Reproducible Enhancement of Fluorescence by Bimetal Mediated Surface Plasmon Coupled Emission for Highly Sensitive Quantitative Diagnosis of Double‐Stranded DNA

Abstract

Plasmonic enhancement of fluorescence from SYBR Green I conjugated with a double-stranded DNA (dsDNA) amplicon is demonstrated on polymerase chain reaction (PCR) products. Theoretical computation leads to use of the bimetallic (Au 2 nm-Ag 50 nm) surface plasmons due to larger local fields (higher quality factors) than monometallic (Ag or Au) ones at both dye excitation and emission wavelengths simultaneously, optimizing fluorescence enhancement with surface plasmon coupled emission (SPCE). Two kinds of reverse Kretschmann configurations are used, which favor, in signal-to-noise ratio, a fluorescence assay that uses optically dense buffer such as blood plasma. The fluorescence enhancement (12.9 fold at maximum) with remarkably high reproducibility (coefficient of variation (CV) < 1%) is experimentally demonstrated. This facilitates credible quantitation of enhanced fluorescence, however unlikely to obtain by localized surface plasmons. The plasmon-induced optical gain of 46 dB due to SPCE-active dye molecules is also estimated. The fluorescence enhancement technologies with PCR enables LOD of the dsDNA template concentration of ≈400 fg µL (CV < 1%), the lowest ever reported in DNA fluorescence assay to date. SPCE also reduces photobleaching significantly. These technologies can be extended for a highly reproducible and sufficiently sensitive fluorescence assay with small volumes of analytes in multiplexed diagnostics.

Label-free localized surface plasmon resonance biosensor composed of multi-functional DNA 3 way junction on hollow Au spike-like nanoparticles (HAuSN) for avian influenza virus detection

“…The electron oscillation originating from electromagnetic waves triggers a binding interaction event in the nanoparticle interface, thus providing high sensitivity [19]. Moreover, this plasmonic event can be tuned to excite the fluorescence dye-labeled bioprobe that exhibits ultra-sensitivity in order to detect the H5N1 virus [20,21]. Advanced bioprobes have been developed to detect H5N1 accurately with high sensitivity.…”

“…The 5′ end of DNA 3 W Jb was labeled with FAM dye (FAM/3 W Jb) for signal enhancement. It is reported that the fluorescence dye can be excited by a plasmonic field, which increases the detection sensitivity effectively [20,21]. To increase the LSPR enhancement effect, FAM dye was introduced.…”

Directional Modulation of Fluorescence by Nanowire‐Based Optical Traveling Wave Antennas

“…Efficient detection of fluorescence from quantum emitters (QEs), such as semiconductor quantum dots (QDs), fluorescent dyes, or J‐aggregates, is vital for optical sensing and microscopic imaging in the fields of quantum information, molecular biology, and analytical chemistry . The radiation shape of the fluorescence flowing into the far field is a critical factor for efficient photon collection.…”

Fluorescence Enhancement Using Bimetal Surface Plasmon-Coupled Emission from 5-Carboxyfluorescein (FAM)

“…This is then followed by a near-field coupling of the excited state of dye molecules with the surface plasmons, at an emission wavelength of (λ em ). This leads to directional radiation at λ em into a transparent high index medium interfaced with the plasmonic metal film [ 5 , 6 , 7 , 8 , 9 , 10 , 23 , 24 , 35 , 36 ]. The directional radiation would favor fluorescence collection efficiency, which also contributes to the SNR elevation.…”