Mapping Fluorescence Enhancement of Plasmonic Nanorod Coupled Dye Molecules

Abstract

Plasmonically enhanced fluorescence is a widely studied and applied phenomenon, however, only a comparative theoretical and experimental analysis of coupled fluorophores and plasmonic nanoresonators makes it possible to uncover how this phenomenon can be controlled. A numerical optimization method was applied to design configurations that are capable of resulting in an enhancement of excitation and emission, moreover, of both phenomena simultaneously in coupled Cy5 dye molecule and gold nanorod systems. Parametric sensitivity studies revealed how the fluorescence enhancement depends on the molecule’s location, distance and orientation. Coupled systems designed for simultaneous improvement exhibited the highest (intermediate directional) total fluorescence enhancement, which is accompanied by intermediate sensitivity to the molecule’s parameters, except the location and orientation sensitivity at the excitation wavelength. Gold nanorods with a geometry corresponding to the predicted optimal configurations were synthesized, and DNA strands were used to control the Cy5 dye molecule distance from the nanorod surface via hybridization of the Cy5-labelled oligonucleotide. State-of-the-art dSTORM microscopy was used to accomplish a proof-of-concept experimental demonstration of the theoretically predicted (directional) total fluorescence enhancement. The measured fluorescence enhancement was in good agreement with theoretical predictions, thus providing a complete kit to design and prepare coupled nanosystems exhibiting plasmonically enhanced fluorescence.

Triggered cagedSTORM microscopy

“…The brightness of the blinking events (emitted photons over time) carries useful information about the local excitation level, which is often used for local excitation intensity mapping [ 37 – 41 ] or even for determining axial position [ 42 ]. This requires a frame that captures the blinking event during the entire exposure [ 43 ], which necessitates at least three consecutive frames for spontaneous activation or at least two frames for triggered activation.…”

Optimization of Interfacial Properties Improved the Stability and Activity of the Catalase Enzyme Immobilized on Plastic Nanobeads

“…The immobilization of CAT in the AL-CAT and SL-GC-CAT composites was visualized by direct stochastic optical reconstruction microscopy (dSTORM). , First, the particle dispersions were placed on a cover glass and incubated for 20 min to achieve adsorption. After 5 min of fixation with 4% PFA in PBS, specific binding sites were blocked using 10% BSA in PBS for 2 h at 37 °C.…”

Luminescence transformation mechanisms of indocyanine green dye in the presence of gold nanorods

“…When preparing mixtures of ICG with Au NRs/SiO 2 , along with the increase in their quantum yield luminescence, we observed a considerable acceleration of the luminescence attenuation kinetics down to the limit of the experimental setup resolution (about 0.12 ns). Such behavior of luminescent properties indicates the manifestation of the Purcell effect [47][48][49]. Presumably, creation of structures of the Au NRs/SiO 2 type with a SiO 2 layer thickness of 26 nm breaks the conditions for charge transfer between components of the mixture, and Au NRs/SiO 2 play the role of nanoresonators with oscillation modes close to the frequency of ICG monomer luminescence.…”

“…The effect of metal nanoparticles on dye properties can vary in a very wide range [12,27,[31][32][33][34][35][36][42][43][44][45][46]. Possible effects are a change in type and probability of self-association of the dye, an extinguishing of fluorescence of the dye due to nonradiative transfer of electron excitation, as well as a change in the probability of spontaneous emission due to the Purcell effect [47][48][49]. Also, a decrease in the number of degrees of freedom and achievement of molecular skeleton rigidity of the molecule at its adsorption on the surface of a plasmon nanoparticle are possible.…”