Engineering single-molecule fluorescence with asymmetric nano-antennas.

As a powerful tool for studying molecular dynamics in bioscience, single-molecule fluorescence detection provides dynamical information buried in ensemble experiments. Fluorescence in the near-infrared (NIR) is particularly useful because it offers higher signal-to-noise ratio and increased penetration depth in tissue compared with visible fluorescence. The low quantum yield of most NIR fluorophores, however, makes the detection of single-molecule fluorescence difficult. Here, we use asymmetric plasmonic nano-antenna to enhance the fluorescence intensity of AIEE1000, a typical NIR dye, by a factor up to 405. The asymmetric nano-antenna achieve such an enhancement mainly by increasing the quantum yield (to ~80%) rather than the local field, which degrades the molecules' photostability. Our coupled-mode-theory analysis reveals that the enhancements stem from resonance-matching between antenna and molecule and, more importantly, from optimizing the coupling between the near- and far-field modes with designer asymmetric structures. Our work provides a universal scheme for engineering single-molecule fluorescence in the near-infrared regime.

Quantitative Single-Particle Fluorescence Imaging Elucidates Semiconductor Shell Influence on Ag@TiO2 Photocatalysis.

The understanding of the structure-reactivity relationship is helpful for the nanocatalyst (NC) design. However, though precisely parse, this information is challenging due to the heterogeneity of NCs and the complex mechanism of energetic charge carrier (e-/h+ pairs) generation and transfer within the catalysts upon light irradiation. Here, the effect of the semiconductor shell on the photocatalytic redox reaction is probed at the single-Ag@TiO2 NC level with single-molecule imaging. By engineering the TiO2 shell thickness, catalytic activities of the NCs are precisely controlled and quantitatively measured to show a parabolic-like distribution with increasing TiO2 thickness. Besides, the varied activity among different NCs and the dynamic activity fluctuation of single NCs during continuous redox conversion are observed. Mathematical analysis indicates that the TiO2 layer affects the activity of the core-shell NCs by simultaneously affecting the fate of photo-induced e-/h+ pairs and hot electrons generated at the Ag core. This work sheds light on molecular-scale elucidation of the impact of metal-semiconductor NC structures on their reactivities.

Textile Display for Electronic and Brain-Interfaced Communications.

Textile displays are poised to revolutionize current electronic devices, and reshape the future of electronics and related fields such as biomedicine and soft robotics. However, they remain unavailable due to the difficulty of directly constructing electroluminescent devices onto the textile-like substrate to really display desired programmable patterns. Here, a novel textile display is developed from continuous electroluminescent fibers made by a one-step extrusion process. The resulting displaying textile is flexible, stretchable, three-dimensionally twistable, conformable to arbitrarily curved skins, and breathable, and can dynamically display a series of desired patterns, making it useful for bioinspired electronics, soft robotics, and electroluminescent skins, among other applications. It is demonstrated that these displaying textiles can also communicate with a computer and mouse brain for smart display and camouflage applications. This work may open up a new direction for the integration of wearable electroluminescent devices with the human body, providing new and promising communication platforms.