Gold/Silver/Gold Trilayer Films On Nanostructured Polycarbonate Substrates For Direct And Label‐Free Nanoplasmonic Biosensing

G. A. López‐Muñoz, M. -C. Estévez, M. Vázquez‐García, M. Berenguel‐Alonso, J. Alonso‐Chamarro, A. Homs‐Corbera and L. M. Lechuga

J. of Biophotonics, 2018 - DOI: 10.1002/jbio.201800043

Abstract: Ultrasmooth gold/silver/gold trilayer nanostructured plasmonic sensors were
obtained using commercial Blu-ray optical discs as nanoslits-based flexible polymer
substrates. A thin gold film was used as an adhesion and nucleation layer to improve the
chemical stability and reduce the surface roughness of the overlying silver film, without
increasing ohmic plasmon losses. The structures were physically and optically characterized
and compared with nanostructures of single gold layer. Ultrasmooth and chemically stable
trilayer nanostructures with a surface roughness <0.5 nm were obtained following a simple
and reproducible fabrication process. They showed a Figure of Merit (FOM) value up to 69.2
RIU-1 which is significantly higher (more than 95%) than the gold monolayer counterpart.
Their potential for biosensing was demonstrated by employing the trilayer sensor for the
direct and refractometric (label-free) detection of CRP protein biomarker in undiluted urine
achieving a LOD in the pM order.

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