The quantification of single cell adhesion on functionalized surfaces for cell sheet engineering.

The use of force spectroscopy to measure and quantify the forces involved in the adhesion of 3T3 fibroblasts to different chemically functionalized surfaces has been investigated. Cells were grown on glass surfaces as well as on surfaces used for cell sheet engineering: surfaces coated with polyelectrolyte multilayers (poly-L-lysine and hyaluronic acid) and thermally-responsive poly(N-isopropylacrylamide) (PNIPAM) brushes. Individual adherent cells were detached from their culture substrate using an AFM cantilever coated with fibronectin. The maximum forces of detachment of each cell were measured and taken as characteristic of the cellular adhesion. Large differences in cellular adhesion were observed on polyelectrolyte coatings depending on the number of polyelectrolyte layers. On PNIPAM-grafted surfaces, changes of more than an order of magnitude were observed in cell adhesion above and below the lower critical solution temperature. Glass surfaces patterned with periodic PNIPAM microdomains were also investigated, and it was shown that cellular adhesion could be reduced while keeping cellular morphology unchanged.