Geometric Sensing in Cells - a Molecular Approach

Abstract

Cells sense changes in substrate geometry and respond by modifying their behavior. Finding the dimensions and characteristics that elicit a response is crucial to understand this phenomenon. To analyze this, grooves and ridges with width = 1.2 μm, pitch = 3μm and varying heights (1μm to 50 nm) were fabricated in fused silica using photolithography and dry etching. Fused silica was used as material as the roughness post etching is very little (less than 8 nm). Also, to probe the effect of curvature on the cells, the grooves and ridges were given a curvature using shallow trench fabrication process. In this method the grooves and ridges are made using photolithography and dry etching, which is followed by controlled oxide deposition leading to curved sidewalls. Fibroblasts were seeded and fixed after 75 min of spreading. DIC and actin immunofluorescence was used to image the cells. Plots of spreading area and anisotropy ratio v/s different heights revealed that a height of 100 nm is the minimum feature height that the cells can detect. Below this height, they tend to spread isotropically as on a plane glass coverslip. Above 100 nm the cells tend to align in the direction of the grooves and show strong alignment with increased heights of ridges. Currently we are looking at the effect of curvature on the cells.