Nanostructured Artificial Biointerfaces

Doctoral thesis, 2006

Abstract The interactions occurring between biological systems and the surface of biomaterials has been an area of strong research focus for a number of decades. There has been a realisation of the importance of macromolecular interactions and a consequent need to understand biointerfacial events at the nanometer length-scale. A set of tools for working at the nanometer scale are critical for the study, design and evaluation of new biomaterials for application to improve medical devices and therapies and there has been a significant research drive to develop engineering approaches able to perform in the nanometer regime. One such engineering approach to nanopattern model biomaterial interfaces over large areas is colloidal lithography. In this thesis work colloidal lithography is extended from metals and ceramics for use with organic materials including bulk homopolymers, thin films of both homopolymers and block copolymers and monolayers of proteins. Large area arrays of topographic nanostructures with a range of aspect ratios and shapes are demonstrated by systematic control of processing parameters. Templating of block copolymers via topographic or chemical nanopatterns was shown and a templated PLL-g-PEG layer was subsequently used to create large area nanopatterns of the protein Laminin. A novel approach to quantifying protein binding from AFM height histograms was developed and utilised to characterise the functional properties of the surface bound Laminin. Artificial nanostructured biointerfaces produced by these approaches giving nanoscale topographic or chemical cues were used to study the influence of nanoscale surface structures on the behaviour of adherent cells in culture. Significant changes in cellular morphology and cytoskeletal arrangement were observed which correlated to reduced focal adhesion formation. Cells adherent to nanopatterns of protein adhesive domains and high aspect ratio (<1) cylindrical nanostructures showed similar behaviour suggesting that effects of nanoscale topography in biointerfaces research may relate to their presentation of non-specifically bound protein adsorbing from the extra cellular matrix in a particular 3D architecture with resultant influences on availability of those proteins to interact with cells. Key words: Nanofabrication, Electrostatic Self Assembly, Colloidal Lithography, Cell adhesion, Cell Morphology, Focal Contact, Block Copolymer, Protein Patterning