Nanofeaturing materials for specific cell responses
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AA8.10.1
Nanofeaturing materials for specific cell responses Adam Curtis, CCE, University of Glasgow, Glasgow, G12 8QQ, Scotland ABSTRACT A review of the ways in which cells react to nanofeatured surfaces is given. One of the prime reactions is of adhesion or otherwise to such surfaces. Topography appears to be of considerable importance and a wide range of cell properties are affected by the type, scale and regularity of topography. Chemistry can be combined with topography to fine- tune effects. Mechanical forces are also of importance but in practice it is hard to control these. Examples will be given of methods of controlling adhesion, morphology, orientation, movement, phagocytic activity and activation and gene expression of cells, Effects vary according cell type and also the spacing and size of nanofeatures. A discussion of the application of these findings to the medical devices concludes this short review.
INTRODUCTION In the last few years there has been a developing realisation that there are at least three main routes for the phenotypic modification of cells in addition to modifying the genetic background. The three routes are chemical signaling, mechanical signals and topography; some references which establish these three routes are given by [1] Nanofeaturing implies fabrication and the possibilities are already extensive for producing topography [ 1,2]. Nanoprinting, as opposed to microprinting, is still a technique in its infancy and microprinting gives too poor edge definition to be considered as a method of obtaining nanomerically defined edges. But fabrication methods are very likely to improve, see [ 3 ]. Nanomechanical devices are possible but at the moment probably impractical chiefly because of the difficulty of removing the devices from the body This is in contrast to the chemical signals which are likely to be degraded enzymatically and those of nanotopography which can be made on a biodegradable polymer. EXPERIMENTAL DETAILS Fabrication Precise nanotopography can be made by many techniques but electron beam lithography followed by dry etching to produce a master die or polymer demix systems are widely used [2,4]. Multiple replicas of these surfaces were made by embossing or injection moulding in polycaprolactone or polycarbonate. Cell culture and assessment. Primary cell cultures as well as cell lines were used to investigate the biological effects of these surfaces in a variety of manners, see [5].
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RESULTS Order and random patterns One important question not yet fully answered is whether nanofeatures either topographic or chemical must be presented to the cell in a non-random manner. Early results suggest that random patterns of topography may have little effect on cells see [6] whereas order, scale and symmetry may be very important [ 6,7]. The fabrication of ordered chemical features is only just beginning so there is little data available to resolve this question in the chemical field, but see [8]. The extent and accuracy of order required needs to be examined but it is c
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