Although
luminescence spectroscopy has been a promising sensing
technology with widespread applications in point-of-care diagnostics
and chem-bio detection, it fundamentally suffers from low signal collection
efficiency, considerable background noise, poor photostability, and
intrinsic omnidirectional emission properties. In this regard, surface
plasmon-coupled emission, a versatile plasmon-enhanced detection platform
with >50% signal collection efficiency, high directionality, and
polarization
has previously been explored to amplify the limit of detection of
desired analytes. However, high Ohmic loss in metal-dependent plasmonic
platforms has remained an inevitable challenge. Here, we develop a
hybrid nanocavity interface on a template-free and loss-less photonic
crystal-coupled emission (PCCE) platform by the quintessential integration
of high refractive index dielectric Nd2O3 “Huygens
sources” and sharp-edged silver nanoprisms (NPrs). While efficient
forward light scattering characteristics of Nd2O3 nanorods (NRs) present 460-fold emission enhancements in PCCE, the
tunable localized plasmon resonances of NPrs display high electromagnetic
field confinement at sharp nanotips and protrusions, boosting the
enhancements 947-fold. The judicious use of silver NPr (AgNPr) metal-Nd2O3 dielectric hybrid resonances in conjugation
with surface-trapped Bloch surface waves of the one-dimensional photonic
crystal (1DPhC) displayed unprecedented >1300-fold enhancements.
The
experimental results are validated by excellent correlations with
numerical calculations. The multifold hotspots generated by zero and
nonzero nanogaps between the coassembly of NPrs, NRs, and 1DPhCs are
used for (i) determination of hyper and hypothyroidism levels through
monitoring the concentration of iodide (I–) ions
and (ii) single-molecule detection (zeptomolar) of the stress hormone,
cortisol, through the synthesized cortisol-rhodamine B conjugate obtained
using a simple esterification reaction.
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