Development of a novel dry process to functionalize membranes for the covalent attachment of antibodies used in immunochemical - Based environmental strip tests

The controlled attachment of antibodies is a prime requirement for developi ng membrane-based immunoassays used in field tests. A novel dry process was developed to functionalize a nitrocellulose membrane by introducing amino groups on the surface, allowing an oriented covalent linkage of antibodies through their oxidized carbohydrate moieties. A non-equilibrium low pressur e plasma of NH3 and NH3/H-2 mixtures was used to incorporate an average of 2.4 amine functions per nm(2) of porous surface. A mechanism of the functio nalization process was proposed using on-line emission spectroscopy and mas s spectrometry analysis to monitor the reaction process. The modification o f the physical properties and the chemical composition of the treated mater ial was also investigated by X-ray Spectrophotometric (XPS) analysis and sc anning electron microscopy. The immobilization of radiolabelled antibodies resulted in an average binding capacity of 60 mu g/cm(2). Their activity wa s retained as shown by an enzyme linked immunosorbent assay. This fast and reproducible process was demonstrated to be efficient in developing functio nalized membranes suitable for environmental strip tests.