Synthetic nano-sized crystalline calcium phosphate and method of production

Abstract

Synthetic nano-sized crystalline calcium phosphate, particularly hydroxyapatite, having a specific surface area in the range of 150 m 2 /g to 300 m 2 /g, is described. The nano-sized crystalline calcium phosphate may be in the form of a powder or in the form of a coating on a surface. A method of producing a nano-sized crystalline calcium phosphate powder or coating is also described.

1 . A synthetic nano-sized crystalline calcium phosphate having a specific surface area in the range of 50 m 2 /g to 300 m 2 /g. 
     
     
         2 . The synthetic nano-sized crystalline calcium phosphate of  claim 1 , wherein the calcium phosphate is hydroxyapatite. 
     
     
         3 . The synthetic nano-sized crystalline calcium phosphate of  claim 1 , wherein the specific surface is selected from the group consisting of 180 m 2 /g, 220 m 2 /g and 280 m 2 /g. 
     
     
         4 . The synthetic nano-sized crystalline calcium phosphate of  claim 1 , wherein the calcium phosphate is in the form of a powder. 
     
     
         5 . The synthetic nano-sized crystalline calcium phosphate of  claim 1 , wherein the calcium phosphate is in the form of a coating on a surface. 
     
     
         6 . The synthetic nano-sized crystalline calcium phosphate of  claim 1 , wherein the surface is a metal surface. 
     
     
         7 . The synthetic nano-sized crystalline calcium phosphate of  claim 6 , wherein the metal surface is a titanium surface. 
     
     
         8 . The synthetic nano-sized crystalline calcium phosphate of  claim 1 , wherein the coating has a thickness of less than or equal to 100 nm. 
     
     
         9 . The synthetic nano-sized crystalline calcium phosphate of  claim 1 , wherein the calcium to phosphor ratio is 1.67. 
     
     
         10 . A method of producing a powder or coating of nano-sized crystalline calcium phosphate comprising the steps of
 a) providing a solution of water and stoichiometric solved amounts of a phosphor precursor and of a calcium salt precursor,   b) adding a surfactant, and optionally a hydrophobic organic solvent, to the solution of a) to create a liquid crystalline phase,   c) allowing the liquid crystalline phase to equilibrate, and   d) placing the equilibrated liquid crystalline phase in an ammonia atmosphere to raise the pH so that nano-sized crystals of calcium phosphate are formed in the water domains of the liquid crystalline phase, the steps a)-d) being performed at ambient temperature, followed by either   e1) removing the surfactant from the ammonia-treated liquid crystalline phase of d) with a solvent and   f1) filtering, washing and drying the nano-sized crystals of calcium phosphate to obtain the powder, or   e2) diluting the ammonia-treated liquid crystalline phase of d) with a hydrophobic organic solvent to create a microemulsion of the nano-sized crystals of calcium phosphate in water,   f2) dipping an oxide layer-coated surface of an object into the microemulsion of e2) to deposit the microemulsion onto the surface,   g2) evaporating the organic solvent from the surface of f2) to obtain the coating of nano-sized crystalline calcium phosphate, and   h2) heating under inert atmosphere in order to remove the surfactant, or alternatively omitting step d) and   e3) diluting the liquid crystalline phase of c) with a hydrophobic organic solvent to create a microemulsion,   f3) dipping an oxide layer-coated surface of an object into the microemulsion of e3) to deposit the microemulsion onto the surface,   g3) evaporating the organic solvent from the surface of f3) to form a liquid crystalline phase, and   h3) placing the surface of g3) in an ammonia atmosphere to raise the pH so that nano-sized crystals of calcium phosphate are formed in the water domains of the liquid crystalline phase and are deposited on the surface, followed by   i2) heating under inert atmosphere in order to remove the surfactant.   
     
     
         11 . The method of  claim 10 , wherein the surfactant in b) is a non-ionic surfactant. 
     
     
         12 . The method of  claim 10 , wherein the oxide layer-coated surface of f2) or f3) is a metal surface. 
     
     
         13 . The method of  claim 12 , wherein the metal surface is a titanium surface. 
     
     
         14 . The method of  claim 10 , wherein the object of f2) or f3) is a body implant. 
     
     
         15 . The method of  claim 14 , wherein the body implant is a dental implant. 
     
     
         16 . The method of  claim 10 , wherein the calcium phosphate is hydroxyapatite. 
     
     
         17 . The method of  claim 10 , wherein the phosphor precursor is phosphoric acid. 
     
     
         18 . The method of  claim 10 , wherein the calcium salt precursor is calcium nitrate. 
     
     
         19 . The method of  claim 10 , wherein the calcium to phosphor ratio is 1.67.