Summary: Micro‐ and nanofabrication methods are essential today in microelectronics, optoelectronics, catalysis, and analytics. Recent advances in biomaterials show that micro‐ and nanofeatures, either at the surface or embedded in materials, can drive specific responses both in in vivo and in vitro biological systems. With such an approach, scientists can understand better, and possibly exploit, biological responses stimulated by properly designed biomedical surfaces. Because of their versatility, plasma treatment, deposition, and etching processes are often part of procedures optimized to create micro‐ and nanofeatures of different shape, size, and position, onto and inside materials. Presented here are recent examples of such processes developed in our group for biomedical applications.

In designing new biomaterials, it is of outstanding importance to consider how cells respond to specific chemical and topographical features on the material surface. The behavior of most cell types in vivo is strictly related to specific chemical and topographical cues that characterize the extra cellular environment. In particular, during their lives cells react to topographical patterns such as those of the extracellular matrix (ECM), of micro and/or nanometric dimensions. The production of micrometric and/or nanometric features on artificial materials usually involves expensive and time-consuming methods of manufacturing, such as electron beam and colloidal lithography. In this article, different "Teflon-like" structured surfaces were deposited from tetrafluoroethylene (C(2)F(4))-fed plasmas, for the study of cell adhesion and growth. The reaction of different cell lines to different topographical features was evaluated and compared with cell behavior on flat samples with the same chemical composition. Cell adhesion was calculated from area covered by cells at different time of culture. Beside this, cell proliferation was determined with the MTT test. Cell morphology and filopodia interaction with the nanofeatures were also estimated by optical and scanning electron microscopy. A dramatic difference both in adhesion and growth was found between cells seeded on flat and rough surfaces with the density and spreading of adhered cells varying as a function of the roughness of coatings.

We describe the tailoring of polymer surfaces with CF x composition and roughness/density of different micro-/nanometric relieves (ribbons, petals, domes, dots) tuned independently in low pressure plasma deposition and etching processes. Similarity of outer chemical composition grants the comparison of cell culture results to analyze the impact of topographical features on cellular behavior. Such surfaces are of interest for biomedical substrates since tuning their surface composition and morphology can drive the behavior of cells in contact with them.

In this work, the response of Saos2 cells to polymeric surfaces with different roughness/density of nanometric dots produced by a tailored plasma-etching process has been studied. Topographical features have been evaluated by atomic force microscopy, while wetting behavior, in terms of water-surface adhesion energy, has been evaluated by measurements of drop sliding angle. Saos2 cytocompatibility has been investigated by scanning electron microscopy, fluorescent microscopy, and optical microscopy. The similarity in outer chemical composition has allowed isolation of the impact of the topographical features on cellular behavior. The results indicate that Saos2 cells respond differently to surfaces with different nanoscale topographical features, clearly showing a certain inhibition in cell adhesion when the nanoscale is particularly small. This effect appears to be attenuated in surfaces with relatively bigger nanofeatures, though these express a more pronounced slippery/dry wetting character.

No abstract