Biomedical Engineering Reference
In-Depth Information
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CHAPTER 2
The Cell-Substrate Surface
Interaction
2.1 Cells and Surfaces
Any treatment of the application of sensors, and devices in general, in neuro-
science must take account of how cells behave at the surface of solids. This is
the case whether studies are of an in vitro nature or whether implantables are
involved. The key issues are how surfaces influence the response of cells and just
as important, as it pertains to implantable technology, what do cells and tissues
do to the device. A host of factors are anticipated to be important such as
surface free energy, morphology, crystal structure, role of interfacial water and
ionic charge, and the nature of chemical functional groups present on the
substrate (device) surface. A number of these properties are inextricably
integral to each other, for example, surface free energy and both functional
group chemistry and morphology.
How the various physicochemical factors influence cells will obviously
depend on the structure and components that define the biological moiety.
Essentially, eukaryotic cells at the simplest level consist of a lipid bilayer
membrane which encloses the cytoplasm and internal cellular machinery. They
are embedded in a material termed the extracellular matrix (ECM), which
serves as a scaffold for the support of cellular populations. Over recent years it
has become abundantly clear that interaction of surfaces with the various
cellular and extracellular components can affect a large number of parameters,
including not only biochemical behavior, but also mechanical properties. In
this section we describe, at a concise level, our present understanding of how
solid surfaces influence the behavior of cells. For the non-chemistry specialist
we start with key surface chemical aspects and for the non-biology specialist
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