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Hemocompatibility of Surface Modified Si
Incorporated Diamond-like Carbon Films
R. K. Roy, S.-J. Park, H.-W. Choi, K.-R. Lee
Future Technology Research Laboratories, KIST, Seoul, Korea
T. HasebeTachikawa Hospital, Keio University, Tokyo, Japan
ICMCTF-2007, Apr. 23-27, San Diego, USA
Vascular Stents
• Formation of blood clots Restenosis• Release of metal ions
Hemocompatible and Hermetic CoatingHemocompatible and Hermetic Coating
Clotted Artery
Surface Modification
• Biocompatible Coating : Heparin, PEG, DLC (Hepacoat, Phytis)• Drug Release Coating : Antistenosis, Anticancer, Antibiotic (Cordis)• Isotope Radiation Coating : Radiation therapy
Si-DLC Film
10-14 10-13 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 101
-600
-400
-200
0
200
400
600
800
1000
1200
1400
1600
Po
ten
tial (
mV
vs
SC
E)
Current Density (A/cm2)
Substrate Si-C:H, Bias voltage = -400V a-C:H, Bias voltage = -800V a-C:H, Bias voltage = -400V
Potentiodynamic Polarization
Thin Solid Films, 475, 291-397 (2005)
Sl.No.
ReferencesHemocompatibility
Improves by
1Baier,
Academic Press,New York, 1970.
Critical surface tension of materials ~ 20-30dyne/cm
2Akers,
J.Colloid Interface Sci. 59 (1977) 461.
Zone of biocompatibility
3Ruckensten & 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
5Yu,
Surf. Coat. Technol.128-129 (2000) 484.
Low blood biomaterial interfacial tension
(8.5 dyne/cm)
6Kwok,
Diam. Rel. Mater. 14 (2005) 78.
interfacial tension of about the same magnitude as cell-medium interfacial
tension (1-3 dyne/cm)
Hemocompatibility and Surface Tension
Surface modification of Si-DLC
20
40
60
80
100W
ater
co
nta
ct a
ng
le (
in d
egre
e)
SiDLC( O2treated)
SiDLC(N2treated)
SiDLC(H2treated)
SiDLC(CF4treated)
SiDLCSi Nitinol
Schematic diagram of RF PACVD system.
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
Surface modification of Si-DLC
20
40
60
80
100W
ater
co
nta
ct a
ng
le (
in d
egre
e)
SiDLC( O2treated)
SiDLC(N2treated)
SiDLC(H2treated)
SiDLC(CF4treated)
SiDLCSi Nitinol
Energetics of Surface
(cos ) lv sv sl
22ll
pl
dllv
22ss
ps
dssv
)(2
cos1
)(2)(2cos1
lslslv
lv
pl
ps
lv
dl
ds
Liquid αl βl
γlv
(ergs/cm2)
Water 4.67 7.14 72.8
Formamide 6.28 4.32 58.2
2 : Fowkes' Eq.d dsl sv lv s l
Surface Energy
Polar component
0
10
20
30
40
50
60
SiDLC SiDLC (O
2
treated)
SiDLC (N
2
treated)
SiDLC (H
2
treated)
SiDLC (CF4
treated)
Sur
face
ene
rgy
(dyn
e/cm
)
Dispersive component
Polar Component and Wetting
0 10 20 30 40 50 600
20
40
60
80
100W
ater
co
nta
ct a
ng
le (
deg
ree)
Polar component of surface energy (dyne/cm)
Interfacial Tension with Human Blood
α (dyne/cm)1/2
β (dyne/cm)1/2
Human Blood
3.3 6.0
221
22112 )()(
0
5
10
15
20
25
SiDLC(O2
treated)
SiDLC(N2
treated)
SiDLC(H2
treated)
Blo
od B
iom
ater
ial i
nter
faci
al t
ensi
on
(dyn
e/cm
)
SiDLC SiDLC(CF4
treated)
α β
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
100 102 104 106
4
8
12
16
Inte
nsi
ty (
x1
0 )
Binding energy (eV)
Si-C
Si 2pSiDLC
Si2O3
SiO2
(b)
280 284 288 2920
10
20
30
40
50
Inte
nsi
ty (
x1
0 2
)
Binding energy (eV)
C=C
C-C
Si-DLC
C 1s(a)
280 284 288 2920
10
20
30
40
Inte
nsity
( x
10
2 )
Binding energy (eV)
C=C
C-CC-OH
H2-Si-DLC
C 1s(c)
100 102 104 106
4
8
12
16In
tens
ity (
x10
)
Binding energy (eV)
Si-C
Si-Si
Si2O3
Si 2pH2-Si-DLC(d)
XPS Anaysis
280 284 288 2920
5
10
15
20
25
Inte
nsity
( x
10 2 )
Binding energy (eV)
C-CFn
CF-CFn
CF2 CF3
1
2
C 1sCF4-Si-DLC(e)
100 102 104 106
4
6
8
10
Inte
nsi
ty (
x 1
0 )
Binding energy (eV)
Si-C
Si2O3
SiO2
Si-Si
Si 2pCF4-Si-DLC(f)
684 688 692
10
20
30
40
Inte
nsity
( x
10 2
)
Binding energy (eV)
F 1s
CF4-Si-DLCCFn(g)
_
_
100 102 104 106
5
10
15
20
25
Inte
nsity
(x1
0)
Binding energy (eV)
Si-N
Si-CSiO2
Si 2pN2-Si-DLC(i)
280 284 288 2920
5
10
15
20
25In
tens
ity (
x 1
0 2
)
Binding energy (eV)
C 1sN2-Si-DLCC=C
C=N
C=N
C-C
C-N
(h)
394 396 398 400 402 4044
8
12
16
Inte
nsity
( x
10
2 )
Binding energy (eV)
N 1s
N2-Si-DLC
C-N
C=N
N1
N2
(j)
N1 : Si-NN2 : C=N
280 284 288 2920
4
8
12
16
Inte
nsity
( x
10 2
)
Binding energy (eV)
C=C
C-C C-O C=O
C 1sO2-Si-DLC(k)
100 102 104
20
40
60
80
Inte
nsi
ty (
x10
)
Binding energy (eV)
Si 2pO2-Si-DLC
Si2O3
SiO2
Si-C
(l)
528 530 532 534 536
10
20
30
40
50
Inte
nsi
ty (
x1
0 2
)
Binding energy (eV)
O 1sO2-Si-DLC
Si=O
C=O
(m)
_
_
100 102 104 106
4
8
12
16
Inte
nsi
ty (
x1
0 )
Binding energy (eV)
Si-C
Si 2pSiDLC
Si2O3
SiO2
(b)
280 284 288 2920
10
20
30
40
50
Inte
nsi
ty (
x1
0 2
)
Binding energy (eV)
C=C
C-C
Si-DLC
C 1s(a)
XPS Anaysis
280 284 288 2920
4
8
12
16
Inte
nsity
( x
10 2
)
Binding energy (eV)
C=C
C-C C-O C=O
C 1sO2-Si-DLC(k)
100 102 104
20
40
60
80
Inte
nsity
(x1
0)
Binding energy (eV)
Si 2pO2-Si-DLC
Si2O3
SiO2
Si-C
(l)
XPS Analysis
FilmsChemical bonds present on surface
(XPS analysis)
Si-DLC C=C, C-C, Si-C, Si-O
Si-DLC(CF4 plasma treated)
C=C, C-C, C-CFn, Si-C, Si-O
Si-DLC(N plasma treated)
C=C, C-C, C-N, Si-N, Si-O
Si-DLC(H plasma treated)
C=C, C-C, Si-C, Si-O
Si-DLC(O plasma treated)
C=C, C-C, C-O, Si-O
aPTT Measurement
• Soaking for 60min in platelet poor plasma (PPP: 7x103/l) using human whole blood from healthy volunteer
• aPTT measurement system by Sysmex Instrument
25
26
27
28
29
30
SiDLC(O2
treated)
SiDLC(N2
treated)
SiDLC(H2
treated)
SiDLC(CF4
treated)
aPT
T (
sec)
1 hour
Plasma Protein Adsorption
• Done by treating the samples with albumin (3mg/ml) and fibrinogen (0.2mg/ml) solution.
• ELISA analysis method to characterize the proten adsorption
0.0
0.5
1.0
1.5
2.0
SiDLC (H2
treated)
SiDLC(O2
treated)
SiDLC(N2
treated)
SiDLC (CF4
treated)
SiDLC
Alb
umin
/ f
ibri
noge
n ra
tio
5 mins
60 mins
Platelet Adhesion Measurement
• PRP (1.5x1015/ml) from human whole blood from healthy volunteer• Soaked in PRP for 60min • Adherent platelet are fixed and dehydrated for observation under OM
and SEM
Si-DLC Si-DLC(CF4) Si-DLC(N2) Si-DLC(O2)0
10
20
30
40
50
60
70
80
90
100
Pla
tele
t Ad
he
sio
n A
rea
Ra
tio (
%)
Specimen
Platelets on Surface
Goodman and Allen et al.
On a-C:H surface
Platelets on Si-DLC
Platelets on Si-DLC (CF4)
Platelets on Si-DLC (N2)
Platelet on Si-DLC (O2)
Nitrogen or Oxygen Plasma Treatment
25
26
27
28
29
30
SiDLC(O2
treated)
SiDLC(N2
treated)
SiDLC(H2
treated)
SiDLC(CF4
treated)
aPT
T (
sec)
1 hour
0.0
0.5
1.0
1.5
2.0
SiDLC (H2
treated)
SiDLC(O2
treated)
SiDLC(N2
treated)
SiDLC (CF4
treated)
SiDLC
Alb
umin
/ fib
rinog
en r
atio
5 mins
60 mins
Si-DLC Si-DLC(CF4) Si-DLC(N2) Si-DLC(O2)0
10
20
30
40
50
60
70
80
90
100
Pla
tele
t A
dh
esi
on
Are
a R
atio
(%
)
Specimen
Sl.No.
ReferencesHemocompatibility
Improves by
1Baier,
Academic Press,New York, 1970.
Critical surface tension of materials ~ 20-30dyne/cm
2Akers,
J.Colloid Interface Sci. 59 (1977) 461.
Zone of biocompatibility
3Ruckensten & Gourisanker,J. Colloid Interface Sci. 101
(1984) 436.
Blood biomaterial interfacial tension of the order of 1-3 dyne/cm
4Callow,
International Biodeterioration & degradation, 34 (1994) 333.
Surfaces having initial surface tension20-30 dyne/cm
5Yu,
Surf. Coat. Technol.128-129 (2000) 484.
Low blood biomaterial interfacial tension (8.5 dyne/cm)
6Kwok,
Diam. Rel. Mater. 14 (2005) 78.
interfacial tension of about the same magnitude as cell-medium interfacial
tension (1-3 dyne/cm)
Interfacial Tension?
0
5
10
15
20
25
SiDLC(O2 treated)
SiDLC(N2 treated)
SiDLC(H2 treated)
Blo
od B
iom
ater
ial i
nter
faci
al te
nsio
n (d
yne/
cm)
SiDLC SiDLC(CF4 treated)
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
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.