Epitaxial
growth of an inert shell around the optical active lanthanide
upconversion nanoparticles (UCNPs) is a general strategy to enhance
their brightness. Yet, its potential as a tool in multiplexing emission
tailoring has rarely been reported. Here, by developing the atomic
vacancies into color selectivity actuators, we present an efficient
strategy to achieve inert-shell-modulated multiplexing upconversion
in 1540 nm activated UCNPs. Artificially generated fluoride atomic
vacancies, owing to the decreased NaOH/NH4F dosage during
shell growth, reduce the coordination number of Y–F and lattice
densities in the inert shell, leading to the core–engineered
shell nanoparticles with distinctive emission profiles. The multicolor
tailoring is independent of shell thickness and can be readily applied
to Lu3+/Gd3+-based shells. The upconversion
emission can be exploited to visualize in security decoding and in vivo multiplexing bioimaging. This method of regulating
atomic vacancies based on the inert-shell engineering opens new insights
of upconversion modulation in core–shell lanthanide nanostructures.
The optogenetic neuron ablation approach enables noninvasive remote decoding of specific neuron function within a complex living organism in high spatiotemporal resolution. However, it suffers from shallow tissue penetration of visible light with low ablation efficiency. This study reports a upconversion nanoparticle (UCNP)–based multiplex proteins activation tool to ablate deep‐tissue neurons for locomotion modulation. By optimizing the dopant contents and nanoarchitecure, over 300‐fold enhancement of blue (450–470 nm) and red (590–610 nm) emissions from UCNPs is achieved upon 808 nm irradiation. Such emissions simultaneously activate mini singlet oxygen generator and Chrimson, leading to boosted near infrared (NIR) light–induced neuronal ablation efficiency due to the synergism between singlet oxygen generation and intracellular Ca2+ elevation. The loss of neurons severely inhibits reverse locomotion, revealing the instructive role of neurons in controlling motor activity. The deep penetrance NIR light makes the current system feasible for in vivo deep‐tissue neuron elimination. The results not only provide a rapidly adoptable platform to efficient photoablate single‐ and multiple‐cells, but also define the neural circuits underlying behavior, with potential for development of remote therapy in diseases.
Since the fingerprints of numerous crucial biologic materials can be identified by terahertz (THz) spectroscopy, THz sensing have become an important approach of biological and medical detections. Particularly, benefit from the excellent capability of metasurface, strong interactions between the metasurface and THz waves can be realized, thus the THz sensing with high sensitivity becomes reality. However, the common configuration of metasurface-based THz sensor is composed of metallic subwavelength structure. Due to the inherent resistive loss of metal, it is still a great challenge to further enhance the quality factor (Q-factor) of resonance and sensitivity of THz sensor. In this work, we designed an all-dielectric metasurface with high Q-factor for highly sensitive THz sensors. The metasurface is a windmilllike structure consisting of four cuboids, and every adjacent two cuboids are arranged alternately vertically and horizontally. The transmission spectrum of metasurface exhibits four polarizationindependent and strong resonance peaks with high Q-factor in 0.1-2.5THz, and all of them show high sensitivity related to ambient refractive index. The transmitted structure and polarizationindependent resonances can relief the difficulty of measurement. We believe these studies will lay the theoretical and technical foundation for the design of high-sensitivity terahertz sensing.
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