Hemocompatibility of Plasma Treated Si Incorporated Diamond-like Carbon Films

1
Hemocompatibility of Plasma Treated Si
Incorporated Diamond-like Carbon Films

• R. K. Roy, M.-W. Moon, K.-R. Lee
• Future Convergence Research Laboratories, KIST,
  Seoul, Korea
• D.K. Han
• Biomaterials Research Center, KIST, Seoul, Korea
• J.-H. Shin
• Department of Radiology, Asan Medical Center,
  Universtiy of Ulsan, Korea
• KamijoUniv. Tokyo Hospital, Tokyo, Japan
• T. Hasebe
• Tachikawa Hospital, Keio University, Tokyo, Japan

ICMCTF 2008, San Diego, USA
2
Bioimplant Materials

• Requirements for Bioimplants
• Should not cause infections
• Prevent uncontrolled cell growth
• Maintain their integrity inside the body
• Interact in a controllable way with the
  biological environment
• Avoid formation of debris

Surface Properties
3
DLC for biomaterials

• Biological Compatibility
• Nontoxic, Noncarcinogenic, Noninflammatory
• Chemical Compatibility
• Corrosion Resistance
• Mechanical Compatibility
• Surface Hardness, Wear Resistance

4
Vascular Stents
Clotted Artery

• Suppress the formation of blood clots
• Prevent the release of metal ions

5
DLC Coated Blood Contacting Implants
6
The present work

• Plasma treatment of Si-DLC coating
• Characterization of the surface
• Wetting behavior
• Surface chemical bonds
• Hemocompatibility tests
• Protein adsorption (Albumin/Fibrinogen ratio)
• Activated Partial Thromboplastin time
• Platelet adhesion and activation

7
Si-DLC Film
Potentiodynamic Polarization in Saline Solution
Thin Solid Films, 475, 291-397 (2005). J. Biomed.
Mater. Res. A in press (2007).
8
Film Preparation

• Film Deposition
• C6H6 SiH4
• Pressure 1.33 Pa
• Bias voltage -400V
• Film thickness 500nm
• Si Concentration in the film 2 at.
• Surface Treatment
• O2, N2, H2, CF4
• Pressure 1.33 Pa
• Bias voltage -400V
• 10min

Schematics of RF PACVD system.
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Surface modification of Si-DLC
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Energetics of Surface
Liquid al ßl ?lv (ergs/cm2)
Water 4.67 7.14 72.8
Formamide 6.28 4.32 58.2
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Surface Energy
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Interfacial Tension with Human Blood
a (dyne/cm)1/2 ß (dyne/cm)1/2
Human Whole Blood 3.3 6.0
a ß
Si-DLC 5.4 0.5 3.3 0.6
Si-DLC (CF4 treated) 5.0 0.4 2.0 0.5
Si-DLC (N2 treated) 5.1 0.2 5.5 0.3
Si-DLC (O2 treated) 4.2 0.1 7.3 0.1
Si-DLC (H2 treated) 5.5 0.3 3.5 0.4
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XPS Anaysis
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XPS Analysis
Films Chemical bonds present on surface (XPS analysis)
Si-DLC or Si-DLC (H plasma treated) CC, C-C, Si-C, Si-O
Si-DLC (CF4 plasma treated) CC, C-C, C-CFn, Si-C, Si-O
Si-DLC (N plasma treated) CC, C-C, C-N, Si-N, Si-O
Si-DLC (O plasma treated) CC, C-C, C-O, Si-O
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XPS Anaysis
Si-DLC (O2)
Si-DLC
Si-DLC (CF4)
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XPS Anaysis
Si-DLC
Si-DLC (N2)
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Plasma Protein Adsorption

• Better hemocompatibility can be expected on the
  surface with higher ratio of albumin/fibrinogen
  adsorption.
• ELISA analysis after treating the samples with
  albumin (3mg/ml) and fibrinogen (0.2mg/ml)
  solution.

18
aPTT Measurement

• Activated partial thromboplastin time (aPTT)
  determines the ability of blood to coagulate
  through the intrinsic coagulation mechanism. The
  longer aPTT time is obtained on better
  hemocompatible surface.
• Soaking for 60min in platelet poor plasma (PPP
  7x103/ml) using human whole blood from healthy
  volunteer.

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Platelet Adhesion Measurement

• Soaked for 60 min in PRP (1.5x105/ml) from human
  whole blood from healthy volunteer.
• Adherent platelet are fixed and dehydrated for
  observation under OM and SEM.

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Platelet Activation
Goodman and Allen et al.
Lose discoid shape
Develope thin pseudopodia
Become large, spiny sphere covered by pseudopodia
On a-CH surface
Fully spread
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Platelets on Si-DLC
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Platelets on Si-DLC (N2)
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Platelet on Si-DLC (O2)
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Nitrogen or Oxygen Plasma Treatment
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XPS Analysis
Films Chemical bonds present on surface (XPS analysis)
Si-DLC or Si-DLC (H plasma treated) CC, C-C, Si-C, Si-O
Si-DLC (CF4 plasma treated) CC, C-C, C-CFn, Si-C, Si-O
Si-DLC (N plasma treated) CC, C-C, C-N, Si-N, Si-O
Si-DLC (O plasma treated) CC, C-C, C-O, Si-O
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Which surface bond is significant?
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Conclusions

• Hemocompatibility of Si-DLC film was improved by
  the surface treatment using nitrogen and oxygen
  plasma.
• Large surface energy (large polar component)
• Low interfacial energy with blood
• Both C-O and Si-O bonds on the plasma treated
  Si-DLC surface play a significant role in
  improving the hemocomptatibility.

R. K. Roy et al,Diam. Rel. Mater (2007).
Submitted to Acta Biomater.
(2008).
28
Acknowledgement

• Financial Support from 'Center for Nanostructured
  Materials Technology' under '21st Century
  Frontier RD Programs' of the Ministry of Science
  and Technology of Korea (code 06K1501-01610),
  and Taewoong Medical Co. Ltd.