Hydroxyapatite Coatings by Pulsed Laser Deposition

1. Hydroxyapatite Coatings by Pulsed Laser Deposition Andreece Richardson Department of Physics University of Alabama at Birmingham

2. Orthopedic and Dental Implants Typically made of Titanium Alloys ? Good corrosion and fatigue life ? Acceptable biocompatibility Deposition of a coating of a material known as Hydroxyapatite on titanium implants ? Improves bioactivity ? Improves biocompatibility Hydroxyapatite is an important component of human bone! An example of an hip replacement made of titanium an HA coating.An example of an hip replacement made of titanium an HA coating.

3. What type of material is Hydroxyapatite? Ceramic material Main mineral constituent of bone and teeth Bone and teeth 50 wt.% mineral (mainly Hydroxyapatite) 50 wt.% organic molecules + water (collagen, mucopolysaccharides) and water

4. A great way of depositing Hydroxyapatite: Pulsed Laser Deposition Explain the process of depositionExplain the process of deposition

5. Pulsed Laser Deposition is a Great Technique Versatile technique for preparing a wide range of thin films and multi-layer structures Can work under controlled gas ambient Allows deposition of different coatings by changing the parameters of deposition Gives researchers the opportunity to discover novel coatings with long-term stability

6. Pulsed Laser Deposition The actual machine we made the deposition with. Show were the laser hits the chamber.The actual machine we made the deposition with. Show were the laser hits the chamber.

7. Mixed Argon and Water Pathway Explain importance of this pathway and how we would not be able to get HA without this pathway Explain what is shown. First just pure Argon Because water will form oxide layer Oxide layer makes the adhesion strength weak Don�t turn on mixed water and Argon until we start firing the laserExplain importance of this pathway and how we would not be able to get HA without this pathway Explain what is shown. First just pure Argon Because water will form oxide layer Oxide layer makes the adhesion strength weak Don�t turn on mixed water and Argon until we start firing the laser

8. Deposition Experiments Explain the five experiments Why we decreased laser Fluence changes in ambient pressure temperature the change in distance Meaning of astricks * Ar/H2O ambient created by bubbling Ar gas through deionized water kept at room temperature. ** Ar/H2O ambient created by bubbling Ar gas through deionized water heated to 50 ?C. � Explain the five experiments Why we decreased laser Fluence changes in ambient pressure temperature the change in distance Meaning of astricks * Ar/H2O ambient created by bubbling Ar gas through deionized water kept at room temperature. ** Ar/H2O ambient created by bubbling Ar gas through deionized water heated to 50 ?C. �

9. X-Ray Diffraction Results *Although the spectrum of sample #1 shows a few clear diffraction peaks indicating crystalline material, a broad amorphous-like background is observed in the scan. *strongest peak obtained from sample #1 (indicated by an asterisk in the figure) cannot be ascribed to HA. It is likely due to the presence of tetracalcium phosphate in the coating. *sample #2 shows more crystalline peaks. The feature associated with tetracalcium phosphate (*) is still present, as is the amorphous band. However, sample #2 shows clear evidence of the presence of crystalline HA. * For samples #3 and #4, however, lower temperatures were used and these samples were dominated by amorphous material as can be seen in Fig. 2. *Results for samples #1 and #2, suggested that a higher water content should be used to achieve HA growth. Also, measurements on samples #3 and #4 demonstrated that the substrate temperature must be maintained at 600?C for the formation of crystalline material. Based on this information we deposited sample #5 using a higher ambient pressure (500 mTorr) and a substrate temperature of 600?C. In addition, a new method was used to increase the water content in the argon carrier gas. In this case Ar gas was bubbled through deionized water heated to 50 ?C while previously the water was kept at room temperature. These factors led to the deposition of a good quality HA coating. Figure 2 shows that this HA film displays all the peaks of the HA target. There is evidence, however, that some tetracalcium phosphate is still present in the film. *Although the spectrum of sample #1 shows a few clear diffraction peaks indicating crystalline material, a broad amorphous-like background is observed in the scan. *strongest peak obtained from sample #1 (indicated by an asterisk in the figure) cannot be ascribed to HA. It is likely due to the presence of tetracalcium phosphate in the coating. *sample #2 shows more crystalline peaks. The feature associated with tetracalcium phosphate (*) is still present, as is the amorphous band. However, sample #2 shows clear evidence of the presence of crystalline HA. * For samples #3 and #4, however, lower temperatures were used and these samples were dominated by amorphous material as can be seen in Fig. 2. *Results for samples #1 and #2, suggested that a higher water content should be used to achieve HA growth. Also, measurements on samples #3 and #4 demonstrated that the substrate temperature must be maintained at 600?C for the formation of crystalline material. Based on this information we deposited sample #5 using a higher ambient pressure (500 mTorr) and a substrate temperature of 600?C. In addition, a new method was used to increase the water content in the argon carrier gas. In this case Ar gas was bubbled through deionized water heated to 50 ?C while previously the water was kept at room temperature. These factors led to the deposition of a good quality HA coating. Figure 2 shows that this HA film displays all the peaks of the HA target. There is evidence, however, that some tetracalcium phosphate is still present in the film.

10. Conclusion We have found good conditions for depositing Hydroxyapatite by Pulsed Laser Deposition:

11. Acknowledgments Thanks to Two Outstanding Mentors Hyunbin Kim and Dr. Renato Camata!