Biomedical Engineering Reference
In-Depth Information
Chapter 8
Specific Adhesion of Soft Elastic Materials
Jizeng Wang
8.1
Introduction
Cell adhesion plays a central role in many biological functions, such as cell
migration, spreading, differentiation, and growth. The capability to control cell-
substrate and cell-cell interactions, for which a quantitative description of cell
adhesion is a critical step, is essential for tissue and cellular engineering. A contin-
uum treatment of cell adhesion at the focal adhesion level might be inappropriate, as
the typical focal adhesion size is only about ten times larger than molecular bond
spacing. Rupture of even one molecular bond may lead to apparent changes in
adhesion stress. As a result, the stochastic association/dissociation processes of
discrete molecular bonds will significantly influence the strength of a focal adhesion.
This adds a new phenomenon of direct relevance to the traditional continuum
treatment of elastic adhesion. A key objective of this chapter is to link stochastic
theories of ligand-receptor bonds and continuum mechanics descriptions of dissim-
ilar soft elastic materials contacted via specific interactions of molecular bonds.
Although overly simplified in a number of aspects, we show in this chapter that such
a model seems to give predictions that are consistent with relevant experimental
observations on focal adhesion dynamics.
8.2 Facts on Cellular Adhesions
Biological cells actively adhere to their extracellular matrix (ECM) and to other cells
through a large variety of ligand-receptor bonds that engage various energy-
consuming motor, signaling, and internalization pathways. This adhesion plays a
J. Wang (
*
)
Key Laboratory of Mechanics on Disaster and Environment in Western China
Lanzhou University, Lanzhou, Gansu, China
e-mail:
jzwang@lzu.edu.cn
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