Highly Efficient Antibacterial Surfaces Based on Bacterial/Cell Size Selective Microporous Supports

We report on the fabrication of efficient antibacterial substrates selective for bacteria, i.e., noncytotoxic against mammalian cells. The strategy proposed is based on the different size of bacteria (1–4 μm) in comparison with mammalian cells (above 20 μm) that permit the bacteria to enter in contact with the inner part of micrometer-sized pores where the antimicrobial functionality are placed. On the contrary, mammalian cells, larger in terms of size, remain at the top surface, thus reducing adverse cytotoxic effects and improving the biocompatibility of the substrates. For this purpose, we fabricated well-ordered functional microporous substrates (3–5 μm) using the breath figures approach that enabled the selective functionalization of the pore cavity, whereas the rest of the surface remained unaffected. Microporous surfaces were prepared from polymer blends comprising a homopolymer (i.e., polystyrene) and a block copolymer (either polystyrene-b-poly­(dimethylaminoethyl methacrylate) (PDMAEMA) or a quaternized polystyrene-b-poly­(dimethylaminoethyl methacrylate)). As a result, porous surfaces with a narrow size distribution and a clear enrichment of the PDMAEMA or the quaternized PDMAEMA block inside the pores were obtained that, in the case of the quaternized PDMAEMA, provided an excellent antimicrobial activity to the films.