Biomedical Engineering Reference
In-Depth Information
Table 14.2
Approximate mobilities of the proton (or hydronium H
3
O
C
), deuteron (or deutero-
nium D
3
O
C
), monovale
nt cations and OH
. Collated from [
98
,
461
]
Ion
Mobility cm
2
s
1
V
1
Water
M
C
5.10
4
H
2
O
liq
H
C
H
2
O
liq
36.10
4
M
C
10
8
H
2
O
ice
H
C
10
7
1
H
2
O
ice
D
C
25.10
4
D
2
O
liq
OH
20.10
4
H
2
O
liq
+
+
H
H
H
H
H
H
O
H
O
H
O
O
H
O
O
H
H
H
H
H
-
-
H
H
H
H
H
H
O
H
O
H
O
H
O
O
H
O
Mobility of H
C
and OH
Fig. 14.2
not move as such but a
cooperative transfer
in ensembles of three or more molecules
explains (?) the high mobility.
Wetting of Biomaterial Surfaces
Our pessimism about progress was a provoking statement and is not paying tribute
to the high quality scientists involved in the painstaking unravelment of the interac-
tion of water molecules with surfaces. A topic, edited by Morra and recommended
literature because it advertises the unsolved aspects of the role of water in biomate-
rials, is comprehensive in the sense that the substantial part of the theoretical field
and the practical relation to surface wetting is passing the review; the state-of-the-
art, however, does not offer yet an off-the-shelf-receipt on how to reshuffle a surface
for a dedicated application. It does offer a perspective view on foundation of the
subject. Studies on solvation interactions of protein adsorption to biomaterials at
the water-solid interface are highly relevant to understand and consequently to try
developing surfaces that do or do not adsorb proteins. A typical field of application
is the adsorption of proteins on biomaterials in contact with blood where adsorption
has mostly undesirable consequences (artificial arteries, heart valves, stents, sensors,
contact lenses).
Protein adsorption on surfaces has to do everything with water. Let us try to
schematize (extremely simplified!) what is or could be going on in the interaction of
proteins with hydrophilic and hydrophobic surfaces. The distinction between both
is currently based on the measurement of the contact angle of a water droplet (or
other liquids) on the surface. The work of adhesion
W
adh
is:
