Colloidal gold solution and method for producing same

Abstract

The purpose of the present invention is to provide a stable colloidal gold solution and a method for producing the stable colloidal gold solution. A colloidal gold solution which contains, in water, gold nanoparticles having particle diameters of 100 nm or less and anions represented by general formula (a); and a method for producing the colloidal gold solution. R—COO − (a) (In the formula, R represents a linear or branched alkyl group having 1-4 carbon atoms.)

1 . A colloidal gold solution, comprising:
 water;   gold nanoparticles with a particle size of 100 nm or less; and   an anion represented by formula
   R—COO—  (a)
 
   
       wherein R represents a linear or branched alkyl group of 1 to 4 carbon atoms. 
     
     
         2 . The colloidal gold solution according to  claim 1 , wherein the anion is an acetate ion. 
     
     
         3 . The colloidal gold solution according to  claim 1 , further comprising a protective colloid. 
     
     
         4 . The colloidal gold solution according to any one of  claim 1 , wherein the protective colloid is at least one selected from the group consisting of polyvinylpyrrolidone, polyethylene glycol, polyacrylic acid, poly(sodium acrylate), polyvinyl alcohol, and carboxymethyl cellulose. 
     
     
         5 . The colloidal gold solution according to any one of  claim 1 , further comprising a reducing agent comprising an alcohol with a primary hydroxyl group and/or a secondary hydroxyl group. 
     
     
         6 . The colloidal gold solution according to any one of  claim 1 , wherein the gold nanoparticles have a concentration of 0.001 to 50% by weight. 
     
     
         7 . The colloidal gold solution according to any one of  claim 1 , which is substantially free of chloride ions. 
     
     
         8 . A method for producing a colloidal gold solution, comprising the steps of:
 (i) dispersing a gold carboxylate in water to form a dispersion; and   (ii) allowing a reducing agent to react with the gold carboxylate in the dispersion obtained in the step (i) so that a colloidal gold solution is obtained by reduction.   
     
     
         9 . The method according to  claim 8 , wherein the reduction is performed using at least one selected from the group consisting of an alcohol with a primary hydroxyl group and/or a secondary hydroxyl group, polyvinylpyrrolidone, polyvinyl alcohol, polyethylene glycol, gelatin, starch, dextrin, carboxymethyl cellulose, methyl cellulose, and ethyl cellulose. 
     
     
         10 . The method according to  claim 8 , wherein the gold carboxylate is gold acetate. 
     
     
         11 . The method according to any one of  claim 8 , wherein the dispersion contains a protective colloid. 
     
     
         12 . The method according to any one of  claim 8 , wherein the protective colloid is at least one selected from the group consisting of polyvinylpyrrolidone, polyethylene glycol, polyacrylic acid, poly(sodium acrylate), polyvinyl alcohol, and carboxymethyl cellulose.