Micropatterning gradients and controlling surface densities of photoactivatable biomolecules on self-assembled monolayers of oligo(ethylene glycol) alkanethiolates

Background: Bioactive molecules that are covalently immobilized in patterns on surfaces have previously been used to control or study cell behavior such as adhesion, spreading, movement or differentiation. Photoimmobilization techniques can be used, however, to control not only the spatial pattern of molecular immobilization, termed the micropattern, but also the surface density of the molecules - a characteristic that has not been previously exploited. Results: Oligopeptides containing the bioactive Arg-Gly-Asp cell-adhesion sequence were immobilized upon self-assembled monolayers of an oligo(ethylene glycol) alkanethiolate in patterns that were visualized and quantified by autoradiography. The amount and pattern of immobilized peptide were controlled by manipulating the exposure of the sample to a UV lamp or a laser beam. Patterns of peptides, including a density gradient, were used to control the location and number of adherent cells and also the cell shape. Conclusions: A photoimmobilization technique for decorating surfaces with micropatterns that consist of variable densities of bioactive molecules is described. The efficacy of the patterns for controlling cell adhesion and shape has been demonstrated. This technique is useful for the study of cell behavior on micropatterns.