查看更多>>摘要：Formaldehyde (FA) is widely applied as a fixative for proteins such as collagen. Current studies have confirmed that the reversible oligomer-to-monomer equilibrium of FA in aqueous solution and the proportion of FA monomer is a significant factor affecting tissue fixation. Since the hydrolysis of FA oligomers is a dynamic process affected jointly by different factors, its real time monitoring has proved to be challenging. In this work, by utilizing the well-established Raman technique as an analytical platform, we identified the factors affecting the hydrolysis of FA oligomers by rationally examining the nu(s) (OCO) and nu(as) (OCO) modes with varying conditions, such as time, pH, temperature, and FA concentration. The optimized conditions of the highest hydrolysis rate of oligomers into monomers for fixation on collagen and tissues have been found to be relatively low FA concentration (<= 5%) in phosphate-buffered saline at pH 9.0 in room temperature. In order to compare the fixation quality of the optimized conditions to that of the conventional conditions used by current medical practices (4% FA concentration in tap water under room temperature), Raman spectroscopy and chemical derivatization methods with o-phthalaldehyde and fluorescent probe FAP-1 have been investigated, and our results revealed that the FA molecules under our optimized conditions have reacted with at least 15% more amino groups within collagen compared to those under the conventional conditions mentioned above. This study provides direct evidence of the FA equilibrium in solution by Raman spectroscopy, which could be applied for the optimal use of FA in medicine, even at an industrial scale. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：We developed a fluorescent probe, named 2-(4-(acryloyloxy) phenyl)-4-(2-carboxyphenyl)-7-(diethyla mino) chromenylium (PA-A), for detecting Cys using the -OH protection/deprotection strategy, which can react with Cys to form a red-emitting anthocyanidin derivative fluorophore. The probe has high selectivity to Cys over Hcy and GSH in phosphate buffer solution (PBS, 10 mM, pH = 7.4), high sensitivity, a low detection limit of 4.48 x 10(-8) mol/L, and it can be recognized with the naked eye. Fluorescence imaging experiment of Cys with PA-A at the cellular successfully showed excellent tissue penetration. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The geometrical configurations of the XBiSe3 (X = Ga, In, Tl) monolayers are identified by employing the first-principles density functional theory calculations, and the stabilities are confirmed by phonon dispersion, formation energy, and ab initio molecular dynamics simulation, respectively. The bandgap and band edges, the density of states, the optical absorption, mobility, and effect of strain engineering are evaluated to understand the photoelectronic properties of the monolayers. The results show that the XBiSe3 mono layers have the indirect bandgaps of 1.14-1.69 (1.20-1.84) eV by HSE06(GW), leading to the enhanced optical absorption from the visible to near-ultraviolet region. The large mobility of the electron and hole are also observed, which is helpful for the separation and transfer of the photogenerated carrier pair. The band edges and bandgaps, as well as the optical absorptions, can effectively be tuned by strain engineering. It should be noted that the band edges of the InBiSe3 monolayer could satisfy the condition of redox potential for the hydrogen evolution reaction under the compressive strain heavier than -3%, implicating this monolayer can also be used for photocatalytic water splitting to produce hydrogen. Therefore, these monolayers have potential applications in photocatalytic materials or photoelectronic devices such as energy harvesters and visible-light sensors. (C) 2021 Elsevier B.V. All rights reserved.
Gerasimova, Yu. V.Aleksandrovsky, A. S.Gerasimov, M. A.Krylov, A. S....
6页
查看更多>>摘要：Raman and optical absorption spectra of disordered hydrated iron fluoridotitanate (HITF) single crystal were studied. Temperature transformations of the Raman spectra indicate independent ordering processes of the [TiF6](2-) and [Fe(H2O)(6)](2+) complexes below the structural phase transition. The absorption spectrum in the near-infrared and visible ranges includes transitions from the high spin ground state T-5(2) of Fe2+ ion to the excited E-5 state and a set of excited triplets. Analysis by Tanabe-Sugano method gives crystal field Dq = 490 cm(-1) and Racah parameters B = 340 cm(-1) and C = 1904 cm(-1). Considerable decrease of B parameter as compared to the free ion value indicates a decrease of interelectron repulsion in the disordered neighborhood of Fe2+ ions. (C) 2021 Published by Elsevier B.V.
Sanchez-Gonzalez, RodrigoSilva, VivianaSuazo, ConstanzaSoto, Juan Pablo...
7页
查看更多>>摘要：In this work, was studied the adsorption and orientation of three dipyridinic derivatives 9,10-bis-((E)-2(pyridin-4-yl)vinyl)anthracene (DPAC), 1,4-bis-((E)-2-(pyridin-4-yl)vinyl)naphthalene (DPNA-T) and 2,6bis-((E)-2-(pyridin-4-yl)vinyl)naphthalene (DPNA-L) on gold nanoparticles, using Surface Enhanced Raman Scattering (SERS). Systematic modification in the shapes of the bifunctional systems (Cross shape, T-shape and Linear-shape) shows changes significant in the preferential orientation of these analytes on the nanostructured gold surface. Additional data from UV-vis measurements and TEM images are in agreement with the Reaction Limited Colloid Aggregation (RLCA) mechanisms for DPAC and DPNA-T and Diffusion Limited Colloid Aggregation (DLCA) mechanisms for DPNA-L, showing that for the same analyte concentration, the aggregation mechanism depends on the molecular shape. These results allow us to rationalize the fundamental aspects involved in the development of devices based on plasmonic resonance with potential applications in the field of molecular electronics. (c) 2021 Elsevier B.V. All rights reserved.
El Sharkasy, Mona E.Aboshabana, RashaBelal, F.Walash, M....
9页
查看更多>>摘要：Curcumin is a natural product that is frequently utilized in cancer prevention and treatment. The significant benefit of vegetable-derived nutraceuticals in combination with widespread cytostatic medication such as ponatinib is to reduce toxicity and side effects. In this paper, we focus the study on analytical quantification of ponatinib and curcumin through highly sensitive synchronous spectrofluorometric method. Applying this method at Delta lambda = 160 nm, each of ponatinib and curcumin could be measured at 303 and 412 nm without interference from each others. The diverse experimental factors impacting the performance of the method were studied and optimized. The method exhibited a reasonable linearity in the ranges of 5.0-60.0 and 10.0-200.0 ng/mL for ponatinib and curcumin, respectively with detection limits of 1.48 and 1.22 ng/mL and quantitation limits of 4.49 and 3.68 ng/mL, respectively. The anticipated method was employed for the assessment and evaluation of the studied drugs in the spiked human plasma samples. The mean % recoveries in plasma samples (n = 6) for each of ponatinib and curcumin were 99.84 +/- 1.86 and 100.06 +/- 2.72, accordingly. The developed method was validated in conformity with the requirements of International Council of Harmonization (ICH). (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Endometriomas are typically an advanced form of endometriosis that leads to the formation of scar tissue, adhesions, and an inflammatory reaction. There is no certain serum marker for the diagnosis of endometriosis. This study aims to research the correlation between the amount of peaks corresponding to proteins and lipids with the volume of endometrioma and determine the chemical structure of blood serum collected from women suffering from endometriosis patients with endometrioma and healthy subjects using Fourier Transform Infrared (FTIR) spectroscopy. FTIR spectroscopy is used as a non-invasive diagnostic technique for the discrimination of endometriosis women with endometrioma and control blood sera. The FTIR spectra of 100 serum samples acquired from 50 patients and 50 healthy individuals were used for this study. For this purpose, multivariate analyses such as Principal Component Analysis (PCA), Partial Last Square analysis (PLS) with Variables Importance in Projection (VIP), and probability models, were performed. Our results showed that FTIR range 1500 cm(-1) and 1700 cm(-1) and around 2700 cm(-1) - 3000 cm(-1), regions may be used for the diagnosis of endometriosis. Also, we find that proteins and lipids fraction increase with the volume of endometrioma. Moreover, PLS and VIP analysis suggested that lipids could be helpful in the diagnosis of endometriosis women with endometrioma. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：To achieve the ultrastable LMOFs with predominant luminescent sensing performances, the aromatic pi-electron mixed ligands strategy was introduced, and the ternary LMOF of {[Zn-2(HDDB)(bib)(1.5)]center dot 3H(2)O}n (1), was fabricated based on 3,5-di(2',4'-dicarboxylphenyl)benozoic acid (H5DDB) and the N-donor of meta-bis(imidazol-1-yl)benzene (bib) under mixed solvothermal condition. LMOF 1 features the first reported 3D 3,4,4-c {6(2).8(3).10}{6(2).8}(2){6(3).8(2).10}(2) framework with 21.2 % porosity as well as high thermal and chemical stability. Further luminescent sensing showed that LMOF 1 as a bifunctional chemosensor possessing predominant detectability for sensitive detect the hexavalent chromates and nitroimidazoles/nitrofurans antibiotics in water through strong luminescent quenching effects, with excellent reusability as well as trace detection limits. Moreover, luminescent quenching mechanisms were further investigated from electron transfer and energy transfer viewpoints. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：As an important component of atmospheric aerosols, water is profoundly related with aerosol hygroscopicity and provides a medium for atmospheric heterogeneous reactions. The quantitative analysis of water content in aerosol droplets is instrumental to understanding atmospheric chemistry, as well as to addressing the related environmental issues, such as air pollution and climate change. Fourier transform infrared (FTIR) spectroscopy has been widely adopted to quantify the amount of water content in atmospheric aerosols, which is based on the absorbance of OH functional group in proportion to water content. However, in the OH stretching vibration band around 3400 cm(-1), spectral distortions may occur, making a quantitative analysis impossible. In addressing this issue, here we put forth a model to simulate the FTIR absorption of hemispherical water droplets, along with a quantitative description of the spectral distortion. Our model prediction was benchmarked with the microscopic-FTIR experiments conducted on sodium sulfate droplets, and good agreements between theoretical and experimental results were found. We observed that the absorbance spanning across the mid-wavenumber infrared region increases with water absorption coefficients; while such an increasing trend was not seen in the 3400 cm(-1) band. We speculate that the spectral saturated absorption is related to the absorption coefficient of water and the ratio of the projected area of droplets to the aperture area. In addition, the effects of droplet size and number density on the absorption spectra were investigated. The waveband range of the saturated absorption broadens with an increase in droplet radius. On the other hand, as the number density of water droplets increases, the absorption at 3400 cm(-1) is enhanced, and the characteristic peak of condensed water becomes increasingly sharper, asymptotic to the typical infrared spectra of water collected by the pressing method. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Discrimination of human serum albumin (HSA) from bovine serum albumin (BSA) based on the fluores-cence probe technique is still challenging due to similar chemical structures. In this work, a novel flavonoid-based fluorescent probe AF is reported for successful discrimination of HSA from BSA. The sens -ing performances of probe, including sensing dynamic, sensitivity and selectivity, have been carefully studied. Moreover, sensing mechanism was elucidated by Job's plot, displacement experiment, and molecular docking, suggesting that the specific response to HSA originated from the albumin-induced restricted intramolecular rotation (RIR) of probe. This work may provide a simple way for designing of novel probes for HSA with high selectivity. (c) 2021 Published by Elsevier B.V.
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