Direct detection of proteins adsorbed on synthetic materials by matrix-assisted laser desorption ionization-mass spectrometry

The irreversible accumulation of biological material on synthetic surfaces ("biofouling") adversely affects for instance contact lenses, implantable b iomedical devices, biosensors, water purification, transport and storage sy stems, and marine structures. It is shown here that proteins adsorbed on co ntact lenses can be detected directly, rapidly, and conveniently, with high sensitivity, by matrix-assisted laser desorption ionization (MALDI)-mass s pectrometry, This new approach allows detection of minor (and major) protei naceous constituents of biofouled layers on samples retrieved from clinical usage and in vitro protein adsorption studies, at levels substantially bel ow monolayer coverage. Identification of the detected biological molecules can be done by comparison of the detected mass peaks with known protein mol ecular masses or with spectra recorded of pure compounds or by separate bio chemical assays. The MALDI mass spectra re; corded on different contact len ses contain peaks assignable to lysozyme and a number of smaller proteins. Such sensitive characterization of the early stages of biofouling enhances the understanding of protein/materials interactions and assists in designin g guided strategies toward control of biological adsorption processes. (C) 1999 Academic Press.