used as a color material of red to purple. <P>SOLUTION: Spiculisporic acid as a biosurfactant (a surfactant produced by an organism) with a tribasic acid type structure derived from an organism, safe and having biodegradability and various alkali salts of the lactone ring opened body thereof are used as a reducing agent of Au<SP>3+</SP>of a chloroauric acid aqueous solution in the coexistence of monovalent inorganic salts. After reduction reaction, the unreacted biosurfactant and the oxide thereof are adsorbed on gold nano fine particles in the produced gold hydrosol and gold hydrogel so as to stabilize a water dispersion system of the gold nano fine particles. Alternatively, the blue coloring agent is made of a water dispersion system of gold nanofine particles prepared by adding monovalent inorganic salts to a red system gold hydrosol obtained by reducing chloroauric acid by the biosurfactant. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention reduces the Au ³⁺ in chloroauric acid aqueous solution by utilizing the characteristics that spikrispolic acid and its derivative alkali salt have both reducing power and dispersion stabilizing action, and also, before or after the reaction, inorganic salts and gelation. By adding a third substance such as an agent, the aqueous dispersion of gold nanoparticles (gold hydrogel or gold colloid) is stabilized, and the particle size of the primary particles of gold nanoparticles in the dispersion is controlled. The present invention also relates to provision of a blue colorant comprising a gold hydrosol obtained by controlling the size and density of secondary particles in which the primary particles are aggregated, and a gold hydrogel.

Red-colored gold colloids are widely known for use in stained glass, bohemian glass, coating color materials, colorants for synthetic resins, oxidation catalysts, metal nanoparticle-dispersed hybrid thin films, and surface-enhanced Raman spectroscopy (SERS). Yes. A colloidal gold is one in which colloidal gold particles having a size of 1 nm to 1 μm are stably dispersed in a dispersion medium such as water. Also called gold hydrosol. The coloring power (the color depth of the solution) of colloidal gold is 20,000 times that of Cu ²⁺ and 400 times that of Au ³⁺ (Non-patent Document 4). However, below a dilute concentration (for example, 0.1 mmol / l or less), the color is thin and various substrates cannot be dyed as a colorant. Dilute gold colloids are stable, but high concentrations of gold colloids are unstable, and the addition of a protective colloid agent is essential to stabilize the colloidal system. In general, colloidal gold rapidly changes from red-purple-blue-gray-black by the addition of a small amount of salt such as sodium chloride, and easily precipitates, so that stable blue-type gold colloids have been realized in the past. Absent.

The inventors of the present invention have previously described an alkali salt [II] of splicrispolic acid [I] represented by [Chemical Formula 1] and a ring-opened alkaline salt [II] of [L] represented by [Chemical Formula 2] in an aqueous solution. In addition, it has been found that Au ³⁺ such as chloroauric acid is reduced at room temperature and a concentrated colloidal gold solution is stably dispersed (Patent Document 5). The mechanism of this reduction reaction is that the carboxyl group of [I] and [II] reduces Au ³⁺ to Au ⁰ (single gold) as well as the reduction reaction of Au ³⁺ with citric acid, and itself is oxidized. It is thought to change to a carbonyl group. In addition, although the produced gold colloid is a hydrophobic colloid and unstable, the carbonylated {I} and [II] derivatives are also surface active, and unreacted {I} and {I II} is adsorbed to gold nanoparticles of Au ⁰ to give negative charge, and the alkyl group surrounds the particles to prevent coalescence and aggregation with other particles, thereby stabilizing the gold colloid. In the present invention, based on the above knowledge, control of the primary particle diameter of Au ⁰ produced by the reduction reaction, and control of the secondary particle size by coalescence of the primary particles are carried out as a monovalent inorganic salt or a formula. This was achieved in the presence of the Mg salt of [II].

Japanese Patent Laid-Open No. 11-61209 JP-A-62-299587 Japanese Patent Laid-Open No. 2-118186 Japanese Patent Laid-Open No. 11-80647 JP 2009-57627 A

Takao Fukuoka, Yasushi Mori, Chemical Engineering, 2004-8, 36 (2004) Kazuo Kanno, Masakatsu Ota, Junichi Matsui, Cosmetic Technology Journal, 31 (2), 158 (1997) Kensuke Akamatsu, Shingo Ikeda, Hidemi Ropefune, Chemical Industry, 2005-10, 40 (2005) Masayuki Nakagaki, Kiyonari Fukuda, “Basics of Colloid Chemistry”, p. 58, Dai Nippon Books (1993)

The present invention prepares a blue-based gold hydrosol that is stable at a gold nanosol concentration of 1,3,12 mmol / l as high as possible, and also provides an in-situ composition of a blue-based gold hydrosol composition. A technique that enables preparation is provided. It is important in the present invention that spikrispolic acid used as a reducing agent for chloroauric acid and the alkali salt of the ring-opened product thereof have a surface activity such as a dispersing action as well as a reducing action. Therefore, adsorption to Au ³⁺ in the aqueous chloroauric acid solution before the reduction reaction, reduction and stabilization to Au ^{3 + −} − → Au ⁰ during the reduction reaction, and secondary particles from the primary particles of Au ⁰ after the reduction reaction are completed. By balancing the control of agglomeration into the particles, the color is developed in a blue hue / tone. In this case, it is assumed that the primary particles of the gold nanoparticle are spherical. While protecting and stabilizing the gold colloid (gold hydrosol), which is a hydrophobic colloid, the size of the primary particles of the gold nanoparticles and the gentle aggregation of the primary particles are determined while determining the magnitude of the salt effect of the added inorganic salt. It is an object of the present invention to make it possible to prepare a gold hydrosol and a gold hydrogel composition that keeps the aggregate size of about 100 to 200 nm on average and keeps it stable.

The inventors of the present invention have made extensive studies to solve the above problems, have been confirmed to be safe and biodegradable due to microorganisms, and have a unique chemical structure (unprecedented polybasic acid type anionic surfactant). Of the lactone ring of spiccrisporic acid [(4S, 5S) -4,5-dicarboxy-4-pentadecanolide] alkali salt [I], [Chemical Formula 1] and [I] [ (4S, 5S) -3-Hydroxy-1,3,4-tetradecanetricarboxylic acid] alkali salt [II], [Chemical Formula 2] is used to convert Au ³⁺ in a chloroauric acid solution in an aqueous solution and an aqueous organic solvent. It has already been found that gold colloid is produced by reduction and adsorbed on the produced gold nanoparticles to stabilize the dispersion (Patent Document 5). The present inventors further advanced these findings, and the formulas [I] and [II] are adsorbed and stabilized on the gold nanoparticles, and an excess of splicrispolic acid derivative not adsorbed on the gold nanoparticles, [ The present invention has been completed based on the concept that blue gold colloid can be hydrogelated and stabilized by coexistence with micelles or liquid crystals (Non-patent Document 5) of [I] and [II]. It has been well known and should be avoided in the past that coagulation easily occurs when inorganic salts are added to gold colloid (gold hydrosol) which is a hydrophobic colloid. That is, hydrocolloids (associative colloids) such as [I] and [II] that originally have a charged group in the molecule do not aggregate (salting out) unless a large amount of inorganic salts are added. In the case of a hydrophobic colloid that does not have a charged group, such as fine particles, precipitation occurs (coagulation) even when a small amount of inorganic salt is added. In addition, it is known that the coagulation action by inorganic salts dramatically increases the coagulation force as the valence of inorganic ions increases (Schulze-Hardy rule). The coagulation number is defined as the minimum electrolyte concentration (mmol / l) required to coagulate the colloidal solution. Although the numerical value is unique depending on the combination of each hydrophobic colloid and each inorganic salt, it is roughly 10 to 200 mmol / l for a monovalent inorganic salt, 0.2 to 2 mmol / l for a divalent inorganic salt, The trivalent inorganic salt is 0.01 to 1 mmol / l. It is also shown that there is a negative gradient linear relationship when the logarithm of the coagulation value is plotted on the vertical axis and the logarithm of the valence of the complex salt is plotted on the horizontal axis (Non-Patent Document 4). In fact, when the inventors added a 0.1 M KAl (SO ₄ ) ₂ aqueous solution with divalent 1MCaCl ₂ .2H ₂ O or trivalent Al ³⁺ to a reddish purple gold hydrosol, a reddish purple precipitate was easily formed. It has been found to occur. However, some Mg salts of [II] form hydrogels or emulsified gels alone, and have been found to have the effect of stabilizing gold hydrogels. The present invention uses a spicrispolic acid homologue, which is a biosurfactant that has both surface activity such as reduction action and dispersion action, as a protective colloid agent for gold nanoparticles, and is made stable by making it coexist with inorganic salts. A blue-based gold hydrogel coloring material is obtained.

Hiroshi Ishigami, Yasuo Tsuji, Shinsuke Yamazaki, Yukagaku, 36,490 (1987)

The inventors of the present invention first made inorganic salts against a red-colored gold colloid (Patent Document 5) prepared using a spikrispolic acid (hereinafter abbreviated as S-acid) homologue as a reducing agent. To obtain a blue colloidal gold colloid consisting of large gold nanoparticles (primary particles and secondary particles), and to stabilize the surface activity of the same spicrispolic acid analog It is. In addition, secondly, a third substance such as an inorganic salt is added to the aqueous reaction mixture for reducing Au ^{3+ of} chloroauric acid to obtain a gold colloid of Au ⁰ together with a surface active spiculisporic acid derivative. In addition, a reduction reaction is performed to ensure stabilization of the hue and tone of the gold colloid obtained. The above two approaches include stabilization by gel (hydrogel) formation. For this purpose, spikrispolic acid alkali salt [I] represented by [Chemical Formula 1] and ring-opened lactone ring (hereinafter abbreviated as O-acid) alkali salt [Chemical Formula 2] represented by [Chemical Formula 2] [II] ], All of the three carboxyl groups are neutralized with n-hexylamine (hereinafter abbreviated as O-3n-HA), and two of the carboxyl groups are neutralized with 2-ethylhexylamine ( Hereinafter, it is abbreviated as O-2EHA), 1.5 of which are neutralized with arginine (hereinafter abbreviated as O-1.5Arg), and a Mg1.5 neutralized salt (hereinafter referred to as O-1. (Abbreviated as 5Mg) may be added later. Thus, the inventors have found a method for dispersing and stabilizing gold fine particles exhibiting a blue color in a gold hydrosol, and have completed the present invention.

  That is, the present invention has the following formula:

[X in the formula represents an inorganic alkali (Na, K, Li, NH ₄ , Mg, etc.), an organic alkali (alkylamine, arginine, etc.), or H. n ⁺ represents the valence of X as a cation]

The compound [I] represented by the formula:

[X in the formula represents an inorganic alkali (Na, K, Li, NH ₄ , Mg, etc.), an organic alkali (alkylamine, arginine, etc.), or H. n ⁺ represents the valence of X as a cation]

Compound [II] represented by

A blue colorant comprising gold fine particles, characterized in that

Various alkali salts of polybasic acid biosurfactant, spicrispolic acid (hereinafter abbreviated as S-acid) and its lactone ring ring-opened product (hereinafter abbreviated as O-acid) have a hydrophilic / lipophilic balance (HLB). ) Of different homologues, and their aqueous solutions have large surface activity [surface tension lowering action, emulsification / dispersion action (with salt resistance), metal ion scavenging action, pH buffering action, moderate wetting / penetration action, It has been found that it has a thickening / gelling action and a liquid crystal (vesicle) forming action by selecting ions (Non-Patent Documents 5, 6 to 10). Spikrispolic acid sodium salt has been shown to be biodegradable and safe for humans and organisms (Non-patent Document 9). As a result of diligent research on the properties and functions of the S-acid, the present inventors have found that the alkaline salt of the S-acid and its ring-opened compound exhibits a strong reducing power against chloroauric acid (Patent Document). 5). Since the S-acid ring-opened substance is a tribasic acid type surfactant, Au ³⁺ ions are strongly attracted to the surface of the micelle associating structure (near the stern layer) and concentrated locally. By the way, the critical micelle concentration (cmc) of the O-3Na aqueous solution is 1.7 × 10 ⁻¹ , O-2Na: 1.01 × 10 ⁻¹ , O-1Na: 3.6 × 10 ⁻³ mol / l (Non-patent Document 10). . The tri-n-hexylamine salt of O-acid (hereinafter abbreviated as O-3n-HA) and the disubstituted 2-ethylhexylamine salt of O-acid (hereinafter abbreviated as O-2EHA) have a neutralization degree ( The cmc is smaller and the surface activity is larger than the sodium salt having the same carboxyl group substitution degree (Non-patent Document 10). These carboxyl groups are oxidized to carbonyl groups, and at this time, Au ^{3+ of} chloroauric acid is considered to be converted to Au ⁰ gold n nanoparticles. This is similar to the reduction mechanism of chloroauric acid by trisodium citrate. Due to the strong acidity of chloroauric acid during the reaction, O-3Na is converted to O-2Na or O-1Na, which is advantageous for obtaining a blue-type gold colloid with increased surface activity such as increased dispersion action. Thus, in order to stabilize the colloidal gold, the O-acid alkali salt, which is a bulky and polybasic acid, is adsorbed on the surface of the generated Au ⁰ gold alone by ionic and van der Waals forces of alkyl groups. Thus, a negative charge is applied to prevent coalescence between the gold fine particles. Furthermore, due to the coexistence of O-2Na and O-1Na converted from O-3Na due to the strong acidity of chloroauric acid, a slightly turbid slurry or hydrogel can contribute to stabilization.

Supervised by Kunio Furusawa, New Dispersion / Emulsification Science and New Development of Applied Technology, Part I, Section 5 Natural Emulsifier (Hiroshi Ishigami), p. 216, Techno System Corporation, 2006 Y. Ishigami, Y. et al. Zhang, F.M. Ji, CHIMICA OGGI, July / August Issue, 1 (spiculsporic acid) (2000) Tsuji, Ishigami, Oreoscience, 2,649 (2002) Hiroshi Ishigami, Chemical Industry, 1990-9, 28 (1990) Hiroshi Ishigami, Shinsuke Yamazaki, Kaken Kengakuho, 80, 231 (1985)

Next, the present inventors balanced the dispersion action of the gold fine particles in the aqueous solution of the splicrispolic acid derivative and the limit of salt resistance, and averaged the particle diameter of the primary or secondary particles of the gold fine particles to be 100 to 200 nm. As a result, the present invention has been completed by finding a method of controlling to a level of ## EQU1 ## and stabilizing by quasi-stabilization or gelation (hydrogelation) with a third additive. That is, spikrispolic acid analogs [I] and [II] used as a reducing agent and colloidal gold dispersion stabilizer are classified as anionic surfactants. The colloidal dispersion system (gold hydrosol) is large (Non-Patent Document 11), has a pH buffering action (Non-Patent Document 12), and converts the molecular assembly form into a liquid crystal state depending on pH (Non-Patent Document 5). It was developed as an applied technology with the prospect of being excellent for stabilization. Here, in order to obtain a stable blue color of a gold hydrosol by adding an inorganic salt, the hue is reddish purple when absorbing light having a wavelength of 500 to 560 nm, and the particle diameter of the gold fine particles at this time is 80 nm. If it absorbs light with a wavelength of 560 to 580 nm, the particle size of the gold fine particles is 100 nm or more, and if it absorbs light with a wavelength of 595 to 605 nm, it is greenish blue, and absorbs light with a wavelength of 605 to 750 nm. Blue-green (Non-Patent Document 14). The third substance as an additive is classified into the following four categories A, B, C, and D. These may be added alone or in a mixture of two or three. Here, A. Monovalent inorganic salts (NaCl, KCl, etc.), B.I. It is a hydrogel-forming splicrispolic acid derivative (n-hexylamine salt, octylamine salt, and 2-ethylhexylamine salt of O-acid), and has a viscosity of 10 mPa · s (100 cps) or less and exhibits remarkable thixotropic properties. C. Water-based gelling agent / thickening agent (polymer gelling agent, water-soluble polymer such as gum arabic, alginic acid, pectin, gelatin, kelco gum, xanthan gum, pullulan, polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), Those limited to post-addition include water-soluble organic acids (such as acetic acid, butyric acid, isovaleric acid, ascorbic acid) and O-1.5Mg.

M.M. Osman, Y .; Ishigami, K .; Furusawa, H .; Holmsen, J. et al. Jpn. Oil Chem. Soc. (Yukagaku), 46, 741 (1997) Y. Ishigami, S .; Yamazaki, Y. et al. Gama, J .; Colloid and Interface Sci. , 94, 131 (1983) Hiroshi Ishigami, Yasuo Tsuji, Shinsuke Yamazaki, Yukagaku, 36,490 (1987) Katsumi Nakahara, Science of Color, Bafukan Co., Ltd. (1999)

Placed in a 100ml volume flask in crowded weighed <Preparation of aqueous chloroauric acid _solution> HAuCl ₄ · 4H 2 _O1.030g, and 100ml was added deionized-distilled water to the mark (hereinafter, referred to as pure water), and 25. A 0 mmol / l (1.03%) HAuCl ₄ .4H ₂ O aqueous solution was prepared. A low concentration solution was prepared by diluting this stock solution. Separately, a highly concentrated solution of 71.6 mmol / l was also prepared.

<Preparation of Splicrispolic Acid Alkaline Salt {I} and Ring-Opening Alkaline Salt [II] According to the Present Invention>
The O-acid is dissolved in an ethanol-water mixed aqueous solution of S-acid, then added with an aqueous NaOH solution, heated and stirred at 70 ° C. to open the lactone ring, and then gradually added the same amount of HCl to add an O-acid. And O-acid was obtained by recrystallization from hydrous ethanol. Alkali this O- acid was suspended in a predetermined amount of water, corresponding with stirring (NaOH, KOH, LiOH, Mg (OCH 2 CH 3) 2, butylamine, n- hexylamine, 2-ethylhexylamine, arginine, etc.) Was gradually added to obtain a neutralized salt. It should be noted that the preparation of the O-acid alkali salt is not practically hindered by adding a predetermined amount of alkali to the S-acid and heating to 70 ° C. However, a small amount of S-acid may be contaminated, and the reproducibility of the properties of the gold hydrogel may be partially changed.

<Determination of the particle size of gold particles in colloidal gold solution>
UV measurement of a monodispersed commercially available gold colloid with known gold nanoparticle size [manufactured by Tanaka Kikinzoku Kogyo Co., Ltd. and British Biocell International Co., Ltd.] There is a demand for a relationship with particle diameter (Patent Document 1). From the comparison of this relationship diagram and the spectral waveform of 150 to 200 nm, the number of gold nanoparticle particles of the prepared gold colloid sample was adjusted to 10 ⁹ to ¹⁰ 10 particles / ml (adjusted to a corresponding concentration such as dilution). The average particle diameter of the gold nanoparticle was determined by performing spectrum measurement using a visible / ultraviolet spectrophotometer (UV). Separately, using a scanning electron microscope (Hitachi S-4700 type), it was observed at 50,000 times, and the photographed image was enlarged and observed in detail. All SEM photographs of colloidal gold reduced at 70 ° C. with a 111 mmol / lO-3Na aqueous solution of 71.6 mmol / l HAuCl ₄ .4H ₂ O had 10-20 nm primary particles closely dispersed. On the other hand, in the NaCl addition system during or after the reaction, a particle size distribution was observed. This was particularly noticeable at a high Au ⁰ concentration. All were large primary particles and aggregates of various numbers of secondary particles.

<Composition of reaction mixture and synthesis reaction of gold colloid by reduction of HAuCl ₄ .4H ₂ O>
The reducing power of the O-3Na aqueous solution with respect to 2.5 mmol / l HAuCl ₄ · 4H ₂ O had a reducing action at a molar ratio of O-3Na0.9: Au ³⁺ 1.0 or more, but in the presence of NaCl, The reaction became difficult to occur. When a 7.4 mmol / lO-3Na aqueous solution was used for the study, a blue color was obtained when the NaCl concentration was around 170 mmol / l. The red-purple gold colloid changed from bluish purple to blue-gray in the same manner by the subsequent addition of NaCl. When the reduction reaction was performed by increasing the concentration of O-3Na and HAuCl ₄ · 4H ₂ O by 10 times, the salt resistance was remarkably improved even when NaCl was present.
<Coloring various base materials of blue color obtained by the present invention>
A gold hydrosol with 1 mmol / l Au ⁰ concentration well dyed natural materials such as filter paper and papers. Further, among plastics, they were deposited on polyethylene terephthalate plates, polyvinyl acetate pellets, and 6,6-nylon plates, deposited, and dyed a blue color after drying. The surface of the polyvinyl formal powder was not repelled and dyed. Moreover, although it adapts to a polyester fiber (nonpatent literature 15) and a nylon fiber, since the said gold colloid liquid was surface active, it was hard to osmose | permeate and diffuse and to be dyed. Therefore, by adding O-3n-HA or O-2EHA in advance to the reaction mixture before the reaction or after adding it to a slurry-like or paste-like gold hydrogel, the surface is more concentrated in a blue color. It was possible to color.

Nobuhiro Tsujimura, Coloring Material, 79,492 (2006)

Next, the present invention will be described in detail with reference to examples.

_{2.5mM (0.103%) HAuCl 4 ·} 4H 2 O-solution 1ml placed in 5ml ml two-out tube, and then after shaking added 1MNaCl aqueous solution 0.4 ml, and more 7.43mMO-3Na aqueous 1ml In addition, it was heated at 70 ° C. for 60 minutes. The NaCl concentration in the reaction mixture corresponds to 167 mmol / l. A dull blue gold hydrosol (gold colloid) was obtained by the reduction reaction. When UV measurement was carried out after centrifuging at room temperature for 1 day, a spectrum having a maximum absorption wavelength at 565 nm inherent to gold nanoparticles was obtained. From this, the particle diameter corresponded to about 105 nm. Subsequently, when a differential scanning electron microscope observation was performed, primary particles of 20 to 60 nm of Au ⁰ and aggregates of secondary particles made of them and having different sizes were scattered.

2.5mMHAuCl ₄ · 4H ₂ O-solution 10ml was placed in 30ml ml stoppered screw tube bottle, then shaken added 7.4mMO-3Na solution 10ml, and heated for 5 minutes at 70 ° C., gold hydrosols dark red-purple Obtained. The UV spectrum had a broad absorption over 500-600 nm. From this, 1 ml was taken, 0.4 ml of 1M NaCl was added, the mixture was shaken and allowed to stand at room temperature, the color gradually changed, and the color after 30 minutes was blue. One day later, UV measurement showed a maximum absorption at a wavelength of 616 nm and a characteristic spectral waveform. This wavelength and waveform corresponded to an average particle diameter of 150 nm.

Add 3.6 ml of 2.5 mM HAuCl ₄ · 4H ₂ O aqueous solution to a stoppered 10 ml screw tube bottle, add 3.6 ml of 7.4 mMO-3Na aqueous solution, shake and mix, and then add 0.4 ml of 1M NaCl at 70 ° C. When heated for 30 minutes, a blue-violet dispersion was obtained. According to SEM observation, primary particles of 20 to 60 nm are loosely or densely attached at random (fractal aggregation), and a large number of aggregates including large aggregates having a diameter of 200 nm or more as a whole are scattered and dispersed. There are many. It corresponded to the distribution of Au in the characteristic X-ray analysis. When this dispersion was hung on a nylon plate, a polycarbonate plate, and a polyethylene terephthalate plate and air-dried, it was dyed blue. Polyvinyl formal powder could not be dyed.

In a mixed solution of 1 ml of 25 mM HAuCl ₄ .4H ₂ O and 1 ml of 1M NaCl in a 5 ml lidded test tube, 0.15 ml of 111mMO-3Na, 0.45 ml of 100mMO-3n-HA, and 50mMO-2EHA When 0.4 ml of the mixed solution was added and heated at 70 ° C. for 40 minutes, a blue-gray dispersion was obtained, and when left at room temperature, it gelled. This gel had a viscosity of about 20 mPa · s (Brookfield viscometer), but showed marked thixotropy.

Add 0.7 ml of 7.4 mMO-3Na aqueous solution to 1 ml of 2.5 mM HAuCl ₄ .4H ₂ O aqueous solution and 0.4 ml of 1M NaCl aqueous solution placed in a 5 ml lidded test tube, and heat at 70 ° C. for 60 minutes. A purple dispersion was obtained. Immediately after adding 0.2 ml of 50mMO-2EHA aqueous solution, the mixture was shaken and allowed to stand, a gold hydrogel was obtained. This gel showed a greater viscosity than the gel of Example 4 and stably retained the gold nanoparticles.

In a solution plus the 25mMHAuCl ₄ · 4H ₂ O and 2ml and 3MNaCl0.4ml taking into 5ml ml two-out tube, added 111mMO-3Na solution 2ml, dark purple gold and heated 10 minutes at 70 ° C. A hydrosol was obtained. Furthermore, although it was heated and reacted for 50 minutes, the gold nanoparticle grew larger and did not change to a blue color, and a stable deep purple color was maintained. From SEM observation, primary particles of 20 to 80 nm were uniformly dispersed.
To 5 ml of the obtained gold hydrogel, 10 ml of 3M NaCl was added and allowed to stand at room temperature (about 25 ° C.), but it did not change color, so when heated at 70 ° C. for 10 minutes, it turned dark purple. After standing for one day, when ultrafiltered using a filter having a pore size of 0.2 μm from Millipore, the filtrate was pink to red, while the remaining liquid was grayish blue. When both were hung on the filter paper, the color difference was obvious. Subsequently, the same base material as in Example 3 was dyed, and the same dyeing result was obtained.

Claims (6)

The splicrispolic acid alkali salt [I] represented by the following formula [Chemical Formula 1] and the ring-opened alkali salt [II] of the lactone ring represented by the following formula [Chemical Formula 2] [Chemical Formula 1] are salified. Use as a reducing agent for Au ³⁺ such as gold acid (also serves as a stabilizer for the generated gold hydrogel), and carry out a reduction reaction at a reaction temperature of 10 to 90 ° C., particularly 40 to 80 ° C. An aqueous dispersion of gold nanoparticles having a blue color obtained by obtaining a system (gold colloid, gold hydrosol, gold hydrogel) and then adding a monovalent inorganic salt (NaCl, KCl, LiCl, etc.).

[X in the formula represents an inorganic alkali (Na, K, Li, NH ₄ , Mg, etc.), an organic alkali (alkylamine, arginine, etc.), or H. n ⁺ represents the valence of X as a cation]

[X in the formula represents an inorganic alkali (Na, K, Li, NH ₄ , Mg, etc.), an organic alkali (alkylamine, arginine, etc.), or H. n ⁺ represents the valence of X as a cation] The compounds of [I] and [II] of claim 1 are all or part of Au ³⁺ reducing agent such as chloroauric acid, and in the presence of inorganic salts, the reaction temperature is 10 to 90 ° C., and particularly 40 to 80 ° C. gold in performs reduction of Au ^3+, the completion of the reaction at the same time as [I] and [II] oxide carbonyl fluoride of (indicating surfactant) and the excess unreacted [I] and [II], the resulting An aqueous dispersion of gold nanoparticles having a blue color, which serves as a dispersion stabilizer for an aqueous dispersion of nanoparticles.   3. A monovalent inorganic salt or a gel-forming [II] Mg salt in a red-red purple-violet colloidal gold solution obtained by carrying out a reduction reaction in the absence of an inorganic salt. An aqueous dispersion of gold nano-particles having a blue color obtained by adding Nb.   From the aqueous dispersion of gold nanoparticles obtained in claims 1, 2 and 3, fine particles are removed by ultrafiltration, and large particles in the submicron region or more are No. An aqueous dispersion of gold nano-particles with a blue hue and tone adjusted by removing them as filter cake with 7C filter paper.   The spikrispolate represented by the formulas [I] and [II] with respect to the aqueous dispersion of gold nanoparticles obtained in claim 1, 2, 3, and 4, particularly an alkylamine having gel-forming ability. Hydrogels and pastes having a high concentration of gold nanoparticles of 10 mmol / l or more by post-adding concentrated aqueous solutions of salts, arginine salts, and Mg salts to gel the entire system.   The gold hydrogel and paste obtained by using a known aqueous gelling agent as a hydrogelling agent to be added later.