Surface Plasmon Coupled Fluorescence-Enhanced Interfacial "Molecular Beacon" To Probe Biorecognition Switching: An Efficient, Versatile, and Facile Signaling Biochip.

Integrating probes and a substrate together, a fluorescence-enhanced interfacial "molecular beacon" (FEIMB) is demonstrated, based on directional surface plasmon coupled emission. Through this simple yet efficient interfacial modulation engineering to create an interfacial quencher (graphene oxide)-enhancer (gold nanofilm) pair, the quenching-to-enhancing region of FEIMB can be actively tuned. Therefore, it provides a spatial match between signal transduction and interface-mediated biorecognition switching. Via combination of strong quenching and efficient plasmonic coupling, a synergistically amplified signal-to-background ratio of >1000-fold has been achieved. FEIMBs have been employed in protein and DNA detection, creating a high-performance and universal chip-based plasmon-mediated fluorescence sensing platform.

The synergistic enhancement of silver nanocubes and graphene oxide on surface plasmon-coupled emission.

The enhancement of surface plasmon-coupled emission (SPCE) by the synergistic effect of silver nanocubes (AgNCs) and graphene oxide (GO) on gold film has been observed with the enhancement factor over 30. The enhancement mechanisms were investigated through simulating the electromagnetic (EM) field patterns of near field and testing different concentration of AgNCs and thickness of dye layer. The enhancement was mainly triggered by the high electromagnetic field of AgNCs, the interaction between localized surface plasmons (LSP) and propagating surface plasmons (PSP) and the assistance of GO. This synergistic enhancement strategy provides a simple way to increase SPCE signal and enable develop a new fluorescence-based detection system.

Optical modulator based on propagating surface plasmon coupled fluorescent thin film: proof-of-concept studies.

We demonstrate that the propagating surface plasmon coupled fluorescent thin film can be utilized as a fluorescence modulator to mimic multiple representative Boolean logic operations. Surface plasmon mediated fluorescence presents characteristic properties including directional and polarized emission, which hold the feasibility in creating a universal optical modulator. In this work, through constructing the thin layer with the specific thickness, surface plasmon mediated fluorescence can be modulated with an ON-OFF ratio by more than 5-fold, under a series of coupling configurations.