Biomedical Engineering Reference
In-Depth Information
enhance protein adsorption in order to increase signal detection by antibod-
ies in ELISA plates.
A promising strategy to direct cellular responses is to engineer surfaces
that control the biological activity of adsorbed proteins. Using SAMs of
ω
-functionalized alkanethiols on gold to present well-defined chemistries
(CH
3
,OH,COOH,NH
2
), García and colleagues demonstrated that surface
chemistry modulates the structure of adsorbed FN [46]. The structure of the
cell-binding domain of FN, which includes the integrin-binding RGD site,
is particularly sensitive to the underlying support chemistry. These surface-
dependent differences in FN structure alter integrin receptor binding, result-
ing in selective binding of
α
5
β
1
integrin on OH and NH
2
surfaces, binding
of both
3
in the COOH surface, and poor binding of either
integrin on the CH
3
support [46] (Fig. 3). Surface-chemistry-dependent dif-
ferences in integrin binding differentially regulate focal adhesion assembly
in terms of molecular composition and signaling [47]. Furthermore, differ-
ences in integrin binding specificity modulate osteoblastic differentiation and
mineralization [48] (Fig. 3). Biomaterial-chemistry-dependent differences in
integrin binding specificity also regulate the switch between myogenic prolif-
eration and differentiation [49], demonstrating a general surface engineering
approach to control cell function. This strategy of biomaterial-directed con-
α
β
1
and
α
β
5
V
Fig. 3
Biomaterial surface chemistry modulates cellular responses.
A
SAMs presenting
different chemistries differentially modulate integrin receptor binding in osteoblasts.
B
Substrate-dependent differences in osteoblast-specific gene expression correlate with
integrin binding specificity.
C
Matrix mineralization is dependent on integrin binding
specificity. Surfaces that support specific binding of
α
5
β
1
integrin exhibit high levels of
mineralization. Adapted from [46, 48]
