MICROPATTERNING GRADIENTS AND CONTROLLING SURFACE DENSITIES OF PHOTOACTIVATABLE BIOMOLECULES ON SELF-ASSEMBLED MONOLAYERS OF OLIGO(ETHYLENEGLYCOL) ALKANETHIOLATES

Background: Bioactive molecules that are covalently immobilized in pat terns on surfaces have previously been used to control or study cell b ehavior such as adhesion, spreading, movement or differentiation. Phot oimmobilization techniques can be used, however, to control not only t he spatial pattern of molecular immobilization, termed the micropatter n, but also the surface density of the molecules - a characteristic th at has not been previously exploited. Results: Oligopeptides containin g the bioactive Arg-Gly-Asp cell-adhesion sequence were immobilized up on self-assembled monolayers of an oligo(ethylene glycol) alkanethiola te in patterns that were Visualized and quantified by autoradiography. The amount and pattern of immobilized peptide were controlled by mani pulating the exposure of the sample to a UV lamp or a laser beam. Patt erns of peptides, including a density gradient, were used to control t he location and number of adherent cells and also the cell shape. Conc lusions: A photoimmobilization technique for decorating surfaces with micropatterns that consist of variable densities of bioactive molecule s is described. The efficacy of the patterns for controlling cell adhe sion and shape has been demonstrated. This technique is useful for the study of cell behavior on micropatterns.