Figure 2.

Molecular strategy for creating substrates that can be electrically switched to permit cell attachment. A monolayer presenting a mixture of hydroquinone groups and penta(ethylene glycol) groups (Left) is converted to a monolayer presenting the corresponding quinone groups (Center) by application of a potential to the underlying gold (500 mV versus Ag/AgCl). Both monolayers are inert to the attachment of cells. Addition of a conjugate of cyclopentadiene and the peptide Gly-Arg-Gly-Asp-Ser-NH₂ (RGD-Cp) to the monolayer presenting the quinone group results in the Diels-Alder-mediated immobilization of peptide (Right). 3T3 fibroblasts attach and spread on the resulting surface. Monolayers presenting the hydroquinone group are unaffected by the treatment with RGD-Cp and remain inert to cell attachment.