Pathogen detection using single mode planar optical waveguides

We utilize an optical waveguide-based biosensor recently developed at Los Alamos National Laboratory for the sensitive and specific detection of protein markers. Our planar optical waveguides are based on single mode structures that provide high optical field intensity at the active surface while providing discrimination from sample background fluorescence through spatial filtering. We have incorporated sandwich immunoassays where the capture antibody is immobilized on a biocompatible film attached to the surface of an optical waveguide. The approach can be adapted to any marker protein and is faster (< 10 min), more sensitive, and as specific as conventional enzyme-linked immunosorbent assays (ELISA, the current lab standard). Results are presented for the detection of several analytes of Bacillus anthracis including protective antigen, a virulence marker for B. anthracis, and the bacterial cell or cellular debris.