Red blood cells do not attenuate the SPCE fluorescence in surface assays

Surface plasmon-coupled emission: what can directional fluorescence bring to the analytical sciences?

Surface plasmon-coupled emission (SPCE) arose from the integration of fluorescence and plasmonics, two rapidly expanding research fields. SPCE is revealing novel phenomena and has potential applications in bioanalysis, medical diagnostics, drug discovery, and genomics. In SPCE, excited fluorophores couple with surface plasmons on a continuous thin metal film; plasmophores radiate into a higher-refractive index medium with a narrow angular distribution. Because of the directional emission, the sensitivity of this technique can be greatly improved with high collection efficiency. This review describes the unique features of SPCE. In particular, we focus on recent advances in SPCE-based analytical platforms and their applications in DNA sensing and the detection of other biomolecules and chemicals.

Low-cost plastic plasmonic substrates for operation in aqueous environments

We report a novel design of a multilayer stack to attain surface-plasmon-coupled emission (SPCE) enhancements in liquid medium. Variation in thickness of the multilayer affects the position and depth of resonance plasmon dips. Numerical investigation resulted in an optimal stack configuration that supports long-range surface plasmons. SPCE substrates were prepared on plain BK7 glass and Teflon-AF coated polycarbonate (PC-T) substrates by modifying their surface functionalities using plasma etching. The changes in refractive indices due to the presence of the fluoropolymer layer help reduce the SPCE exit angle from α = 75° (plain BK7) to α = 60° (PC-T) in water without requiring specialized optics.