Flexible Self-Powered Weak Light Detectors Based on ZnO/CsPbBr3/γ-CuI Heterojunctions.

Halide perovskites (HPs) with marvelous optical and electrical properties are regarded as one of the competitive candidates for building next-generation photodetectors (PDs). However, combining their excellent properties with satisfactory long-term robustness is still challenging, ultimately limiting the practical applications of HP-based PDs. Herein, a high vacuum deposition system is employed to fabricate flexible self-powered PDs with a ZnO/CsPbBr3/γ-CuI structure, which shows excellent stability and outstanding performance in weak light detection. Benefiting from the improved crystallinity and optimized device structure, a high detectivity of 8.1 × 1013 Jones and a rapid response speed (rise/decay time of 3.9/1.8 µs) are obtained in this self-powered device. Furthermore, the unencapsulated device exhibits intriguing environmental stability and mechanical flexibility. The photocurrent remains unchanged after 7000 s of continuous operation or 100 bending cycles. Furthermore, a 15 × 15 PD array is fabricated as an image sensor. A high contrast image of the target object can be obtained owing to the high sensitivity and uniformity of the self-powered PDs. These results demonstrate the feasibility and practicality of the ZnO/CsPbBr3/γ-CuI heterojunction for applications in weak light detection and image formation.

Quasi-two-dimensional α-molybdenum oxide thin film prepared by magnetron sputtering for neuromorphic computing.

Two-dimensional (2D) layered materials have attracted intensive attention in recent years due to their rich physical properties, and shown great promise due to their low power consumption and high integration density in integrated electronics. However, mostly limited to mechanical exfoliation, large scale preparation of the 2D materials for application is still challenging. Herein, quasi-2D α-molybdenum oxide (α-MoO3) thin film with an area larger than 100 cm2 was fabricated by magnetron sputtering, which is compatible with modern semiconductor industry. An all-solid-state synaptic transistor based on this α-MoO3 thin film is designed and fabricated. Interestingly, by proton intercalation/deintercalation, the α-MoO3 channel shows a reversible conductance modulation of about four orders. Several indispensable synaptic behaviors, such as potentiation/depression and short-term/long-term plasticity, are successfully demonstrated in this synaptic device. In addition, multilevel data storage has been achieved. Supervised pattern recognition with high recognition accuracy is demonstrated in a three-layer artificial neural network constructed on this α-MoO3 based synaptic transistor. This work can pave the way for large scale production of the α-MoO3 thin film for practical application in intelligent devices.

Separately enhanced dual emissions of the amphiphilic derivative of 2-(2'-hydroxylphenyl) benzothiazole by supramolecular complexation.

Here, we report separately enhanced dual emissions of the amphiphilic derivative of 2-(2'-hydroxyphenyl)benzothiazole (denoted as HBT-11) by supramolecular complexation with cyclodextrins (CDs). When dispersed in water, HBT-11 shows two relatively weak emission bands, which can be assigned to the emissions of enol- and keto-forms, the two tautomers, owing to excited-state intramolecular proton transfers. Upon the addition of α-CD and ß-CD, the keto- and enol-emissions, respectively, are separately enhanced; the enhancement effect is due to the formation of HBT-11/α-CD and HBT-11/ß-CD complexes through multiple hydrogen bonding and host-guest interactions, respectively. It is worth to note that the keto-emission caused by the complex of HBT-11/α-CD has a much shorter wavelength compared with that of the aggregates formed by pure HBT-11. To the best of our knowledge, this is the first time that a study on keto-emission of the isolated HBT chromophore has been reported.

Tuning the emission of a water-soluble 3-hydroxyflavone derivative by host-guest complexation.

3-Hydroxyflavone derivatives have great potential as fluorescent probes for bio-labeling in aqueous medium. They were extensively studied in various organic solvents for the "excited state intramolecular proton transfer" process, but seldom addressed in aqueous solution due to the poor water solubility. Herein, an amphiphilic molecule bearing 3-hydroxyflavone and oligo(ethylene oxide) (denoted as 3HF-EO) was designed and synthesized. Different from the fluorescence in organic solvents, 3HF-EO in aqueous solution showed a remarkable single fluorescence emission, which is ascribed to the fluorescence of its anionic species. We found that the fluorescence intensity could be efficiently tuned via host-guest complexation. α-CD has little effect on the emission, while ß-CD and γ-CD lead to enhanced and reduced emissions of 3HF-EO, respectively. The 1H NMR and 2D NOESY NMR spectra indicate that α-CD barely had any interaction with 3HF-EO, while ß-CD and γ-CD formed complexes with one and two 3HF-EO molecules, respectively. These results provide a sound explanation for the modulated fluorescence intensity.

A near-infrared multifunctional fluorescent probe with an inherent tumor-targeting property for bioimaging.

A mitochondria-targeting probe, by conjugating a quaternary ammonium cation with glucosamine modified pH-activated cyanine, was designed and synthesized. This probe has excellent selectivity and sensitivity toward pH, stability, cellular membrane permeability and low cytotoxicity. Owing to the acidic feature of tumors and the more negative mitochondrial membrane potential of tumor cells than that of normal cells, this probe can selectively accumulate in tumor cells and light up its fluorescence. It has been successfully applied for in vivo tumor imaging with a high signal-to-noise ratio. Moreover, this multifunctional switchable sensor was also employed for the fluorescent imaging of the fluctuation of intracellular pH in HeLa cells.

[Study on cell senescence induced by D-galactose in cultured rat mesenchymal stem cells].

OBJECTIVE: To study morphological and biological senescence changes induced by D-galactose in the cultured rat mesenchymal stem cells. METHODS: After 3rd generations cultured in the DMEM-F12, MSCs were changed into DMEM-F12 medium containing 8 g/L D-galactose and cultured to the 6th generations as the inducement group. The comparison were the 6th generations which was cultured in the DMEM-F12 medium all along, and then identified by surface wave. Using flow cytometer to check the comparisons cell cycle change after swing in with 8 g/L D-galactose within the 4 days. In the first 7 days to draw the growth curve to the two groups. Optical and electronic microscope were used to identify the influences of characteristic morphological of mesenchymal stem cells of the two groups, the influences of biological markers were identified by single cell gel electrophoresis and beta-galactose dye. Results After treatment with D-galactose, the mesenchymal stem cells displayed morphological and biological changes in the cell senescence with the senescent characteristic morphological markers; 85% of the cells were X-gal dye masculine, and the signal cell gel electrophoresis showed DNA damnification. The flow cytometry showed that 90% of the cells stayed in G0/G1, but the cells in S and G2/M almost disappeared. However, the cells in the control group had no such DNA damages. CONCLUSION: D-galactose can induce senescence of the mesenchymal stem cells, and 8 g/L is the best concentration to do so. This study has provided a good model for the research of the mesenchymal stem cells senescence.