Cellphone Monitoring of Multi-Qubit Emission Enhancements from Pd-Carbon Plasmonic Nanocavities in Tunable Coupling Regimes with Attomolar Sensitivity

Abstract

We demonstrate for the first time the tuning of qubit emission based on cavity engineering on plasmonic silver thin films. This tunable transition from weak to strong coupling regime in plasmon-coupled fluorescence platform was achieved with the use of palladium nanocomposites. In addition to our recently established correlation between Purcell factor and surface plasmon-coupled emission enhancements, we now show that the qubit-cavity environment experiences the Purcell effect, Casimir force, internal fano resonance, and Rabi splitting. Finite-difference time-domain simulations and time correlated single photon counting studies helped probe the molecular structure of the radiating dipole, rhodamine-6G, in palladium-based nanocavities. The sensitivity of the qubit-cavity mode helped attain a DNA detection limit of 1 aM (attomolar) and multianalyte sensing at picomolar concentration with the use of a smartphone camera and CIE color space. We believe that this low-cost technology will lay the groundwork for mobile phone-based next-gen plasmonic sensing devices.

Femtomolar Detection of Spermidine Using Au Decorated SiO2 Nanohybrid on Plasmon-Coupled Extended Cavity Nanointerface: A Smartphone-Based Fluorescence Dequenching Approach

“…Unlike the cost intensive spectrophotometer detection platforms that are commonly used for this purpose, in this study we demonstrate a label-free smartphone-based SPCE detection technique that is portable and economically viable for resource-limited settings. SPCE has been used for studying spectral shifts in fluorescence emission patterns to gather noteworthy information such as DNA-hybridization, attomolar sensitivity and influence of Purcell factor on quantum confinement from nanointerfaces. − In this regard, we also present a consistent shift in molecular fluorescence from AuSil-spermidine ensemble in SPCE with increasing concentration of spermidine. This spectral red shift in fluorescence was found to be in excellent agreement with shift in the color observed in CIE chromaticity diagram obtained using smartphone-based detection technique.…”

“…After the first time utilization of silver nanoparticles (AgNPs) as spacer material by Lakowicz et al to realize 60-fold increase in SPCE, there has been extensive use of this plasmonic architecture in biochemical research for multifarious applications. − In this context, several templates such as DNA, proteins, intermetallics (like TiC, TiN, and TiCN), low dimensional carbon substrates and graphene (Dirac Fermions) decorated with AgNPs have been explored to comprehend the modulation in hot-spot intensities at the nanointerface due to interaction of these templates with AgNPs. − These investigations have provided novel insights into physicochemical aspects of plasmonic coupling at interfaces pertaining to Purcell effect, Casimir force, Fabry–Perot mode-coupling, quantum confinement, and Rabi splitting to name a few. − However, these assessments have been restricted to the use of AgNPs as the primary plasmonic material. Silver suffers from quick oxidation and parasitic material Ohmic losses due to coarseness of the surface.…”

Surface Plasmon-Coupled Dual Emission Platform for Ultrafast Oxygen Monitoring after SARS-CoV-2 Infection

“…To augment the emission from a radiating dipole or fluorophore, different nanomaterials were used to fabricate the SPCE substrate. This increases the plasmon-dipole interaction and in turn, the fluorescence emission, either by manipulating the hotspot intensity , or increasing the radiative emission and outcoupling of the fluorescence . So far, there have been multiple studies on augmented enhancements in fluorescence emission with the use of several plasmonic substrates − and their application as ultra-sensitive sensors.…”

Engineering of Exciton–Plasmon Coupling Using 2D-WS2 Nanosheets for 1000-Fold Fluorescence Enhancement in Surface Plasmon-Coupled Emission Platforms

“…As a consequence, there is efficient charge transfer from the emitting dipole (RhB) to the surface plasmons of silver thin films . This phenomenon resulted in enhanced coupling of the emitting dipole with surface plasmons, thereby augmenting the fluorescence emission by increasing the “hotspot” intensity. ,, However, in the case of thermally treated intermediate–WS 2 , the augmented fluorescence emission can be ascribed to the formation of the incomplete 2H-phase providing synergistic contribution of the metallic as well as semiconducting phase of WS 2 , resulting in increased coupling of the fluorophore with the surface plasmons. Further studies are underway to understand this intermediate phase.…”

“…9 Fluorescence enhancement studies are carried out by fabrication of the SPCE substrate in either a cavity or spacer architecture. 10,11 In the spacer architecture, the radiating dipole is separated from the metal thin film due to the presence of a spacer layer of the plasmonic nanomaterial. In the cavity architecture, the radiating dipole is sandwiched in the infinitesimal gap between the metal thin film and the plasmonic nanomaterial.…”