Demonstration of a surface plasmon-coupled emission (SPCE)-based immunoassay in the absence of a spacer layer |
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Authors: | Jong Seol Yuk Colette McDonagh Brian D MacCraith |
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Institution: | (1) Biomedical Diagnostics Institute, National Centre for Sensor Research, School of Physical Sciences, Dublin City University, Glasnevin, Dublin 9, Ireland; |
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Abstract: | The technique of surface plasmon-coupled emission (SPCE) involves the coupling of light which is emitted from a fluorophore
into the surface plasmon of an adjacent thin metal film, giving rise to highly directional emission. We have combined the
advantages of SPCE with the high light collection efficiency of supercritical angle fluorescence by carrying out an immunoassay
on a paraboloid array biochip in the absence of the conventional SPCE spacer layer normally used to minimize metal quenching
of the fluorescence. In this work, we have successfully demonstrated an SPCE-based assay by utilizing the protein assay layer
as the spacer layer. A novel 3 × 3 injection molded polymer biochip with paraboloid elements was used. The paraboloid elements
served to enhance the light collection efficiency while the top surface was coated with a gold layer to use excitation of
surface plasmons and detection of SPCE emission. Theoretical modeling of the gold-protein layer structure showed that the
surface plasmon resonance angles were located in the detection range of the paraboloid biochip. The polarization dependence
of SPCE emission was also demonstrated. Finally, a human IgG sandwich immunoassay was carried out which exhibited a limit
of detection of ~10 ng/ml using 3σ. The results demonstrate the potential of the SPCE-based paraboloid array biochip as a novel platform for high-throughput
analysis of biomolecular interactions. |
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