ABSTRACT
We report the synthesis and characterization of a stable polymerized monolayer of peptide-amphihiles on a planar solid support that promotes mouse fibroblast cell adhesion and spreading. Peptide-amphiphiles consisting of a polymerizable fatty acid attached to a short RGD containing peptide sequence are self-assembled and polymerized at the water-air interface by means of the Langmuir- Blodgett technique. The surface concentration of the peptide-amphiphile is varied by co-spreading the peptide-amphiphile with an analogous non-modified polymerizable amphiphile at the water/air interface, prior to UV light-induced polymerization. The polymerized monolayer is transferred onto a hydrophobized smooth mica surface and the resulting surfaces have been investigated with respect to directing the cell adhesion and spreading of mouse fibroblast cells in a serum-free medium. Fibroblast cells adhere and spread on surfaces exposing the bioactive ligand but do not spread on reference surfaces without peptide. We find a maximum number of adherent cells at rather high peptide surface concentrations of about 10 mol% in the mixed monolayer, equivalent to more than 50 pmol/cm2 peptide on the surface of the film. We attribute this finding to a limited accessibility of the ligands by the integrins. Because of the stability of the polymerized peptide-amphiphile monolayer, these surfaces can be re-seeded multiple times with cells, i.e. adherent cells can be removed from the surface, the surface can be sterilized and cells can be re-attached.
Subject(s)
Fibroblasts/physiology , Oligopeptides , Surface-Active Agents , Aluminum Silicates , Animals , Cell Adhesion/physiology , Cells, Cultured , Mice , Microscopy, Atomic ForceABSTRACT
The aging dynamics under a periodic shear of a concentrated suspension of saponite particles is measured. It is observed that the dynamics is fastened by the application of a moderate shear amplitude. Nevertheless, this acceleration does not affect the dynamics of the suspension when the shear is ceased. By applying a succession of shear of various amplitudes, we conclude that the dynamics of the suspension at a time t(w) after complete rejuvenation is independent of the shear history between times 0 and t(w) , as soon as the amplitude of the applied shear is smaller than the characteristic shear gamma(c) necessary to completely rejuvenate the suspension.
