Grafting of nanoporous alumina membranes and films with organic acids

In this study, direct surface grafting of nanoporous alumina membranes and glass-supported alumina films was carried out with three different fluorinated organic acids: trifluoroacetic acid, perfluoropentanoic acid and 2,3,4,5,6-pentafluorobenzoic acid. Elemental surface composition and chemical environment of alumina were investigated using X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). Alumina surfaces grafted with fluoro-organic acids exhibited increased hydrophobic properties compared to ungrafted surfaces when measured using goniometry and atomic force microscopy (AFM). This work describes the evidence for surface chemical modification of alumina using direct reaction with organic acids. An AFM study of the adsorption of the immunoglobulin G (IgG) molecules on the fluoro-organic-acid-grafted surfaces is reported. The results show that an ordered arrangement of immunoglobulin G structures with in-filling of pores could be achieved only on the more hydrophobic fluoro-organic-acid-grafted alumina membranes. Copyright (c) 2007 John Wiley & Sons, Ltd.