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
-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-
1 and
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]
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