Example of a dynamic substrate for spatial and temporal control of cell migration and growth.

<p>(A) (a) Surfaces compatible with cell imaging were prepared by evaporating titanium (3 nm) and then gold (12 nm) onto glass coverslips. (b) Microcontact printing, a soft lithography technique, was used to pattern hydrophobic islands of hexadecanethiol. (c) The remaining bare gold regions were filled with a mixed monolayer of tetra(ethylene glycol) (EG_<b>4</b>OH) and hydroquinone (H_<b>2</b>Q) terminated alkanethiol (99:1 in ratio). (d) The patterned hydrophobic area was adsorbed by fibronectin and fibroblasts attached, proliferated and remained confined to the patterned regions. (e) Application of oxidative potential to the monolayer and subsequent addition of RGD-oxyamine (20 mM for 2 hours) (RGD-ONH_<b>2</b>) resulted in the rapid immobilization of peptide and hence the migration and proliferation of cells off of the circular islands. (B) Representative figures from fluorescence microscopy over the period of time with three different sizes of circular patterns. The diameters of the pattern are 160 μm, 110 μm, and 60 μm, respectively. In all three sizes of the patterns, upon ligand presentation cells gradually migrated out and broke down the patterns completely within 30 hrs after RGD immobilization. Color: green, tubulin; red, actin filaments; blue, nuclei.