Förster energy transfer in ultrathin polymer layers as a basis for biosensors

A method of detecting the binding of analyte molecules to biospecific receptors, like antibodies, is described. Förster energy transfer is used in connection with monomolecular organic films. The films are built up from pre-polymerized materials using the Langmuir-Blodgett or self-assembly techniques. Fluorescent dyes (as energy transfer donors) as well as reactive groups for covalent immobilization of protein receptors are integrated into the polymers. Several different methods for immobilizing biomolecules are described, including the use of protein A and the biotin/streptavidin couple. The studies suggest that the combination of Förster transfer and ultrathin organic films can be used for the construction of biosensors working either by displacement or by competitive assays. The mannose/concanavalin A, digoxin/antibody, and mouse immunoglobulin G/antibody systems are investigated. Further, a simplified meter optimized for measuring the fluorescence ratio at two wavelengths is described.