Paper BI+NC-TuA8
Nano-Rough Surfaces Produced by Glancing Angle Deposition (GLAD) for Protein Adsorption Measurements and Cellular Assays

Tuesday, October 21, 2008, 4:00 pm, Room 202

Currently, there is a strong focus on the fabrication of nanostructured artificial surfaces in order to tailor the biological response of artificial materials. The nanostructures are mainly used for more fundamental protein and cell studies, but in some cases also for applications like implants and cell/tissue engineering. Here a simple method to generate nano-rough platinum surfaces with varying morphological characteristics and a well-controlled surface roughness has been employed. The surfaces were fabricated by glancing angle deposition (GLAD) with varying angles and deposition times. Afterwards the biological response of the characterized nanorough samples were examined by protein adsorption and cell adhesion/proliferation assays in order to evaluate their potential as biomaterials surfaces. The effect of the deposition angle, θ, and deposition time, t, on the morphological characteristics of the thin films was investigated by utilizing Atomic force microscopy (AFM) and analyzing the images in order to determine the surface roughness and the size of the nano-rough surface features. The chemical composition of the platinum coatings were examined by X-ray Photoelectron Spectroscopy (XPS). From the AFM images it is observed, that the surface nano-features residing on the substrates can be changed by varying the deposition angle: as the deposition angle approaches grazing incidence sharp columnar protrusions are grown, while more smoothly shaped surface features appear for the thin films fabricated at higher deposition angles. The surface root-mean-square roughness, w_rms, increased from 1.49 nm to 15.2 nm as grazing incidence was approached. The surface roughness was additionally enhanced from w_rms = 6.6 nm to 26.3 nm for films grown at θ = 5° by increasing the deposition time. It is found that the blood fluid protein, fibrinogen, is influenced by the nano-rough substrates as compared to a flat control surface. Furthermore, the proliferation of primary human fibroblasts is almost completely inhibited on the nano-rough substrates. A maximum difference of almost 200% is observed between the tallest columnar surface features (44 ± 5 cells/mm2) and the flat platinum reference (125 ± 6 cells/mm2). These results show that GLAD is a versatile technique for fabrication of varying nano-rough model surface morphologies capable of influencing both the protein and cell behavior on the surface.