Biosensing Technologies: A Focus Review on Recent Advancements in Surface Plasmon Coupled Emission

Abstract

In the past decade, novel nano-engineering protocols have been actively synergized with fluorescence spectroscopic techniques to yield higher intensity from radiating dipoles, through the process termed plasmon-enhanced fluorescence (PEF). Consequently, the limit of detection of analytes of interest has been dramatically improvised on account of higher sensitivity rendered by augmented fluorescence signals. Recently, metallic thin films sustaining surface plasmon polaritons (SPPs) have been creatively hybridized with such PEF platforms to realize a substantial upsurge in the global collection efficiency in a judicious technology termed surface plasmon-coupled emission (SPCE). While the process parameters and conditions to realize optimum coupling efficiency between the radiating dipoles and the plasmon polaritons in SPCE framework have been extensively discussed, the utility of disruptive nano-engineering over the SPCE platform and analogous interfaces such as ‘ferroplasmon-on-mirror (FPoM)’ as well as an alternative technology termed ‘photonic crystal-coupled emission (PCCE)’ have been seldom reviewed. In light of these observations, in this focus review, the myriad nano-engineering protocols developed over the SPCE, FPoM and PCCE platform are succinctly captured, presenting an emphasis on the recently developed cryosoret nano-assembly technology for photo-plasmonic hotspot generation (first to fourth). These technologies and associated sensing platforms are expected to ameliorate the current biosensing modalities with better understanding of the biophysicochemical processes and related outcomes at advanced micro-nano-interfaces. This review is hence envisaged to present a broad overview of the latest developments in SPCE substrate design and development for interdisciplinary applications that are of relevance in environmental as well as biological heath monitoring.

Smartphone-Based Attomolar Cyanide Ion Sensing Using Au-Graphene Oxide Cryosoret Nanoassembly and Benzoxazolium-Based Fluorophore in a Surface Plasmon-Coupled Enhanced Fluorescence Interface

“…Furthermore, it is informative to discuss the observation of the high 964-fold fluorescence enhancements with the AuGOCS + GO hybrid system in the SPCE platform, from the perspective of plasmon–exciton coupling. 2D materials with a graphene parent structure present several opportunities for investigating light–matter interactions in the infrared region of the electromagnetic spectrum, as compared to the visible region. , However, a strategic combination of such materials with the plasmonically active interfaces has resulted in strong light–matter interactions in the visible region. − The metal–graphene interfaces have been explored by Sun and co-workers in AuNP–graphene–AuNP hybrid configurations, where the electromagnetic “hotspot” distribution from different dimensions is reported in addition to the charge transfer between graphene and the probe molecule. − Such a coupling effect of the plasmon–exciton results in the local density of states being significantly enhanced with a concomitant change in the lifetime distribution. As a result of this, the surface-enhanced Raman scattering (SERS) of the adsorbed rhodamine moieties is strongly enhanced. − In light of these observations, we anticipate the formation of a plasmon–exciton hybrid as the GO is present in and around the cryosoret of AuNPs in the AuGOCS nanoassembly.…”

Synergy between plasmonic nanocavities and random lasing modes: a tool to dequench plasmon quenched fluorophore emission

“…Finally, the synergy between the RL modes and spectral overlap optimized plasmonic nanocavities has been utilized as a tool to dequench the metal quenched emissions. Several methods have been reported in the literature to dequench the plasmon quenched fluorophore emission, such as surface plasmon coupled emission, 83,84 photonic crystal coupled emission, 85 etc. However, these methods require special optical setup (to fulfil phase matching criteria) to obtain the dequenched emission.…”

Photonic Crystal Enhanced Fluorescence: A Review on Design Strategies and Applications

“…The experiments with PCCE and PCEF substrates can be further explored with different types of nano-engineering over these substrates, presenting newer opportunities for modulating the fluorescence signal intensity. While the metallic NPs suffer from inevitable Ohmic losses, it is important to carefully chose such nanomaterials by taking into consideration the different photonic modes sustained by the PCs [ 224 , 225 , 226 , 227 ]. In this regard, it is important to comprehensively evaluate the physics calculations pertaining to the photonic band gap sustained by different types of PC platforms [ 228 , 229 , 230 ].…”