The regulation of cellular signaling in vivo has been a challenging task owing to the lack of effective methods for tunable control of the amplitude, location, and duration of cell-signaling events at a deep-tissue level. In this issue of ACS Nano, an intriguing paper by Ambrosone et al. demonstrates that deep-tissue-penetrating near-infrared (NIR) light can be used to control the Wnt/β-catenin-signaling pathway in a single-cell organism (Hydra) by utilizing microcapsules that contain plasmonic gold nanoparticles. In parallel, in recent work, we proposed upconversion nanoparticles (UCNPs) as NIR-light-activatable “wireless” optogenetic tools, and we showed their ability to modulate cell signaling pathways in both mammalian cells and mice. We believe that these interesting NIR-light-responsive nanotechnologies will open new avenues for both basic research and clinical applications.

Near-infrared (NIR) persistent phosphor ZnGa2O4:Cr3+ (ZGC) has unique deep-tissue rechargeable afterglow properties. However, the current synthesis leads to agglomerated products with irregular morphologies and wide size distributions. Herein, we report on in vivo rechargeable mesoporous SiO2/ZnGa2O4:Cr3+ (mZGC) afterglow NIR-emitting nanocomposites that are made by a simple, one-step mesoporous template method. At less than 600 °C, pores in mesoporous silica nanoparticles (MSNs) act as nanoreactors to generate in situ ZnGa2O4:Cr3+ NIR-persistent phosphors. The as-synthesized mZGC preserves defined size, morphology, and mesoporous nanostructure of the MSNs. The persistent luminescence of the as-synthesized mZGC is recharged in a simulated deep-tissue environment (e.g., ≈8 mm pork slab) in vitro by using red light (620 nm). Moreover, mZGC can be repeatedly activated in vivo for persistent luminescence imaging in a live mouse model by using white LED as a light source. Our concept of utilizing mesoporous silica as nanoreactor to fabricate ZGC PL nanoparticles with controllable morphology and preserved porous nanostructure paves a new way to the development and the wide application of deep tissue rechargeable ZGC in photonics and biophotonics.

A multilayer Rosen-type piezoelectric transformer with the size of 20 mm length, 4 mm width and 2.8 mm thickness has been fabricated using ferroelectric single crystal Pb(Mg1/3Nb2/3)O3–PbTiO3. The electrical properties of the prepared transformer were systematically investigated. Results show that the efficiency of this transformer can reach 92% and the voltage step-up ratio under open circuit exceeds 100. Comparing this with the single-layer Rosen-type transformer, we reported lower output impedance and larger step-up voltage ratios have been obtained under the same load resistance. Near the resonance frequency, this transformer has a much purer vibration mode and wider working bandwidth. Furthermore, this transformer can successfully drive a 0.5 W LCD backlight under a lower input voltage without obvious temperature rise. These global properties make this piezoelectric transformer a promising candidate for small power inverters and cryogenic applications.

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