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  1. 1. A Hybrid Laser/Aerosol Method for the Synthesis of Porous Nanostructured Calcium Phosphate Materials for Bone Tissue Engineering Applications Shatoya Brown, Hyunbin Kim, Renato P. Camata University of Alabama at Birmingham, Dept. of Physics, Birmingham, AL
  2. 2. MOTIVATION <ul><li>Engineering and regeneration of bone tissue </li></ul><ul><ul><li>Outstanding problem in medicine and dentistry </li></ul></ul><ul><ul><li>Calcium phosphate bioceramic substrates are known to stimulate bone regeneration </li></ul></ul><ul><ul><li>Nanoscale design in these bioceramics may significantly affect osteoconduction and improve implant performance/bone regeneration </li></ul></ul><ul><ul><li>Technological improvements in this are area bound to affect millions of people </li></ul></ul>
  3. 3. Areas of Human Skeleton Where Biomaterials are Used for Bone Repair Hip Implant Dental implant How Biomaterials are Used
  4. 4. RESEARCH GOAL <ul><li>Demonstrate a new laser / aerosol method capable of synthesızıng porous nanostructure calcıum phosphate materıals </li></ul>Ratıonale For Desıgn of Porous Nanostructure Calcium Phosphate Layer Porous structure after cell adhesion Partial sintering during deposition osteoblasts Calcıum p hosphate particles as building blocks for porous bioceramic networks
  5. 5. <ul><li>Flush out vacuum chamber removing all gases found in the air </li></ul><ul><li>Fill chamber with Argon/water gas mixture </li></ul><ul><li>Place Hydroxyapatite target into ablation chamber </li></ul><ul><li>Clean titanium substrate using acetone and methanol in ultrasonic cleaner </li></ul><ul><li>Place substrate into vacuum chamber </li></ul><ul><li>Heat substrate to desired temperature </li></ul><ul><li>Align lens and laser </li></ul><ul><li>Start laser and proceed with deposition </li></ul><ul><li>When deposition is completed, allow substrate to cool </li></ul><ul><li>Remove substrate with adhered product from chamber </li></ul><ul><li>Product undergoes x-ray diffraction/SEM to identify calcium phoshates </li></ul>DEPOSITION METHOD
  6. 6. Experimental Set-up for Depositoin of Calcium Phosphate by Laser/Aerosol Method Ar/H 2 O Continuous flow (2 L/min) Titanium substrate Target holder Substrate holder 500-800  C lens Calcium Phosphate nanoparticles Exhaust HA target KrF excimer laser
  7. 7. X-Ray Diffraction Measurements of Calcium Phosphate Materials Deposited by Hybrid Laser/Aerosol
  8. 8. HA by new Laser/Aerosol Method 760C Area 1 SEM 5000x HA by Conventional Pulsed Laser Deposition (For Comparison) Scanning Electron Microscopy (SEM) Results
  9. 9. HA Aerosol 760C Area 2 SEM 5000x Scanning Electron Microscopy (SEM) Results Mostly Microparticles Partially Sintered
  10. 10. HA Aerosol 760C Area 2 SEM 10000x Scanning Electron Microscopy (SEM) Results Coatings seem To have Good mechanical stability and adherence to substrates
  11. 11. HA Aerosol 760C Area 1 SEM 40000x Scanning Electron Microscopy (SEM) Results <ul><li>Resulting Material: </li></ul><ul><li>Microporous </li></ul><ul><li>Framework of </li></ul><ul><li>partially sintered microparticles: </li></ul><ul><li> May provide good mechanical stability </li></ul><ul><li>Surrounded by </li></ul><ul><li>Nanoparticles </li></ul><ul><li> May provide stimulation of biological activity </li></ul>
  12. 12. HA Aerosol 760C Area 1 SEM 10000x Scanning Electron Microscopy (SEM) Results <ul><li>Nanostructured porous calcium phosphate </li></ul><ul><li>Possible. </li></ul><ul><li>Can we control it? </li></ul><ul><li>Pore size </li></ul><ul><li>Framework Stability </li></ul><ul><li>Nanoparticle size </li></ul><ul><li>and concentration </li></ul><ul><li>Crystalline phase </li></ul><ul><li>Future </li></ul><ul><li>Work… </li></ul>
  13. 13. <ul><li>Laser ablation of crystalline HA targets was used to generate a calcium phosphate nanoparticle aerosol that is deposited on a titanium substrate </li></ul><ul><li>KrF excimer laser is used at fluences between 0.5 J/cm 2 and 4 J/cm 2 and temperatures ranging from 500  C to 760  C </li></ul>SUMMARY
  14. 14. <ul><li>Unstable calcium phosphate networks were found at temperatures below 600  C </li></ul><ul><li>Samples deposited above 750  C exhibit good mechanical stability as a result of partial sintering of the micron scale building blocks </li></ul><ul><li>X-ray diffraction and scanning electron microscopy studies show: </li></ul><ul><ul><li>Crystalline calcium phosphate material </li></ul></ul><ul><ul><li>Porous material made up of micro-particle frameworks surrounded by nanoparticles </li></ul></ul>CONCLUSIONS
  15. 15. We acknowledge support from the National Science Foundation (NSF)-Research Experiences for Undergraduates (REU)-site award to the University of Alabama at Birmingham (UAB) under Grant No. DMR-0243640. ACKNOWLEDGMENTS <ul><li>Dr. Camata </li></ul><ul><li>Hyunbin Kim </li></ul>NANOMATERIALS LABORATORY