Large-Area Photomodification of Nanotopography for Controlling Cell Behavior

Nanotopographic surfaces are a powerful tool for studying and controlling cell behavior. However, the fabrication of nanotopographic master patterns using conventional photolithography is expensive, which limits the range of designs that can be explored. In this study, a method is demonstrated for the photoreshaping of large-area patterns of nanoridges. The original master pattern is created using conventional lithography, and an azopolymer replica is prepared using soft lithography. The manipulation of the nanoridges is achieved by projecting light with specific polarizations and exposure times, resulting in controllable widening, buckling, or removal of the ridges. The reprogrammed azopolymer master patterns can then be replicated, creating reproducible new nanotopographies that can be transferred into other materials using a molding procedure. Diffraction can be used for in situ monitoring of the reprogramming during exposure. Image-analysis methods are used to characterize buckled ridges as a function of exposure time. The response of MCF10A epithelial cells are investigated to buckled nanoridges. A substantial impact of buckling on the dynamics and location of actin polymerization, as well as on the distribution and lengths of contiguous polymerized regions is also observed.