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971.
Colorimetric sensing strategies as a powerful point-of-care testing(POCT) tool have attracted significant interest in various chem/biosensing applications.Taking the excellent bare-eye-detectable signaling feature,nanozymes-based colorimetric sensors enable more potential applications and have been a new forefront in the colorimetric POCT analysis toward different target analytes.However,the low catalytic activity of nanozymes in most cases limits their practical application.Recent efforts demonstrate that the aggregation-induced nanozymes provide a general means to modulate nanozymes activity and enhance colorimetric sensing performances of some nanozymes-based colorimetric sensors.But there are few reports are explored to discuss and review such aggregation-induced nanozymes and their colorimetric sensing applications.To highlight the advances and progress in aggregation-induced nanozymes based colorimetric assays,we herein summary the fundamentals,classify and applications of this newlydeveloping field,focusing on the aggregation-induced activity enhancement of nanozymes(AIAEnanozymes) with a significant "signal-on" feature and aggregation-induced activity inhibition of nanozymes(AIAI-nanozymes) with a dramatical "signal-of" characteristics.Finally,we also propose the current challenges and the future prospects on both AIAE-nanozymes and AIAI-nanozymes. 相似文献
972.
Leyu Xin Limin Guo Salamet Edirs Zepeng Zhang Chenyang Cai Yongxing Yang Yali Lian Haiyan Yang 《Molecules (Basel, Switzerland)》2022,27(7)
Safflower seed oil (SSO) is considered to be an excellent edible oil since it contains abundant essential unsaturated fatty acids and lipid concomitants. However, the traditional alkali-refined deacidification process of SSO results in a serious loss of bioactive components of the oil and also yields massive amounts of wastewater. In this study, SSO was first extracted by ultrasonic-assisted ethanol extraction (UAEE), and the extraction process was optimized using random centroid optimization. By exploring the effects of ethanol concentration, solid–liquid ratio, ultrasonic time, and the number of deacidification times, the optimum conditions for the deacidification of safflower seed oil were obtained as follows: ethanol concentration 100%, solid–liquid ratio 1:4, ultrasonic time 29 min, and number of deacidification cycles (×2). The deacidification rate was 97.13% ± 0.70%, better than alkali-refining (72.16% ± 0.13%). The values of acid, peroxide, anisidine and total oxidation of UAEE-deacidified SSO were significantly lower than those of alkali-deacidified SSO (p < 0.05). The contents of the main lipid concomitants such as tocopherols, polyphenols, and phytosterols in UAEE-decidified SSO were significantly higher than those of the latter (p < 0.05). For instance, the DPPH radical scavenging capacity of UAEE-processed SSO was significantly higher than that of alkali refining (p < 0.05). The Pearson bivariate correlation analysis before and after the deacidification process demonstrated that the three main lipid concomitants in SSO were negatively correlated with the index of peroxide, anisidine, and total oxidation values. The purpose of this study was to provide an alternative method for the deacidification of SSO that can effectively remove free fatty acids while maintaining the nutritional characteristics, physicochemical properties, and antioxidant capacity of SSO. 相似文献
973.
Multivariate Curve Resolution Alternating Least Squares (MCR-ALS) can analyze three-way data under the assumption of a trilinear model using the trilinearity constraint. However, the rigid application of this constraint can produce unrealistic solutions in practice due to the inadequacy of the analyzed data to the characteristics and requirements of the trilinear model. Different methods for the relaxation of the trilinear model data requirements have been proposed, like in the PARAFAC2 and in the direct non-trilinear decomposition (DNTD) methods. In this work, the trilinearity constraint of MCR-ALS is adapted to different data scenarios where the profiles of all or some of the components of the system are shifted (not equally synchronized) or even change their shape among different slices in one of their data modes. This adaptation is especially useful in gas and liquid chromatography (GC and LC) and in Flow Injection Analysis (FIA) with multivariate spectroscopic detection. In a first data example, a synthetic LC-DAD dataset is built to investigate the possibilities of the proposed method to handle systematic changes (shifts) in the retention times of the elution profiles and the results are compared with those obtained using alternative methods like ATLD, PARAFAC, PARAFAC2 and DNTD. In a second data example, multiple wine samples were simultaneously analyzed by GC-MS where elution profiles presented large deviations (shifts) in their peak retention times, although they still preserve the same peak shape. Different modelling scenarios are tested and the results are also compared. Finally, in the third example, sample mixtures of acid compounds were analyzed by FIA under a pH gradient and monitored by UV spectroscopy and also examined by different chemometric methods using a different number of components. In this case, however, the departure of the trilinear model comes from the acid base speciation of the system depending on the pH more than from the shifting of the FIA diffusion profiles. 相似文献
974.
975.
976.
原子转移自由基聚合(ATRP)是制备分子量以及分散度可控聚合物的重要途径。然而,受制于除氧步骤复杂、金属催化剂残留以及单体适用范围有限等因素,ATRP难以应用于批量制备功能化聚合物/共聚物材料,限制了其进一步应用。近年来提出和发展的酶催化聚合,为高效便捷除氧、拓展单体适用范围以及制备具有特殊(纳米)结构的纯净聚合物/共聚物提供了新思路。本文详细介绍了酶的结构与催化机理,以酶的种类进行分类,系统总结了具有不同结构的酶催化体系(包括过氧化辣根酶、血红蛋白、血红素、漆酶等)的催化机理、适用单体、优缺点及应用等;综述了酶以及酶模拟物催化ATRP体系的发展现状;最后,对酶催化ATRP的发展前景和挑战进行了探讨和展望。 相似文献
977.
The recent promising applications of deuterium-labeled pharmaceutical compounds have led to an urgent need for the efficient synthetic methodologies that site-specifically incorporate a deuterium atom into bioactive molecules. Nevertheless, precisely building a deuterium-containing stereogenic center, which meets the requirement for optimizing the absorption, distribution, metabolism, excretion and toxicity (ADMET) properties of chiral drug candidates, remains a significant challenge in organic synthesis. Herein, a catalytic asymmetric strategy combining H/D exchange (H/D-Ex) and azomethine ylide-involved 1,3-dipolar cycloaddition (1,3-DC) was developed for the construction of biologically important enantioenriched α-deuterated pyrrolidine derivatives in good yields with excellent stereoselectivities and uniformly high levels of deuterium incorporation. Directly converting glycine-derived aldimine esters into the deuterated counterparts with D2O via Cu(i)-catalyzed H/D-Ex, and the subsequent thermodynamically/kinetically favored cleavage of the α-C–H bond rather than the α-C–D bond to generate the key N-metallated α-deuterated azomethine ylide species for the ensuing 1,3-DC are crucial to the success of α-deuterated chiral pyrrolidine synthesis. The current protocol exhibits remarkable features, such as readily available substrates, inexpensive and safe deuterium source, mild reaction conditions, and easy manipulation. Notably, the synthetic utility of a reversed 1,3-DC/[H/D-Ex] protocol has been demonstrated by catalytic asymmetric synthesis of deuterium-labelled MDM2 antagonist idasanutlin (RG7388) with high deuterium incorporation.A strategy of combining H/D-Ex and azomethine ylide-involved 1,3-DC was developed for the construction of α-deuterated pyrrolidine derivatives in good yields with excellent stereoselectivities and uniformly high levels of deuterium incorporation. 相似文献
978.
Unprotected 2-acetamido sugars may be directly converted into their oxazolines using 2-chloro-1,3-dimethylimidazolinium chloride (DMC), and a suitable base, in aqueous solution. Freeze drying and acid catalysed reaction with an alcohol as solvent produces the corresponding 1,2-trans-glycosides in good yield. Alternatively, dissolution in an aprotic solvent system and acidic activation in the presence of an excess of an unprotected glycoside as a glycosyl acceptor, results in the stereoselective formation of the corresponding 1,2-trans linked disaccharides without any protecting group manipulations. Reactions using aryl glycosides as acceptors are completely regioselective, producing only the (1→6)-linked disaccharides.Un-protected 2-acetamido sugars are stereoselectively converted into 1,2-trans glycosides and (1→6)-linked disaccharides without any protecting groups. Reaction proceeds via intermediate oxazolines which react with acceptors under acid catalysis. 相似文献
979.
An efficient sustainable and scalable strategy for the synthesis of porous cobalt/nitrogen co-doped carbons(Co@NCs) via pyrolysis of aniline-modified ZIFs,has been demonstrated.Aniline can coordinate and absorb on the surface of ZIF(ZIF-CoZn3-PhA),accelerate the precipitation of ZIFs,thus resulting in smaller ZIF particle size.Meanwhile,the aniline on the surface of ZIF-CoZn3-PhA promotes the formation of the protective carbon shell and smaller Co nanoparticles,and increases nitrogen content of the catalyst.Because of these prope rties of Co@NC-PhA-3,the oxidative esterification of 5-hydroxymethylfurfural can be carried out under ambient conditions.According to our experimental and computational results,a synergistic catalytic effect between CoN_x sites and Co nanoparticles has been established,in which both Co nanoparticles and CoN_x can activate O_2 while Co nanoparticles bind and oxidize HMF.Moreover,the formation and release of active oxygen species in CoN_x sites are reinfo rced by the electronic interaction between Co nanoparticles and CoN_x. 相似文献
980.