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Proceedings Paper

Preparation of chemical gradients on porous silicon by a dip coating method
Author(s): Lauren Clements; Ljiljana Puskar; Mark J. Tobin; Frances Harding; Helmut W. Thissen; Nicolas H. Voelcker
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Paper Abstract

Gradient surfaces have become invaluable tools for the high-throughput characterisation of biomolecule- and cellmaterial surface interactions as they allow for the screening and optimisation of surface parameters such as surface chemistry, topography and ligand density in a single experiment. Here, we have generated surface chemistry gradients on oxidised porous silicon (pSi) substrates using silane functionalisation. In these studies, pSi films with a pore size of 15- 30 nm and a layer thickness of around 1.7 ìm were utilised. The manufacture of gradient surface chemistries of silanes was performed using a simple dip coating method, whereby an increasing incubation time of the substrate in a solution of the silane led to increasing surface coverage of the silane. In this work, the hydrophobic n-octadecyldimethyl chlorosilane (ODCS) and pentafluorophenyldimethyl chlorosilane (PFPS) were used since they were expected to produce significant changes in wettability upon attachment. Chemical gradients were characterised using infrared (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and sessile drop water contact angle measurements. In addition, the surface chemistry of the gradient was mapped using synchrotron IR microscopy. The ODCS gradient displayed sessile drop water contact angles ranging from 12° to 71°, confirming the successful formation of a gradient. IR microscopy and an XPS line scan confirmed the formation of a chemical gradient on the porous substrate. Furthermore, the chemical gradients produced can be used for the high-throughput in vitro screening of protein and cell-surface interactions, leading to the definition of surface chemistry on nanostructured silicon which will afford improved control of biointerfacial interactions.

Paper Details

Date Published: 30 December 2008
PDF: 12 pages
Proc. SPIE 7267, Smart Materials V, 72670Q (30 December 2008); doi: 10.1117/12.810718
Show Author Affiliations
Lauren Clements, Flinders Univ. (Australia)
CSIRO Molecular and Health Technologies (Australia)
CSIRO Food Futures Flagship (Australia)
Ljiljana Puskar, Australian Synchrotron (Australia)
Mark J. Tobin, Australian Synchrotron (Australia)
Frances Harding, Flinders Univ. (Australia)
Helmut W. Thissen, CSIRO Molecular and Health Technologies (Australia)
CSIRO Food Futures Flagship (Australia)
Nicolas H. Voelcker, Flinders Univ. (Australia)
CSIRO Food Futures Flagship (Australia)

Published in SPIE Proceedings Vol. 7267:
Smart Materials V
Nicolas H. Voelcker; Helmut W. Thissen, Editor(s)

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