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41.
Stephanie M. Delgado Sam C. P. Norris Andrea M. Kasko 《Journal of polymer science. Part A, Polymer chemistry》2022,60(5):825-841
Hydrogels are attractive materials for generating 4D shapes due to their ability to undergo pronounced volume changes in response to several stimuli, including light. We previously reported shape-changing hydrogels actuated by long-wave UV and visible light in the presence of live cells using poly(ethylene glycol) macromers incorporating different photodegradable ortho-nitrobenzyl (o-NB) groups. In this comprehensive study, we determine the effect of chemical structure of different o-NB macromers (which influences molar absorptivity and rate constant of degradation), composition (macromer weight percent), fabrication design (initial gel thickness) and environment (ionic strength of solution) on light-induced hydrogel folding. We demonstrate successful photopolymerization and subsequent photodegradation of hydrogels, multistep folding, and live-cell encapsulation. This hydrogel system may be useful as new tool in stem cell differentiation and developmental biology research, facilitating the in vitro investigation of processes that are sensitive to both physical and temporal stimuli. 相似文献
42.
Thies Dirksmeyer Paul Stahl Dr. Cecilia Vallet Prof. Dr. Shirley Knauer Prof. Dr. Michael Giese Prof. Dr. Carsten Schmuck Dr. Christoph Hirschhäuser 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(43):e202104618
A transfection vector that can home in on tumors is reported. Whereas previous vectors that allow moderately cell selective gene transfection used larger systems, this small-molecule approach paved the way for precise structure-activity relationship optimization. For this, biotin, which mediates cell selectivity, was combined with the potent DNA-binding motif tetralysine-guanidinocarbonypyrrol via a hydrophilic linker, thus enabling SAR-based optimization. The new vector mediated biotin receptor (BR)-selective transfection of cell lines with different BR expression levels. Computer-based analyses of microscopy images revealed a preference of one order of magnitude for the BR-positive cell lines over the BR-negative controls. 相似文献
43.
乏燃料贮存格架是核电厂贮存乏燃料的重要设备,在满载条件下和地震/跌落事故中,都应保持稳定和安全状态.本文基于LS-DYNA对乏燃料贮存格架进行了跌落事故冲击分析,考虑了最重重物从可能最高处意外跌落的情况.分析时考虑了碰撞、几何大变形、材料非线性等非线性因素.分析发现,浅跌落情况下贮存格架变形较大,但为局部变形,冲击载荷不影响贮存格架的安全功能.深跌落情况下,组件跌落在支座上方时支座承受的载荷最大,并在许用载荷范围内.为确保核电厂安全性和可靠性,基于分析得到的现象,设计和开展了乏燃料贮存格架浅跌落和深跌落试验.试验采用了等比例贮存腔和真实燃料组件的管座.同时对试验件进行了跌落分析,并与试验结果进行了对比,验证了分析技术的保守性和准确性.掌握的分析技术可应用于所有压水堆核电站乏燃料贮存格架的跌落事故分析. 相似文献
44.
《Macromolecular bioscience》2018,18(5)
A method is developed that can rapidly produce blood vessel‐like structures by bonding cell‐laden electrospinning (ES) films layer by layer using fibrin glue within 90 min. This strategy allows control of cell type, cell orientation, and material composition in separate layers. Furthermore, ES films with thicker fibers (polylactic‐co‐glycolic acid, fiber diameter: ≈3.7 µm) are used as cell‐seeding layers to facilitate the cell in‐growth; those with thinner fibers (polylactic acid, fiber diameter: ≈1.8 µm) are used as outer reinforcing layers to improve the mechanical strength and reduce the liquid leakage of the scaffold. Cells grow, proliferate, and migrate well in the multilayered structure. This design aims at a new type of blood vessel substitute with flexible control of parameters and implementation of functions. 相似文献
45.
Hongmei Ma Hong Zhu Zhongming Wang 《Journal of polymer science. Part A, Polymer chemistry》2019,57(10):1087-1096
The anion exchange membranes (AEMs) with both high ionic conductivity and alkali stability are always the research focus of the AEM fuel cells. Here, a novel nonplanar polymer for AEMs manufacture, mPBI‐TP‐x‐R, with excellent hydroxide stability and satisfactory processability is reported for the first time. The serial mPBI‐TP‐x resins with steric hindrance were prepared by copolymerization among 3,3′,4,4′‐tetraaminobiphenyl, isophthalic acid and tetraphenyl‐terephthalic acid (TP) in different ratios under microwave condensation. The copolymers mPBI‐TP‐x were quaternized at N1/N3‐sites of benzimidazole unit in backbone with alkyl groups (R?CH3, C2H5, n‐C3H7, or n‐C4H9) to prepare soluble ionomers, and the corresponding membranes in hydroxyl ion form were prepared by a solution casting method and subsequent ion‐exchange process. The chemical structure of all membranes was characterized using FTIR and 1H NMR spectroscopy. The properties of ion exchange capacity, water uptake, swelling ratio, tensile strength, ionic conductivity, and alkaline stability were measured. Among the prepared membranes, the mPBI‐TP‐15%‐(n‐Bu) exhibited the excellent alkaline stability (only degradation ca. 5% under 1M NaOH aqueous solution at 60 °C for 800 h) and satisfactory OH? conductivity (46.66 mS/cm at 80 °C). The current research provides a useful exploration to commercial application of alkaline fuel cell. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 1087–1096 相似文献
46.
Calixarenes are known to form host–guest complexes and supramolecular nanoassemblies with well-defined architectures. However, the use of these materials in conjunction with drug moieties is still under explored. One reason is the insufficient biocompatibility studies. Our present study represents a systematic in vitro investigation of the cytotoxicity associated with C-methylresorcin[4]arene, C-methylpyrogallol[4]arene, p-phosphonated calix[8]arene and a metal-seamed calixarene–copper(II) complex, using human HEK293 and rat C6G cell lines and two different cell viability assays (MTT and CellTiter-Glo) to avoid species-biased results. All compounds showed low to moderate toxicity. The trend in the CC50 values indicated that the suppression of the coordination ability and the presence of phosphonate groups decrease the overall cytotoxicity of the compounds. The results of this study not only establish calixarenes and their immediate families as potential drug carriers and drug modifiers, but also reveal a pathway for fine-tuning their toxicological behaviour by appropriate chemical modification. 相似文献
47.
Dr. Samuel Oger Damien Schapman Dr. Romain Mougeot Dr. Stéphane Leleu Dr. Noëlle Lascoux Dr. Patrice Baldeck Dr. Magalie Bénard Dr. Thibault Gallavardin Dr. Ludovic Galas Dr. Xavier Franck 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(46):10954-10964
Epicocconone 1 is a natural chromophore isolated from the fungus Epicoccum nigrum that has shown applications in proteomics and fluorescent microscopy thanks to its unique pro-fluorescence properties. The modification of the skeleton of the natural product by replacing the triene side chain by a fluorenyl scaffold can noticeably increase the fluorophore's absorption coefficient. The synthesis of the analogues of the natural product has been made possible by the use of a palladium-catalyzed carbonylation reaction, allowing the construction of the β-keto-dioxinone key intermediate. Two-photon absorption cross-section measurements of the fluorenyl epicocconone analogues show a structure dependency with values ranging from 60 to 280 GM and live cell imaging show intense staining of intracellular vesicle-like structures around the nucleus. 相似文献
48.
The effect of non‐thermal plasma generated by the direct current (DC) corona discharge in the mode of transition spark is studied on a yeast Saccharomyces cerevisiae. The exposure to plasma increases production of reactive oxygen species (ROS) in cells, possibly causing the induction of apoptosis. To clarify the mechanism of apoptosis, its induction is tested not only on a wild strain of S. cerevisiae, but also on mutant strains: A deletion mutant Δyca1 without yeast metacaspase proves that in S. cerevisiae the apoptosis occurs partly by the caspase‐independent pathway. A petite strains with mutation in the mitochondria do not show pronounced ROS formation, but in spite of this, apoptosis is detected. Hence, mitochondrial ROS probably do not play an important role in induction of apoptosis. 相似文献
49.
Yanni Lv Xianpeng Shi Jia Fu Qianqian Jia Yuanyuan Lin Hongying Wang Xin Yang Shengli Han 《Biomedical chromatography : BMC》2019,33(9)
Marsdenia tenacissima, or Tongguanteng in Chinese, is a traditional Chinese herb and has a broad application in clinical practice for its pharmacological effects of treating asthma, pneumonia, tonsillitis, pharyngitis tumors, etc. However, few studies have reported the screening of the active components of this medicine for tumor therapy. In this work, a two‐dimensional analytical system was developed to screen antagonists of epidermal growth factor receptor (EGFR) from M. tenacissima. A fraction was retained on the EGFR cell membrane chromatography (CMC) column, separated and identified as tenacissoside G (TG), tenacissoside H (TH) and tenacissoside I (TI) by two‐dimensional HPLC–IT–TOF–MS. Molecular docking and 3‐(4,5‐dimethyl‐2‐thiazolyl)‐2,5‐diphenyl‐2‐H‐tetrazolium bromide (MTT) assay were carried out to assess the activity of TS (including TG, TH and TI). Molecular docking results showed that the binding mode of TS on EGFR is similar to that of gefitinib. The MTT assay demonstrated that gefitinib and TS (especially TI) could inhibit the growth of EGFR highly expressed cell lines in a dose‐dependent manner in the range of 5–50 μmol/L. In conclusion, the two‐dimensional EGFR/CMC–HPLC–IT–TOF–MS system could be a useful approach in drug discovery from traditional Chinese medicines for searching for potential antitumor candidates. 相似文献
50.
Rajalingam Agneeswari Yeongkwon Kang Jihoon Lee Ji Hyeon Kwon Vellaiappillai Tamilavan Seong Soo Park Sung Heum Park Youngeup Jin 《Journal of polymer science. Part A, Polymer chemistry》2019,57(4):545-552
We synthesized two new alternating polymers, namely P(Tt‐FQx) and P(Tt‐DFQx) , incorporating electron rich tri‐thiophene and electron deficient 6‐fluoroquinoxaline or 6,7‐difluoroquinoxaline derivatives. Both polymers P(Tt‐FQx) and P(Tt‐DFQx) exhibited high thermal stabilities and the estimated 5% weight loss temperatures are 425 and 460 °C, respectively. Polymers P(Tt‐FQx) and P(Tt‐DFQx) displayed intense absorption band between 450 and 700 nm with an optical band gap (Eg) of 1.78 and 1.80 eV, respectively. The determined highest occupied/lowest unoccupied molecular orbital's (HOMO/LUMO) of P(Tt‐DFQx) (?5.48 eV/?3.68 eV) are slightly deeper than those of P(Tt‐FQx) ( ?5.32 eV/?3.54 eV). The polymer solar cells fabricated with a device structure of ITO/PEDOT:PSS/ P(Tt‐FQx) or P(Tt‐DFQx) :PC70BM (1:1.5 wt %) + 3 vol % DIO/Al offered a maximum power conversion efficiency (PCE) of 3.65% with an open‐circuit voltage (Voc) of 0.59 V, a short‐circuit current (Jsc) of 10.65 mA/cm2 and fill factor (FF) of 59% for P(Tt‐FQx) ‐based device and a PCE of 4.36% with an Voc of 0.69 V, a Jsc of 9.92 mA/cm2, and FF of 63% for P(Tt‐DFQx) ‐based device. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 545–552 相似文献