Figure 3.

Use of an electroactive substrate to pattern two cell populations into a coculture. (A) Substrates were prepared by evaporating titanium (5 nm) and then gold (15 nm) onto glass coverslips. (B) Microcontact printing was used to pattern hexadecanethiolate into lines that are 300 μm wide and separated by 800 μm. (C) A second monolayer was assembed on the remaining regions of gold by immersing the substrate into a solution of hydroquinone-terminated alkanethiol (HQ) and penta(ethylene glycol)-terminated alkanethiol (EG₅OH). (D) The substrate then was immersed in a solution of fibronectin in PBS for 4 h. A scanning electron micrograph shows that protein adsorbed only to the methyl-terminated regions of the monolayer. (E) 3T3 fibroblasts attached only to the regions presenting fibronectin, and when cultured in serum-containing media, divided to fill these regions entirely. The surrounding inert monolayer strictly confined the cell to the rectangular regions. (F) Electrochemical oxidation of the monolayer in the presence of media containing RGD-Cp (2 nM) led to the immobilization of the peptide. Fluorescence microscopy shows that the two cell populations are patterned on the substrate. All micrographs were taken by ×5 magnification.