Formation of colloidal metal dispersions using aminodextrans as reductants and protective agents

Claim 1

A method for preparing colloidal metal(O) particles from a solution of a metal salt and coating said particles with a polymeric organic compound which also is used as a reductant for said metal salt, said method comprising: (a) heating a solution containing an amine derivatized, oxidizable sugar containing polysaccharide and a metal salt capable of being reduced by said oxidizable sugar containing polysaccharide for a time and at a temperature sufficient to reduce said metal salt to colloidal metal particles and simultaneously coating said particles with said polysaccharide; and (b) stabilizing the amine derivatized polysaccharide coating on said particles by means of a bifunctional crosslinking agent, a diamine and a reducing agent.

Claim 2

A method for preparing colloidal metal(O) particles from a solution of a metal salt and coating said particles with a polymeric organic compound which also is used as a reductant for said metal salt, said method comprising: (a) heating a solution containing an amine derivatized, oxidizable sugar containing polysaccharide and a metal salt capable of being reduced by said oxidizable sugar containing polysaccharide for a time and at a temperature sufficient to reduce said metal salt to colloidal metal particles and simultaneously coating said particles with said polysaccharide; and (b) stabilizing the amine derivatized polysaccharide coating on said particles by means of a bifunctional crosslinking agent, a diamine and a reducing agent.

Claim 7

A method of preparing colloidal metal(O) particles coated with an amine derivatized, oxidizable sugar containing polysaccharide, said method comprising: (a) heating an aqueous solution of a sugar reducible metal salt and adding to said solution an aqueous solution of an amine derivatized polysaccharide having at least one reducing sugar component; (b) heating and mixing the solution resulting from step (a) for about 10-30 minutes at a temperature in the range of about 90°-100° C. to reduce said metal salt by said polysaccharide to colloidal metal(O) particles suspended in said polysaccharide solution and coated with said polysaccharide; (c) cooling the solution resulting from step (b) to room temperature and adding to the cooled solution an aqueous first bifunctional reagent capable of reacting with amine groups on said amine derivatized polysaccharide; (d) adding an organic diamine to the product of step (c); (e) reducing the reducible groups formed in step (d); (f) dialyzing the solution of step (e) against water; and (g) centrifuging the product of step (f) to obtain amine derivatized polysaccharide coated particles capable of being dispersed as colloids.

Claim 8

A method of preparing colloidal metal(O) particles coated with an amine derivatized, oxidizable sugar containing polysaccharide, said method comprising: (a) heating an aqueous solution of a sugar reducible metal salt and adding to said solution an aqueous solution of an amine derivatized polysaccharide having at least one reducing sugar component; (b) heating and mixing the solution resulting from step (a) for about 10-30 minutes at a temperature in the range of about 90°-100° C. to reduce said metal salt by said polysaccharide to colloidal metal(O) particles suspended in said polysaccharide solution and coated with said polysaccharide; (c) cooling the solution resulting from step (b) to room temperature and adding to the cooled solution an aqueous first bifunctional reagent capable of reacting with amine groups on said amine derivatized polysaccharide; (d) adding an organic diamine to the product of step (c); (e) reducing the reducible groups formed in step (d); (f) dialyzing the solution of step (e) against water; and (g) centrifuging the product of step (f) to obtain amine derivatized polysaccharide coated particles capable of being dispersed as colloids.