Biomedical Engineering Reference
In-Depth Information
Table 6.3
Measured parameters related to fi brinogen adsorption
Process
Value
Surface
Source
Reference
Diffusion
2 × 10
-7
cm
2
/s
n/a
Protein
solution
93
Initial
adsorption
1-8 ng/cm
2
/s
Hydrophobic and
hydrophilic
SAM
Protein
solution
93,95,96
2.5 ng/cm
2
/s
(Un)oxidized
MTS surface
Protein
solution
94
Desorption
6.7-7.4 s
−1
(Un)oxidized
MTS surface
Protein
solution
94
Interfacial
relaxation
0.15 nm
2
/s
per molecule
Hydrophobic
SAM
Protein
solution
93,95,96
0.04 nm
2
/s
per molecule
Hydrophilic SAM
Protein
solution
93,95,96
Lateral diffusion
~0
Hydrophobic and
hydrophilic
silicon
Protein
solution
101
Final surface
coverage
0.1-0.6 μg/cm
2
Hydrophobic
SAM
Protein
solution
93,95,96
≤0.2 μg/cm
2
Glass
(Un)diluted
plasma
98
Adhesion
strength
Integer
multiples of
180-200 pN
Hydrophilic silica
Protein
solution
189
Note
: SAM: self-assembled monolayer; MTS: 3-mercaptopropyltriethoxysilane.
adsorbed molecules is in end-on conformation, whereas some maintain a
side-on conformation.
93
This has been shown qualitatively by surface plasma
resonance on fi brinogen adsorbed on a gold-plated surface, in which a low
and high surface coverage of fi brinogen correspond to side-on and end-on
conformations respectively.
102
A similar model has been proposed to explain
the end-on packing of fi brinogen on a cholesterol-coated surface when the
surface density of fi brinogen is high.
103
Nevertheless, conformational varia-
tions of adsorbed fi brinogen are related to its coating density. In a study sup-
porting this it was found that when the surface conformations are probed by
mAb, immobilized fi brinogen at high surface coverage more likely resem-
bles its solution structure than that at low surface coverage.
80
Fluid dynamic
studies on fi brinogen adsorption from diluted and undiluted plasma under
unsteady-state conditions suggest that natural convection (i.e. blood fl ow)
is a key factor in fi brinogen adsorption out of blood plasma. The tempo-
ral and spatial distribution of fi brinogen deposition suggest more adsorbed
fi brinogen that is physiologically functional is found near the initial blood-
contacting site of the device and adsorbed fi brinogen has a sustained period
