Diverse clustered protocadherins are thought to function in neurite morphogenesis and neuronal connectivity in the brain. Here, we report that the protocadherin alpha (Pcdha) gene cluster regulates neuronal migration during cortical development and cytoskeletal dynamics in primary cortical culture through the WAVE (Wiskott-Aldrich syndrome family verprolin homologous protein, also known as Wasf) complex. In addition, overexpression of proline-rich tyrosine kinase 2 (Pyk2, also known as Ptk2b, Cakβ, Raftk, Fak2, and Cadtk), a non-receptor cell-adhesion kinase and scaffold protein downstream of Pcdhα, impairs cortical neuron migration via inactivation of the small GTPase Rac1. Thus, we define a molecular Pcdhα/WAVE/Pyk2/Rac1 axis from protocadherin cell-surface receptors to actin cytoskeletal dynamics in cortical neuron migration and dendrite morphogenesis in mouse brain.

The growing demands for optical anti-counterfeiting technology require the development of new environmentally friendly materials with single component, multimodal fluorescence and high stability. Herein, the Bi/Sb codoped Cs2Ag0.1Na0.9InCl6 lead-free double perovskite material is reported as an efficient multimodal luminescence material with excitation-wavelength-dependent emission. When excited by 360 nm UV light, dual-emission is observed at 455 and 560 nm, which comes from the 3P1–1S0 transition of Sb3+ ions and self-trapped excitons (STEs), respectively. Under the 320 nm UV lamp, the microcrystals show only a blue emission centered at 455 nm. Therefore, the Bi/Sb codoped Cs2Ag0.1Na0.9InCl6 double perovskite emits blue and yellow lights under the 320 and 360 nm UV lamp, respectively. Moreover, the obtained double perovskite shows a high PLQY up to 41% and excellent stability against both air and high temperature, which make it a promising anti-counterfeiting material.

Single component nanocrystals (NCs) with white fluorescence are promising single layer color conversion media for white light-emitting diodes (LED) because the undesirable changes of chromaticity coordinates for the mixture of blue, green and red emitting NCs can be avoided. However, their practical applications have been hindered by the relative low photoluminescence (PL) quantum yield (QY) for traditional semiconductor NCs. Though Mn-doped perovskite nanocube is a potential candidate, it has been unable to realize a white-light emission to date. In this work, the synthesis of Mn-doped 2D perovskite-related CsPbClBr nanoplatelets with a pure white emission from a single component is reported. Unlike Mn-doped perovskite nanocubes with insufficient energy transfer efficiency, the current reported Mn-doped 2D perovskite-related CsPbClBr nanoplatelets show a 10 times higher energy transfer efficiency from perovskite to Mn impurities at the required emission wavelengths (about 450 nm for perovskite emission and 580 nm for Mn emission). As a result, the Mn/perovskite dual emission intensity ratio surprisingly elevates from less than 0.25 in case of Mn-doped nanocubes to 0.99 in the current Mn-doped CsPbClBr nanoplatelets, giving rise to a pure white light emission with Commission Internationale de l'Eclairage (CIE) color coordinates of (0.35, 0.32). More importantly, the highest PL QY for Mn-doped perovskite-related CsPbClBr nanoplatelets is up to 49%, which is a new record for white-emitting nanocrystals with single component. These highly luminescent nanoplatelets can be blended with polystyrene (PS) without changing the white light emission but dramatically improving perovskite stability. The perovskite-PS composites are available not only as a good solution processable coating material for assembling LED, but also as a superior conversion material for achieving white light LED with a single conversion layer.

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In this work, we reported original synthesis of ZnTe nanoparticles in aqueous solution. The solution pH is believed to be a major factor governing the synthesis of thioglycolic acid (TGA)capped ZnTe nanoparticles. In the pH range of 5.9-7.1 and the pH range over 10.0, TGA-capped ZnTe nanoparticles can be successfully prepared. In the pH range of 7.1-10.0, TGA-capped ZnTe nanoparticles rapidly precipitate from the solution, which is caused by the formation of Zn(OH) 2 precipitates and the strong adsorption incapacity of Zn(OH) 2 with TGA-capped ZnTe nanoparticles. When 1-thiolglycerol (TG) is selected as the ligand, ZnTe nanoparticles show good stability in the pH range of 7.1-10.0 due to the weak adsorption capacity of Zn(OH) 2 with TG-capped ZnTe nanoparticles. As a result, ZnTe nanoparticles can be prepared in a wide pH range using TGA and TG as the ligands.

In reeler mutant mice, which are deficient in reelin (Reln), the lamination of the cerebral cortex is disrupted. Reelin signaling induces phosphorylation of LIM kinase 1, which phosphorylates the actin-depolymerizing protein cofilin in migrating neurons. Conditional cofilin mutants show neuronal migration defects. Thus, both reelin and cofilin are indispensable during cortical development. To analyze the effects of cofilin phosphorylation on neuronal migration we used in utero electroporation to transfect E14.5 wild-type cortical neurons with pCAG-EGFP plasmids encoding either a nonphosphorylatable form of cofilin 1 (cofilin S3A ), a pseudophosphorylated form (cofilin S3E ) or wild-type cofilin 1 (cofilin WT ). Wild-type controls and reeler neurons were transfected with pCAG-EGFP. Real-time microscopy and histological analyses revealed that overexpression of cofilin WT and both phosphomutants induced migration defects and morphological abnormalities of cortical neurons. Of note, reeler neurons and cofilin S3A -and cofilin S3E -transfected neurons showed aberrant backward migration towards the ventricular zone. Overexpression of cofilin S3E , the pseudophosphorylated form, partially rescued the migration defect of reeler neurons, as did overexpression of Limk1. Collectively, the results indicate that reelin and cofilin cooperate in controlling cytoskeletal dynamics during neuronal migration.

To prepare biologically available Zn-based NCs in aqueous solution, we herein reported the synthesis of aqueous Cu:ZnSe/ZnS NCs with internally doped aqueous Cu:ZnSe NCs as the core template. Due to the dual protection of Cu impurities by the ZnSe core and ZnS shells, the as-prepared Cu:ZnSe/ZnS NCs show excellent stability in the open air, which overcomes the intrinsic instability of traditional aqueous Cu:ZnSe NCs. The as-prepared Cu:ZnSe/ZnS NCs possess extremely good stability, good biocompatibility and lower cytotoxicity, and thus can be used as a promising candidate for fluorescent NC-based biological applications.

The photoluminescence (PL) quantum yield (QY) is a significant parameter for evaluating the optical properties of fluorescent nanocrystals (NCs). Over the past two decades, different experimental conditions were used for the QY measurement of fluorescent NCs. It makes the reported QY value incomparable in different reference works. Up to now, a definite standard for the QY measurement of fluorescent NCs is still lacking. In this work, NC exciton absorbance in range of 0.01-0.05 is recommended as a new standard condition for the QY measurement of NCs, which is established by consideration of the accuracy of both integrated fluorescent emission and absorbance at excitation wavelength. The measured QY of NCs only convincing in the recommended standard condition. For NCs with a much higher exciton absorbance than the standard condition, their actual PL QY can be obtained by two different ways. First, fluorescent NCs are directly used for the QY measurement. Then the actual QY is available after calibration of the measured apparent QY. Second, fluorescent NCs are diluted to the standard condition before the QY measurement. In this case, the measured QY is the actual QY.