1. R. K. Roy, S.-J. Park, H.-W. Choi, K.-R. Lee
Surface Properties and Hemocompatibility of Si Incorporated Diamond-like Carbon Films
R. K. Roy, S.-J. Park, H.-W. Choi, K.-R. Lee
Future Technology Research Division, KIST, Seoul, Korea
J. H. Kim, D. K. Han
Biomaterials Research Center, KIST, Seoul, Korea
J.-H. Shin
Department of Radiology, Asan Medical Center, Seoul, Korea
The 2nd Korea-Japan Asian Core Program, , Yonsei Univ. Seoul, Korea

2. Hemocompatible and Hermetic Coating
Vascular Stents
Clotted Artery
Formation of blood clots  Restenosis
Release of metal ions
A stent is a metal tube that is inserted permanently into an artery. The stent helps open an clotted artery so that blood can flow through it. The cardiovascular implantation of stents is increasing day by day throughout the world. But the application of stents is largely limited by restenosis, occlusion and stent associated thrombosis. The main side effect with artery stents lies in its release of metal ions and thrombogenicity. It is thus necessary to coat metallic stents with suitable biomaterial that are hemocompatible, corrosion resistant and long lasting in human blood environment.
Hemocompatible and Hermetic Coating

3. Surface Modification
Biocompatible Coating : Heparin, PEG, DLC (Hepacoat, Phytis)
Drug Release Coating : Antistenosis, Anticancer, Antibiotic (Cordis)
Isotope Radiation Coating : Radiation therapy
Many coated stents are already found in the market. Heparin, PEG and DLC films are coated on the stent to meet the requirements of the hemocompatible surface. DLC coating can suppress the metal release in addition to the hemocompatiblility. This figure shows the DLC coated stent. More active concept is to use the drug release coating for antistenosis and treatment such as anticancer or antibiotic. There is also isotope radiation coating for radiation therapy.
This presentation is about the DLC application for these purpose.

4. Diamond-like Carbon Film
Amorphous Solid Carbon Film
Mixture of (sp1), sp2 and sp3 Hybridized Bonds
High Content of Hydrogen (20-60%)
Properties
High Hardness and Excellent Tribological Properties
Smooth Surface with Optical Transparency
Chemical Inertness and Hemo-compatibility
2-D Analogy of the Structure
Heart valve
Hard disk

5. Diamond-like Carbon Film
Amorphous Solid Carbon Film
Mixture of (sp1), sp2 and sp3 Hybridized Bonds
High Content of Hydrogen (20-60%)
Properties
High Hardness and Excellent Tribological Properties
Smooth Surface with Optical Transparency
Chemical Inertness and Hemo-compatibility
Heart valve
Hard disk

6. Si-DLC Film Potentiodynamic Polarization
Purpose of the present work
Potentiodynamic Polarization
Water Contact Angle Measurement

7. Hemocompatibility and Surface Tension
Sl.
No.
References
Hemocompatibility
Improves by 1
Baier,
Academic Press,
New York, 1970.
Critical surface tension of materials
~ 20-30dyne/cm 2
Akers,
J.Colloid Interface Sci.
59 (1977) 461.
Zone of biocompatibility 3
Ruckensten & Gourisanker,
J. Colloid Interface Sci. 101
(1984) 436.
Blood biomaterial interfacial tension of
the order of 1-3 dyne/cm 4
Callow,
International Biodeterioration & degradation, 34 (1994) 333.
Surfaces having initial surface tension
20-30 dyne/cm 5
Yu,
Surf. Coat. Technol.
(2000) 484.
Low blood biomaterial interfacial tension
(8.5 dyne/cm) 6
Kwok,
Diam. Rel. Mater. 14 (2005) 78.
interfacial tension of about the same magnitude as cell-medium interfacial tension
(1-3 dyne/cm)

8. Si-DLC Film Potentiodynamic Polarization
Purpose of the present work
Potentiodynamic Polarization
Water Contact Angle Measurement

9. Film Preparation Film Deposition Surface Treatment 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
10min
Schematic diagram of RF PACVD system.

10. Energetics of Surface q Liquid αl βl γlv (ergs/cm2) Water 4.67 7.14
72.8
Formamide
6.28
4.32
58.2

11. Surface Energy

12. Polar Component and Wetting

13. Interfacial Tension with Human Bloodα
(dyne/cm)1/2 β
Human
Blood
3.3
6.0 α β
Si-DLC
5.4 ± 0.5
3.3 ± 0.6
(CF4 treated)
5.0 ± 0.4
2.0 ± 0.5
(N2 treated)
5.1 ± 0.2
5.5 ± 0.3
(O2 treated)
4.2 ± 0.1
7.3 ± 0.1
(H2 treated)
3.5 ± 0.4

14. XPS Anaysis

15. Single bond C-C increased C-F bond increase_ _
Single bond C-C increased
C-F bond increase
Si-C bond Si-O bond

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

17. _ _

18. XPS Anaysis

19. _ _

20. Chemical bonds present on surface
XPS Analysis
Films
Chemical bonds present on surface
(XPS analysis)
Si-DLC
C=C, C-C, Si-C, Si-O
(CF4 plasma treated)
C=C, C-C, C-CFn, Si-C, Si-O
(N plasma treated)
C=C, C-C, C-N, Si-N, Si-O
(H plasma treated)
(O plasma treated)
C=C, C-C, C-O, Si-O

21. aPTT Measurement
Activated partial thromboplastin time (aPTT) determines the ability of blood to coagulate through the intrinsic coagulation mechanism.
It measures the clotting time from the activation of the factor XII through the formation of fibrin clot.
Incubation time : 1h in platelet poor plasma (PPP: 7x103/ml) using fresh blood
aPTT measurement system by Sysmex Instrument

22. Plasma Protein Adsorption
The plasma protein adsorption tests were done by treating the samples with albumin (3mg/ml) and fibrinogen (0.2mg/ml) solution.
The absorbances was measured by ELISA analysis method.
Fibronogen
Albumin

23. Plasma Protein Adsorption

24. Platelet Adhesion
After 2hr soaking in a platelet rich plasma (PRP: 1.05x105/ml) of fresh blood.
Uncoated Si
N2 treated Si-DLC
H2 treated Si-DLC
O2 treated Si-DLC

25. Platelet Adhesion

26. Oxygen Plasma Treatment
O2 treated Si-DLC

27. Interfacial Tension? Sl. No. References Hemocompatibility Improves by1
Baier,
Academic Press,
New York, 1970.
Critical surface tension of materials
~ 20-30dyne/cm 2
Akers,
J.Colloid Interface Sci.
59 (1977) 461.
Zone of biocompatibility 3
Ruckensten & Gourisanker,
J. Colloid Interface Sci. 101
(1984) 436.
Blood biomaterial interfacial tension of
the order of 1-3 dyne/cm 4
Callow,
International Biodeterioration & degradation, 34 (1994) 333.
Surfaces having initial surface tension
20-30 dyne/cm 5
Yu,
Surf. Coat. Technol.
(2000) 484.
Low blood biomaterial interfacial tension
(8.5 dyne/cm) 6
Kwok,
Diam. Rel. Mater. 14 (2005) 78.
interfacial tension of about the same magnitude as cell-medium interfacial tension
(1-3 dyne/cm)

28. Which is more significant?

29. Which is more significant?
Films
Chemical bonds
on surface
Wetting
angle (o) α
(dyne/cm)1/2 β
a-Si:H
(O plasma treated)
Si-O
7.5 ± 1.3
4.1 ± 0.02
7.4 ± 0.03
a-C:H
C=C, C-C, C=O
20.4 ± 2.5
4.5 ± 0.11
7.0 ± 0.15

30. Conclusions
Hemocompatibility of Si-DLC film would be improved by surface plasma treatment using oxygen.
Large surface energy (large polar component)
Low interfacial energy with blood
Need to find more definite evidence of improved hemocompatibility by in vivo test.
Surface C=O bonds seem to play an important role in improving hemocompatibility.

31. 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 #: 06K ), and Taewoong Medical Co. Ltd.

32. _ _
N1 : Si-N
N2 : C=N