Cell Adhesion on Micro-Nanostructured Surfaces

Dec. 21, 2009

Motivation:
Many aspects of cellular adhesion to the surrounding, the extracellular matrix (ECM), are of great interest as they control and influence various fundamental cell actions such as motility, differentiation, proliferation and apoptosis and hence, even the function of an organism may depend on this complex and highly regulated process.
A better understanding of the contact formation procedure and the demands to the ECM for a succesfull adhesion would provide opportunities to externally control cellular response. Research concerning a broad variety of biological processes including embryonic development, assembly of tissues and the nervous system, inflammation and wound healing, tumor metastasis, viral and bacterial infections requires controlled cellular adhesion. To gain more insights into the cellular adhesion process surfaces with defined adhesion properties in terms of bioactivity are important tools.

Project:
This work uses gold nanoparticles arranged in a quasi hexagonal pattern in the nanometer regime where each gold dot serves as a single anchor point for the cell`s integrins, the receptors mediating the connection between cell and environment. The distance of the binding sites can precisely be defined and a quantification of available binding sites is possible. Furthermore, a micro structuring of the gold particles allows for varying the global density of these integrin binding sites without changing the spacing between those. Such patterns can be used to investigate whether an effect, in this case the cellular adhesion, is distance or density dependent.
Former experiments have shown that adhesive interparticle distances of more than 73 nm reduce cell spreading as well as cell attachment and almost prevent the formation of focal adhesion and actin stress fibers.
To verify if this finding is due to insufficient available binding sites or only to an existing critical binding site distance which may prevent clustering of adhesive sites, the quality of cell adhesion is investigated on different patterns by optical microscopy and Single Cell Force Spectroscopy (SCFS). The optical techniques are utilitzed to analyze cell spreading and circularity, both are parameters by which the quality of adhesion can be quantified.

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SCFS is performed by means of Atomic Force Microscopy. A biofunctionalized tipless cantilever is used for detaching adherent cells from the surface to quantify their adhesion strength.
The present results propose that a successfull adhesion process depends mainly on the distance of available anchor points. The overall density, thus the number of available binding sites is significantly less important for strong and stable cellular adhesive clusters than their spacing.

This poster was presented at NanoBioViews 2009; 14-15 October 2009: http://www.nanobioviews.net

Contact:
Janosch Deeg
Biophysical Chemistry
University of Heidelberg
INF 253
69120 Heidelberg, Germany
janoschdeeg@gmail.com

Authors:
J. Deeg
I. Louban
D. Aydin
J.P. Spatz

Imaging-GIT.com

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Cell Adhesion on Micro-Nanostructured Surfaces

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