Hemocompatibility of Surface Modified Diamond-like Carbon Coatings

1. Hemocompatibility of Surface Modified Diamond-like Carbon Coatings • R. K. Roy, M.-W. Moon, K.-R. Lee • Future Technology 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 ABMC 2007, Tsukuba, 2007. 12. 6.

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. Required Surface Properties • Biological Compatibility • Nontoxic, Noncarcinogenic, Noninflammatory • Chemical Compatibility • Corrosion Resistance • Mechanical Compatibility • Surface Hardness, Wear Resistance Diamond-like Carbon : as a Strong Candidate Coating

4. Vascular Stents • Formation of blood clots  Restenosis • Release of metal ions Clotted Artery Hemocompatible and Hermetic Coating

5. CarbofilmTM by Sorin Biomedica, Inc. DLC Coated Blood Contacting Implants

6. DLC is sufficiently hemocompatible? • DLC filmis not a specific material but a group of amorphous carbon thin films. For each application, we need to optimize the property. Understanding of hemocompatibility of various DLC surfaces Si incorporated DLC films with modified surface

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 Schematic diagram of RF PACVD system.

9. Surface modification of Si-DLC

10. q Energetics of Surface

11. Surface Energy

12. Polar Component and Wetting CF4 plasma As deposited H2 plasma Si wafer N2 plasma O2 plasma

13. Interfacial Tension with Human Blood

14. XPS Anaysis

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16. N1 : Si-N N2 : C=N

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18. XPS Anaysis

19. XPS Analysis

20. aPTT Measurement • Activated partial thromboplastin time (aPTT) determines the ability of blood to coagulate through the intrinsic coagulation mechanism. • Soaking for 60min in platelet poor plasma (PPP: 7x103/ml) using human whole blood from healthy volunteer.

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

22. Platelet Adhesion Measurement • Soaked for 60 min in PRP (1.5x1015/ml) from human whole blood from healthy volunteer. • Adherent platelet are fixed and dehydrated for observation under OM and SEM.

23. Platelet Activation Goodman and Allen et al. Lose discoid shape Develope thin pseudopodia Become large, spiny sphere covered by Pseudopodia On a-C:H surface Fully spread

24. Platelets on Si-DLC

25. Platelets on Si-DLC (N2)

26. Platelet on Si-DLC (O2)

27. Nitrogen or Oxygen Plasma Treatment

28. Hemocompatibility and the Surface

29. Conclusions • Hemocompatibility of Si-DLC film would be improved by surface treatment using nitrogen and oxygen plasma. • Large surface energy (large polar component) • Low interfacial energy with blood • Aging of the surface with large surface energy should be carefully considered in characterizing their surface properties. Characterization should be done within 12 hours after the treatment.

30. Acknowledgement Financial Support from 'Center for Nanostructured Materials Technology' under '21st Century Frontier R&D Programs' of the Ministry of Science and Technology of Korea (code #: 06K1501-01610), and Taewoong Medical Co. Ltd.