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A series of new compounds were synthesised by adding azo functional groups and chlorine substituent to the central bent-cores to form a 4-chloro-1,3-dizaophenylene bent-core. The structure, mesogen...

Nematic liquid crystals are promising materials for microwave communication owing to their continuous tunability as dielectrics and wide frequency range selection. However,conventional liquid crystals exhibit large dielectric loss and high freezing point, hindering their research and application in microwave communication. in this paper,14 novel liquid crystal polyphenylene compounds with lateral methyl substitute were synthesised. Their structures were characterized by IR, NMR,MS and the elemental analyses. Their mesogenic properties were analyzed by POM and DSC. The dielectric properties in microwave frequencies(10-35 GHz)of eight target compounds (6a,7b,8a~8e) with LC matrix were obtained by extrapolation and perturbation techniques. The results show that i. fluorinated polyphenylene compounds with lateral methyl generally exhibited low melting points (���75��C), ii. compounds with isothiocyanate group yielded high birefringence 0.385-0.441, iii. compounds based on quaterphenyl displayed a wide temperature range of nematic phase, and iv. the maximum dielectric loss of compounds 6e,8c,8e are less than 6.51��10-3,which are better than those of using fluorine replace the methyl group derivative. Therefore, the proposed approach can effectively reduce dielectric loss,reduce the melting temperature, improve the dielectric properties of liquid crystal materials for microwave communication.

Polysaccharides are capable of being modified by polycations to adjust their physical and chemical properties, which accordingly are considered as potential candidate materials for safe and efficient gene delivery. Here, we extracted and purified polysaccharides from rice bran, and their physicochemical properties were determined by various methods. Polyethyleneimine (PEI) modified rice bran polysaccharide (PRBP) was prepared by grafting RBP with low molecular weight PEI and the preparation was determined by FTIR. The potential of PRBP as a gene vector was systematically evaluated in vitro. The results show that PRBP can compact DNA and form PRBP/DNA polylexes with a particle size of 50–100 nm. The PRBP/DNA polylexes can protect DNA degradation from DNase I efficiently. Compared with PEI, higher transfection efficiency was achieved by the PRBP. At weight ratio of 3, the highest efficiency of gene transfection mediated by PRBP-2000 was obtained, which was 37.5% and significantly higher than PEI and commercial reagents (calcium phosphate cell transfection kit) and was closed to lipo6000. Furthermore, according to MTT results, the cytotoxicity of PRBP is much lower than that of PEI, especially for PEI2000. We hope these results will provide new strategy for rice bran polysaccharides development and application as biomaterials.

A Lactobacillus buchneri GBS3 strain isolated from the traditional Chinese pickles was used for the production of 3-phenyllactic acid (PLA), an important compound with antimicrobial activities against a wide species of gram-positive and gram-negative bacteria and some fungi. The growth performance of this strain in the de Man, Rogosa and Sharpe (MRS) medium, the production of metabolites of valuable organic acids, and the biosynthesis of PLA using this strain as the whole-cell biocatalyst and phenylpyruvic acid (PPA) as the precursor, were investigated experimentally. The uniform design method with overlay sampling was developed for the optimization of the biotransformation conditions. The results showed that although it produced naturally lactic acid with the maximum concentration of 1.84 g·L− 1 and PLA with the concentration of 0.015 g·L− 1 after 66 to 72 h cultivation in MRS broth by fermentation, the present strain displayed an effective utilization ability by transforming PPA to PLA. By the uniform design method with overlay sampling for the design and optimization of transformation conditions, a maximum yield of 10.93 g·L− 1 PLA with the mole conversion ratio of 83.07% from PPA to PLA was achieved under the optimized condition, i.e., 20 g·L− 1 glucose, 270 g·L− 1 cells, 13 g·L− 1 PPA, pH 8.0 and the reaction time of 15 h, indicating that Lactobacillus buchneri GBS3 was an interesting strain for the biosynthesis of PLA via the microbial transformation. The prediction of PLA yield under different conditions was achieved successfully based on the limited information of only a small number of experiments by the uniform design with overlay sampling. Therefore, the present methodology is effective and helpful for the optimization of the biosynthesis processes of PLA.

Phenyllactic acid (PLA) is an important organic acid with wide antimicrobial activities against gram-positive and gram-negative bacteria and some fungi. This interesting compound can be synthesized by the microbial fermentation or the bioconversion using phenylpyruvic acid (PPA) as the key substrate and microorganisms as the whole-cell biocatalysts. However, the isolation of high-purity PLA with a high recovery from the crude fermentation or conversion broth is a challenging task. In this work, the separation of PLA from the crude conversion broth prepared by employing Lactobacillus buchneri cells as the whole-cell catalysts was achieved by the chromatography using the poly(hydroxyethyl methacrylate) (pHEMA)-based cryogel with a combination of anion-exchange and hydrophobic benzyl groups. The static adsorption behaviors of PLA under different salt concentrations and the adsorption capacities of PLA on the cryogel were measured experimentally. The chromatographic performance of PLA from the crude conversion broth was compared with that from the clarified broth. The results showed that the pHEMA-based cryogel has a high capacity of PLA, i.e., 14.64 mg mL−1 cryogel, and the adsorption of PLA was influenced by the salt concentration. By using deionized water as running buffer, PLA with a high purity of 97.6% was obtained with one step elution using 0.3 M NaCl as the elution solution with the recovery at the range of 80.2–90.8% from crude feedstock without any pretreatment at various flow velocities. These values were close to those obtained for the clarified broth, i.e., the purity of 98.4% and the recovery of 92.3% under the same chromatography conditions at 1 cm min−1. The cryogel was then applied to separate PLA from clarified feedstock, high purity (>96.7%) and recovery (>91.4%) of PLA were found with 20 cycles, which verified the selectivity and robustness of prepared pHEMA-VBTAC cryogel. Therefore, the chromatography using pHEMA-based cryogel with the dual functional groups is an effective approach for the isolation of PLA directly from the crude bioconversion broth and thus could be interesting in the separation and production of high-purity PLA in industry.

The dynamic formation of alginate droplets containing Lactobacillus buchneri cells by the microtube dripping method was investigated experimentally. Supermacroporous cell-entrapped cryogel beads we...

Metal complexes, as a type of potential non-virus gene carriers, have gained much attention due to their properties of high charge density and unique three-dimensional structure. This study investigated the potential of polyethyleneimine (PEI)-modified rice bran polysaccharide-Fe(III) complex (PEI-PI) as a safe gene delivery system and explored the effect of Fe(III) on the efficiency of gene transfection mediated by PEI modified rice bran polysaccharide (PEI-P) and PEI-PI. Gel retardation assay was used to study the DNA binding and protection capability, MTT assay was performed to evaluate the biocompatibility, and PEI-PI complex-mediated EGFP gene transfection was studied in vitro. Results showed the PEI-PI could induce DNA condensation and protect DNA from degradation by DNase I at a low weight ratio (vector/DNA) of 2. At the same weight ratio, PEI exhibited the strongest DNA binding capability but PEI-PI exhibited the highest gene transfection efficiency among all carrier systems. Compared with the PEI-P + Fe(III) system, PEI-PI not only had a more significant capability to condense DNA but also presented higher gene transfection efficiency. Moreover, PEI-PI exhibited no obvious cytotoxicity to cells. This work provides a strategy for the design and development of gene vectors based on PI complexes.

Finding a safe and efficient gene delivery vector is a major international challenge facing the development of gene therapy. Tannic acid (TA) is a natural cross-linker owing to its hydroxyl and carboxyl groups that can interact with biopolymers for different biomaterial design. In this work, three polyethyleneimine-modified TA polymers were prepared, and the polymers were characterized by FTIR, UV-vis, elemental analysis and 1H NMR. The potential of PTAs as gene vector was studied in vitro, including DNA loading capacity, DNA protection ability and biocompatibility. In addition, the particle size, zeta potential, DNA encapsulation efficiency, cell uptake and transfection efficiency of the PTA-pDNA polyplexes were also studied. The results showed that PTA2k and PTA30k could completely condense DNA at N/P of 2, and PTA600 could only completely condense DNA at N/P of 50. The PTA/pDNA polyplexes could protect DNA from degrading by DNA enzymes and could be efficiently uptaked by cells. Biocompatibility assay showed that PTA had no significant cytotoxicity and effect on cell proliferation compared to PEI. At low N/P ratios of 1-4, PTA showed higher transfection efficiency than PEI, and the transfection efficiency increased with the increase of PEI molecular weight in PTA. At N/P of 3, PTA30k showed the highest transfection efficiency of 23.8%, while PEI30k showed only 6.7%. These results indicate that PTA is a promising candidate vector for safe and efficient gene delivery.

With the rapid development of switchable devices for the K-band (≤40GHz) frequency range, there is a strong demand for liquid crystals (LCs) exhibiting high birefringence, low melting point and low dielectric loss ,low viscosity and good miscibility. The novel series of difluorovinyl liquid crystal compounds with Δn value around 0.4, relatively low melting point which can be as low as 34.4℃ were designed and synthesized. Comparing the difluorovinyl liquid crystal compound with isothiocyanide-containing liquid crystals, UV absorption test and dielectric loss test analysis at high frequency were performed. Difluorovinyl liquid crystals were prepared into a mixed liquid crystal material for high-frequency dielectric loss test and viscosity performance test analysis at different temperatures to explore its low temperature viscosity dependenceon temperature. The experimental results show that the difluorovinyl liquid crystal compounds not only have higher Δn value and lower melting point, but also have lower dielectric loss at high frequency and low temperature viscosity, which can improve the low temperature viscosity performance of liquid crystal materials.

The effect on the intracellular reactive oxygen species (ROS) generation, and the antioxidant and cytotoxicity properties of rice bran polysaccharides (RBP) and RBP-metal complexes RBP-Fe(III), RBP-Cu, RBP-Zn and RBP-Ca, were evaluated using atomic absorption spectroscopy (AAS), scavenging activity assays, cell viability assay and fluorescence microscopy. The RBP-metal complexes were prepared using the hydrothermal method. The RBP-Fe(III) complexes were found to be potent scavengers for superoxide (O2− ) free radicals. The RBP alone and RBP-Ca complex showed high scavenging activity for 2,2-diphenyl-1-picrylhydrazyl (DPPH ) free radicals. In addition, the RBP-Fe(III) complex also showed good biocompatibility and lowered the intracellular ROS levels, while RBP alone, RBP-Zn and RBP-Ca complexes were observed to increase the intracellular ROS level. Our findings suggest that among the tested RBP-metal complexes, RBP-Fe(III) complex is a strong candidate as an antioxidant therapeutic.