Poly (ethylene glycol) grafted nanoporous alumina membranes

Membranes currently used for separation of sub-micron particles in biomedical applications are of asymmetric or anisotropic variety and are made from polymers such as polysulfone or polyacrylonitrile. Several bioincompatibilities are associated with these polymeric membranes limiting their applications. Aluminum oxide substrates have been chosen for several reasons, including compatibility with our processing protocols, chemical and thermal stability, and ease in post-processing surface modification. Several studies have shown this material to be bioinert. However, the biocompatibility of the membrane material must be further investigated and improved. With proper surface modification, the protein adsorption can be lowered and the non-fouling characteristics can be improved. In this study we graft alumina membranes with a biocompatible polymer like poly (ethylene glycol) to investigate protein adsorption. Albumin and fibrinogen were selected as model proteins since they are important components in immunogenic and thrombogenic reactions. X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were used to characterize PEG films on alumina membranes.