In this work a low-cost parallel technique for creating chemical nano-patterned surfaces using nano-spheres as masks is presented. This technique, called nano-sphere lithography, makes use of different steps of plasma etching and deposition processes, for the creation of polymeric nano-structures of different chemical functionalities with relevant applications to bio-interfaces. In this study, the attention is focused on the plasma processing aspects for the etching of the polymeric masks (colloidal masks) in order to control the shape and the size of the etched nano-structures. The bio-functionality of the nano-patterned surfaces has been proved with a selective immobilization of proteins on the bioactive spots. ; JRC.I.4-Nanotechnology and Molecular Imaging