Ordered arrays of polymeric nanopores by using inverse nanostructured PTFE surfaces

Abstract

We present a simple, efficient, and high-throughput methodology for the fabrication of ordered nanoporouses polymeric surfaces with areas in the range of cm2. The procedure is based on a two-stage replication of a master nanostructured pattern. The process starts with the preparation of an ordered array of PTFE (poly(tetrafluorethylene)), PTFE) free-standing nanopillars by wetting self-ordered porous Anodic Aluminum Oxide (AAO) templates with molten PTFE. The nanopillars are 120 nm in diameter and approximately 350 nm in length, while the array extends over cm2. The PTFE nanostructuration process induces a surface hydrocarbonation of the nanopillars, as revealed by confocal Raman microscopy/spectroscopy, which enhances the wettability of the originally hydrophobic material and facilitates its subsequent use as an inverse pattern. Thus, the PTFE nanostructure is then used as a negative master for the fabrication of macroscopic hexagonal arrays of nanopores composed of biocompatible poly(vinylalcohol) (PVA). In this particular case, the nanopores are 130-140 nm in diameter and the interpore distance is around 430 nm. Features of such characteristic dimensions are known to be well recognizable by the living cells. Moreover, the inverse mold is not destroyed in the pore array demoulding process and can be reused again for a new pore array fabrication. Therefore, the developed method allows the high throughput production of cm2-scale biocompatible nanopores surfaces that could be interesting as two-dimensional scaffolds for tissue repairing or wound healing. Moreover, our approach can be extrapolated to almost any polymer and biopolymer ordered pore array fabrication.