Large Spontaneous Polarization Ferroelectric Property, Switchable Second-Harmonic Generation Responses, and Magnetism in an Fe-Based Compound.

Since the switchable spontaneous polarization of ferroelectric materials endows it with many useful properties such as a large pyroelectric coefficient, switchable spontaneous polarization, and semiconductor, it has a wide range of application prospects, and the research of high-performance molecular ferroelectric materials has become a hot spot. We obtained a 0D organic-inorganic hybrid ferroelectric [(CH3)3NCH2CH2CH3]2FeCl4 (1) with well-defined ferroelectric domains and excellent domain inversion and exhibited a relatively large spontaneous polarization (Ps = 9 µC/m-2) and a Curie temperature (Tc) of 394 K. Furthermore, compound 1 belongs to the non-centrosymmetrical space group Cmc21 and has a strong second-harmonic generation signal. Interestingly, we also performed magnetic tests on 1, which confirmed that it is a magnetic material. This work provides clues for exploring the application of high-performance molecular ferroelectric materials in future multifunctional smart devices.

Regulating Reversible Phase Transition Behaviors by Poly-H/F Substitution in Hybrid Perovskite-Like 2[CH2FCH2NH3]·[CdCl4].

The molecular design and regulation has shown bright future for constructing smart molecular materials such as ferroelectrics, dielectric switches, electro-optic effect, and so forth. Here, by poly-H/F substitution in a simple organic-inorganic hybrid 2[CH2FCH2NH3]·[CdCl4], 1 (CH2FCH2NH3 = fluorine ethylamine cation), we obtained two novel hybrids, namely, 2[CHF2CH2NH3]·[CdCl4], 2 (CHF2CH2NH3 = 2,2'-difluorine ethylamine cation) and 2[CF3CH2NH3]·[CdCl4], 3 (CF3CH2NH3 = 2,2',2″-trifluorine ethylamine cation). Further investigations show that compounds 1, 2, and 3 experience solid reversible phase transitions with temperatures at 294, 319, and 329 K respectively. These unique phase transitions were confirmed by their remarkable dielectric and heat anomalies around the phase transition temperatures. X-ray single-crystal diffraction analyses before and after the phase transitions show that the order-disorder motions of F atoms and the twist motions from the 2D [CdCl4]2- framework lead to these solid reversible phase transitions. Also, the Hirshfeld surface calculation of compounds 1, 2, and 3 suggests that the increasing ratio of the F···F interaction from the intermolecular interaction makes a major contribution for the substantial increase of their phase transition temperatures.

Reversible phase transition and switchable dielectric behaviors triggered by rotation and order-disorder motions of crowns.

Solid-to solid-state reversible phase transitions are widely used in switchable dielectrics, ferroelectrics, piezoelectrics, and pyroelectric and non-linear optical materials. Herein we report a new crown ether clathrate, [Habf-(18-crown-6)1.5]+ [PF6]- (Habf = p-ammonium benzene formamide) which shows an interesting reversible phase transition near room temperature (263 K). X-ray single crystal diffraction analysis shows that the synergetic rotation motion between the 18-crown-6 crown ethers and the order-disorder motions of both hexafluorophosphate guest anions and 18-crown-6 crown ether host molecules lead to the phase transition. This reversible phase transition is confirmed by an evident thermal anomaly behavior around 263 K. The apparent step-like dielectric change around the phase transition indicates that it has potential application in dielectric switches.

Reversible Phase Transition with Ultralarge Dielectric Relaxation Behaviors in Succinimide Lithium(I) Hybrids.

Dielectric relaxations have widely applied on high permittivity capacitors, dielectric switches, ferroelectrics, pyroelectrics, and electrical insulating materials. However, few investigations of large dielectric relaxation behaviors on organic-inorganic hybrid materials have been documented before. Here we present a novel two-dimensional succinimide lithium(I) hybrid compound, [Li(PDD)2ClO4]n, 1, (PDD = 2,5-pyrrolidinedione = succinimide) which shows reversible phase transition behavior in the vicinity of 228 K accompanied by an unusual symmetry breaking from I41/amd to C2/c. X-ray single crystal diffractions analysis indicates the twist motion of pyrrolidine heterocycles, and order-disorder motion of ClO4- anions triggered the reversible phase transition. By means of an intuitive crystallographic model (rattling ion model), we further illustrated the mechanism of the interesting reversible phase transition. Particularly, 1 shows ultralarge dielectric relaxation behavior in the vicinity of the phase transition by its dielectric constant dependence on temperatures and frequencies as well as its Cole-Cole relation.

A high-throughput screening strategy for accurate quantification of menaquinone based on fluorescence-activated cell sorting.

To enhance the screening efficiency and accuracy of a high-yield menaquinone (vitamin K2, MK) bacterial strain, a novel, quantitative method by fluorescence-activated cell sorting (FACS) was developed. The staining technique was optimized to maximize the differences in fluorescence signals between spontaneous and MK-accumulating cells. The fluorescence carrier rhodamine 123 (Rh123), with its ability to reflect membrane potential, proved to be an appropriate fluorescent dye to connect the MK content with fluorescence signal quantitatively. To promote adequate access of the fluorescent molecule to the target and maintain higher cell survival rates, staining and incubation conditions were optimized. The results showed that 10 % sucrose facilitated uptake of Rh123, while maintaining a certain level of cell viability. The pre-treatment of cells with MgCl2 before staining with Rh123 also improved cell viability. Using FACS, 50 thousands cells can easily be assayed in less than 1 h. The optimized staining protocol yielded a linear response for the mean fluorescence against high performance liquid chromatography-measured MK content. We have developed a novel and useful staining protocol in the high-throughput evaluation of Flavobacterium sp. mutant libraries, using FACS to identify mutants with increased MK-accumulating properties. This study also provides reference for the screening of other industrial microbial strains.

Seipin mutation at glycosylation sites activates autophagy in transfected cells via abnormal large lipid droplets generation.

AIM: Seipin is a protein that resides in endoplasmic reticulum, and involved in both lipid metabolic disorders and motor neuropathy. The aim of this study was to investigate the effects of mutant seipin on autophagy system and the morphology of lipid droplets in vitro. METHODS: HEK-293, H1299 and MES23.5 cells were transfected with the plasmids of mutated seipin at glycosylation sites (N88S or S90L) and GFP-LC3 plasmids. The cells were subjected to immunofluorescence and flow cytometry assays, and the cell lysates were subjected to immunoblot analysis. Nile Red was used to stain the lipid droplets in the cells. RESULTS: Overexpression of the mutated seipin proteins N88S or S90L activated autophagy in the 3 cell lines, and substantially altered the sub-cellular distribution of the autophagosome marker GFP-LC3, leading to a number of large vacuoles appearing in the cytoplasm. The sub-cellular location of GFP-LC3 and mutated seipin proteins highly overlapped. Moreover, and the mutated seipin proteins caused diffuse small lipid droplets to fuse into larger lipid droplets. Treatment of mutated seipin-transfected cells with the autophagy inhibitor 3-MA (5 mmol/L) facilitated the fusion of mutated seipin-induced large vacuoles. The protein glycosylation inhibitor tunicamycin could mimic the mutated seipin-induced effects, and treatment of the wild-type seipin-transfected cells with tunicamycin (2.5 µg/mL) produced similar morphological and biochemical properties as in the mutated seipin-transfected cells. CONCLUSION: The mutation of seipin at glycosylation sites disrupt its function in regulating lipid droplet metabolism, and the autophagy acts as an adaptive response to break down abnormal lipid droplets. The interruption of autophagy would accelerate the fusion of abnormal lipid droplets.

Gold nanoparticles-coated magnetic microspheres as affinity matrix for detection of hemoglobin A1c in blood by microfluidic immunoassay.

A novel microfluidic immunoassay system for specific detection of hemoglobin A1c (HbA1c) was developed based on a three-component shell/shell/core structured magnetic nanocomposite Au/chitosan/Fe(3)O(4), which was synthesized with easy handling feature of Fe(3)O(4) by magnet, high affinity for gold nanoparticles of chitosan and good immobilization ability for anti-human hemoglobin-A1c antibody (HbA1c mAb) of assembled colloidal gold nanoparticles. The resulting HbA1c mAb/Au/chitosan/Fe(3)O(4) magnetic nanoparticles were then introduced into microfluidic devices coupled with a gold nanoband microelectrode as electrochemical detector. After that, three-step rapid immunoreactions were carried out in the sequence of HbA1c, anti-human hemoglobin antibodies (Hb mAb) and the secondary alkaline phosphatase (AP)-conjugated antibody within 20 min. The current response of 1-naphtol obtained from the reaction between the secondary AP-conjugated antibody and 1-naphthyl phosphate (1-NP) increased proportionally to the HbA1c concentration. Under optimized electrophoresis and detection conditions, HbA1c responded linearly in the concentration of 0.05-1.5 µg mL(-1), with the detection limit of 0.025 µg mL(-1). This system was successfully employed for detection of HbA1c in blood with good accuracy and renewable ability. The proposed method proved its potential use in clinical immunoassay of HbA1c.

Lab-on-a-chip for analysis of triglycerides based on a replaceable enzyme carrier using magnetic beads.

In this paper an enzyme-carrier-based microfluidic chip coupled with a gold nanoband microelectrode as electrochemical detector for Triglyceride (TG) determination was developed by co-immobilized lipase, Glycerokinase (GK) and glycerol-3-phosphate oxidase (GPOx) on chitosan/Fe(3)O(4) composite nanoparticles with a shell-core structure, which combined the advantageous features of microfluidic chips technology with magnetic beads. This procedure enabled the easy renewal of the microchip enzyme carrier after each determination in a highly reproducible manner. Several operational parameters such as working potential, buffer pH, adenosine triphosphate concentrations (ATP, mM), separation voltage and temperature were evaluated and optimized. The performance of enzyme-carrier-based microfluidic chip for TG determination was modulated by changing the length of enzyme carrier from 1.0 to 3.0 cm, and the linear ranges were changed from 0-4.0 mM to 0-10.0 mM with the detection limits from 15 µM to 6.0 µM. The enzyme carrier remained its 70% activity after 40 days storage. This system was successfully employed for on-line detection of TG in serums. The experimental results demonstrated that this enzyme carrier using magnetic beads based microfluidic chip provided a relatively simple, sensitive, miniature, and replaceable means for the accurate determination of TG in serum.

Multi-parameter detection of diabetes mellitus on multichannel poly(dimethylsiloxane) analytical chips coupled with nanoband microelectrode arrays.

This article demonstrates a novel method for multi-parameter detection of diabetes mellitus. We propose an approach for fabrication of a 3-D metal films array with gold and copper using electroless deposition technique on PDMS substrate. The obtained PDMS slices containing metal films are superimposed layer by layer as a sandwich structure to form 3-D metal films array. The cross-sections of the array could be used as nanoband array electrochemical detectors, which are further integrated with a multichannel microchip for simultaneously detecting multi-parameter of diabetes mellitus, including glucose and metabonomics of diabetes containing aldehyde compounds (glyoxal and methylglyoxal) and short organic acids (lactate, urate and 2-hydroxybutyrate). Under optimized separation and detection conditions, glucose, aldehyde compounds and short organic acids respond linearly in the concentration range of 10-2000, 1-500 and 5-600 µM, with the LODs of 4, 0.5 and 3 µM for glucose, aldehyde compounds and short organic acids, respectively. This system is successfully employed to detect these compounds in serums. This study reveals that the electrochemical array detectors with different materials integrated with multichannel microchip provide a flexible and inexpensive approach for routine, simultaneous and direct detection of some metabolites in metabonomics.

Preparation of metal nanoband microelectrode on poly(dimethylsiloxane) for chip-based amperometric detection.

We proposed herein a novel approach for fabricating nanoband microelectrodes for electrochemical detection on an electrophoresis microchip. The metal films were first obtained via region-selective electroless deposition of gold or copper films on PDMS substrates by selective region plasma oxidation through shadow masking. Both metal films show uniform surfaces with the thickness at the level of 100 nm. By casting another PDMS layer on the metal films, the cross section of the sandwich structures can be used as nanoband microelectrodes, which can be renewed just by cutting. These nanoband microelectrodes are successfully used as electrochemical detectors in microchip electrophoresis for the detection of amino acids, proteins and neurotransmitter molecules. Moreover, integrating an Au-Cu double-metal detector with a double-channel electrophoresis system, we can easily distinguish electroactive amino acids from that of non-electroactive amino acids.

[Culture and identify the human umbilical vein endothelial cells and investigate the expression of tyrosine kinase-2 with immunoglobulin-like and epidermal growth factor homology domains in the cells].

OBJECTIVE: To study the cultural method and identification of human umbilical vein endothelial cells (HUVECs), and investigate the expression of tyrosine kinase-2 with immunoglobulin-like and epidermal growth factor homology domains(Tie-2) in HUVECs. METHODS: HUVECs were isolated from umbilical veins by the technique of irrigative digestion, and were cultivated in plates. The cells were identified by VIII monoclonal antibody. Tie-2 mRNA and protein were detected by reverse transcription-polymerase chain reaction (RT-PCR) and SABC immunocytochemistry. RESULTS: HUVECs could adhere to the plates completely after 24 hours, and confluence a monolayer 4-5 days later. The band of Tie-2 mRNA was obviously and the expression of Tie-2 protein was strongly positive by immunocytochemistry in HUVECs. The positive rate was over 85%. CONCLUSION: Highly purified endothelial cells were isolated. And there were overexpression of Tie-2 in HUVECs.