Insight into a reversible energy transfer system

Temperature-sensitive metal-enhanced fluorescence and plasmon resonance energy transfer

Experimental decoupling of the effects of plasmon resonance energy transfer (PRET) and metal-enhanced fluorescence (MEF) within the same nanometal-fluorophore pair is fascinating but challenging. In this study, we presented a possible solution for this by coating plasmonic Au nanoparticles (AuNPs) with temperature-sensitive poly(N-isopropylacrylamide) (pNIPAM) shells and R6G hybrids, termed the Au@p-R nanoplatform, which could reversibly adjust the separation between dyes and the AuNP surface, enabling an ON/OFF switch between MEF and PRET. In our optimization process, we discovered that 20 kDa of pNIPAM causes an MEF effect owing to an appropriate shrinking distance of 6.86 ± 0.85 nm. This dual-model nanoplatform exhibits great potential for tracking temperature-dependent transitions.

Plasmon Resonance Energy Transfer Nanoruler for Pinpointing Molecular Distance and Interaction on the Living Cell Membrane

Developing novel strategies to measure nanoscale distance and molecular interaction on a living cell membrane is of great significance but challenging. Here we develop a model of a linker-free plasmon resonance energy transfer, termed "PRET nanoruler", which is composed of a single-sized nanogold-antibody conjugates donor (G26@antiCD71) and a fluorophore-labeled XQ-2d aptamer receptor (XQ-2d-Cy3), that produces a separation distance (r) dependent energy transfer (ηPRET). Both the theoretical finite element simulation and experiments evidence the observable PRET between single G26NPs and XQ-2d-Cy3. Regardless of the size of ηPRET, we could confirm r is less than 5 nm, the separation of two binding sites is in the range of 13.0-18.0 nm. There is a competitive binding of Tf and XQ-2d-Cy3 on CD71 receptors. PRET nanoruler realizes the estimation of the nanoscale separation distance, and determines the molecular interaction and competitive binding. It is an alternative tool for observing nanoscale single molecular events in the future.

Plasmonic resonance energy transfer from a Au nanosphere to quantum dots at a single particle level and its homogenous immunoassay

PRET from a AuNS to a QD is discovered at a single particle level, and then is used to develop ultra-sensitive homogenous immunoassays.

Tunable quantum dot arrays as efficient sensitizers for enhanced near-infrared electroluminescence of erbium ions

Under electrical pumping conditions, high-efficiency Si-based near-infrared light generation and amplification on a chip have long been pursued for future optical interconnection technology. However, the overall performance of Si-based near-infrared electroluminescence (EL) devices, including the overall efficiency, turn-on voltage and stability under operational conditions, can rarely meet the requirements of monolithic optoelectronic integration. In this work, we designed a confined crystallization growth strategy for fabricating metal oxide quantum dot (QD) arrays embedded in Si-based films as sensitizers of Er³⁺ ions. Through the precise control of particle size and number density of QD sensitizers, the near-infrared photoluminescence (PL) emission of Er³⁺ ions can be enhanced by more than three orders of magnitude. More significantly, such hierarchical control over the regular arrangement of QD arrays not only considerably enhances the resonance energy transfer efficiency, but also offers an effective conduction path for carrier transport. Therefore, the corresponding near-infrared EL device exhibits a decreased turn-on voltage of 4.5 V, a high external quantum efficiency of 0.7%, and a long operational lifetime of more than 1000 hours, making this device superior to most Si-based on-chip near-infrared EL devices. This well-controlled metal oxide QD array represents an ideal sensitizer to effectively promote the EL emission of rare earth ions and reduce the turn-on voltage. Meanwhile, the analysis of the carrier transport mechanism paves the way for future research into resonance energy transfer under electrical pumping conditions.