Description
- Abstract:
- Cell-matrix adhesion depends on the collective behavior of a large number of molecular bonds. While the behavior of a single molecular bond is governed by statistical mechanics, continuum mechanics should be valid at a large scale. How can this transition be modeled and can this tell us something about the mechanics of cell adhesion? We consider in this thesis an idealized theoretical model of molecular bond clusters between two dissimilar elastic media subjected to various forms of mechanical load. The distribution of interfacial traction is assumed to obey classical elasticity equations while the rupture and rebinding of individual molecular bonds are governed by stochastic equations. We show that the interfacial traction is generally shared among the molecular bonds in a non-uniform manner governed by the elasticity of the system. Monte Carlo simulations that combine the elastic and stochastic descriptions are conducted to investigate the lifetime of molecular bond clusters as a function of the loading magnitude for given adhesion sizes. Generally, the average cluster lifetime asymptotically approaches infinity as the applied load is reduced to below a critical value, defined as the adhesion strength. The effects of cluster size, cell/matrix modulus, rebinding rate and loading direction on the cluster lifetime and strength are systematically investigated. While overly simplified in a number of aspects, the model discussed in this thesis seems to give predictions that are broadly consistent with relevant experimental observations on cell-matrix adhesion. The second topic of this thesis deals with the capillary adhesion in insects like beetles and blowflies. We investigate the scaling effects of wet adhesion mediated by a liquid bridge between a fiber and a solid surface. The influences of liquid volume and contact angles are discussed via a scaling law indicating that the adhesion strength can be enhanced by contact size reduction. Due to the negative pressure in the liquid bridge, there exists a critical length scale at which the system achieves the theoretical tensile strength of the liquid. We conclude that size reduction down to a critical scale results in optimization of the adhesion strength.
- Notes:
- Thesis (Ph.D.) -- Brown University (2010)
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Citation
Qian, Jin,
"Mechanics of Molecular Bond Clusters between Elastic Media: Stochastic-elastic Coupling in Cell-matrix Adhesion"
(2009).
Engineering Theses and Dissertations, Mechanics of Solids Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://doi.org/10.7301/Z0DF6PHJ
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Mechanics of Solids Theses and Dissertations
Theses and Dissertations for the Mechanics of Solids department....