Method For Preparing BioMedical Surfaces

Abstract

A method for selectively dissolving the beta (β) phase of a titanium alloy out of the surface of the alloy, thereby leaving behind a nano-scale porous surface having enhanced bonding properties with either a biological tissue, such as bone, or an adhesive material, such as a polymer or ceramic by immersing the alloy in an ionic aqueous solution containing high levels of hydrogen peroxide and then exposing the alloy to an electrochemical voltage process resulting in the selective dissolution of the beta phase to form a nano-topographic metallic surface.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more fully understood and appreciated by reading the following Detailed Description in conjunction with the accompanying drawings, in which:

FIG. 1 is a flowchart of a process according to the present invention.

FIGS. 2( a)-(b) are Scanning Electron Micrographs of Ti-6Al-4V: (a) at 7000× after treatment with hydrogen peroxide and electrochemical treatment showing selective dissolution of the beta phase; and (b) at 3500× after standard etching treatments with the beta phase still intact.

FIG. 3 is a graph of potentiodynamic polarization plots of Ti-6Al-4V in hydrogen peroxide containing solutions.

FIG. 4 is a reproduction of an Atomic Force Microscopy image (height) of Ti-6Al-4V after selective dissolution of beta crystals (dark regions of image).

FIG. 5 is a SEM micrograph of Ti-6Al-4V after selective dissolution of beta phase.

FIGS. 6( a)-(c) are SEM micrographs of Ti-6Al-4V after processing as described in Example 2: (a) holding for 1000 s at −0.5 V; (b) Holding for 1000 s at −0.1 V; and (c) holding for 1000 s at 0.1 V.

FIG. 7 is a SEM micrograph of Cp-Ti after processing in 1 M H₂O₂ PBS solution.

Claims

1. A method of preparing a metallic biomedical surface, comprising the steps of: positioning a titanium alloy in an electrochemical cell;immersing said alloy in an ionic aqueous electrolyte solution containing hydrogen peroxide;cathodically biasing said alloy to a negative voltage state for a first predetermined time period; andraising the anodic potential of the alloy for a second predetermined period of time.

2. The method of claim 1, wherein said alloy comprises a multiphase titanium alloy.

3. The method of claim 2, wherein said alloy comprises Ti-6Al-4V.

4. The method of claim 1, wherein said alloy comprises a single phase titanium alloy.

5. The method of claim 1, wherein said ionic aqueous electrolyte solution comprises a phosphate buffered saline solution modified with hydrogen peroxide.

6. The method of claim 5, wherein said solution comprises hydrogen peroxide in a molar concentration range of 0.3 to 5.0 M.

7. The method of claim 6, wherein said solution comprises 0.154 M phosphate buffered saline modified with 1 M hydrogen peroxide.

8. The method of claim 1, wherein said first predetermined period of time is about ten minutes.

9. The method of claim 1, wherein the step of cathodically biasing said alloy to a negative voltage state for a first predetermined time period comprises electrochemically holding said alloy at a voltage of −1V.

10. The method of claim 9, wherein the step of raising the anodic potential of the alloy comprises anodically scanning said alloy at 1 mV per second to a voltage of 1 V.

11. A method of preparing a metallic biomedical surface, comprising the steps of: positioning said titanium alloy in an electrochemical cell;immersing said alloy in a phosphate buffered solution of saline and hydrogen peroxide;cathodically biasing said alloy to voltage state of about −1V for a predetermined time period; andraising the anodic potential of the alloy to a voltage of about 1V.

12. The method of claim 11, further comprising the step of preparing the surface of said titanium alloy before positioning said titanium alloy in said electrochemical cell.

13. The method of claim 12 wherein the step of preparing the surface of said titanium alloy comprises mechanically polishing said titanium alloy.

14. The method of claim 13, wherein mechanically polishing said titanium alloy comprises polishing with aluminum oxide particles suspended in water.

15. The method of claim 14, wherein the step of preparing the surface of said titanium alloy comprises the steps of heating said titanium alloy into the beta-phase region of said titanium alloy and cooling said titanium alloy, thereby forming a Widmanstatten structure.

16. A biomedical surface comprising a titanium alloy having an alpha phase and a beta phase, wherein said beta phase has been selectively dissolved to provide nanotopographic roughness.

17. The surface of claim 16, wherein the nanotopographic roughness is formed by positioning said alloy in an electrochemical cell, immersing said alloy in a phosphate buffered solution of saline and hydrogen peroxide, cathodically biasing said alloy to a negative voltage state, and raising the anodic potential of the alloy.

18. The surface of claim 17, wherein said nanotopographic roughness comprises pits formed in said surface.