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排序方式: 共有311条查询结果,搜索用时 15 毫秒
301.
《Chemie in Unserer Zeit》2017,51(2):106-111
Woehlk's test is a detection reaction for lactose and maltose from 1904. It was first used clinically for the analysis of sugars in urine. In science education the test can show in a simple way the lactose content of dairy products. This is interesting because many people react intolerant to lactose. The exact reaction mechanism of Woehlk reaction (similarly: Umikoff reaction, Woehlk‐Malfatti‐proof, Fearon's test) is still unknown despite many efforts. 相似文献
302.
Dr. Fan Yang Dr. Ting Geng Prof. Hang Shen Yan Kou Prof. Guanjun Xiao Prof. Bo Zou Prof. Yulan Chen 《Angewandte Chemie (International ed. in English)》2023,62(39):e202308662
Optical force probes that can release force-dependent and visualized signals with minimal changes in the polymer main chains under mechanical load are highly sought after but currently limited. In this study, we introduce a flex-activated mechanophore (FA) based on the Diels–Alder adduct of anthracene and dimethyl acetylenedicarboxylatea that exhibits turn-on mechanofluorescence. We demonstrate that when FA is incorporated into polymer networks or in its crystalline state, it can release fluorescent anthracenes through a retro-Diels–Alder mechanochemical reaction under compression or hydrostatic high pressure, respectively. The flex-activated mechanism of FA is successfully confirmed. Furthermore, we systematically modulate the force delivered to the mechanophore by varying the crosslinking density of the networks and the applied macroscopic pressures. This modulation leads to incremental increases in mechanophore activation, successive release of anthracenes, and quantitative enhancement of fluorescence intensity. The exceptional potential of FA as a sensitive force probe in different bulk states is highlighted, benefiting from its unique flex-activated mode with highly emissive fluorophore releasing. Overall, this report enriches our understanding of the structures and functions of flex-activated mechanophores and polymeric materials. 相似文献
303.
Dr. Masafumi Minoshima Taro Umeno Kohei Kadooka Margaux Roux Namiko Yamada Prof. Dr. Kazuya Kikuchi 《Angewandte Chemie (International ed. in English)》2023,62(18):e202301704
To understand the function of protein in live cells, real-time monitoring of protein dynamics and sensing of their surrounding environment are important methods. Fluorescent labeling tools are thus needed that possess fast labeling kinetics, high efficiency, and long-term stability. We developed a versatile chemical protein-labeling tool based on fluorophore-conjugated diazabicyclooctane β-lactamase inhibitors (BLIs) and wild-type TEM-1 β-lactamase protein tag. The fluorescent probes efficiently formed a stable carbamoylated complex with β-lactamase, and the labeled proteins were visualized over a long period of time in live cells. Moreover, use of an α-fluorinated carboxylate ester-based BLI prodrug enabled the probe to permeate cell membranes and stably label intracellular proteins after unexpected spontaneous ester hydrolysis. Lastly, combining the labeling tool with a pH-activatable fluorescent probe allowed visual monitoring of lysosomal protein translocation during autophagy. 相似文献
304.
Dr. Penghui Cheng Dr. Shasha He Dr. Chi Zhang Dr. Jing Liu Prof. Kanyi Pu 《Angewandte Chemie (International ed. in English)》2023,62(26):e202301625
NETosis, the peculiar type of neutrophil death, plays important roles in pro-tumorigenic functions and inhibits cancer immunotherapy. Non-invasive real-time imaging is thus imperative for prognosis of cancer immunotherapy yet remains challenging. Herein, we report a T andem-locked N ETosis R eporter 1 (TNR1) that activates fluorescence signals only in the presence of both neutrophil elastase (NE) and cathepsin G (CTSG) for the specific imaging of NETosis. In the aspect of molecular design, the sequence of biomarker-specific tandem peptide blocks can largely affect the detection specificity towards NETosis. In live cell imaging, the tandem-locked design allows TNR1 to differentiate NETosis from neutrophil activation, while single-locked reporters fail to do so. The near-infrared signals from activated TNR1 in tumor from living mice were consistent with the intratumoral NETosis levels from histological results. Moreover, the near-infrared signals from activated TNR1 negatively correlated with tumor inhibition effect after immunotherapy, thereby providing prognosis for cancer immunotherapy. Thus, our study not only demonstrates the first sensitive optical reporter for noninvasive monitoring of NETosis levels and evaluation of cancer immunotherapeutic efficacy in tumor-bearing living mice, but also proposes a generic approach for tandem-locked probe design. 相似文献
305.
Xiaoguang Ge Lichao Su Dr. Zhongxiang Chen Kang Zhu Xuan Zhang Dr. Ying Wu Prof. Jibin Song 《Angewandte Chemie (International ed. in English)》2023,62(29):e202305744
Radiotherapy (RT) is an effective and widely applied cancer treatment strategy in clinic. However, it usually suffers from radioresistance of tumor cells and severs side effects of excessive radiation dose. Therefore, it is highly significant to improve radiotherapeutic performance and monitor real-time tumor response, achieving precise and safe RT. Herein, an X-ray responsive radio-pharmaceutical molecule containing chemical radiosensitizers of diselenide and nitroimidazole (BBT-IR/Se-MN) is reported. BBT-IR/Se-MN exhibits enhanced radiotherapeutic effect via a multifaceted mechanisms and self-monitoring ROS levels in tumors during RT. Under X-ray irradiation, the diselenide produces high levels of ROS, leading to enhanced DNA damage of cancer cell. Afterwards, the nitroimidazole in the molecule inhibits the damaged DNA repair, offering a synergetic radiosensitization effect of cancer. Moreover, the probe shows low and high NIR-II fluorescence ratios in the absence and presence of ROS, which is suitable for precise and quantitative monitoring of ROS during sensitized RT. The integrated system is successfully applied for radiosensitization and the early prediction of in vitro and in vivo RT efficacy. 相似文献
306.
Wei Li Dr. Shaohua Zhang Dr. Sjoerd J. Rijpkema Prof. Dr. Daniela A. Wilson 《Angewandte Chemie (International ed. in English)》2023,62(29):e202305795
The surface area of anisotropic polymeric assemblies is a critical parameter concerning their properties. However, it is still a grand challenge for traditional techniques to determine the surface area. Here, a molecular probe loading (MPL) method is developed to measure the surface area of anisotropic polymersomes in the shape of tube, disc, and stomatocyte. This method uses an amphiphilic molecular probe, comprising hydrophobic pyrene as the anchor and hydrophilic tetraethylene glycol (EG4) as the float. The surface area of spherical polymersomes determined by dynamic light scattering is quantitatively correlated with the loading amount of probes, allowing the calculation of the average separation distance between the loaded probes. With the separation distance, we successfully determine the surface area of anisotropic polymersomes by measuring the loading amount. We envision that the MPL method will assist in the real-time surface area characterization, enabling the customization of functions. 相似文献
307.
Dr. Umme Tamima Dr. Sourav Sarkar Dr. Md Reyazul Islam Anushree Shil Dr. Kyeong Hwan Kim Dr. Ye Jin Reo Dr. Yong Woong Jun Hasanul Banna Soobin Lee Prof. Kyo Han Ahn 《Angewandte Chemie (International ed. in English)》2023,62(15):e202300580
Fluorescence monitoring of ATP in different organelles is now feasible with a few biosensors developed, which, however, show low sensitivity, limited biocompatibility, and accessibility. Small-molecule ATP probes that alleviate those limitations thus have received much attention recently, leading to a few ATP probes that target several organelles except for the nucleus. We disclose the first small-molecule probe that selectively detects nuclear ATP through reversible binding, with 25-fold fluorescence enhancement at pH 7.4 and excellent selectivity against various biologically relevant species. Using the probe, we observed 2.1–3.3-fold and 3.9–7.8-fold higher nuclear ATP levels in cancerous cell lines and tumor tissues compared with normal cell lines and tissues, respectively, which are explained by the higher nuclear ATP level in the mitosis phase. The probe has great potential for studying nuclear ATP-associated biology. 相似文献
308.
Fan Chen Dr. Baoxin Zhang Dr. Zhenjiang Ding Miao Zhong Dr. Yanan Hou Fang Zhang Dr. Guodong Hu Prof. Jianguo Fang 《Angewandte Chemie (International ed. in English)》2023,62(21):e202301598
The development of small-molecule probes suitable for live-cell applications remains challenging yet highly desirable. We report the first fluorescent probe, RBH, for imaging the heme oxygenase-1 (HO-1) activity in live cells after discovering hemin as a universal dark quencher. Hemin works via a static quenching mechanism and shows high quenching efficiency (>97 %) with fluorophores across a broad spectrum (λex=400–700 nm). The favorable properties of RBH (e.g. long excitation/emission wavelengths, fast response rate and high magnitude of signal increase) enable its use for determining HO-1 activity in complex biological samples. As HO-1 is involved in regulating antioxidant defence, iron homeostasis and gasotransmitter carbon monoxide production, we expect RBH to be a powerful tool for dissecting its functions. Also, the discovery of hemin as a general static dark quencher provides a straightforward strategy for constructing novel fluorescent probes for diverse biological species. 相似文献
309.
Johannes Seibel Giulio Fittolani Hossein Mirhosseini Xu Wu Stephan Rauschenbach Kelvin Anggara Peter H. Seeberger Martina Delbianco Thomas D. Kühne Uta Schlickum Klaus Kern 《Angewandte Chemie (International ed. in English)》2023,62(39):e202305733
Carbohydrates are the most abundant organic material on Earth and the structural “material of choice” in many living systems. Nevertheless, design and engineering of synthetic carbohydrate materials presently lag behind that for protein and nucleic acids. Bottom-up engineering of carbohydrate materials demands an atomic-level understanding of their molecular structures and interactions in condensed phases. Here, high-resolution scanning tunneling microscopy (STM) is used to visualize at submolecular resolution the three-dimensional structure of cellulose oligomers assembled on Au(1111) and the interactions that drive their assembly. The STM imaging, supported by ab initio calculations, reveals the orientation of all glycosidic bonds and pyranose rings in the oligomers, as well as details of intermolecular interactions between the oligomers. By comparing the assembly of D- and L-oligomers, these interactions are shown to be enantioselective, capable of driving spontaneous enantioseparation of cellulose chains from its unnatural enantiomer and promoting the formation of engineered carbohydrate assemblies in the condensed phases. 相似文献
310.
Ria Thielhorn Isabelle Heing-Becker Nadja Hümpfer Jakob Rentsch Rainer Haag Kai Licha Helge Ewers 《Angewandte Chemie (International ed. in English)》2023,62(28):e202302318
Expansion microscopy (ExM) is a recently developed technique that allows for the resolution of structures below the diffraction limit by physically enlarging a hydrogel-embedded facsimile of the biological sample. The target structure is labeled and this label must be retained in a relative position true to the original, smaller state before expansion by linking it into the gel. However, gel formation and digestion lead to a significant loss in target-delivered label, resulting in weak signal. To overcome this problem, we have here developed an agent combining targeting, fluorescent labeling and gel linkage in a single small molecule. Similar approaches in the past have still suffered from significant loss of label. Here we show that this loss is due to insufficient surface grafting of fluorophores into the hydrogel and develop a solution by increasing the amount of target-bound monomers. Overall, we obtain a significant improvement in fluorescence signal retention and our new dye allows the resolution of nuclear pores as ring-like structures, similar to STED microscopy. We furthermore provide mechanistic insight into dye retention in ExM. 相似文献