Moniraj Ghosh, Christina Alves, Kathleen J. Stebe, and Konstantinos Konstantopoulos. johns Hopkins University, Baltimore, MD
Patterned surfaces presenting one or two functionalities are widely used in studies ranging from patterned electrodeposition of materials to the studies of cell adhesion. These surfaces are often made using microcontact printing followed by backfilling, allowing the creation of functionalized regions of submicron dimensions. Here, we generalize this technique to allow the creation of multifunctional surfaces using a novel combination of microcontact printing, backfilling and microfluidics to present multiple functionalities (proteins, antibodies, surfactants) and lengthscales (sub-micron and above) over areas of large extent. First, microcontact printing is used to place an active species in desired locations of the surface. The open regions are passivated by backfilling with a blocking agent, e.g. PEG via suitable surface linkers. This substrate is then used as a lid to a microfluidics device to form several channels. Species of interest are pumped through the channels to adsorb on to the active regions. Alternatively, a PEGylated surfactant can be microcontact printed to form a lattice pattern with open adherent regions. Thereafter, microfluidics can deliver desired functionalities to these open areas. The feature size on the printing stamp determines the size (i.e. resolution) of the printed species. The width and the geometry of the microfluidics channels determine the number of patches presenting a particular functionality. The nature of the functionalization is guided by suitable surface chemistry. These patterned multifunctional surfaces are of particular interest in material manufacture and bioassays. Examples of multifunctional surfaces for cell adhesion studies are shown.