Projects/2004PPointPresentations/Brown.ppt

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

MOTIVATION

Engineering and regeneration of bone tissue

Outstanding problem in medicine and dentistry

Calcium phosphate bioceramic substrates are known to stimulate bone regeneration

Nanoscale design in these bioceramics may significantly affect osteoconduction and improve implant performance/bone regeneration

Technological improvements in this are area bound to affect millions of people

Areas of Human Skeleton Where Biomaterials are Used for Bone Repair

Hip Implant

Dental implant

How Biomaterials are Used

RESEARCH GOAL

Demonstrate a new laser/aerosol method capable of synthesızıng porous nanostructure calcıum phosphate materıals

Ratıonale For Desıgn of Porous Nanostructure Calcium Phosphate Layer

Porous structure after cell adhesion

Partial sintering during deposition

osteoblasts

Calcıum phosphate particles as building blocks for porous bioceramic networks

•Flush out vacuum chamber removing all gases found in the air

•Fill chamber with Argon/water gas mixture

•Place Hydroxyapatite target into ablation chamber

•Clean titanium substrate using acetone and methanol in ultrasonic cleaner

•Place substrate into vacuum chamber

•Heat substrate to desired temperature

•Align lens and laser

•Start laser and proceed with deposition

•When deposition is completed, allow substrate to cool

•Remove substrate with adhered product from chamber

•Product undergoes x-ray diffraction/SEM to identify calcium phoshates

DEPOSITION METHOD

Experimental Set-up for Depositoin of Calcium Phosphate by Laser/Aerosol Method

Ar/H2OContinuous flow(2 L/min)

Titanium substrate

Target holder

Substrate holder 500-800C

lensCalcium Phosphate nanoparticles Exhaust

HA target

KrF excimer laser

26 31

2 Theta

HA Target

As Deposited Room Temperature

As Deposited RT/Annealed 780 C

As Deposited 760 C

As Deposited 500

X-Ray Diffraction Measurements of Calcium Phosphate Materials Deposited by Hybrid Laser/Aerosol

HA by new Laser/Aerosol Method760C Area 1 SEM 5000x

HA by Conventional Pulsed Laser Deposition(For Comparison)

Scanning Electron Microscopy (SEM)Results

HA Aerosol 760C Area 2 SEM 5000x

Scanning Electron Microscopy (SEM)Results

MostlyMicroparticles

PartiallySintered

HA Aerosol 760C Area 2 SEM 10000x

Scanning Electron Microscopy (SEM)Results

Coatingsseem To have Good mechanicalstability andadherenceto substrates

HA Aerosol 760C Area 1 SEM 40000x

Scanning Electron Microscopy (SEM)Results

Resulting Material:

•Microporous

•Framework ofpartially sintered

microparticles: May provide good

mechanical stability

•Surrounded by Nanoparticles May provide

stimulation of biological activity

HA Aerosol 760C Area 1 SEM 10000x

Scanning Electron Microscopy (SEM)Results

Nanostructured porous calcium phosphate Possible.

Can we control it?•Pore size•Framework Stability•Nanoparticle size

and concentration•Crystalline phase

Future Work…

•Laser ablation of crystalline HA targets was used to generate a calcium phosphate nanoparticle aerosol that is deposited on a titanium substrate

•KrF excimer laser is used at fluences between 0.5 J/cm2 and 4 J/cm2 and temperatures ranging from 500C to 760C

SUMMARY

•Unstable calcium phosphate networks were found at temperatures below 600C

•Samples deposited above 750C exhibit good mechanical stability as a result of partial sintering of the micron scale building blocks

•X-ray diffraction and scanning electron microscopy studies show:•Crystalline calcium phosphate material•Porous material made up of micro-particle frameworks surrounded by nanoparticles

CONCLUSIONS

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.

NANOMATERIALS LABORATORY

ACKNOWLEDGMENTS

•Dr. Camata

•Hyunbin Kim