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Interferometric biosensor based on planar optical waveguide sensor chips for label-free detection of surface bound bioreactions

: Schmitt, K.; Schirmer, B.; Hoffmann, C.; Brandenburg, A.; Meyrueis, P.


Biosensors & bioelectronics 22 (2007), Nr.11, S.2591-2597
ISSN: 0956-5663
ISSN: 1873-4235
Fraunhofer IPM ()
interferometric biosensor; label-free detection; evanescent field; Ta2O5 waveguide; Protein G

A label free optical biosensor based on a free-space Young interferometer configuration is presented. Commercial planar Ta2 O5 waveguides are used as sensing elements and allow the investigation of surface bound bioreactions like immunoreactions or biological affinity systems. Design criteria are discussed and a detailed characterization of the sensor performance is presented. The developed interferometer yields an effective refractive index resolution of 9x10(exp -9), corresponding to a surface coverage of about 13 fg/mm2. The performance of the system is characterized by two different affinity systems: the antibody-antigen complex protein G-immunoglobulin G is used as a model system for monitoring reaction kinetics. Further measurements on a silanized surface show the formation of a streptavidin monolayer on a biotinylated surface.