Cell response to micropatterned surfaces produced with polymeric microspheres

Surface topography plays an important role in cell function. We fabricated microstructured patterns from monolayers of polymeric microspheres, which were arranged on a flat polystyrene dish. Such patterns could be quickly formed by spin-coating microspheres and were easily controlled by changing the size of the settled microspheres. Polystyrene (PS) microspheres having different sizes were prepared by soap-free emulsion polymerization in the presence of sodium chloride with different concentrations. The zeta potential of these microspheres was approx. -25 mV regardless of their diameter. Electron microscopic observations revealed that the microspheres were deposited on a PS dish in hexagonally-packed monolayers with a pitch equal to the diameter of each microsphere. The water contact angles gradually decreased with an increase of the pitch. To investigate the topographical effect of these surfaces on the neutrophil-like cell function, microscopic observations and measurements of active oxygen released from cells were carried out. Microscopic observation revealed that spreading cells adhered on PS microsphere-settling surfaces as well as on a PS film. As for active oxygen release, cell response to a PS microsphere-settling surface depended on the diameter of settling microspheres and showed a maximum for diameters of approx. 1 μm. This tendency was observed in phosphate-buffered solutions both with and without serum. Continuous activation which followed by the initial attachment seems to relate to the change of cytoskeletal systems. These results indicate that cells recognize the roughness of the micropatterned surface covered with PS microspheres, and a pitch between the tops of settled microspheres is an important factor for cell recognition. Copyright (C) 1999 Elsevier Science B.V. All rights reserved.