Porous biomaterials and method of making same

• US 3,929,971 A
• Filed: 03/30/1973
• Issued: 12/30/1975
• Est. Priority Date: 03/30/1973
• Status: Expired due to Term

• Current Assignee: Research Corporation Technologies
• Original Assignee: Della M. Roy
• Inventors: Roy, Della M.
• Primary Examiner(s): Vertiz, Oscar R.
• Assistant Examiner(s): Heller, Gregory A.
• Application Number:
  US05/346,644
• Time in Patent Office: 1,005 Days
• Field of Search: 423/308-313 128/92C
• US Class Current: 423/308
• CPC Class Codes: A61F 2/28 Bones joints A61F2/30
• CPC Class Codes: A61F 2310/00293 containing a phosphorus-containing compound, e.g. apatite
• CPC Class Codes: A61K 35/56 Materials from animals other than mammals
• CPC Class Codes: A61L 27/12 Phosphorus-containing materials, e.g. apatite
• CPC Class Codes: A61L 27/36 containing ingredients of undetermined constitution or reaction products thereof , e.g. transplant tissue, natural bone, extracellular matrix isolated natural compounds, e.g. collagen A61L27/24
• CPC Class Codes: B01D 39/06 Inorganic material, e.g. asbestos fibres, glass beads or fibres
• CPC Class Codes: B01J 27/18 with metals other than Al or Zr

Abstract

Synthetic material having a microstructure substantially corresponding to the microstructure of porous carbonate skeletal material of marine life and made up of hydroxyapatite or whitlockite is useful as a biomaterial. These synthetic materials are made by converting porous carbonate skeletal material of marine life into a phosphate skeletal material possessing a microstructure substantially the same as or corresponding to the microstructure of the carbonate skeletal source material by subjecting the carbonate skeletal material to hydrothermal chemical exchange with a phosphate.

Claims

1. SYNTHETIC MATERIAL USEFUL AS A BIOMATERIAL CHARACTERIZED BY A SUBSTANTIALLY UNIFORM PORE VOLUME IN THE RANGE FROM ABOUT 10% TO ABOUT 90% AND HAVING A MICROSTRUCTURE CHARACTERIZED BY A PRONOUNCED THREEDIMENSIONAL FENESTRATE STRUCTURE CORRESPONDING TO THE MICROSTRUCTURE OF THE POROUS CARBONATE ECHINODERM OR SCHLERACTINIAN CORAL SKELETAL MATERIAL OF MARINE LIFE AND PROVIDING A PERIODIC MINIMAL SURFACE, SAID PERIODIC MINIMAL SURFACE DIVIDING THE VOLUME OF SAID MATERIAL INTO TWO INTERPENETRATING REGIONS, EACH OF WHICH IS A SINGLE, MULTIPLY CONNECTED DOMAIN, SAID MATERIAL HAVING A SUBSTANTIALLY UNIFORM PORE SIZE DIAMETER AND SUBSTANTIALLY UNIFORM PORE CONNECTIONS OR OPENINGS IN THE RANGE FROM ABOUT 5 MICRONS TO ABOUT 500 MICRONS, SAID SYNTHETIC MATERIAL BEING MADE UP OF A MATERIAL SELECTED FROM THE GROUP CONSISTING OF HYDROXYAPATITE AND WHITLOCKITE.

2. Synthetic material in accordance with claim 1 having the microstructure of echinodeRm skeletal calcite and consisting essentially of whitlockite.

3. Synthetic material in accordance with claim 2 wherein said echinoderm skeletal calcite is echinoid spine calcite.

4. Synthetic material in accordance with claim 1 possessing the microstructure of coral skeletal aragonite and consisting essentially of hydroxyapatite.

5. Synthetic material in accordance with claim 4 said coral skeletal aragonite is Porites skeletal aragonite.

6. Synthetic material in accordance with claim 1 wherein said hydroxyapatite contains about 0.1-10% by weight carbonate.

7. Synthetic material in accordance with claim 1 wherein said whitlockite contains about 0.1-10% by weight carbonate.

8. Synthetic material in accordance with claim 1 having the microstructure of the calcite spine of Acanthaster planci and consisting essentially of whitlockite.

9. Synthetic material in accordance with claim 1 having the microstructure of the calcite spine of the sea urchin Diadema and consisting essentially of whitlockite.

10. Synthetic material in accordance with claim 1 possessing the microstructure of Goniopora skeletal aragonite and consisting essentially of hydroxyapatite.

11. Synthetic material in accordance with claim 10 wherein said hydroxyapatite contains about 0.1-10% by weight carbonate.

12. Synthetic material in accordance with claim 1 possessing the microstructure of Alveopora skeletal aragonite and consisting essentially of hydroxyapatite.

13. Synthetic material in accordance with claim 12 wherein said hydroxyapatite contains about 0.1-10% by weight carbonate.

14. Synthetic material in accordance with claim 1 wherein said marine life is scleractinian coral.

15. Synthetic material in accordance with claim 1 wherein said marine life is of the phylum Coelenterate.

16. Synthetic material in accordance with claim 1 wherein the carbonate of said porous skeletal material is aragonite or calcite.

17. Synthetic material in accordance with claim 1 possessing the microstructure of Acropora skeletal aragonite and consisting essentially of hydroxyapatite.

18. Synthetic material in accordance with claim 1 wherein said hydroxyapatite contains about 0.1-10% by weight carbonate.

19. Synthetic material in accordance with claim 1 wherein the microstructure is such that the synthetic material has the ratio of pore volume to the volume of solid of approximately 1 and has a cross-sectional diameter of both the pore and solid phase of about the same dimension ranging from about 5 microns to about 500 microns.

20. Synthetic material in accordance with claim 1 having a pore size in the range 40-200 microns.

21. Synthetic material in accordance with claim 1 having a pore size in the range 5-15 microns.

22. Synthetic material in accordance with claim 1 shaped or formed substantially into the shape of a cylinder.

23. Synthetic material in accordance with claim 1 shaped or formed substantially into the shape of a flat sheet.

24. Synthetic material in accordance with claim 1 shaped or formed substantially into the shape of a curved sheet.

25. Synthetic material in accordance with claim 1 shaped or formed substantially into the shape of a threaded or serrated screw-like form.

26. A method of converting porous carbonate skeletal material of marine life into a phosphate skeletal material possessing substantially the same microstructure of said carbonate skeletal material which comprises subjecting said porous carbonate skeletal material to hydrothermal chemical exchange with a soluble or solubilized phosphate, said hydrothermal chemical exchange being carried out at a temperature in the range from about 100*C. to about 600*C. and at an elevated pressure in the range about 1,500-100,000 psig for a period of time sufficient to convert said carbonate skeletal material to a phosphate skeletal material wherein the phosphate of sAid phosphate skeletal material is hydroxyapatite or whitlockite.

27. A method in accordance with claim 26 wherein said period of time is in the range from about 1 hour to about 2 weeks.

28. A method in accordance with claim 26 wherein the carbonate of said porous carbonate skeletal material is aragonite and wherein the phosphate of said phosphate skeletal material is hydroxyapatite.

29. A method in accordance with claim 28 wherein said phosphate skeletal material consists essentially of hydroxyapatite and a minor amount of carbonate is in the range 0.1% to about 10% by weight CO3.

30. A method in accordance with claim 26 wherein the carbonate of said carbonate skeletal material is calcite and wherein the phosphate of said phosphate skeletal material is whitlockite.

31. A method in accordance with claim 30 wherein said phosphate skeletal material consists essentially of whitlockite and a minor amount of carbonate in the range 0.05% to about 5.0% by weight CO3.

32. A method in accordance with claim 26 wherein said phosphate employed in the hydrothermal chemical exchange is (NH4)2HPO4.

33. A method in accordance with claim 26 wherein said phosphate employed in the hydrothermal chemical exchange is (NH4)2HPO4 and wherein Ca(OH)2 is present during the hydrothermal chemical exchange.

34. A method in accordance with claim 26 wherein said phosphate employed in the hydrothermal chemical exchange is CaHPO4.2H2O together with (NH4)2HPO4.

35. A method in accordance with claim 26 wherein said phosphate employed in the hydrothermal chemical exchange is 3CaO.P2O5.

36. A method in accordance with claim 26 wherein said phosphate employed in the hydrothermal chemical exchange is CaHPO4 together with orthophosphoric acid H3PO4.

37. A method in accordance with claim 26 wherein the phosphate employed in the hydrothermal chemical exchange is Ca(H2PO4)2.H2O.

38. A method in accordance with claim 26 wherein the phosphate employed in the hydrothermal chemical exchange for reaction with the carbonate of said porous carbonate skeletal material is a phosphate selected from the group consisting of alkali metal phosphates, ammonium orthophosphates, calcium orthophosphates and acid phosphates thereof, orthophosphoric acid and hydrates thereof, and mixtures of weak acids with phosphates.

39. A method in accordance with claim 38 wherein said alkali metal phosphates are sodium orthophosphates.

40. A method in accordance with claim 38 wherein said alkali metal phosphates are potassium orthophosphates.

41. A method in accordance with claim 38 wherein said weak acid is acetic acid.

42. A method in accordance with claim 26 wherein the hydrothermal chemical exchange is carried out at a temperature in the range from about 180*C. to about 350*C.

43. A method in accordance with claim 26 wherein the hydrothermal chemical exchange is carried out at a pressure in the range from about 8,000 psi to about 15,000 psi.

44. A method in accordance with claim 26 wherein the hydrothermal chemical exchange is carried out for a period of time from about 12 hours to about 48 hours.

45. A method in accordance with claim 26 wherein the hydrothermal chemical exchange is carried out at a pressure in the range from about 8,000 psi to about 15,000 psi, for a period of time of from about 12 hours to about 48 hours and wherein the phosphate employed in said hydrothermal chemical exchange is derived from (NH4)2HPO4.