Hollow bone mineral-like calcium phosphate particles

Abstract

Hollow particles having a shell substantially composed of calcium-phosphate, methods for preparing the same, and methods of use are disclosed. The particles are obtained by differential immersion of silica-based, calcium and phosphate containing glass particles.

What is claimed is:  
     
         1 . A hollow particle having a shell, said shell comprising calcium-phosphate and having an outer diameter of up to about 5 mm.  
     
     
         2 . The particle of  claim 1  wherein said shell further comprises silicon.  
     
     
         3 . The particle of  claim 1  wherein said shell further comprises biologically active molecules.  
     
     
         4 . The particle of  claim 2  wherein said biologically active molecules comprise an antibiotic.  
     
     
         5 . The particle of  claim 3  wherein said antibiotic is EXAMPLE 1  
     
     
         6 . The particle of  claim 2  wherein said biologically active molecules comprise cell attachment molecules.  
     
     
         7 . The particle of  claim 2  wherein said biologically active molecules comprise growth factors.  
     
     
         8 . The particle of  claim 1 , said particle having an apparent density of about 1.1 g/cm 3 .  
     
     
         9 . A method for transforming silica-based glass particles into calcium-phosphate shells in vitro comprising immersing silica-based glass particles comprising silica in an aqueous solution undersaturated in soluble silica for a period sufficient to allow substantially all the silica to dissolve from said particles.  
     
     
         10 . The method of  claim 9  wherein said glass particles are melt-derived.  
     
     
         11 . The method of  claim 9  wherein said glass particles are sol-gel derived.  
     
     
         12 . The method of  claim 9  wherein said glass particles further comprise calcium.  
     
     
         13 . The method of  claim 12  wherein said glass particles further comprise phosphate.  
     
     
         14 . The method of  claim 13  wherein said calcium and phosphate are present as a layer on the surface of said glass particles.  
     
     
         15 . The method of  claim 9  wherein said particles are immersed in said solution until from about 80% to about 100% of the silica has dissolved from said particles.  
     
     
         16 . The method of  claim 9  wherein the weight to volume ratio of the glass particles to solution is from about 0.1 to about 5 mg/ml.  
     
     
         17 . The method of  claim 9  wherein the aqueous solution is supplied as a continuous flow.  
     
     
         18 . The method of  claim 9  wherein said solution further comprises biologically active molecules.  
     
     
         19 . The method of  claim 18  wherein said biologically active molecules comprise an antibiotic.  
     
     
         20 . The method of  claim 19  wherein said antibiotic is vancomycin.  
     
     
         21 . The method of  claim 18  wherein said biologically active molecules comprise cell attachment molecules.  
     
     
         22 . The method of  claim 18  wherein said biologically active molecules comprise growth factors.  
     
     
         23 . A particle prepared according to the method of  claim 9 .  
     
     
         24 . A method for preparing a particle according to  claim 1  comprising immersing silica-based glass particles comprising silica in an aqueous solution undersaturated in soluble silica for a period sufficient to allow substantially all the silica to dissolve from said particles.  
     
     
         25 . The method of  claim 24  wherein said glass particles further comprises calcium.  
     
     
         26 . The method of  claim 25  wherein said glass particles further comprises phosphate.  
     
     
         27 . The method of  claim 26  wherein said calcium and phosphate are present as a layer on the surface of said glass particles.  
     
     
         28 . A carrier for use in microgravity tissue culture comprising particles according to  claim 8 .  
     
     
         29 . A method for filling a bone defect comprising implanting hollow particles having a shell comprising a carbonated, bone-mineral like, calcium-phosphate layer into said defect, said particles further having an outer diameter of up to about 5 mm.