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排序方式: 共有158条查询结果,搜索用时 31 毫秒
71.
Jiang-Pei Yuan Dr. Zong-Jie Guan Heng-Yu Lin Bing Yan Kang-Kai Liu Prof. Dr. Hong-Cai Zhou Prof. Dr. Yu Fang 《Angewandte Chemie (International ed. in English)》2023,62(31):e202303896
Mimicking the active site and the substrate binding cavity of the enzyme to achieve specificity in catalytic reactions is an essential challenge. Herein, porous coordination cages (PCCs) with intrinsic cavities and tunable metal centers have proved the regulation of reactive oxygen species (ROS) generating pathways as evidenced by multiple photo-induced oxidations. Remarkably, in the presence of the Zn4-μ4-O center, PCC converted dioxygen molecules from triplet to singlet excitons, whereas the Ni4-μ4-O center promoted the efficient dissociation of electrons and holes to conduct electron transfer towards substrates. Accordingly, the distinct ROS generation behavior of PCC-6-Zn and PCC-6-Ni enables the conversion of O2 to 1O2 and O2⋅−, respectively. In contrast, the Co4-μ4-O center combined the 1O2 and O2⋅− together to generate carbonyl radicals, which in turn reacted with the oxygen molecules. Harnessing the three oxygen activation pathways, PCC-6-M (M=Zn/Ni/Co) display specific catalytic activities in thioanisole oxidation ( PCC-6-Zn ), benzylamine coupling ( PCC-6-Ni ), and aldehyde autoxidation ( PCC-6-Co ). This work not only provides fundamental insights into the regulation of ROS generation by a supramolecular catalyst but also demonstrates a rare example of achieving reaction specificity through mimicking natural enzymes by PCCs. 相似文献
72.
Qinlei Liu Dr. Wenjie Ge Dr. Sandra Martínez-Jarquín Yuliang He Dr. Ri Wu Prof. Dr. Markus Stoffel Prof. Dr. Renato Zenobi 《Angewandte Chemie (International ed. in English)》2023,62(19):e202213703
Reactive oxygen species (ROS) are critical for many cellular functions, and dysregulation of ROS involves the development of multiple types of tumors, including pancreatic cancer. However, ROS have been grouped into a single biochemical entity for a long time, and the specific roles of certain types of ROS in tumor cells (e.g., pancreatic ductal adenocarcinoma (PDAC)) have not been systematically investigated. In this work, a highly sensitive and accurate mass spectrometry-based method was applied to study PDAC cells of humans and of genetically modified animals. The results show that the oncogenic KRAS mutation promotes the accumulation of hydrogen peroxide (H2O2) rather than superoxide or hydroxyl radicals in pancreatic cancer cells. We further identified that the enriched H2O2 modifies cellular metabolites and promotes the survival of pancreatic cancer cells. These findings highlight the specific roles of H2O2 in pancreatic cancer development, which may provide new directions for pancreatic cancer therapy. 相似文献
73.
Peiqing Sun Kunlun Li Xiao Liu Jing Wang Dr. Xusheng Qiu Prof. Wei Wei Prof. Jing Zhao 《Angewandte Chemie (International ed. in English)》2023,62(14):e202300085
Pathogenic microorganisms in the environment are a great threat to global human health. The development of disinfection method with rapid and effective antibacterial properties is urgently needed. In this study, a biomimetic silver binding peptide AgBP2 was introduced to develop a facile synthesis of biocompatible Ag2S quantum dots (QDs). The AgBP2 capped Ag2S QDs exhibited excellent fluorescent emission in the second near-infrared (NIR-II) window, with physical stability and photostability in the aqueous phase. Under 808 nm NIR laser irradiation, AgBP2-Ag2S QDs can serve not only as a photothermal agent to realize NIR photothermal conversion but also as a photocatalyst to generate reactive oxygen species (ROS). The obtained AgBP2-Ag2S QDs achieved a highly effective disinfection efficacy of 99.06 % against Escherichia coli within 25 min of NIR irradiation, which was ascribed to the synergistic effects of photogenerated ROS during photocatalysis and hyperthermia. Our work demonstrated a promising strategy for efficient bacterial disinfection. 相似文献
74.
Hui Yang Dr. Lili Xia Xuanxuan Ye Jiayi Xu Dr. Tianfeng Liu Dr. Linping Wang Assoc. Prof. Shuai Zhang Prof. Wei Feng Prof. Dongshu Du Prof. Yu Chen 《Angewandte Chemie (International ed. in English)》2023,62(26):e202303539
Hypertension, as a leading risk factor for cardiovascular diseases, is associated with oxidative stress and impairment of endogenous antioxidant mechanisms, but there is still a tremendous knowledge gap between hypertension treatment and nanomedicines. Herein, we report a specific nanozyme based on ultrathin two-dimensional (2D) niobium carbide (Nb2C) MXene, termed Nb2C MXenzyme, to fight against hypertension by achieving highly efficient reactive oxygen species elimination and inflammatory factors inhibition. The biocompatible Nb2C MXenzyme displays multiple enzyme-mimicking activities, involving superoxide dismutase, catalase, glutathione peroxidase, and peroxidase, inducing cytoprotective effects by resisting oxidative stress, thereby alleviating inflammatory response and reducing blood pressure, which is systematically demonstrated in a stress-induced hypertension rat model. This strategy not only opens new opportunities for nanozymes to treat hypertension but also expands the potential biomedical applications of 2D MXene nanosystems. 相似文献
75.
Wanling Liu Yihong Zhang Gen Wei Minxuan Zhang Tong Li Quanyi Liu Zijun Zhou Yan Du Prof. Dr. Hui Wei 《Angewandte Chemie (International ed. in English)》2023,62(33):e202304465
Senescent cells are the critical drivers of atherosclerosis formation and maturation. Mitigating senescent cells holds promise for the treatment of atherosclerosis. In an atherosclerotic plaque microenvironment, senescent cells interact with reactive oxygen species (ROS), promoting the disease development. Here, we hypothesize that a cascade nanozyme with antisenescence and antioxidant activities can serve as an effective therapeutic for atherosclerosis. An integrated cascade nanozyme with superoxide dismutase- and glutathione peroxidase-like activities, named MSe1, is developed in this work. The obtained cascade nanozyme can attenuate human umbilical vein endothelial cell (HUVEC) senescence by protecting DNA from damage. It significantly weakens inflammation in macrophages and HUVECs by eliminating overproduced intracellular ROS. Additionally, the MSe1 nanozyme effectively inhibits foam cell formation in macrophages and HUVECs by decreasing the internalization of oxidized low-density lipoprotein. After intravenous administration, the MSe1 nanozyme significantly inhibits the formation of atherosclerosis in apolipoprotein E-deficient (ApoE−/−) mice by reducing oxidative stress and inflammation and then decreases the infiltration of inflammatory cells and senescent cells in atherosclerotic plaques. This study not only provides a cascade nanozyme but also suggests that the combination of antisenescence and antioxidative stress holds considerable promise for treating atherosclerosis. 相似文献
76.
Julia Tanner 《Acta Analytica》2008,23(4):337-347
The fact that humans have a special relationship to each other insofar as they belong in the same species is often taken to
be a morally relevant difference between humans and other animals, one which justifies a greater moral status for all humans, regardless of their individual capacities. I give some reasons why this kind of relationship is not an appropriate
ground for differential treatment of humans and nonhumans. I then argue that even if relationships do matter morally species
membership cannot justify a difference in moral status. This has important implications because it removes one barrier to
giving animals greater moral status.
相似文献
Julia TannerEmail: |
77.
Prof. Dr. Feng Shao Dr. Zhaoming Xia Futian You Jun Kit Wong Dr. Qi Hang Low Prof. Dr. Hai Xiao Prof. Dr. Boon Siang Yeo 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(3):e202214210
We have employed in situ electrochemical shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) and density functional theory (DFT) calculations to study the CO reduction reaction (CORR) on Cu single-crystal surfaces under various conditions. Coadsorbed and structure-/potential-dependent surface species, including *CO, Cu−Oad, and Cu−OHad, were identified using electrochemical spectroscopy and isotope labeling. The relative abundance of *OH follows a “volcano” trend with applied potentials in aqueous solutions, which is yet absent in absolute alcoholic solutions. Combined with DFT calculations, we propose that the surface H2O can serve as a strong proton donor for the first protonation step in both the C1 and C2 pathways of CORR at various applied potentials in alkaline electrolytes, leaving adsorbed *OH on the surface. This work provides fresh insights into the initial protonation steps and identity of key interfacial intermediates formed during CORR on Cu surfaces. 相似文献
78.
In this paper, the feasibility of using optical computerized tomography (OCT) methods for measuring the distribution of species concentration for flow fields is analyzed and discussed. First, feasible methods are chosen for two or three objects composed flow fields from the perspective of the measurable principle. Second, both common gas and plasma are chosen as two typical examples for specific analysis and discussion. The results show that the feasibility and applicable range of OCT methods are related to the temperature, pressure, and species composition of the measured flow fields. Finally, the study indicates that OCT methods are more suitable for measuring the distribution of species composition for common gas rather than plasma. In a word, this study could be helpful for extending the applicable range of OCT methods, which are based on the measurement of the refractive index. 相似文献
79.
解决数值计算、科学绘图等科学和工程问题的一般步骤是:先利用Fortran、C或Pascal等计算机语言进行编程,再经过调试,最后得到结果。这种方法要求计算者对所运用的计算机语言具有一定的编程能力。本文以分析化学中的pH计算、型体曲线绘制和滴定曲线绘制为例,讨论了MATLAB在分析化学中的应用。并由此想到能否参照其它的工具箱编制用于分析化学的MATLAB的M函数库。结果表明,这种方法简单实用,效率高,数值稳定性好。 相似文献
80.
C. RuckebuschAuthor VitaeM. SliwaAuthor Vitae P. PernotAuthor VitaeA. de JuanAuthor Vitae R. TaulerAuthor Vitae 《Journal of Photochemistry and Photobiology, C: Photochemistry Reviews》2012,13(1):1-27
Nowadays, time-resolved spectroscopy data can be routinely and accurately collected in UV-vis femtosecond transient absorption spectroscopy. However, the data analysis strategy and the postulation of a physically valid model for this kind of measurements may be tackled with many different approaches ranging from pure soft-modeling (model-free) to hard-modeling, where the elaboration of a parametric spectro-temporal model may be required. This paper reviews methods that are used in practice for the analysis of femtosecond transient absorption spectroscopy data. Model-based methods, common in photochemistry, are revisited, and soft-modeling methods, which originate from the chemometrics field and that recently disseminated in the photo(bio)chemistry literature, are presented. These soft-modeling methods are designed to suit the intrinsic nature of the multivariate (or multi-way) measurement. Soft-modeling tools do not require a priori physical or mechanistic models to provide a decomposition of the data on the time and wavelength dimensions, the only requirement being that these two (or more) dimensions are separable. Additionally, Bayesian data analysis, which provides a probabilistic framework for data analysis, is considered in detail, since it allows uncertainty quantification and validation of the model selection step. 相似文献