Search

An efficient nitrogen doping strategy is developed to accelerate the disorder-to-order phase transition of Pt3Co catalyst, and the as-prepared ordered Pt3Co shows a PEMFC power density of 1.27 W cm−2 at 0.6 V.

MOF-based foam has potential applications in removing antibiotics from water.

The effective control of the sample concentration within droplets is essential in a broad range of assays in chemistry and biochemistry. Here we provide an electrical method for producing batches of aqueous droplets with various chemical concentrations by exploiting fixed-potential induced-charge electroosmosis (ICEO) flow around a bipolar electrode. By applying an AC electric signal to the bipolar electrode and changing the zeta potential on it, the bipolar electrode acts as a gate electrode for generating asymmetric ICEO flow. The ICEO flow induced transverse vortexes interact with two parallel laminar streams with different chemical compositions. Controlled mixing of the aqueous solutions can be achieved by adjusting the shape and size of the asymmetric vortexes

A novel inverse photoconductivity horizon in perovskite photo-memristor applications with various iodine concentrations, electrodes, and modified layers.

On the basis of the 3-(pyrazin-2-yl)-1H-pyrazole-5-carboxylic acid (H2L) ligand, four new polymers [Cu2(L2−)2] (1), [Zn3(L2−)2(H2O)4Cl2]n (2), [Pb(HL−)Cl]n (3), and {[Ni(L2−)(H2O)]·(H2O)}n (4) have been synthesized under solvothermal conditions. Polymer 1 possesses a discrete (0D) binuclear structure, which is further formed into a three-dimensional (3D) supramolecular structure by hydrogen bonding and π⋯π stacking interactions. Polymers 2 and 3 display one-dimensional (1D) infinite chain structures, which further extend into 3D supramolecular structures through hydrogen bonding interactions. Polymer 4 features two-dimensional (2D) layers which can form a 3D supramolecular architecture via interlayer hydrogen bonds. The ligand in the four polymers adopts different coordination modes for constructing versatile structures. Moreover, luminescence sensing study shows that polymer 2 is a promising luminescent sensor for the detection of Cu2+, Co2+ and Fe3+via drastic luminescence quenching in aqueous solution with high efficiency. The quenching constants KSV for Cu2+, Co2+ and Fe3+ are 6.35 × 103 M−1, 8.70 × 103 M−1 and 1.62 × 104 M−1, respectively. What's more, 1–4 with electrochemical luminescence (ECL) properties show high intensity in N,N-dimethylformamide (DMF) solution and high thermal stability.

Organic–inorganic hybrid perovskites have recently emerged as promising potential candidate materials in the area of photoelectrics due to their unparalleled optoelectronic features. However, the performance of an optoelectronic device is always affected by the mixed ionic and electronic conducting behavior within perovskites. Herein, the hysteresis effect on carrier mobility and photoresponse characteristics of perovskites were investigated through adding rational additives to the precursor solution. The results show that the perovskite with foreign fullerene derivative (PCBM) additive can suppress hysteresis behavior and increase the mobility by two-fold, while the perovskite with native iodine (I) additive will amplify hysteresis and reduce the mobility by two orders of magnitude at the room temperature compared with that of the pure perovskite. Furthermore, we found that the response characteristics of the photodetectors are strongly affected by the carrier mobility. Capacitance–voltage results confirm the significant change in hysteresis after the introduction of different additives, which explains the changes in mobility and photoresponse time. Our results enlighten the hysteresis effect related to carrier transport and photoresponse characteristics, and provide guidance for the development of reliable, high performance perovskite devices.

A rhodamine-based derivative, (Z)-2-((3,5-dibromo-2-hydroxybenzylidene)amino)-3′,6′-bis(diethylamino)spiro-[isoindoline-1,9′-xanthen]-3-one (RhDBS), has been chosen as a representative dual chemosensor for VO2+ and Cu2+ among twenty-five Schiff-base receptors. It has been synthesized by Schiff-base condensation and characterized by standard techniques including single crystal X-ray crystallography. RhDBS can hypersensitively detect VO2+via fluorescence “off–on” type switching with a high quantum yield. Meanwhile, the chemosensor exhibits Cu2+-selective chromogenic behavior and Cu2+ ions can be detected by the naked-eye. The detection limits for VO2+ and Cu2+ have been determined to be 3.65 nM and 0.84 μM respectively, which are much lower than the allowable maxima set by the WHO, demonstrating the reliability and high efficiency of this chemosensor. Job's plot and mass spectral analysis show 1 : 1 stoichiometry between RhDBS and metal ions. RhDBS has also shown distinct responses to VO2+ through electrochemical (CV) signals. Additionally, the RhDBS·Cu2+ and RhDBS·VO2+ adducts can act as two secondary colorimetric and fluorescent sensors for pyrophosphate (PPi) anions. Advanced molecular memory devices have been constructed through these properties and interpreted. Notably, the analytical applicability of RhDBS can be further achieved by using test paper strips and silica gel plates. More excitingly, RhDBS can be resoundingly employed to trace intracellular VO2+ ions in living cells and it is the first reported smart chemosensor capable of detecting VO2+in vitro. In the solid state, RhDBS displays distinguished VO2+ and Cu2+ responsiveness along with obvious colour changes and different emission wavelengths which lead to large red shifts of the CIE-diagram. More importantly, some meaningful regular patterns are discovered for the first time through theoretical and experimental studies toward the design of multifunctional materials.

In this study, a novel rhodamine-based probe for the detection of Cu2+ which is conjugated with a 2-(1,3,3-trimethylindolin-2-ylidene) acetaldehyde moiety has been designed and synthesized. The detection is based on the fluorescence resonance energy transfer (FRET) mechanism. The probe exhibits colorimetric and ratiometric responses to Cu2+ with a large Stokes shift (237 nm) and is not disturbed by other coexisting metal ions. The probe can achieve the nanomolar detection of Cu2+ with a detection limit of 1.168 × 10−8 mol L−1. The 1 : 1 stoichiometry of the RhF–Cu2+ complex is supported by the Job's plot, ESI-MS analysis, IR spectral data and density functional theoretical (DFT) studies. More importantly, potential applications of the probe can also be achieved by using test paper strips. Furthermore, the probe can be used for the detection of Cu2+ in actual water samples.

High-performance photodetectors based on organic–inorganic hybrid perovskite single crystals and films have attracted extensive attention recently. In this study, a self-powered behavior was observed in a perovskite photodetector with a special asymmetrical metal/silicon dioxide/perovskite (MOS) structure that lacks the hole and electron transport layers. This self-powered behavior originates from the as-formed built-in electric field within the perovskite film due to the light-induced self-poling effect. The photogenerated carriers are well separated and drift in response to the built-in electric field, resulting in a large photocurrent reaching the nA level without an applied bias. Silicon dioxide acted as a barrier for the carriers, resulting in an ultralow dark current equal to the noise current. This self-powered MOS photodetector exhibited an ION/IOFF ratio of 105 and fast rise and fall characteristics (

Protein kinase B (PknB) is an essential serine/threonine protein kinase required for Mycobacterium tuberculosis (M. tb) cell division and cell-wall biosynthesis. A high throughput screen using PknB identified a (E)-4-oxo-crotonic acid inhibitor, named YH-8, which was used as a scaffold for SAR investigations. A significant improvement in enzyme affinity was achieved. The results indicated that the α,β-unsaturated ketone scaffold and “trans-” configuration are essential for the activity against PknB. And compounds with an aryl group, especially with electron-withdrawing substituents on benzene ring, exhibited four fold potency than that of YH-8.

A sandwich-type (phthalocyaninato)(porphyrinato) europium double-decker complex Eu(TPyP){Pc-(OC8H17)8} [TPyP = meso-tetra(4-pyridyl)porphyrin; Pc-(OC8H17)8 = 2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyanine] (2) was designed and prepared. For comparative studies, Eu(TPyP)(Pc) (1) was also prepared. Highly ordered nanotubes of complexes 1 and 2 were successfully fabricated by using an anodized alumina oxide (AAO) template method. The nanotubes were comparatively investigated by electronic absorption spectra, scanning electron microscopy (SEM), low-angle X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and energy dispersive spectroscopy (EDS) techniques. Both nanotubes of complexes 1 and 2 showed good conductivities and presented an efficient gas sensing platform for the ultrasensitive detection of NO2 at room temperature. In particular, the detection limit and response/recovery times for the proposed sensors based on complex 2 were lower and faster than those of complex 1, indicating the significant effect of a molecular packing mode on tuning the gas sensing performance of organic semiconductors.

A uniform, hierarchical porous vaterite calcium carbonate microsphere stacked from nanoparticles is synthesized in dimethylformamide–water (DMF–H2O) mixed solvent without template. We propose a solvent-reaction assisted synthesis of the product by a mesoscale growth pathway. The product shows large removal capacity towards Pb2+, Cd2+ and Zn2+, of 1960 mg g−1, 1040 mg g−1 and 587.3 mg g−1, respectively. It also exhibits efficient and selective adsorption of Congo red (272 mg g−1, 5 min for equilibrium), which is reported for the first time on calcium carbonate. The removal mechanism is demonstrated to be the precipitation transformation for the heavy metal ion sequestration, and adsorption mechanism for the removal of the organic dyes. The good performance of the product is ascribed to the large amount of active adsorption sites provided by the nanoscale building blocks and mesopores, and the short pathway provided by the sunken poles and the hierarchical structure with enhanced mass transfer and decreased blocking of channels.

A novel unsymmetrical ferrocene–porphyrin derivative, namely 5-(4-ferrocamidophenyl)-10,15,20-triphenylporphyrin (H2FcPor), is designed, synthesized and characterized. The self-assembly properties of this novel ferrocene–porphyrin in methanol and n-hexane are comparatively investigated by scanning electron microscopy (SEM), the X-ray diffraction (XRD) technique, Fourier transform infrared (FT-IR) spectroscopy and electronic absorption spectroscopy. Intermolecular π–π interaction in cooperation with the solvent–solute interaction and the absence or presence of intermolecular hydrogen bonding leads to the formation of nanospheres and nanobelts in methanol and n-hexane, respectively. When applied as gas sensors, both the nanospheres and the nanobelts exhibit excellent gas sensitivity, and good stability and selectivity at room temperature for NO2 detection. Under the same measurement conditions, the detection limit and recovery times of nanobelt gas sensors are lower and faster than those for nanosphere gas sensors. Surprisingly, the nanospheres exhibit a normal n-type gas-sensing response to NO2, while the nanobelts display p-type gas-sensing behaviour in different NO2 concentration ranges. The abnormal sensing behavior with transition from n- to p-type NO2 sensing is tuned by solvent–porphyrin molecule interaction and molecular packing mode for the first time.

First-line therapy of chronic myelogenous leukemia (CML) has always involved the use of BCR-ABL tyrosine-kinase inhibitors which is associated with an abnormal chromosome called Philadelphia chromosome. Although the overall survival rate has been improved by the current therapeutic regime, the presence of resistance has resulted in limited efficacy. In this study, an RNA interference (RNAi)-based therapeutic regime is proposed with the aim to knockdown the BCR-ABL hybrid oncogene using small interfering RNA (siRNA). The siRNA transfection rates have usually been limited due to the declining contact probability among polyplexes and the non-adherent nature of leukemic cells. Our work aims at addressing this limitation by using a biodegradable charged polyester-based vector (BCPV) as a nanocarrier for the delivery of BCR-ABL-specific siRNA to the suspension culture of a K562 CML cell line. BCR-ABL siRNAs were encapsulated in the BCPVs by electrostatic force. Cell internalization was facilitated by the BCPV and assessed by confocal microscopy and flow cytometry. The regulation of the BCR-ABL level in K562 cells as a result of RNAi was analyzed by real-time polymerase chain reaction (RT-PCR). We observed that BCPV was able to form stable nanoplexes with siRNA molecules, even in the presence of fetal bovine serum (FBS), and successfully assisted in vitro siRNA transfection in the non-adherent K562 cells. As a consequence of downregulation of BCR-ABL, BCPV-siRNA nanoplexes inhibited cell proliferation and promoted cell apoptosis. All results were compared with a commercial transfection reagent, Lipofectamine2000™, which served as a positive control. More importantly, this class of non-viral vector exhibits biodegradable features and negligible cytotoxicity, thus providing a versatile platform to deliver siRNA to non-adherent leukemia cells with high transfection efficiency by effectively overcoming extra- and intra-cellular barriers. Due to the excellent in vitro transfection results from BCPV-siRNA, a newly developed biodegradable transfection agent, BCPV, is being probed for transfection performance in an animal model.

Taking lessons from the structure-forming process of biominerals in animals and plants, one can find tremendous inspirations and ideas for developing advanced synthesis techniques, which is called bio-process inspired synthesis. Bone, as a typical representative of biominerals, is constituted of mineralized collagen fibrils, which are formed under the functions of non-collagenous proteins (NCPs). Intrafibrillar mineralization is the consequence of a synergy among several NCPs. In the present study, we have designed a multi-functional protein, named (MBP)-BSP-HAP, based on bone sialoprotein (BSP) and hydroxyapatite binding protein (HAP), to mimic the intrafibrillar mineralization process in vitro. The three functional domains of (MBP)-BSP-HAP provide the artificial protein with multiple designated functions for intrafibrillar mineralization including binding calcium ions, binding collagen, and binding hydroxyapatite. Platelet-like hydroxyapatite crystals periodically arranged inside the collagen fibrils have been achieved under the function of (MBP)-BSP-HAP. The mechanism of intrafibrillar mineralization directed by the multi-functional protein was proposed. This work may not only shed light on bio-process inspired approaches for more economic and efficient biomimetic synthesis, but also be helpful in understanding the natural process of bone formation for bone regeneration and tissue repair.

A CdS/Cd2SnO4 composite was successfully synthesized via a one step solvothermal route synergistically assisted by L-cysteine and diethanolamine. The composite is composed of CdS quantum dots stuffed in hierarchical Cd2SnO4 microspheres with a diameter of around 2 μm, which are assembled from nanosheets with a thickness of 20–50 nm. The band gap of the composite is 2.46 eV, which is higher than pure phase CdS and Cd2SnO4, due to the quantum size effect from CdS QDs. One possible formation mechanism of the composite is presented; the initial precipitation of Sn(OH)2 serves as a template, and the complexes of L-cysteine coordinated with metal ion provide structural direction for the hierarchical microspheres. The CdS/Cd2SnO4 composite showed superior adsorption ability and enhanced visible light photocatalytic activity in the degradation of RhB to CdS, Cd2SnO4, and Degussa P-25, due to its microstructure and the efficient charge separation at the interface of CdS and Cd2SnO4.

Multiternary quantum dots (QDs), because of the large degree of freedom in their structure and composition, have a wide tunability in their bandgap but also exhibit an increased uncertainty and complexity in their optical properties. In this work, we synthesized the ternary Cu-In-S (CIS) and quaternary Zn-Cu-In-S (ZCIS) QDs with different composition ratios via a facile aqueous route. The CIS QDs show multi-peak photoluminescence with their peak intensity dependent on the Cu : In ratio, which was illustrated using a donor-acceptor pair recombination process. Upon incorporation of Zn into the CIS QDs under similar conditions, the acquired ZCIS QDs exhibit blue-shifted photoluminescence (PL) spectra with an enhanced emission intensity and a narrowed spectral width (∼100 nm). A comparative study reveals that, reducing the Cu : In ratio in the CIS QDs and increasing the Zn content in the alloyed ZCIS QDs are both feasible strategies for bandgap engineering, although the influences on optical properties of the QDs were different. The XRD and EDX spectra revealed that the widening of the bandgap of the ZCIS QDs was correlated with the alloyed nanostructures and the preferential substitution of Cu by Zn. Compared to the Cu : In ratio variation, incorporation of Zn into CIS QDs is an effective strategy to achieve a more homogeneous absorption band and a wide range of emission wavelength tunability. After ZnS shell coating, the ZCIS/ZnS QDs show a further enhanced PL intensity with a prolonged fluorescence lifetime. Unlike CIS QDs, the blue shift in PL upon the shell growth was not pronounced for ZCIS QDs, for which a surface reconstruction mechanism was proposed and discussed. Finally, the as-prepared ZCIS/ZnS QDs were employed for in vitro cell imaging and exhibited good biocompatibility to macrophage cells.

Shikimate dehydrogenase, an essential protein for the biosynthesis of the chorismate end product, is a highly promising therapeutic target, especially for the discovery and development of new-generation anti-TB agents. Following up the identification of one lead 3,6-disubstituted 1,2,4-triazolo[3,4-b][1,3,4]thiadiazole (1), targeting Mt SD in our previous study, an extensive SAR study for optimization of the lead compound was performed through systematic modification of the 3 and 6 positions. This study has successfully led to the discovery of two highly potent advanced leads 6d-4, 6c-4 and several other compounds with comparable potencies (6d-4, MIC-H37Rv = 0.5 μg mL−1; MIC-MDRTB = 4.0 μg mL−1; MIC-RDRTB = 0.5 μg mL−1; Mt SD-IC50 = 14.20 μg mL−1; and 6c-4, MIC-H37Rv = 0.5 μg mL−1; MIC-MDRTB = 4.0 μg mL−1; MIC-RDRTB = 1.0 μg mL−1; Mt SD-IC50 = 6.82 μg mL−1). These advanced lead compounds possess a para-halogen phenyl at the 3 position. In vitro Mt SD inhibitory assay indicates that Mt SD is the target for their antitubercular activity. Moreover, the BacT/ALERT 3D liquid culture technology and in vitro Mt SD inhibitory assay were initially applied.

A novel kind of high quality thick-walled BN nano-tadpoles was successfully synthesized through an effective catalytic chemical vapor deposition combined with a co-precipitation method using Na2SiO3·9H2O, Mg(NO3)2·6H2O and amorphous boron powders as raw materials. SEM, FSEM, EDX, TEM, HRTEM, SAED, XRD, FTIR and Raman spectroscopy were employed for the characterization of the morphology, composition, structure and bonding features of the as-synthesized BN samples. The as-synthesized BN nano-tadpoles revealed a length of 10–15 μm and homogeneously tapered diameter from the head to the tail of the BN tadpole. The head diameter of every BN nano-tadpole was 0.5–1.5 μm and the tail diameter was less than 50 nm. Besides, ultraviolet-visible absorption spectroscopy indicated that the as-synthesized BN nano-tadpoles present a different band gap (5.39 eV) compared with that of BN nanotubes and hBN. Moreover, on the basis of the experimental results, the possible chemical reactions and the base vapor–liquid–solid (VLS) and diffusion association growth mechanism are also proposed to properly interpret the formation of the thick-walled BN nano-tadpoles.

Quantum dots (QDs) exhibit unique optical properties including size-tunable fluorescence, superior brightness, broad absorption and tiny emission bandwidth. These properties have made QDs promising candidates for bioimaging and biosensing applications. In this work, CdTe QDs were synthesized in aqueous phase using both mercaptopropionic acid (MPA) and Cysteine (Cys) as capping agents. Growth kinetics and optical properties of the resulted QDs were found to be dependent on both species and concentration of surfactant molecules. Considering the distinct nature and advantages of MPA and Cys, a mixed-ligands system was proposed as a potential approach to fabricate QDs with specific optical property and functions for in vitro and in vivo bioimaging applications.

Size-controllable amine-functionalized graphene quantum dots (GQDs) are prepared by an eco-friendly method with graphene oxide sheets, ammonia and hydrogen peroxide as starting materials. Using a Sephadex G-25 gel column for fine separation, for the first time we obtain GQDs with either single or double layers. By atomic force microscopy characterization, we confirm that hydrogen peroxide and ammonia play a synergistic role on graphene oxide (GO), in which the former cuts the GO into small pieces and the latter passivates the active surface to give amine-modified GQDs. Due to the low cytotoxicity and excellent biocompatibility of the obtained amine-functionalized GQDs, besides the multiwavelength imaging properties of GQDs, for the first time we find that this kind of GQD exhibits good antimycoplasma properties. Given the superior antimycoplasma effect of the GQDs and their eco-friendly mass production with low cost, these new GQDs may offer opportunities for the development of new antimycoplasma agents, thus extending their widespread application in biomedicine.

In this paper we report the development of multifunctional nanoprobes based on InP–ZnS quantum dots (QDs) for high contrast multimodal imaging and other applications for cancer in vitro and in vivo. These theranostic nanoprobes were synthesized by co-encapsulating InP–ZnS QDs and anticancer drug molecules within PEGylated phospholipid micelles covalently linked with DOTA-chelated Gd3+. Luminescent biocompatible InP–ZnS QDs and Gd3+ chelates can be used for fluorescence microscopy and magnetic resonance imaging (MRI), respectively. The nanoprobes showed both optical and MRI capabilities. The therapeutic effect of the theranostic nanoprobes was evaluated using cell viability assays and the toxic effect of the released anticancer drugs from the probes was confirmed on the cancer cells. For targeted delivery in vitro, the micelle-encapsulated QDs were conjugated with transferrin and anti-claudin-4 antibody, which target the transferrin- and claudin-4-receptors overexpressed in cancer cells, respectively. Employing in vivo optical imaging of mice bearing pancreatic cancer xenografts, we have demonstrated that systemically-delivered anti-claudin-4 conjugated QD nanoprobes can target and label the tumors with high contrast. These studies suggest that the developed theranostic InP–ZnS QD nanoprobes have the potential to be translated in clinical research for targeted multimodal diagnosis and therapy of cancer.