查看更多>>摘要：Stable conformers of neutral balenine were scanned through molecular dynamics simulations and energy minimizations using Allinger's MM2 force field. For each of the found minimum-energy conformers, geometry optimization and thermochemistry calculations were performed by using B3LYP, MP2, G3MP2B3 methods, 6-31G(d), 6-311++G(d,p) and aug-cc-pvTZ basis sets. The calculation results have indicated that balenine has about twenty stable conformers whose relative energies are in the range of 0-9.5 kcal/mol. Three of these are thought to provide the major contribution to matrix isolation IR spectra of the molecule. Our solvent calculations using the polarized continuum model revealed the stable zwitterion structures which are predicted to dominate IR spectra of balenine in water and heavy water (D2O) solvents. Pulay's SQM-FF method was used in scaling of the harmonic force constants and vibrational spectral data calculated for the neutral and zwitterion structures. These refined calculation data together with those obtained from anharmonic frequency calculations enabled us to correctly interpret the matrix isolation IR spectrum of balenine and the tautomerism-based changes observed in its KBr IR and solution (D2O) IR spectra. The results revealed the crucial role of conformation and zwitterionic tautomerism on the structure and vibrational spectral data of the molecule. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Pesticide use worldwide exhibits a positive effect on agricultural production while it may negatively affect organisms living in soil, water or the air. Importantly, numerous negative health effects also occur in humans exposed to (accumulated) pesticides or their metabolites over a long period of time. To prevent both environmental catastrophes and adverse human health impacts, initial studies of the selected pesticides need to be performed together with the constant post-approval control; risk assessment analysis and on site monitoring have to be continuously carried out. Given this, Raman spectroscopy, especially surface-enhanced Raman spectroscopy (SERS), during the last decade has become a powerful analytical technique since it can offer quick, selective, and in situ detection of selected pollutants found in analyzed samples at very low concentrations. Moreover, the structural changes caused by the pollutant-biomacromolecule interaction can also be recognized in the molecule-specific Raman spectral signatures of biomolecules. In this study, we report a vibrational characterization of the fungicide molecule Tebuconazole (TB) which is listed to be a possible carcinogen. Even though its international and common use there is no evidence about the use of Raman/SERS spectroscopy to detect it sensitively and selectively as well as to analyse its impacts on biological systems. Therefore, we have recorded and calculated Raman and infrared spectra of TB. Furthermore, SERS spectra of TB were also registered and comprehensively analysed in view of the employed SERS substrates, dependence on the excitation wavelengths and pH of the analysed molecular systems. The molecule of TB interacts preferentially through the triazole moiety with the colloidal metal nanoparticles (NPs) whereas the silver NPs prepared by reduction of silver nitrate with hydroxylamine hydrochloride resulted to be the most effective ones. Consequently, the limit of detection was determined to be 1.4 mu M approximate to 430 ppb. The present paper thus could serve significantly for further investigations focused on both conducting vibrational analyses of structurally related molecules as well as providing a more precise explanation of the mechanism of action of TB and its influence on biological macromolecules. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Lipid droplets (LDs), are multi-functional organelles with the storage of neutral lipids and proteins, participating in various of physiological processes. However, abnormal of LDs in morphology and numbers always lead to multiple diseases, including cancer, viral infection, obesity, inflammation. To better understand the physiological function of LDs in living cells, we designed two new fluorescent probes LDs-CA and LDs-BCA based on the triphenylamine and coumarin fluorophores to monitor LDs polarity and numbers variation in this work. The one-step strategy for the regulation of BF2 group realized a gratifying in emission wavelengths from orange fluorescence of LDs-CA to the red fluorescence of LDs-BCA, surprisingly. The two novel probes showed strong positive solvatochromism effect in different solvents and exhibited the aggregation-induced emission (ALE) effect. Based on the above excellent optical properties, LDs-CA and LDs-BCA were applied for imaging of the LDs with high overlap coefficient when co-stained with commercial dyes, respectively. The probes of LDs-CA and LDs-BCA provided an intuitive method to visualize the dynamic changes of LDs in morphology, size, and numbers under nutritional stimulation, affording a powerful tool for fluorescence visualization of LDs related biological processes. Notably, the near-infrared emissive probe LDs-BCA successfully imaged the gastric fat in living obese mouse, which may provide a new idea for medical diagnostics. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：A simple hydrazone probe (1) was designed and synthesized for the successive detection of Al3+ and pyrophosphate (PPi) in almost 100% buffer environment. The probe provided O2N donor set for chelation with Al3+, leading to a distinct fluorescence boost at 510 nm. The in-situ formed 1-Al3+ complex detected PPi with an "on-off" behavior. The detection limits for Al3+ and PPi were 35.7 nM and 76 nM, respectively. Benefiting from the existence of morpholine as lysosome-targeting group, probe 1 was successfully applied to the detection of Al3+ and PPi in lysosomes. (C) 2021 Elsevier B.V. All rights reserved.
Gerasimova, T. P.Gilfanova, A. R.Katsyuba, S. A.Islamova, L. N....
8页
查看更多>>摘要：A series of dialkylaminostyrylhetarene dyes constructed from electron-rich and electron-deficient moieties of various structures connected via vinylene pi-bridges are introduced as temperature-sensitive luminophores. The temperature dependent emission of the dyes in the acidified dichloromethane solutions derives from temperature-induced shift of the equilibrium between neutral and protonated forms of the dyes. The heating-induced blue shift and intensification of emission of neutral form of the dyes make them a promising basis for development of nanoparticles exhibiting temperature-sensitivity in aqueous solutions at pH typical of biological liquids. Hydrophobicity-driven incorporation of the water insoluble dyes into L-alpha-phos phatidylcholine(PC)-based bilayers allows to obtain water dispersible dye-PC aggregates, and to follow their emission in the aqueous solutions. Structure of the dyes has strong impact on the efficacy of the dyes incorporation into the PC-based bilayers, temperature sensitivity of emission of the dye-PC aggregates and its reversibility under the heating/cooling cycles. This enables structural optimization of the dyes in order to obtain the dye-PC species demonstrating maximal temperature dependence and reversibility of their luminescence in aqueous solutions. The selected leader exhibits low cytotoxicity exemplified for M-HeLa and Chang Liver cell lines, while the efficient cell internalization of the dye, manifested in the staining of the cell cytoplasm, opens further opportunities for biosensing applications. (C) 2021 Elsevier B.V. All rights reserved.
Wang, LinlinJana, JayasmitaChung, Jin SukChoi, Won Mook...
9页
查看更多>>摘要：Low-cost nitrogen and boron-doped carbon nanodots (CPAP-CDs) with a high quantum yield (64.07%) were synthesized through a facile hydrothermal treatment. The obtained CPAP-CDs exhibited wide absorption, strong fluorescence, and pH-dependent behavior. The high fluorescence of CPAP-CDs was quenching in the presence of the nitrite ion in a concentration-dependent manner. The detection limit was as low as 6.6 nM with a wide linear detection range of 2 mu M -1 mM. Diazotization between the NO2- ion and CPAP-CDs resulted in the aggregation of CPAP-CDs and aggregation-induced emission quenching. The as-designed method was tested further with different water samples, such as tap, drinking, and seawater. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：In this study, a simple, eco-friendly and low-cost approach was used to fabricate silver nanoparticles (AgNPs) from an aqueous extract of Gleditsia australis (GA) fruit. The nanoparticles synthesized in the optimal condition have an average size of 14 nm. The peroxidase-like activity of GA-AgNP in the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) in combination with hydrogen peroxide (H2O2) was investigated. Further, optimal conditions for the use of peroxidase-like catalytic activity in sensing applications were identified. The colourimetric detection of H2O2 showed a linear range of 1-8 mM with a limit of detection (LOD) of 0.34 mM. The oxidation of TMB (red-TMB) enables the detection of glucose, which is converted into H2O2 and gluconic acid in the presence of the enzyme glucose oxidase. The observations showed linearity from 0.05 to 1.5 mM with a LOD of 0.038 mM. Moreover, the blue colour of oxidized TMB (ox-TMB) was reduced according to ascorbic acid (AA) concentration, with a linear range of 0.030.14 mM and a LOD of 3.0 mu M. The practical use of the sensing system for the detection of AA was studied using real fruit juice and showed good sensitivity. Hence, the easy-to-use peroxidase-like sensor provides a new platform for the detection of bioactive compounds in biological systems. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：A new perovskite BaLaMgTaO6:Mn4+ (BLMTO:Mn4+) red phosphor was synthesized for the first time via the high-temperature solid-state method. The emission band of the phosphor ranges from 650 to 750 nm, which matches well with the absorption band of PFR and PR. By doping of Bi3+ and Ca2+ ions in the BLMTO: Mn4+ phosphor, a 4.76-fold enhancement in the luminescence emission intensity was achieved. The optimized BLMTO:0.5%Mn4+, 1.5%Bi3+, 2%Ca2+ phosphor exhibited a high quantum efficiency of 65% and a high color purity of 98.1% with the chromaticity coordinate (CIE) at (0.733, 0.267). Finally, a LED device was fabricated with the BLMTO:0.5%Mn4+, 1.5%Bi3+, 2%Ca2+ phosphor for further agricultural lighting, which emits warm white light with a low color temperature of 3549 K. The result indicates that the BLMTO:Mn4+, Bi3+, Ca2+ phosphors have a potential for applications in agricultural cultivations. (c) 2021 Elsevier B.V. All rights reserved.
Elkosasy, AmiraSaleh, Ahmed A.Hegazy, MahaAbbas, Samah...
11页
查看更多>>摘要：The ability to detect degradation products of active pharmaceutical ingredients (API) is an essential performance not only for conducting proper stability studies and subsequently gain regulatory approvals; but as well for detecting degradation products during the manufacturing process (In Process Control). Thus, this study aims to present the ability of using Raman Chemical Imaging (Raman-CI) microscope, with its optimum precision, in combination with appropriate chemometrics algorithms, to detect the spectrally similar Salicylic Acid (SA) in Acetylsalicylic Acid (ASA) powder mixture, and then create a chemical distribution map that reflects the distribution of ASA's main degradation product. The generated Hyperspectral images were processed where, a supervised chemometrics soft classifier, Soft Independent Modeling of Class Analogy (SIMCA), is applied to classify pixels and construct the subsequent distribution maps. In addition, due to the challenge of the high structural and spectral similarity between both substances, this study presents a new variable selection and dimensionality reduction technique, called Variable Strength Coefficient (VSC) to maximize the spectral differences and enhance the model precision and selectivity. A High-performance liquid chromatographic (HPLC) method was applied as a reference separation method to assess the results obtained by the proposed technique. The proposed technique was validated, where the obtained results confirmed that Raman Chemical Imaging Microscope, when coupled with SIMCA and VSC, is a powerful tool with outstanding accuracy. In addition, this approach could be suitable in applications where constructing accurate distribution maps of spectrally similar API's is required. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Aggregation-induced phosphorescence emission (AIPE) materials based on transition metal Ir(III) complexes have significant advantages in bioimaging and photodynamic therapy (PDT) due to the long life-time, the reduced photobleaching and the good reactive oxygen species (ROS) generation. Herein, four cationic Ir(III) complexes (Ir1-Ir4) have been synthesized and studied. Tunable phosphorescence from green to red with the excellent properties of AIPE and long lifetimes can be achieved by varying the substituents. Moreover, these phosphorescence Ir(III) complexes exhibited dual-mode PDT potential (type I and type II). Complex Ir4 showed great prospect in bioimaging and PDT with the large Stokes shift (259 nm), the long lifetime (9.85 mu s) and the high ROS yield (0.73). Confocal microscopy demonstrated that Ir4 accumulated in the mitochondria selectively and possessed remarkable photostability (reduced photobleaching up to 600 s). The results indicate that Ir4 may be used in dual-mode PDT guided by mitochondria-targeted imaging. This work provides an in-depth understanding of the relationship between structure and photophysical properties and facilitates the study in PDT applications. (C) 2021 Elsevier B.V. All rights reserved.
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