Division of Information Technology, Engineering and the Environment
School of Advanced Manufacturing and Mechanical Engineering
School of Advanced Manufacturing and Mechanical Engineering
Thesis Abstract
Over the last decade, surface density gradients have become of interest in both fundamental and applied research. Many biological processes, such as chemotaxis, immune response and cancer are driven by gradients of biological signalling molecules or extracellular matrix properties, but to-date remain poorly understood.1-3 We report two easy methods for generating surface density gradients by 1) Producing a plasma polymer gradient containing nitrogen functional groups, including primary amines, that enables electrostatic adsorption of gold nanoparticles4 and 2) producing a homogenous plasma polymer film of nitrogen functional groups and using a dip coater to control the density of nanoparticles. Chemical characterization was done by X-ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscopy (AFM) imaging confirmed the increase density of adsorbed nanoparticles across the samples. We also demonstrate the ability to control the profile of the nanoparticle density gradient simply through nanoparticle concentration of the solution (from which they are adsorbed). These approaches can be used on various surfaces as plasma polymers are used for the gradient layer. Another aspect of using plasma polymerization is the ability to deposit a thin plasma polymer film on top of the nanoparticles which provides homogeneous chemistry but preserves the surface morphology, which we aim to use to understand the effect of pure nanoscale surface roughness on cell behaviour, which has not been possible previously.
[1] J. B. Gurdon and P. Y. Bourillot, Nature, 2001, 413, 8
[2] T. Jin, X. Xu and D. Hereld, Cytokine, 2008, 44, 8.
[3] P. Rorth, Trends in Cell Biology, 2007, 17, 5.
[4] K. Vasilev, T. Zhu, M. Wilms, G. Gillies, I. Leiberwirth, S. Mittler, W. Knoll and M. Kreiter, Langmuir, 2005, 21, 6.
