Patterned and switchable surfaces for biomaterial applications
Patterned and switchable surfaces for biomaterial applications
Patterned and switchable surfaces for biomaterial applications
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Andrew Hook – <strong>Patterned</strong> <strong>and</strong> <strong>switchable</strong> <strong>surfaces</strong> <strong>for</strong> <strong>biomaterial</strong> <strong>applications</strong>Living cells exist in nature within the extracellular matrix (ECM), which is anetwork of biomolecules <strong>for</strong>ming the framework that cells attach to <strong>and</strong> aresupported by. This matrix is composed largely of polysaccharides <strong>and</strong> variousproteins; <strong>and</strong> it is these proteins, in particular collagen, fibronectin <strong>and</strong> vitronectin,that cells use to attach to the ECM. Thus, the adhesion of cells to a tissue is mediatedby proteins that are already present on that tissue or that the cell produces itself. Thesame is true in vitro <strong>and</strong>, there<strong>for</strong>e, the mechanisms used to control proteinadsorption, which have been discussed, can equally be applied to cell attachment.Manipulating cell attachment has attracted much interest <strong>and</strong> is important <strong>for</strong> awide range of biodevice <strong>applications</strong>. Research has been focussed on producing<strong>surfaces</strong> that support or resist cell growth, <strong>and</strong> more specifically, <strong>surfaces</strong> that eitherswitch between an adherent <strong>and</strong> a non-adherent surface on dem<strong>and</strong> or have theability to direct cell growth to localised areas.One of the most effective methods <strong>for</strong> promoting cell attachment is the use ofextracellular proteins <strong>and</strong> in particular the Arg-Gly-Asp (RGD) integrin bindingpeptide based on a cell adhesion mediating site of fibronectin [33, 52-54]. Thismethod is very effective as it utilises the mechanisms by which cells attach to<strong>surfaces</strong> within natural systems. Various other materials <strong>and</strong> surface chemistries,such as tissue culture PS <strong>and</strong> polyurethane, support cell attachment but the use ofECM proteins is unrivalled in its ability to actively promote cell attachment.As well as chemically initiated cell attachment, the effects of topographical cuesto initiate <strong>and</strong> control the attachment, proliferation, orientation <strong>and</strong> migration of cells<strong>and</strong> tissue samples on <strong>surfaces</strong> has been investigated [47, 55-62]. The ability ofsubstratum topography to influence cell outgrowth suggests that the ECM maypresent both chemical <strong>and</strong> topographical signals to cells <strong>and</strong> is noteworthy in terms1-13
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