Nanocrystalline apatites and composites, prostheses incorporating them, and method for their production

Abstract

Methods for synthesis of nanocrystalline apatites are presented, as well as a series of specific reaction parameters that can be adjusted to tailor, in specific ways, properties in the recovered product. Particulate apatite compositions having average crystal size of less than 150 nm are provided. Products also can have a surface area of at least 40 m 2 /g and can be of high density. Hydroxyapatite material is investigated in particular detail. Compositions of the invention can be used as prosthetic implants and coatings for prosthetic implants.

1. A composition, comprising particulate apatite having an average apatite crystal size of less than 100 nm, wherein the crystal is spherical. 
     
     
       2. The composition of  claim 1  comprising particulate apatite having an average apatite crystal size of less than 50 nm. 
     
     
       3. The composition of  claim 1  comprising particulate apatite having an average apatite crystal size of less than 30 nm. 
     
     
       4. The composition of  claim 1  comprising particulate apatite having an average apatite crystal size of less than 20 nm. 
     
     
       5. The composition of  claim 1  wherein the particulate apatite is densified. 
     
     
       6. The composition of  claim 1  comprising apatite having an average particle size of less than 1 μm. 
     
     
       7. The composition of  claim 1  comprising apatite having an average particle size of less than 0.5 μm. 
     
     
       8. The composition of  claim 1  comprising apatite having an average particle size of less than 0.25 μm. 
     
     
       9. A composition comprising particulate apatite having a surface area of at least 40 m 2 /g and a spherical crystal. 
     
     
       10. The composition of  claim 7  comprising particulate apatite having a surface area of at least 100 m 2 /g. 
     
     
       11. The composition of  claim 9  comprising particulate apatite having a surface area of at least 150 m 2 /g. 
     
     
       12. The composition of  claim 9  that undergoes apatite phase decomposition of less than 10% when exposed to conditions of at least 1000° C. for at least 2 hours. 
     
     
       13. The composition of  claim 12  that undergoes apatite phase decomposition of less than 5% when exposed to conditions of at least 1000° C. for at least 2 hours. 
     
     
       14. The composition of  claim 12  that undergoes apatite phase decomposition of less than 3% when exposed to conditions of at least 1000° C. for at least 2 hours. 
     
     
       15. The composition of  claim 12  that undergoes apatite phase decomposition of less than 10% when exposed to conditions of at least 1100° C. for at least 2 hours. 
     
     
       16. The composition of  claim 12  that undergoes apatite phase decomposition of less than 5% when exposed to conditions of at least 1100° C. for at least 2 hours. 
     
     
       17. The composition of  claim 12  that undergoes apatite phase decomposition of less than 3% when exposed to conditions of at least 1100° C. for at least 2 hours. 
     
     
       18. The composition of  claim 12  that undergoes apatite phase decomposition of less than 10% when exposed to conditions of at least 1200° C. for at least 2 hours. 
     
     
       19. The composition of  claim 12  that undergoes apatite phase decomposition of less than 5% when exposed to conditions of at least 1200° C. for at least 2 hours. 
     
     
       20. The composition of  claim 12  that undergoes apatite phase decomposition of less than 3% when exposed to conditions of at least 1200° C. for at least 2 hours. 
     
     
       21. The composition of  claim 12  that undergoes apatite phase decomposition of less than 10% when exposed to conditions of at least 1300° C. for at least 2 hours. 
     
     
       22. The composition of  claim 12  that undergoes apatite phase decomposition of less than 5% when exposed to conditions of at least 1300° C. for at least 2 hours. 
     
     
       23. The composition of  claim 12  that undergoes apatite phase decomposition of less than 3% when exposed to conditions of at least 1300° C. for at least 2 hours. 
     
     
       24. An article having a dimension of at least 0.5 cm made up of the composition of  claim 1 . 
     
     
       25. The article of  claim 24  wherein the particulate apatite is consolidated. 
     
     
       26. The article of  claim 24 , formed into the shape of a prosthesis. 
     
     
       27. The article of  claim 24  that is a prosthesis. 
     
     
       28. The article of  claim 24  comprising an exterior coating on a prosthesis. 
     
     
       29. The article of  claim 28  comprising an exterior coating, on a prosthesis, of at least 0.5 micron in thickness. 
     
     
       30. The article of  claim 24  having a theoretical density of at least 90%. 
     
     
       31. The article of  claim 24  having a theoretical density of at least 95%. 
     
     
       32. The article of  claim 24  having a theoretical density of at least 98%. 
     
     
       33. An article having a dimension of at least 0.5 cm made up of the composition of  claim 9 . 
     
     
       34. The article of  claim 33  having a porosity of at least 20%. 
     
     
       35. The article of  claim 33  having a porosity of at least 30%. 
     
     
       36. The article of  claim 33  having a porosity of at least 50%. 
     
     
       37. The article of  claim 33  having a porosity of at least 75%. 
     
     
       38. The densified article of  claim 33  having compressive strength of at least about 150 MPa. 
     
     
       39. The densified article of  claim 38 , having a density of at least about 98%. 
     
     
       40. The densified article of  claim 33  having compressive strength of at least about 500 MPa. 
     
     
       41. The densified article of  claim 33  having compressive strength of at least about 700 MPa. 
     
     
       42. The densified article of  claim 38 , having a density of at least about 90%. 
     
     
       43. The densified article of  claim 38 , having a density of at least about 95%. 
     
     
       44. The article of  claim 24  that is a part of a prosthesis. 
     
     
       45. A composition, comprising particulate apatite having an average apatite particle size of less than  1  μm, an average apatite crystal size of less than  150  nm, a surface area of at least  40  m 2   /g, and wherein the particulate apatite undergoes apatite phase decomposition of less than  10   %  when exposed to conditions of at least  1300 ° C. for at least  2  hours, and wherein the crystal has an aspect ratio from spherical to about  2 . 9 : 1 .   
     
     
       46. The composition of  claim 45 , wherein the particulate apatite has a surface area of at least  60  m 2   /g.   
     
     
       47. The composition of  claim 46 , wherein the particulate apatite has a surface area of at least  100  m 2   /g.   
     
     
       48. The composition of  claim 45 , wherein the particulate apatite has an average apatite particle size of less than  0 . 5  μm. 
     
     
       49. The composition of  claim 45 , wherein the particulate apatite has an average crystal size of less than  100  nm. 
     
     
       50. The composition of  claim 45 , wherein the particulate apatite is densified. 
     
     
       51. The composition of  claim 45 , further comprising an auxiliary structural additive. 
     
     
       52. The composition of  claim 51 , wherein the auxiliary structural additive comprises a ceramic additive. 
     
     
       53. The composition of  claim 52 , wherein the ceramic additive comprises a metal oxide. 
     
     
       54. The composition of  claim 53 , wherein the metal oxide comprises zirconia. 
     
     
       55. The composition of  claim 51 , wherein the auxiliary structural additive is a metal or alloy. 
     
     
       56. The composition of  claim 51 , wherein the auxiliary structural additive is present in an amount of between about  1 %  and about  50   %  by volume.   
     
     
       57. The composition of  claim 45 , wherein the particulate apatite is carbonated apatite. 
     
     
       58. The composition of  claim 45 , wherein the particulate apatite is admixed with an organic species. 
     
     
       59. The composition of  claim 58 , wherein the organic species is a self- assembling surfactant or a polymer.   
     
     
       60. The composition of  claim 45  wherein the composition comprises an apatite comprising SiO 4   .   
     
     
       61. The composition of  claim 45 , wherein the crystal has a length:width aspect ratio of from spherical to  2 . 8 : 1 . 
     
     
       62. The composition of  claim 45 , wherein the crystal is spherical. 
     
     
       63. The composition of  claim 62 , comprising particulate apatite has an average crystal size of less than  100  nm. 
     
     
       64. The composition of  claim 62 , comprising particulate apatite having an average apatite crystal size of less than  50  nm. 
     
     
       65. The composition of  claim 62 , comprising apatite having an average particle size of less than  0 . 5  μm. 
     
     
       66. The composition of  claim 62 , wherein the particulate apatite has a surface area of at least  100  m 2   /g.   
     
     
       67. The composition of  claim 62 , wherein the particulate apatite has a surface area of at least  150  m 2   /g.   
     
     
       68. The composition of  claim 62 , wherein the particulate apatite undergoes apatite phase decomposition of less than  5 %  when exposed to conditions of at least  1300 ° C. for at least  2  hours.   
     
     
       69. The composition of  claim 68 , wherein the particulate apatite undergoes apatite phase decomposition of less than  3 %  when exposed to conditions of at least  1300 ° C. for at least  2  hours.