title: The application of colloidal nanofabrication to the study of biological systems
Creators: name: Wood, Mairead Anne
Publisher: name: University of Glasgow
Year: 2003
Subjects: subject: Biomedical engineering.

description: Topography plays a vital role in cell and tissue structure and function in situ. Furthermore, investigations into the effects of microtopography on cell behaviour in vitro indicate the ability to manipulate cellular activities according to topographical features and dimensions. The development of high-resolution microscopy techniques indicates nanotopography occurs in vivo, for example in the basement membrane of the corneal epithelia, suggesting its involvement in fundamental cell and tissue processes. By manipulating topographical components and ultimately controlling cell and tissue behaviour, micro- and nanotopography offer potential applications in implant surface modifications and ultimately implant success and also in tissue engineering. Developments in the electronics industry have resulted in the ability to fabricate nanotopography using a variety of methods. The general protocols for nanomanufacturing lie in the high resolution and low cost of fabricating devices. With respect to biological investigations of nanotopography, surfaces patterned with the desired nanofeatures must occur across a large area (cm2 rather than mm2), be reproducible (allowing for consistency in experiments), and accessible (limiting the requirement for specialist equipment). Colloidal particles with nanometric dimensions fit this criteria and can be utilised with a functionalised substrate to produce nanometric spherical features. Colloidal-based nanofabrication techniques were utilised, producing colloidal, nanopillared and grating patterns containing both planar and nanopillared surface topographies. Colloidal-based topographies were characterised using scanning electron microscopy (SEM), atomic force microscopy (AFM), laser profilometry and interference reflection microscopy (IRM). Surface area coverage and interparticle spacing of colloids adhered to a base substrate were calculated from SEM images. Charge screening and mobility restoration of colloids was used to alter area coverage and interparticle spacing. Colloidal surfaces were utilised as a mask for use with reactive ion etching, resulting in nanopillared patterning of substrates. Similarly, conventional photolithography and colloidal lithography were utilised to fabricate grating patterns of planar and nanopillared topographies lying collaterally on the same device. 20nm- and 50nm-diameter colloidal gold particles were used in these investigations, and pillars were fabricated to either 80nm or 200nm in height in fused silica. Epitenon, endothelial and fibroblast cells were investigated for behavioural alterations in relation to colloidal-based nanopattemed topography. Adhesion assays, time-lapse video microscopy and morphological examination utilising immunohistochemistry techniques in combination with fluorescence microscopy and scanning electron microscopy were applied to investigate behavioural alterations. With respect to colloidal topographies, where colloids were adhered to a silica base substrate, utilising analysis of variance tests (ANOVA), the number of fibroblasts adhering to planar, 20nm- and 50nm-diameter colloidal substrates were significantly different, where P=0.01. ANOVA also indicated fibroblast adhesion was significantly different on planar control and colloidal topographies investigated at each time interval studied, namely 20 minutes, 1 hour and 3 hours, where P=0.01. Furthermore, ANOVA revealed that an interactive effect between topography and time acts to influence fibroblast adhesion. Cell-cell contacts were prevalent on colloidal topographies in comparison to controls in epitenon cells and fibroblasts as observed using time-lapse video microscopy, SEM and fluorescent imaging of cell cytoskeletons. (Abstract shortened by ProQuest.).