Plasmonic vertical dimer arrays as elements for biosensing
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Localized surface plasmon resonances of metallic nanoparticles can be used for biosensing because of their sensitive dependence on the refractive index of the surrounding medium. The binding of molecules to the particles causes a change of the effective refractive index in their close vicinity, which leads to a reversible shift of the resonance. We present simulations and sensing experiments of a plasmon resonance based biosensor that makes use of the narrow antisymmetric resonance in coupled plasmonic vertical dimers. The sensitivity of the antisymmetric resonance is compared with that of a surface lattice resonance for refractive index sensing of bulk and of thin layers of molecules. The functionality of such a sensor surface is demonstrated via a testosterone immunoassay for detection of antibody from a solution by binding to surface-immobilized antigen in a fluidic channel.
KeywordsPlasmonic nanostructures Biosensing Label-free immunoassay Vertical dimer Testosterone
This work was financially supported by the Baden-Württemberg Foundation as part of the project GRIN-SEN in the research program Optical Technologies, and by the Deutscher Akademischer Austauschdienst (DAAD) within the scope of the program PROCOPE. The project was performed in the framework of the European Cooperation in Science and Technology COST Action MP1302 Nanospectroscopy. The authors want to thank the partners in the GRIN-SEN and PROCOPE projects for fruitful discussions.