Photo-lithography and soft-lithography of Perfluoropolyethers for the development of fouling release surfaces with biomolecular patterns

The selective and spatially resolved patterning of biomaterials has been increasingly researched as one of the key technologies for the capture of rare cells and for the analysis of individual cellular processes. In vitro traditional cell cultures study the average response within a population of cells but cell shape and hence behavior can vary significantly from cell to cell. Thus, new methods to physically isolate large numbers of individual cells controlling their shape would be extremely valuable. Patterned biomaterials enable us to control the local density and spatial rearrangement of cells by their specific chemical composition, wettability and morphology, that even lead to controlling cell activity on a biocompatible surface. The synthesis of new anti-fouling/fouling-release materials together with the development of photo-lithografic and soft-lithographic technologies are encouraging the research on biomolecular patterning. The performance of the final patterned substrates is strikingly affected by the substrate material itself that should meet specific requirements. In particular, anti-fouling/fouling-release characteristics with respect to protein and cell adhesion are necessary to avoid their non-specific binding on the substrate. Perfluoropolyethers (PFPE) were chosen in this work for their peculiar physico-chemical properties that make them suitable for a wide variety of applications including biomedical ones. Hyaluronic acid (HA) was grafted onto a UV-curable perfluoropolyether substrate with the aim of selectively capturing cancer cells. The interaction between the latter and hyaluronic acid is mediated by the cell transmembrane glycoprotein CD44, overexpressed by cancer cells. Three different routes were employed for HA patterning: (i) Glycidyl Methacrylate modified HA was directly bound to a partially cross-linked PFPE surface by photo-lithography; (ii) Biotinylated-HA was linked to avidin patterned on an underlying photobiotin array obtained by μ-contact printing; (iii) Thiolated-HA was linked to a polydopamine pattern formed by μ-contact printing, exploiting the affinity of polydopamine for thiol and amine-chemical groups.