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2D transition metal carbides, nitrides and carbonitrides, namely the MXenes, attract more and more attentions due to their unique properties. Here, we report a simple one-step molten salt etching method to prepare Co modified MXene hybrid (Ti3C2Tx:Co) by the reaction of Ti3AlC2 with Lewis acid CoCl2 at 750 °C. Most of Co atoms aggregates in the interlayered space of Ti3C2Tx. Benefitting from the improved electron charge transfer efficiency and increased active sites, the sulfuric acid treated Ti3C2Tx:Co-12h hybrid exhibits excellent electrocatalytical activity for hydrogen evolution reaction in alkaline media, delivering a current density of 10 mA cm−2 at an overpotential of 103.6 mV, which is lower than most noble metal free MXene based electrocatalysts. The results illustrate that the proposed method is very facile and useful to incorporate mid-to-late transition metals into the MXene phase to prepare MXene based HER electrocatalysts.

Mechanical or physical cues are associated with the growth and differentiation of embryonic stem cells (ESCs). While the substrate stiffness or topography independently affects the differentiation of ESCs, their cooperative regulation on lineage-specific differentiation remains largely unknown. Here, four topographical configurations on stiff or soft polyacrylamide hydrogel were combined to direct hepatic differentiation of human H1 cells via a four-stage protocol, and the coupled impacts of stiffness and topography were quantified at distinct stages. Data indicated that the substrate stiffness is dominant in stemness maintenance on stiff gel and hepatic differentiation on soft gel while substrate topography assists the differentiation of hepatocyte-like cells in positive correlation with the circularity of H1 clones initially formed on the substrate. The differentiated cells exhibited liver-specific functions such as maintaining the capacities of CYP450 metabolism, glycogen synthesis, ICG engulfment, and repairing liver injury in CCl4-treated mice. These results implied that the coupling of substrate stiffness and topography, combined with the biochemical signals, is favorable to improve the efficiency and functionality of hepatic differentiation of human ESCs.

Currently there is tremendous interest in the discovery of low cost and efficient electrocatalysts for the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER). In this work, iron-doped nickel boride (FexNi1-xB) and nickel boride (NiB) were successfully grown on 3D self-supporting graphene (SSG) electrodes via a one-step reduction approach. The Fe0.2Ni0.8B/SSG electrode required a very low overpotential of only 263 mV for OER (the best OER activity achieved to date for a metal boride). NiB/SSG showed modest OER performance but excellent HER activity. A water electrolyzer comprising Fe0.2Ni0.8B/SSG and NiB/SSG delivered a current density of 10 mA cm−2 at a voltage of only 1.62 V. Further, the Fe0.2Ni0.8B/SSG and NiB/SSG catalysts showed excellent stability with no deactivation observed over 14 h of testing. Results demonstrate that nickel boride-based electrocatalysts are promising lost cost alternatives to precious metal-based electrocatalysts for OER, HER and overall water splitting.

Cytotoxicity of nonylphenol on spermatogonial stem cells via phosphatidylinositol-3-kinase/protein kinase B/mammalian target of rapamycin pathway

The optoelectronic application of fluorescent lead halide perovskite (LHP) nanocrystals is limited by their poor stability in humid atmosphere. However, we found that high-quality and high-stability fluorescent perovskites embedded in PbBrOH can be synthesized via the reaction of PbBr2 with MBr (M: Cs or CH3NH3+) triggered with imidazole derivatives in water. Imidazole can etch and hydrolyze the nonluminescent MPbBr3 to form high-quality fluorescent perovskites. After the perovskites are formed, a protective PbBrOH matrix grows rapidly on the surface of the perovskite nanocrystals and acts as a water-resistant layer. The embedded fluorescent perovskites can exhibit great stability even in water, heat and UV light with a PLQY of up to 30%. Density functional theory (DFT) calculations show that the enhanced stability results from the positive energy cost of the water molecule entering the lattice of PbBrOH, which is much higher than the negative value for water entering CsPbBr3; therefore, water is prevented by the PbBrOH surface from entering the embedded fluorescent perovskite. The PbBrOH surface layer has twofold beneficial effects: (i) preventing water from entering the perovskite nanocrystals, (ii) dispersing the perovskite nanocrystals in the matrix and preventing their aggregation so that highly luminescent composites can be formed. Our strategy opens a new avenue for the development of high-efficiency and high-stability fluorescent inorganic and organic perovskites.

Great attention has been paid to organic–inorganic hybrids in searching for single-phase multiferroics because of their flexible structure design. Here, a new [CuCl4]2− based organic–inorganic hybrid, (bix)CuCl4·H2O (bix = 1,4-bis(imidazol-1-ylmethyl)benzene), is synthesized via a simple solution method. Different from most [CuCl4]2− based organic–inorganic hybrids, tetrahedral [CuCl4]2− units in (bix)CuCl4·H2O are connected to each other through water molecules and form one dimensional chains. The coexistence of ferroelectric and antiferromagnetic ordering in (bix)CuCl4·H2O is demonstrated. Its spontaneous polarization and coercive field at room temperature are 2.03 μC cm−2 and 0.32 kV cm−1, respectively. Furthermore, (bix)CuCl4·H2O films with high quality can be easily prepared, which makes them suitable for application in device fabrication.

The transition metal dichalcogenide MoS2 shows good catalytic properties for the hydrogen evolution reaction (HER). However, the HER activity of 2D MoS2 is limited by its poor electrical conductivity. Bi2Se3 nanosheets are topological insulators possessing metallic surface states, thereby displaying unconventional electron dynamics and excellent conductivity. Therefore, combining Bi2Se3 nanosheets and with MoS2 nanosheets represents a rational approach for improving the HER activity of MoS2. In this work, Bi2Se3 nanoflowers were first synthesized via a hot injection method, followed by the slow growth of MoS2 nanosheets on their surface to form heterostructured MoS2@Bi2Se3 nanoflowers. Compared to pristine Bi2Se3 and MoS2, the MoS2@Bi2Se3 nanoflowers exhibited outstanding HER activity in acidic media with an onset overpotential of 134 mV, an overpotential of 208 mV at 10 mA/cm2, a Tafel slope of 57 mV/dec and remarkable stability. The enhanced HER catalytic activity offered by the MoS2@Bi2Se3 nanoflowers is attributed excellent electron transfer from Bi2Se3 to MoS2, as well as the abundance of edge-rich MoS2 nanosheets vertically aligned on the Bi2Se3 support that act as H2 evolution sites.

The development of efficient, stable and low-cost electrocatalysts for the alkaline hydrogen evolution reaction (HER) is critical for large-scale, economically viable water splitting. In this work, we successfully prepared non-precious metal CoB@MoS2 hybrid electrocatalysts for the HER in alkaline media by the reductive growth of cobalt boride nanoparticles (CoB NPs) on the surface of MoS2 nanoflowers (MoS2 NFs). The CoB@MoS2-0.5–300 hybrid showed an HER overpotential of only 146 mV at a current density of 10 mA cm−2 and a Tafel slope of 80.9 mV dec−1 in 1.0 M KOH solution. The significantly enhanced HER activity of the hybrid is primarily attributable to the ability of CoB to drive the OER in alkaline solution and improved electrical conductivity of the hybrid electrocatalyst relative to the pristine MoS2. Furthermore, the synthetic strategy used to prepare the CoB@MoS2 electrocatalyst was successfully applied to prepare NiB@MoS2 and FeB@MoS2 hybrid electrocatalysts, which similarly showed very good HER activity in 1.0 M KOH solution. Thus, this work conclusively demonstrates that the introduction of transition metal borides is an effective approach for enhancing the HER performance of MoS2 in alkaline media.

Because of the anomalous co-deposition, the preparation of Ni content controllable Zn Ni sacrificial coatings with excellent corrosion resistance from aqueous solutions is a great challenge. In this paper, a novel method was developed to deposit Ni content controllable Zn Ni coating by adding appropriate water (0–7 wt%) to the deep eutectic solvent. It was found that the electrochemical windows of ChCl-2urea deep eutectic solvent were nearly unchanged when the water content was Ni alloy can ranged from ~96 wt% to ~4 wt% by regulating the water content and deposition potential. The Zn alloy coating with ~14 wt% Ni and single γ phase exhibited the best protective effects to carbon steel, which was deposited from reline-5 wt% water at −1.2 V. Deep eutectic solvent-water system provides a promising way of preparing Zn Ni alloy coatings with controlled composition and excellent corrosion resistance.

The catalytic activities of three topotactic phase strontium cobaltites (SCO, hexagonal, orthorhombic and tetragonal) for H2O2 decomposition were studied. All they present excellent catalytic activity with good stability at cycled test, and the mesoporous tetragonal SCO exhibits the best activity. Detailed kinetic research indicates the zero-order process of H2O2 decomposition. Increasing the temperature will accelerate the reactions greatly with the controlled temperature in the range of 20–45 °C. The calculated active energy (Ea) for H-SCO, O-SCO and T-SCO is 93.2, 85.1 and 87.5 (kJ/mol), respectively. The efficient catalytic degradation of Rhodamine B illustrates that SCO is a kind of promising catalysis for the advanced oxidation process.

Artificial synaptic devices are the hardware basis of highly efficient neuromorphic networks with low energy consumption. Great challenges still remain in this research field, like improving the response speed, reducing the energy consumption, and exploring new materials and working principles. In this work, we synthesize a new terthiophene monomer functionalized with a conjugated acrylic acid group (MTAA). The electropolymerization of MTAA results in the formation of a three-dimensional network of conducting polymer nanowires (PMTAA). Based on this nanowire network, a two-terminal artificial synaptic device with multilevel conductance states is fabricated. The device is successfully used to emulate important biological synaptic functions, including paired-pulse facilitation (PPF), spike rate-dependent plasticity (SRDP) and spike timing-dependent plasticity (STDP). The carboxyl groups in the polymer provide a possible way to fast neutralize the positively charged polymer backbone during the oxidation process, which results in the fast response of the device to electrical pulses with an ultralow energy consumption of 6.9 fJ per synaptic event.

Bone marrow-derived mesenchymal stem cells (BMSCs) are able to differentiate into functional hepatocytelike cells, which are expected to serve as a potential cell source in regenerative medicine, tissue engineering, and clinical treatment of liver injury. Little is known about whether and how space microgravity is able to direct the hepatogenic differentiation of BMSCs in the actual space microenvironment. In this study, we examined the effects of space microgravity on BMSC hepatogenic differentiation on board the SJ-10 Recoverable Scientific Satellite. Rat BMSCs were cultured and induced in hepatogenic induction medium for 3 and 10 d in custom-made space cell culture hardware. Cell growth was monitored periodically in orbit, and the fixed cells and collected supernatants were retrieved back to the Earth for further analyses. Data indicated that space microgravity improves the differentiating capability of the cells by up-regulating hepatocyte-specific albumin and cytokeratin 18. The resulting cells tended to be maturated, with an in-orbit period of up to 10 d. In space, mechanosensitive molecules of β1-integrin, β-actin, α-tubulin, and Ras homolog gene family member A presented enhanced expression, whereas those of cell-surface glycoprotein CD44, intercellular adhesion molecule 1, vascular cell adhesion molecule 1, vinculin, cell division control protein 42 homolog, and Rho-associated coiled-coil kinase yielded reduced expression. Also observed in space were the depolymerization of actin filaments and the accumulation of microtubules and vimentin through the altered expression and location of focal adhesion complexes, Rho guanosine 5'-triphosphatases, as well as the enhanced exosome-mediated mRNA transfer. This work furthers the understanding of the underlying mechanisms of space microgravity in directing hepatogenic differentiation of BMSCs.-Lü, D., Sun, S., Zhang, F., Luo, C., Zheng, L., Wu, Y., Li, N., Zhang, C., Wang, C., Chen, Q., Long, M. Microgravity-induced hepatogenic differentiation of rBMSCs on board the SJ-10 satellite.

Stretchable and self-healing polymer gels with luminescent property are very promising materials for next generation soft optical devices. This work presents the preparation of self-healing and luminescent polymer gels by simply blending organometal halide perovskite nanocrystals (OHP NCs) with poly(dimethylsiloxane)-urea copolymer (PDMS-urea). On the one hand, the obtained luminescent gels are not only flexible, stretchable and relatively transparent, they also exhibit excellent self-healing capability due to the reversible hydrogen bonding network in the PDMS-urea copolymer. On the other hand, the embedding of OHP NCs (MAPbBr3 and MAPbI3 NCs) inside the hydrophobic PDMS-urea gel greatly improved the photoluminescence stability of OHP NCs against water. Their applications as phosphors for LEDs have been demonstrated. Both the MAPbBr3/PDMS-urea gel and MAPbI3/PDMS-urea gel can fully convert the blue emission of GaN chip to green and red emissions, respectively. These gels can be used as photoluminescent materials in flexible optical devices with good self-healing capability.

Arthritis remains the notion of a hard-to-treat disease that raises an area of unmet clinical need. The phytomedicine tripterine (Tri) and trace element selenium (Se) have been shown to be of anti-inflammatory activity. This study was devoted to develop nanomedicine containing Tri and Se used for fighting against arthritis via a coordination mechanism. Se-deposited Tri phytosomes (Se@Tri-PTs) were prepared by a melting-hydration/in situ reduction technique and characterized by particle size, ζ potential, morphology, and entrapment efficiency (EE). The resultant Se@Tri-PTs were 126 nm around in particle size with an EE of 98.85%. Se@Tri-PTs exhibited a sustained drug release both in 0.1 M HCl and pH 6.8 PBS compared with Se-free phytosomes (Tri-PTs). The in vivo antiarthritic test demonstrated that Se@Tri-PTs could result in significant resolution of arthritis and decline of inflammatory factors. Phytosomes primely facilitated the transepithelial transport of Tri, while Se enhanced the antiarthritic efficacy of the phytomedicine synergistically. The present work provides a proof-of-concept for the combined therapy of arthritis using Tri and Se in the form of nanoparticles.

Poly(vinylidene fluoride/trifluoroethylene) (PVDF-TrFE) as a representative organic piezoelectric material have recently attracted wide attention. However, low dielectric permittivity limits its applications. We successfully prepared transparent PVDF-TrFE/graphene oxide (GO) ultrathin films. The addition of GO greatly improved the dielectric properties of PVDF-TrFE. The dielectric constant of the composite film is almost three times of that of the PVDF-TrFE film with the addition of 0.1 wt. % of GO nanosheets. Furthermore, the composite film also exhibits enhanced energy harvesting performance. The electric generator based on the PVDF-TrFE/ GO ultrathin film shows an output voltages of 49 mV under a pressure of 3.06 KPa. The advantages of transparence, flexibility and better energy harvesting performance make PVDF-TrFE/GO composite films much more attractive in promising applications of nano/micro electronic devices.

Bi 2 O 3 nanoparticles are prepared by using a facile solution-based thermal decomposition method assisted by oleylamine. These Bi 2 O 3 nanoparticles self assemble into nanobelts. The reaction time and temperature affect self-assembly behaviour of the Bi 2 O 3 nanoparticles. Increasing the reaction time or temperature results in the larger size of nanoparticles, which leads to failure of formation of nanobelts. It is illustrated that oleylamine and the size of nanoparticles play key roles in the self-assembly of nanoparticles. Based on the experimental results, a formation mechanism of the self-assembled nanobelts was proposed and this method may be extended to fabrication of other metal oxide nanobelts.

In this study, MoS2 nanosheets were first prepared by exfoliating its bulk material in HCl/LiNO3 solution with a yield of 45%, and then a facile strategy was developed to synthesize polyaniline/MoS2 (PANI/MoS2) nanocomposite via in situ polymerization. Structural and morphological characterizations of MoS2 nanosheets and the nanocomposite were investigated by scanning electron microscope (SEM), transmission electron microscope (TEM), and X-ray powder diffraction. The results of SEM illustrated that orderly sawtooth polyaniline (PANI) nanoarrays were formed on the surface of MoS2 nanosheets. The nanocomposite displayed good electrochemical performance as a supercapacitor electrode material. The specific capacitance reached 560 F/g at a current density of 1.0 A g−1 in 1.0 M H2SO4 solution. Such good performance is because that the MoS2 nanosheets provided a highly electrolytic accessible surface area for redox-active PANI and a direct path for electrons.

Organometal halide perovskites, as promising semiconductor materials for achieving future low-cost optoelectronic devices, suffer from inherent instability and undergo extremely fast degradation under exposure to moisture, UV light, or high temperature. Herein, we present a facile and low cost approach for the preparation of perovskite-based composite films via blending CH3NH3PbBr3 nanocrystals (MAPbBr3 NCs) with two kinds of commercially available silicone resins. The highest photoluminescence quantum yield of the prepared composite films is up to 62%. The composite films of MAPbBr3 NCs with phenyl methyl silicon resin (PMSR) show unprecedented stability against water, heat and UV exposure. Their applications as paints or as phosphors for the fabrication of green and white light LEDs are demonstrated.

Phosphorous doped carbon dots (P-CDs) are prepared by a one-step hydrothermal method. The phenomenon of aggregation induced red shift emission (AIRSE) is observed in the obtained P-CDs. The emission wavelength of a P-CD solution can be tuned in the range from 455 nm to 595 nm by changing the solution concentration.

The Escherichia coli aspartate aminotransferase gene was introduced into a high 2-phenylethanol (2-PEA) producing Saccharomyces cerevisiae YS58, and the recombinant strain of S. cerevisiae was utilized for the co-production of 2-PEA and l-homophenylalanine (L-HPA) via a fermentation process. The L-HPA productivity of the recombinant S. cerevisiae improved 78.9% in comparison to the wild-type S. cerevisiae. High yields of 43.7 mM L-HPA and 32.4 mM 2-PEA were achieved. As a result, the coupling of the biosynthesis process for these two products in the recombinant strain led to a more complete and efficient utilization of the substrate, l-phenylalanine.

Thermosensitive PNIPAM-coated Au nanoparticles (AuNPs@P(NIPAM-co-MADMAC)) were synthesized by the radical “grafting through” copolymerization of 4-methacryloyloxy-4′-dimethylaminochalcone (MADMAC), MAEL-capped AuNPs and N-isopropylacrylamide (NIPAM) using azobisisobutyronitrile (AIBN) as the initiator. AuNPs@P(NIPAM-co-MADMAC) were characterized by transmission electron microscopy (TEM), ultraviolet-visible (UV-Vis) spectroscopy, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), 1H nuclear magnetic resonance (NMR), and Fourier transform infrared (FTIR) spectroscopy. AuNPs@P(NIPAM-co-MADMAC) exhibited thermo-sensitivity from poly(NIPAM-co-MADMAC) chains and sensitive fluorescence from the MADMAC group. AuNPs@P(NIPAM-co-MADMAC) showed weak fluorescence after the temperature increased from 25°C to 45°C, or after β-cyclodextrin (β-CD) was added. Furthermore, it exhibited strong fluorescence when the solvent was changed to ethanol or chloroform.

Two types of thermosensitive polymer-modified gold nanoparticles (GNPs), P(DMAM-co-MADMAC)-modified GNPs (GNPs@PDM) and P(NIPAM-co-MADMAC)-modified GNPs (GNPs@PNM), are fabricated by the “grafting through” polymerization technique. The as-prepared GNPs are characterized by UV–vis, TEM, XPS, TGA, FT-IR and 1H NMR spectroscopy. The thermosensitivity and fluorescence of the GNPs are investigated. It is found that all GNPs aqueous solutions but GNPs@PDM1 exhibit thermosensitivity originated from thermosensitive polymer chains and sensitive fluorescence from the dimethylaminochalcone group. The lower critical solution temperature (LCST) of the GNPs decreases with the increasing content of MADMAC unit in the GNPs. The GNPs aqueous solution shows weak fluorescence after the temperature increases from 25 °C to 45 °C, or after β-cyclodextrin (β-CD) is added. Furthermore, it exhibits strong fluorescence when the solvent is changed to ethanol or chloroform, and the fluorescent wavelength undergoes a blue shift from ethanol to chloroform.

A series of pyrenyl-containing PDMAA copolymers were prepared by free radical copolymerization of dimethylacrylamide (DMAA) with pyrenebutanoyloxy ethyl methacrylate (PyBEMA). The structure of as-prepared copolymers was characterized by UV, FT-IR and 1H NMR spectroscopy. The effect of cyclodextrins (&alpha, CD, &beta, CD and &gamma, CD) on the thermosensitivity and fluorescence of the copolymers in aqueous solutions were investigated. It was found that the as-prepared copolymers exhibit lower critical solution temperature (LCST)-type thermosensitivity. Cloud point (Tcp) decreases with the increasing molar content of PyBEMA unit in the copolymers. Tcp of the copolymers increases after the CD is added from half molar to equivalent amount relative to pyrenyl moiety, and that further adding twice equivalent CD results in a slight decrease in Tcp. The copolymers exhibit a pyrene emission located at 377 nm and a broad excimer emission centered at 470 nm. The copolymers in water present a stronger excimer emission (Intensity IE) relative to monomer emission (Intensity IM) than that in ethanol. The IE/IM values decrease after the addition of equivalent &alpha, CD into the copolymers in aqueous solution, respectively. The IE/IM values abruptly increase as the copolymers&rsquo, concentration is over 0.2 mg/L whether in ethanol solution or aqueous solution with or without CD, from which can probably be inferred that intra-polymeric pyrene aggregates dominate for solution concentration below 0.2 mg/L and inter-polymeric pyrene aggregates dominate over 0.2 mg/L. Furthermore, the formation of the CD pseudopolyrotaxanes makes it possible to form pyrene aggregates. For high concentration of 5 g/L, the copolymers and their inclusion complexes completely exhibit an excimer emission. The IE values abruptly increased as the temperature went up to Tcp, which indicates that the IE values can be used to research phase separation of polymers.

Luminescent (trimethylbromomethyl) ammonium lead tribromide ((TMBM)PbBr3) nanocrystals are synthesized by a green single-step mechano-grinding method in large scale. The photoluminescence quantum yield (PL QY) of the obtained (TMBM)PbBr3 nanocrystals is 2.61 %. The luminescence of the nanocrystals can be significantly enhanced by introducing water or methanol during the grinding process. The maximum PL QYs of 7.65 % and 4.69 % are obtained for the nanocrystals prepared by the addition of water and methanol, respectively. The emission light of (TMBM)PbBr3 nanocrystals can be tuned by the doping of chloride ion.

The adhesion of superhydrophobic surface is closely correlated with its surface structures. As a new class of high-efficient green solvents, deep eutectic solvents are widely used to deposit superhydrophobic materials. However, there are still no reports of the electrodeposition of high-adhesive superhydrophobic materials from deep eutectic solvent. Herein, a simple method (free-template) is developed to fabricate an ordered hierarchical structured superhydrophobic Zn/Zn stearate coating with superior corrosion resistance from deep eutectic solvent. The Zn/Zn stearate-4 coating is composed of numerous orderly arranged pure Zn micro-slices and tens of thousands of Zn stearate nano-concaves. The unique structures show excellent superhydrophobic (164.8 ± 0.6°) and high adhesive performances due to the synergetic effect of strong capillary adsorption effect, large van der Waals' forces and quasi-continuous three-phase contact lines. The maximum value of water droplet that can be pinned on the overturned Zn/Zn stearate-4 surface is 30 μL. This work provides a new strategy to fabricate ultra-high adhesive superhydrophobic metal coating, which is promising for the application in microfluidic devices.

In this paper, a novel hydrazide compound (N'-(1,3 dimethylbutylene)-3-hydroxy-naphthohydrazide) (BMH) was synthesized by a simple three-stage reaction and its chemical structure was confirmed by 1H NMR, 13C NMR and FTIR characterization. This compound was used as fluorescent sensor for the detection of Ni2+ based on photoluminescence quenching. The fluorescence quenching of BMH upon the addition of Ni2+ is due to the formation of coordination complex which was verified by bind model and density functional theory studies. The Ni2+ concentration dependent fluorescence quenching efficiency of BMH was examined and the detection conditions were optimized. There is a good linear relationship between the emission intensity quenching (ΔF = F0–F) and the Ni2+ concentration (c) between 80 nM and 2 μM and the detection limit is 60 nM. The simple preparation of the compound BMH and the high sensitivity of the fluorescent sensor hold great promise for the determination of Ni2+ in environment.

A facile one-pot strategy has been developed for the aqueous synthesis of Gd doped CdTe (Gd:CdTe) QDs as fluorescence and magnetic resonance imaging dual-modal agent. The prepared Gd:CdTe QDs showed narrow size distribution and the average size was less than 5nm. The amount of Gd(3+) dopant in Gd:CdTe QDs significantly affected the optical properties of obtained QDs. The highest PL QY for the prepared Gd:CdTe QDs was up to 42.5%. The QDs showed the weak toxicity and significant enhancement in MRI signal. The specific relaxivity value (r1) was determined to be 4.22mM(-1)s(-1). These properties make the prepared Gd:CdTe QDs be an effective dual-modal imaging agent and have great potential applications in biomedical field.

Background: Kaempferol, a natural flavonoid, has been shown to induce cancer cell apoptosis and cell growth inhibition in several tumors. Previously we have conducted a full investigation on the chemical constituents of Gynura medica, kaempferol and its glycosides are the major constituents of G. medica. Here we investigated the growth inhibition and apoptosis induction effect of kaempferol extracted from G. medica. Materials and Methods: The inhibition effects of kaempferol were evaluated by MTS assay and soft agar colony formation assay. Fluorescence staining and western blotting were be used to study the apoptosis. The structure was identified by 1H- NMR), 13C-NMR and ESI-MS analyses. Results: Our results showed that kaempferol’s inhibition of MCF-7 breast cancer cell growth may through inducing apoptosis and downregulation of Bcl2 expression. Conclusion: Kaempferol is a promising cancer preventive and therapeutic agent for breast cancer. List of non-standard abbreviations: MTS: 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, HPLC: High-performance liquid chromatography, NMR: Nuclear Magnetic Resonance, ESI-MS Electrospray Ionization Mass Spectral, PARP: Poly ADP-ribose polymerase

Four types of luminescent nitrogen-doped carbon dots (C-dots) are prepared by using glucose (G) or citric acid (C) as carbon source, and dopamine (D) or 4,7,10-trioxa-1,13-tridecanediamine (T) as nitrogen source, named GD-C-dots, GT-C-dots, CD-C-dots and CT-C-dots. The investigation on the optical, pH-sensitivity and photovoltaic properties of these C-dots illustrates that nitrogen source plays a key role in the properties of obtained C-dots. GD-C-dots and CD-C-dots show interesting electrochemical activities, which can provide fluorescent and electrochemical dual signals for practical applications. We demonstrate that not only the optical properties but also other physicochemical properties can be tuned by appropriate choice of the reaction precursors.

A novel electrochemical biosensor was constructed based on the combination of hemoglobin (Hb), silver nanoparticles (AgNPs) assembled on the surface of polyethyleneimine (PEI) functionalized graphene oxide (PEI-GO), and didodecyldimethylammonium bromide (DDAB) surfactant. AgNPs were formed on the surface of PEI-GO through the direct reduction of silver nitrate by the amine-containing PEI. The resulting AgNPs/PEI-GO composite was combined with DDAB to entrap Hb on the surface of a glassy carbon electrode for fabricating the electrochemical biosensor. The synergistic effects of the AgNPs/PEI-GO and DDAB enhanced the effectiveness of Hb immobilization and made possible its direct electrochemistry. The apparent surface concentration (Γ*) of electroactive Hb in the DDAB/Hb/AgNPs/PEI-GO film was estimated at 8.50 × 10−11 mol cm−2. Moreover, this biosensor showed excellent electrocatalytic activities for reduction of H2O2 with rapid response, high sensitivity, and reliable stability. The catalytic current was linear with H2O2 concentration in the range of 0.50 μmol L−1 to 1.87 mmol L−1 with a detection limit of 0.65 μmol L−1. The apparent Michaelis–Menten constant (KappM) was calculated to be 0.29 mmol L−1. The real samples were detected by the proposed sensor with recoveries from 98.7% to 102.7%. Therefore, the strategy based on combining nanocomposite and surfactant demonstrates a new avenue for the interface fabrication of electrochemical biosensors.

Embryonic stem cells (ESCs) are undifferentiated cells that have the capacity to self-renew and differentiate into a variety of cells and provide cell sources for regenerative medicine or biological specimens for cytotoxicity tests. Calcium silicate (CS), a bioactive silicate ceramic, can stimulate the osteogenic differentiation of various types of stem cells, but its role in regulating the biological phenotypes of ESCs remains unclear. Here, the impact of CS on human ESCs was investigated using CS-supplemented medium. The cytotoxicity of CS to hESCs and its effects on apoptosis, growth, proliferation, and differentiation were quantified systematically. Morphological analysis of hESC colonies indicated that the bioactive ions released from CS have little cytotoxicity to hESCs at two CS concentrations. Immunofluorescence and flow cytometry analyses showed that apoptosis was time-independent at early or late stages of hESC growth. In contrast, CS ion extracts regulated hESC differentiation in a time-dependent manner: ESC stemness was preserved by enhancing Oct-4, Sox-2, and Nanog gene expression at day 3, while the cells tended to differentiate at day 6. Combined tests on gene and protein levels further indicated that hESCs tended to differentiate into mesoderm in the presence of CS ion extracts, especially at low CS concentrations. These results demonstrate the effects of CS extracts on hESC stemness and differentiation at the molecular and cellular levels, suggesting that CS-based biomaterials could serve as a potential regulator for ESCs in regenerative medicine.

Lead halide perovskites (LHPs) are very promising for new optoelectronic devices due to their excellent optical and electronic properties. However, the poor stability against water, heat and UV light greatly restricts their practical applications. In this work, a CH3NH3PbBr3/silicon oil/PDMS-urea composite is prepared by encapsulating CH3NH3PbBr3 nanocrystals and silicon oil into the PDMS-urea polymer matrix. This composite shows characteristics of water-enhanced photoluminescence (PL) and water-driven PL recovery. After immersed in water, the photoluminescence quantum yield of the composite increases from initial 26.0%–52.2%, which is ascribed to the passivation of surface defects by the capping of polymer chains, H3O+ and OH−. The composite possesses superior stability against UV light illumination in water. Furthermore, the composite film exhibits a capability of water-driven PL recovery after UV light irradiation. By applying alternate water/UV treatments, the PL can be reversibly switched “on and off”. The “on/off” ratio value of the PL intensity reached more than 4. These advantages make this composite highly promising in applications utilising luminescent switching and for under water lighting.

A simple direct writing technique is developed for preparing helically structured nanobelts. The geometric asymmetry and surface strain contribute to the formation of helical structure. The shape of the helically structured nanobelts can be tuned by the nozzle size of micropipette and pulling speed. The applicability and generality of this technique are illustrated by successfully preparing the helical nanobelts of PPy, PVP, PVDF-TrFE, PEG, PMVE-MA and PVA. The potential applications of such helical structures in the area of sensor and energy harvesting are also demonstrated.

Bismuth selenide (Bi2Se3) has attracted great attention as one of typical topological insulator materials. In this work, size-controllable Bi2Se3 nanoflowers (NFs) composed of numerous thin nanosheets are successfully synthesized by a hot-solution injection method under mild conditions. The structure and morphology of the obtained Bi2Se3 NFs are characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopic (EDS), and selected area electron diffraction (SAED) techniques. The reaction temperature, time, and surfactant ratio (oleylamine/oleic acid) affect the phase purity and morphology of Bi2Se3 samples. Based on the experimental results, the formation mechanism of Bi2Se3 nanoflowers is proposed. Meanwhile, the photocatalytic behavior of the as-prepared Bi2Se3 nanoflowers in the presence of H2O2 is explored and it is found that the degrading rate of RhB can reach 93% after 2 h visible light irradiation.

A series of copolymers with an adamantyl side group (poly(NIPAM-co-AdMA) and poly(DMAM-co-AdMA)) were prepared by radical copolymerization of N-isopropylacrylamide (NIPAM) and N,N-dimethylacrylamide (DMAM) with a 2-methyl-2-adamantylmethacrylate (AdMA) monomer. The structure and composition of the as-synthesized copolymers were characterized by Fourier transform infrared (FT-IR) spectroscopy, proton nuclear magnetic resonance (1H NMR) spectroscopy, gel permeation chromatography (GPC), thermogravimetric analysis (TGA), and elemental analysis. Temperature and recognition dual responsivity of the copolymers was investigated by cloud point (Tcp) and dynamic light scattering (DLS), respectively. The results show that the as-synthesized copolymers are a kind of temperature-responsive polymer with a lower critical solution temperature (LCST). Tcp was approximately consistent with the critical temperature of intermolecular copolymer association (Tass) from DLS. For these copolymers, Tcp decreases with increasing content of AdMA unit in the copolymers. After the addition of β-cyclodextrins (β-CD), Tcp increases, and the increment of Tcp values gradually became large with increasing content of AdMA in the copolymers. It is host-guest molecular recognition of β-CD and adamantyl groups that endows the as-synthesized copolymers with recognition-tunable thermosensitivity.

The solvent-induced precipitation in a mixture of good and poor solvents was often used to synthesize organometal halide perovskite nanocrystals (OMHP NCs). Here we investigate the formation of OMHP NCs by using HBr based precursors in various solvents. Various emission colors and morphologies of perovskite NCs were obtained depending on the solvents used. The nanoplatelets with blue emission were produced for the low polar solvents, such as toluene, PhCl and EtOAc. The increase in polarity of poor solvents results in the red shift of emission of obtained NCs. The much more polar solvents like acetone and CH3CN lead to formation of CH3NH3PbBr3 NCs (MaPbBr3) with cubic phase. The dispersion behaviors of MaPbBr3 NCs in different solvents was also investigated. MaPbBr3 NCs can exist stably in most unpolar solvents. However, they will be dissolved in polar solvents, like acetone and acetonitrile, to give rise to a clear solution with red emission of Pb2+. By injecting this clear solution to unpolar solvents, OMHP NCs can be reproduced.

Poly(N-isopropylacrylamide) terminated with dimethylaminochalcone unit (DMAC-terminated PNIPAM) were prepared by reversible addition-fragmentation chain transfer polymerization using dimethylaminochalcone-functionalized trithiocarbonate (TTC-DMAC) as chain transfer agent. Photodimerization of DMAC-terminated PNIPAM was confirmed by UV-Vis, fluorescence and GPC measurements. The lower critical solution temperature (LCST) of DMAC-terminated PNIPAM first increases and then decreases with increasing molecular weight. When subjected to 365 nm UV irradiation, a large increase of the LCST of DMAC-terminated PNIPAM has been observed especially in the polymer with low molecular weight. Furthermore, the LCST increases with increasing time of 365 nm UV irradiation, which shows photo-controllable thermosensitivity of DMAC-terminated PNIPAM.

In this study, intermediate temperature ionic conducting Ti 0.95 Mg 0.05 P 2 O 7 sample was prepared by solid state reaction. The variation of conductivities as a function of atmosphere, temperatures (100–300 °C) and the p O 2 pressures were studied. The highest conductivities of Ti 0.95 Mg 0.05 P 2 O 7 are observed in dry air atmosphere to be 1.4×10 −2 S cm −1 at 225 °C and in wet air atmosphere ( p H 2 O=3.2×10 3 Pa) to be 2.0×10 −2 S cm −1 at 200 °C, respectively. The log σ –log( p O 2 ) plot result indicates that Ti 0.95 Mg 0.05 P 2 O 7 is almost a pure ionic conductor under high oxygen partial pressure and a mixed conductor of ion and electron under low oxygen partial pressure. The result of water vapor concentration cells indicate that the sample has a few existence of oxide ionic conduction under wet H 2 atmosphere and mainly protonic conduction under wet O 2 atmosphere.

Bioartificial liver (BAL) system has emerged as an alternative treatment to bridge acute liver failure to either liver transplantation or liver regeneration. One of the main reasons that the efficacy of the current BAL systems was not convincing in clinical trials is attributed to the lack of friendly interface between the membrane and the hepatocytes in liver bioreactor, the core unit of BAL system. Here, we systematically compared the biological responses of hepatosarcoma HepG2 cells seeded on eight, commercially available biocompatible membranes made of acetyl cellulose-nitrocellulose mixed cellulose (CA-NC), acetyl cellulose (CA), nylon (JN), polypropylene (PP), nitrocellulose (NC), polyvinylidene fluoride (PVDF), polycarbonate (PC) and polytetrafluoroethylene (PTFE). Physicochemical analysis and mechanical tests indicated that CA, JN and PP membranes yield high adhesivity and reasonable compressive and/or tensile features with friendly surface topography for cell seeding. Cells prefer to adhere on CA, JN, PP or PTFE membranes with high proliferation rate in spheriod-like shape. Actin, albumin and cytokeratin 18 expressions are favorable for cells on CA or PP membrane, whereas protein filtration is consistent among all the eight membranes. These results further the understandings of cell growth, morphology and spreading, as well as protein filtration on distinct membranes in designing a liver bioreactor.

Three donor-acceptor conjugated polymers were synthesized by combining electron donating benzodithiophene and electron accepting pyromellitic diimide. The relationship between structure and optical, electrochemical properties of the polymers were investigated. The results indicate that replacing the 2-ethylhexyl side chain with the longer 2-octyldodecyl side chain stabilized both the HOMO and LUMO level, and the insertion of thiophene π-bridge between pyromellitic diimide and benzodithiophene led to bathochromic-shifted and broader absorption. The polymers were used as donor materials to fabricate polymer solar cells. The highest open-circuit voltages reached 0.69 V and power conversion efficiencies reached 0.11%.

n-Type conjugated polymers were synthesized by using pyromellitic diimide monomers with two different alkyl side chain substitutions as electron-accepting units and benzodithiophene as electron-donating unit via Stille coupling reaction. The obtained polymers were characterized by UV–vis spectroscopy and cyclic voltammetry. The results illustrate that the substituted alkyl side chains 2-ethylhexyl and 2-octyldodecyl have negligible effect on the optical properties of the resulting polymers. The LUMO levels of the polymers located at −3.5 to −3.6 eV. All-polymer bulk heterojunction solar cell with “P3HT” as p-type polymer in standard architecture were fabricated, the cell based on the polymer with 2-octyldodecyl side chain (P2) shows good photovoltaic performance with power conversion efficiency up to 0.47% and a high open circuit voltage of 0.96 V.

Background Keratinocyte (KC) migration in re-epithelization is crucial in repairing injured skin. But the mechanisms of how mechanical stimuli regulate the migration of keratinocytes have been poorly understood. Methods Human immortalized keratinocyte HaCaT cells were co-cultured with skin fibroblasts on PDMS membranes and transferred to the static stretch device developed in-house for additional 6 day culture under mechanical stretch to mimic surface tension in skin. To detect the expression of proteins on different position at different time points and the effect of β1 integrin mechanotransduction on HaCaT migration, Immunofluorescence, Reverse transcription-polymerase chain reaction, Flow cytometry, Western blotting assays were applied. Results Mechanical receptor of β1 integrin that recognizes its ligand of collagen I was found to be strongly associated with migration of HaCaT cells since the knockdown of β1 integrin via RNA silence eliminated the key protein expression dynamically. Here the expression of vinculin was lower but that of Cdc42 was higher for the cells at outward edge than those at inward edge, respectively, supporting that the migration capability of keratinocytes is inversely correlated with the formation of focal adhesion complexes but positively related to the lamellipodia formation. This asymmetric expression feature was further confirmed by high or low expression of PI3K for outward- or inward-migrating cells. And ERK1/2 phosphorylation was up-regulated by mechanical stretch. Conclusion We reported here, a novel mechanotransduction signaling pathways were β1 integrin-dependent pattern of keratinocytes migration under static stretch in an in vitro co-culture model. These results provided an insight into underlying molecular mechanisms of keratinocyte migration under mechanical stimuli.

In this work, we systematically investigated the one-pot aqueous synthesis conditions of CdHgTe nanocrystals (NCs) using sodium tellurite (Na2TeO3) as the Te source, and found that the added content of Hg2+ and the initial pH value of reaction solutions significantly affected the photoluminescence quantum yield (PL QY) of alloyed CdHgTe NCs. When the concentration of Cd was 1.0 mmol L−1, the mole ratio of Cd/Te/Hg/MPA was 1:0.5:0.05:2.4, and the initial pH value of the reaction solution was about 8.78, the PL QY of as-prepared CdHgTe NCs was up to 45%. Characterization by HRTEM and XRD confirmed the crystalline nature of CdHgTe NCs. Compared to other synthetic approaches of CdHgTe NCs, our experimental results indicate that Na2TeO3 could be an attractive alternative Te source to directly synthesize CdHgTe NCs in aqueous media.

Four organic dyes based on indolo[3,2,1-jk]carbazole (IC-1, IC-2, IC-3, and IC-4) with different π-bridges (benzene ring and thiophene ring) are used for dye-sensitized solar cells (DSSCs) to investigate the effect of π-bridge on their photovoltaic performance. The introduction of thiophene ring as π-bridge (the dye IC-2) greatly improves the cell performance compared to benzene ring. The increasing conjugation length of the molecules decreases the performance of DSSCs. The best performance of DSSC based on IC-2 is obtained with a Voc of 0.66 V and a conversion efficiency of 3.68%. The poor performance of DSSCs based on IC-1 and IC-3 which contains only benzene ring as the π-bridge can be attributed to poor spectral coverage and higher electron charge transfer resistance as evaluated from EIS studies.

In this study, an intermediate temperature ionic conductor, Ce0.95Eu0.05P2O7, was prepared by solid state reaction. The variation of conductivities with the pressure pH2O or time were studied. The highest conductivity of Ce0.95Eu0.05P2O7 sample was observed in dry air atmosphere at 300 °C to be 1.1 × 10 �4 S·cm �1 and in wet air atmosphere (pH2O = 7.4 × 10 3 Pa) at 100 °C to be 1.4 × 10 �3 S·cm �1 , respectively. The log σ ~ log (pO2) plot result indicated that Ce0.95Eu0.05P2O7 was almost a pure ionic conductor under high oxygen partial pressure and a mixed conductor of ion and electron under low oxygen partial pressure.