Human fibroblast and human bone marrow cell response to lithographically nanopatterned adhesive domains on protein rejecting substrates.

The separate influence of topographical and chemical cues on cell attachment and spreading are well documented; however, that of duel-cue substrates is less so. In this study graft copolymers that sterically stabilize biological surfaces were employed alongside nanotopographical features fabricated by colloidal lithography. This resulted in the production of a range of substrates whereby the effect of chemistry and or topography on both on human fibroblast and bone marrow cell adhesion and spreading could be observed. The current studies indicate an enhancement of cell response as a consequence of modifications in material topography, whereas the current selected chemical cues inhibited cell function. Critically, in combination, topography modulated the effects of chemical environment.

Study of Staphylococcus aureus adhesion on a novel nanostructured surface by chemiluminometry.

In recent years the progress in the field of nanotechnologies has offered new possibilities to control the superficial features of implant materials down to a nanoscale level. Several studies have therefore tried to explore the effects of nanostructured biomaterial surfaces on the behavior of eukaryotic cells. However, nanotopography could exert an influence also on the behavior of prokaryotic cells, with relevant implications concerning the susceptibility of implant surfaces to infection. Aim of this study was to examine the behavior of Staphylococcus aureus on polyethylene terephthalate (PET) surfaces either cylindrically nanostructured (PET-N) or flat ion-etched (PET-F), and on tissue culture-grade polystyrene (PS). Microbial adherence was assessed by chemiluminometry under 4 different conditions: (a) bacteria suspended in MEM medium, (b) bacteria in MEM supplemented with 10% fetal bovine serum (FBS), (c) test surfaces preconditioned in FBS, and (d) post-exposure of colonised surfaces to serum-supplemented MEM. Under all circumstances, PET-F and PET-N specimens showed identical bacterial adhesion properties. In the absence of serum, all 3 test materials showed a very high adhesivity to microbial cells and both PET surfaces exhibited greater adhesion than PS. On the contrary, the presence of 10% serum in solution significantly affected cell behavior: the number of microbial cells on all surfaces was drastically reduced, and the adhesion properties of PET surfaces with respect to PS were reversed, with PET being less adhesive. Overall, the specific cylindrical nanostructures created on PET did not significantly influence microbial behavior. Ongoing studies are verifying whether other nanotopographies with different geometry could have more substantial effects.

Large area protein nanopatterning for biological applications.

Large area nanopatterns of functional proteins are demonstrated. A new approach to analyze atomic force microscopy height histograms is used to quantify protein and antibody binding to nanoscale patches. Arrays of nanopatches, each containing less than 40 laminin molecules, are shown to be highly functional binding close to 1 monoclonal anti-laminin IgG (site by IKVAV sequence) or 3-4 polyclonal anti-laminin IgG's per surface bound laminin. Complementary quartz crystal microbalance measurements indicate higher functionality at nanopatches than on homogeneous surfaces.

Nanofabrication of polymer surfaces utilizing colloidal lithography and ion etching.

In this paper, we utilize colloidal lithography based on electrostatic self-assembly of polystyrene colloidal particles onto a polymer surface as a nanoscale mask. The pattern is then transferred to the surface by ion beam etching. Each particle acts as an individual mask, resulting in an array of identical structure. Ion beam exposure etches away the unmasked surface between the particles, so the particle mask pattern can be transferred into the polymer surface. This method allows to nanofabricate bulk polymeric surfaces with systematic variation in relief, structure sizes, and aspect ratios. It is a fast, simple, and reliable method to fabricated different polymeric surfaces even on large area samples (> 1 cm2). The structural variation is achieved by use of different conditions during the self-assembly of the mask (e.g., different particles sizes) or different ion etching conditions during the pattern transfer (e.g., ion energy, ion flux, ion incident angle, etching time, gas environment).

Morphological and microarray analysis of human fibroblasts cultured on nanocolumns produced by colloidal lithography.

The environment around a cell during in vitro culture is unlikely to mimic those in vivo. Preliminary experiments with nanotopography have shown that nanoscale features can strongly influence cell morphology, adhesion, proliferation and gene regulation, but the mechanisms mediating this cell response remain unclear. In this study a well defined nanotopography, consisting of 100 nm wide and 160 nm high cylindrical columns, was used in fibroblast culture. In order to build on previously published morphological data that showed changes in cell spreading on the nanocolumns, in this study gene regulation was monitored using a 1718 gene microarray. Transmission electron microscopy, fluorescent observation of actin and Rac and area quantification have been used to re-affirm the microarray observations. The results indicate that changes in cell spreading correlate with a number of gene up- and down-regulations as will be described within the manuscript.