Bacterial adhesion onto nanopatterned polymer surfaces

Two-dimensional nanopore arrays, consisting of hydrophilic SiO2-like holes within hydrophobic poly(hydroxymethylsiloxane) (PHMS) surfaces, were fabricated by using a colloidal template-assisted method. The pores typically were deep 2–3 nm and wide ∼100 nm, as measured by tapping mode AFM. The adhesion behaviour of Pseudomonas aeruginosa, i.e. a micrometer width cell, was investigated by Fluorescence Microscopy both onto the nanopatterned PHMS surfaces and the homogeneous corresponding substrates of unmodified PHMS as well as the SiO2-like surfaces obtained by plasma modification of PHMS films. The nanostructured films were able to induce a general increase of adhered cells with respect to the unmodified hydrophobic surfaces and a spot grown of biofilm-like aggregates. The observed effects are discussed in terms of the surface free energy of the patterned films as well as of the homogeneity and total integrated area of the 2D nanopore array.