Method for preparing hydroxyapatite composite and biocompatible material

Abstract

A method for preparing a hydroxyapatite composite is disclosed. This method comprises alternately soaking a matrix which has been made hydrophilic at least on its surface, in a calcium ion aqueous solution containing calcium ions and substantially free of phosphate ions and in a phosphate ion aqueous solution containing phosphate ions and substantially free of calcium ions to securely form hydroxyapatite at least on the surface of the matrix. Also disclosed is a biocompatible material composed of the hydroxyapatite composite obtained by the method.

What is claimed is:  
     
         1 . A method for preparing a hydroxyapatite composite comprising: 
 alternately soaking a matrix which has been made hydrophilic at least on its surface in a calcium ion aqueous solution containing calcium ions and substantially free of phosphate ions and in a phosphate ion aqueous solution containing phosphate ions and substantially free of calcium ions to securely form hydroxyapatite at least on the surface of the said matrix.    
     
     
         2 . The method of  claim 1  wherein the said matrix which has been made hydrophilic at least on its surface has been prepared by a process selected from the group consisting of subjecting a polymer matrix to at least one of corona treatment, plasma treatment, acid treatment, base treatment, and surface-filing treatment, and subjecting a metal matrix to at least one of acid treatment on its surface, and a surface-filing treatment.  
     
     
         3 . The method of  claim 2  wherein the said polymer matrix is selected from the group consisting of polyurethane, polyethylene, polypropylene, poly(lactic acid), poly(glycolic acid), polyester, polyamide, polycarbonate, a fluoropolymer, a silicon elastomer, polyvinyl alcohol, polyethylene glycol, poly-γ-glutamic acid, collagen, glucosylethyl methacrylate (GEMA), partially sulfated GEMA, a mucopolysaccharide, cellulose, chitin, chitosan, pullulan and fibronectin.  
     
     
         4 . The method of  claim 2  wherein the said process of subjecting a polymer matrix to at least one of corona treatment, plasma treatment, acid treatment, base treatment, and surface-filing treatment is followed by graft-polymerization of a hydrophilic polymerizable compound to its surface.  
     
     
         5 . The method of  claim 4  wherein the said hydrophilic polymerizable compound has at least one of a carboxyl group, a phosphoric acid group, and a sulfonic acid group.  
     
     
         6 . The method of  claim 4  wherein the said hydrophilic polymerizable compound is selected from the group consisting of (meth)acrylic acid, alkyl ester of (meth)acrylic acid, alkydamide of (meth)acrylic acid, (meth)acrylic acid having a urethane bond, (meth)acrylic acid having a urea bond, (meth)acrylic acid having a phosphoric acid group, (meth)acrylic acid having a sulfonic acid group, and mixtures thereof.  
     
     
         7 . The method of  claim 2  wherein the said process of subjecting a polymer matrix to at least one of corona treatment, plasma treatment, acid treatment, base treatment, and surface-filing treatment is followed by reaction of a hydrophilic polymer with its surface.  
     
     
         8 . The method of  claim 7  wherein the said hydrophilic polymer has at least one of a carboxyl group, a phosphoric acid group, and a sulfonic acid group.  
     
     
         9 . The method of  claim 1  further comprising, after soaking the matrix which has been hydrophilic at least on its surface in the calcium ion aqueous solution containing calcium ions and substantially free of phosphate ions, removing the said calcium ion aqueous solution remaining on the matrix before soaking the matrix in the phosphate ion aqueous solution containing phosphate ions and substantially free of calcium ions.  
     
     
         10 . The method of  claim 9  wherein the said removing of the calcium ion aqueous solution containing calcium ions and substantially free of phosphate ions remaining on the matrix includes washing and drying the matrix.  
     
     
         11 . The method of  claim 1  further comprising, after soaking the matrix which has been made hydrophilic at least on its surface in the phosphate ion aqueous solution containing phosphate ions and substantially free of calcium ions, removing the said phosphate ion aqueous solution remaining on the matrix before soaking the matrix in the calcium ion aqueous solution containing calcium ions and substantially free of phosphate ions.  
     
     
         12 . The method of  claim 11  wherein the said removing of the phosphate ion aqueous solution containing phosphate ions and substantially free of calcium ions remaining on the matrix includes washing and drying the matrix.  
     
     
         13 . A biocompatible material consisting essentially of a hydroxyapatite composite prepared in accordance with the method of  claim 1.