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PubMed1991

Output grating couplers on planar optical waveguides as direct immunosensors.

We demonstrated the feasibility of using integrated optical output grating couplers in direct immunosensing. We monitored as functions of time, first the adsorption of an antigen (Ag) on the waveguide's surface, and subsequently, the binding of the corresponding antibody (Ab), i.e. the formation of the immuno-complex Ag-Ab. The Ag was human immunoglobulin G (h-IgG), and the Ab was rabbit anti-h-IgG. We also studied the adsorption of avidin. The refractive indices nF', thicknesses dF', and surface coverages gamma of the adsorbed adlayers and of the immuno-complex Ag-Ab, respectively, were determined.

Adsorption↗

PubMed1991

Model experiments with integrated optical input grating couplers as direct immunosensors.

Using an input grating coupler instrument and monomode optical waveguides, we studied the adsorption of various proteins (e.g. human immunoglobulins G and A (h-IgG and h-IgA), and avidin) on the waveguide surface. In model experiments for immunoassays, we also monitored as a function of time the formation of time formation of the immuno-complex Ag-Ab between antigen (Ag) molecules absorbed on the waveguide surface and antibody (Ab) molecules, for example, of adsorbed h-IgG vs anti-h-IgG, anti-goat-IgG (cross-reaction) and anti-h-IgA (negative test). We also studied the affinity reaction between adsorbed protein A and h-IgG. From the measured changes in the effective refractive indices N(TE0) and N(TM0) of the TE0 and TM0 modes, we determined the thickness dF, the refractive index nF, and the surface coverage gamma of the absorbed protein adlayers and of the immuno-complexes.

Adsorption↗