Optical characterization of aminosilane-modified silicon dioxide surface for biosensing

Silicon dioxide surfaces, functionalized by two aminosilane compounds (3-amino-propyl-triethoxysilane, APTES; 3-amino-propyl-dimethylethoxysilane, APDMES) both dissolved in different solvents (dry ethanol and toluene), have been investigated by standard techniques such as spectroscopic ellipsometry (SE), water contact angle (WCA), and atomic force microscopy (AFM). Silane thicknesses between 5 and 80 Å have been found, depending on deposition conditions; surface wettabilities change, accordingly. These organic-inorganic interfaces have also been modified by a cross-linker (bis-sulfosuccinimidyl suberate) in order to covalently bind a fluorescein labeled protein A. The amount of protein linked to functional surfaces has been quantified by SE and fluorescence microscopy. These results could be very useful in developing new platforms for optical biosensing. © The Authors. All rights reserved.