Comparison of cell interactions with laser machined micron- and nanoscale features in polymer.

Control of cell responses to artificial surfaces is a research goal for much of the biomaterials community. The role that the micron scale topography of a surface can play in controlling cell responses has been well documented and recent advances in nanofabrication techniques have lead to an interest in cells' responses to submicron-scale surface features. The study described here compares the relative influences that nanoscale and micron-scale features exert on cells by examining cytoskeletal organisation. Micron-scale structures were generated on the polyamide Kapton using a 193 nm ArF Excimer laser, at 400 mJ/cm2 fluence. Nanoscale features were generated on Kapton using the excimer laser with a phase mask. Osteoblasts were seeded onto surfaces for 24 h, then the cell membranes were detergent-extracted, and the cells were applied with a primary antibody to actin and a colloidal gold-conjugated secondary antibody. Samples to be examined using the confocal were mounted in glycerol, those for electron microscopy were carbon-coated. The organisation of actin was examined on micron- and nano-scale structures by scoring sections for order of branching and angles of branching to relate changes in the cytoskeleton relative to the control. Although there was a strong influence of micron-scale structures, the cytoskeleton of cells on the nanoscale structures were similar to the controls.