Biomedical Engineering Reference
In-Depth Information
Fig. 3.2.14-4 The chemistry of a typical silane surface modification reaction. (A) A hydroxylated surface is immersed in a non-aqueous
solution containing n-propyl trimethoxysilane (nPTMS). (B) One of the methoxy groups of the nPTMS couples with a hydroxyl group
releasing methanol. (C) Two of the methoxy groups on another molecule of the nPTMS have reacted, one with a hydroxyl group and the
other with a methoxy group from the first nPTMS molecule. (D) A third nPTMS molecule has reacted only with a methoxy group. This
molecule is tied into the silane film network, but is not directly bound to the surface.
Stenger, 1994), biomolecule and polymer immobilization
(Xiao
et al.,
1997; Mao
et al.
, 1997), NFSs (Lee and
Laibinis, 1998), surfaces for DNA studies (Hu
et al.
,
1996), biomineralization (Archibald
et al.
, 1996), and
model surfaces for biointeraction studies (Jenney and
Anderson, 1999).
energy to a localized surface zone in a very short time
interval. Some considerations for the ion implantation
process are illustrated in
Fig. 3.2.14-5
. These surface
changes must be understood quantitatively for engi-
neering of modified surface characteristics. Many review
articles and books are available on ion implantation pro-
cesses
and
their
application
for
tailoring
surface
Ion beam implantation
Table 3.2.14-4 Silanes for surface modification of biomaterials
The ion-beam method injects accelerated ions with en-
ergies ranging from 10
1
to 10
6
eV (1 eV
ΒΌ
1.6
10
19
joules) into the surface zone of a material to alter its
surface properties. It is largely, but not exclusively, used
with metals and other inorganics such as ceramics,
glasses, and semiconductors. Ions formed from most of
the atoms in the periodic table can be implanted, but not
all provide useful modifications to the surface properties.
Important potential applications for biomaterial surfaces
include modification of hardness (wear), lubricity,
toughness, corrosion, conductivity, and bioreactivity.
If an ion with kinetic energy greater than a few elec-
tron volts impacts a surface, the probability that it will
enter the surface is high. The impact transfers much
