Detection of biomolecules and bioconjugates by monitoring rotated grating-coupled surface plasmon resonance

Tóth, Emese and Szalai, Anikó and Somogyi, Anikó and Bánhelyi, Balázs and Csapó, Edit and Dékány, Imre and Csendes, Tibor and Csete, Mária (2017) Detection of biomolecules and bioconjugates by monitoring rotated grating-coupled surface plasmon resonance. OPTICAL MATERIALS EXPRESS, 7 (9). pp. 3181-3203. ISSN 2159-3930

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Abstract

Plasmonic bio-sensing chips were prepared by fabricating wavelength-scaled sinusoidal dielectric-metal interfacial gratings on polymer film covered bimetal layers. Lysozyme biomolecules (LYZ) and gold nanoparticle bioconjugates (AuNP-LYZ) were seeded onto the biochip surfaces. Comparison of the reflectance curves measured in a modified Kretschmann arrangement and computed numerically proved that monitoring of the narrower secondary reflectance minima under optimal rotated-grating coupling condition makes it possible to achieve enhanced sensitivity in biodetection. The enlarged reflectance minimum shift is due to the horizontally and vertically antisymmetric long-range plasmonic mode, which originates from surface plasmon polariton Bragg scattering and propagates at the border of the valley and hill. The sensitivity is significantly increased in case of bioconjugates due to the coupled localized resonances on the gold nanoparticles.

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