查看更多>>摘要：The quality evaluation of nature polysaccharides is a tough nut to crack because of its high Mw distributions and larger polarity property. It is well-known that infrared spectroscopy and multiple regression modeling have been used for quantitative examinations in multiple fields, but it has not been applied to the compositional analysis of polysaccharides. In this study, attenuated total reflectance-fourier transform infrared spectroscopy is used to simultaneously quantify aldoses, ketose and uronic acids in Atractylodes polysaccharides by a combination of multivariate regressions. After experience of different data processing pretreatments, the resulting spectrum contains maximum amount of information of monosaccharide contents in Atractylodes polysaccharides. In this case, different smoothing points, derivatives, SNV and MSC are used in the pre-modeling spectrum processing and VIP screening is used to reduce the number of variables to simplify the calculation of the model. All the most optimal prediction models have both good prediction ability (R-2 >= 0.9 and RPD > 3) and no over fitting (RMSEP/RMSEC < 3). This strategy has opened a new possibility for the nondestructive determination of complex monosaccharide compositions of natural polysaccharides in a short detection time, low equipment requirement and high experimental safety.
查看更多>>摘要：A novel and simple turn-on fluorescence probe (HD) for Al3+ detection was successfully developed based on flavonol derivatives. This probe exhibited a significantly enhanced fluorescence response toward Al3+ in aqueous solution which could be observed by naked-eye from poor fluorescence to strong light green emission. The probe HD displays highly specific detection for Al3+ over other competitive metal ions, and the detection limit of probe HD for Al3+ was determined to be 2.57 x 10(-8) M, which are much lower than the World Health Organization (WHO) guideline value for drinking food/water. The binding stoichiometry of probe HD with Al3+ was determined to be 1:1 according to Job's plot and ESI-HRMS analysis, and the binding constant was calculated to be 2.01 x 10(4) M-1. The probe HD exhibited high selectivity, high sensitivity, good anti-interface ability, and wide pH application range as well as the quantitative determination in the detection of Al3+. The coordination mechanism of probe HD with Al3+ was supported by density functional theory (DFT) calculations and HRMS analysis. In addition, the probe HD was found to have good cell permeability and could be applied for live-cell imaging to detect Al3+ in onions and zebrafish. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：The post-translational modification of amino acid plays a critical role in normal and diseased biological states. Specifically, nitrotyrosine (nTyr) has been linked to diseases, including neurodegeneration, among others. Hence, alternative methods are required for detection and differentiation of nTyr from other structurally similar analogues, such as Tyrosine (Tyr) or phosphotyrosine (pTyr). Herein, the selective detection of nTyr, over other congeners, was achieved by using dual-fluorescent carbon dots (CDs) in buffered solution, artificial saliva, bovine serum albumin and diluted equine serum. The nTyr induced fluorescence quenching of the blue and red emissions of CDs, in the 20-105 mu M linear range, and with the limit of detection (LOD) at 34 mu M, which was well below the physiological concentration required for detection. The sensor was functional at biological pH values, with optimal quenching efficiency at basic pH. The sensor was highly selective for nTyr even in the presence of common biological interferences (metal cations, organic anions, amino acids, nucleosides and other biologicals). The mechanism of quenching (a combination of static and dynamic) was ascribed to the nonradiative energy transfer, due to electronic overlap between nTyr absorbance and CDs fluorescence emission, and electron transfer from excited CDs state to nTyr as an electron acceptor. The dual-fluorescent CDs represent viable sensors for key biological modifications, and their selectivity and sensitivity may be further improved through tailored chemical synthesis of CDs, such as tunable surface chemistry to promote selective recognition of analyte of interest.
查看更多>>摘要：In this study, we mainly aimed to investigate the diagnostic potential of surface-enhanced Raman spectroscopy for bladder cancer and kidney cancer which are the most common cancers of the urinary system, and evaluate the classification ability of three statistical algorithms: principal component analysis-linear discriminate analysis (PCA-LDA), partial least square-random forest (PLS-RF), and partial least square support vector machine (PLS-SVM). The plasma of 26 bladder cancer patients, 38 kidney cancer patients and 39 normal subjects was mixed with the same volume of silver nanoparticles, respectively, and then high-quality SERS signal was obtained. The SERS spectra in the range of 400-1800 cm-1 were compared and analyzed. There were some significant differences in SERS peak intensity, which may reflect the changes in the content of some biomacromolecules in the plasma of cancer patients. Based on the three algorithms of PCA-LDA, PLS-RF and PLS-SVM, the classification accuracy of SERS spectra of plasma from cancer patients and normal subjects was 98.1%, 100% and 100%, respectively. In addition, the classification accuracy of the three diagnostic algorithms to classify the SERS spectra of bladder cancer and kidney cancer was 81.3%, 91.7%, and 98.4%, respectively. This exploratory work demonstrates that SERS combined with PLS-SVM algorithm has superior performance for clinical screening of bladder cancer and kidney cancer through peripheral plasma.(c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：5-Hydroxymethylfurfural (5-HMF) is a useful indicator of thermal damage degree and freshness of milk. It is of great importance to develop simple, rapid and accurate analytical methods for the sensitive detection of 5-HMF in milk and milk-based products. In this work, surface-enhance Raman spectroscopy (SERS) was used for rapid determination of 5-HMF in processed cheese by colloidal Au nanoparticles (AuNPs) substrate synthesized by the classical solvothermal reduction method. Density functional theory (DFT) calculations were carried out to determine the vibration assignments of 5-HMF and the surface enhancement effect of AuNPs substrate. The results found that a good linear response on the AuNPs substrate for 5-HMF in the concentration range of 0.1-75 mM was established with the detection limit of 75 mu M (S/N = 3). Furthermore, the present method could be applied to the determination of 5-HMF in a cheese real sample which revealed its promising application in food safety and analysis. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：A novel near-infrared fluorescent probe CyOE based on hemicyanine dye containing acetyl as a recognition site is reported. The probe CyOE shows high selectivity and sensitivity (LOD = 82 nM, 2.58 ppb), as well as good water solubility and quantitative detectability of hydrazine in the concentration range of 0-75 mu M (R-2 = 0.993). Moreover, CyOE has a significant increase in fluorescence at 735 nm with the addition of N2H4, which provides a rapid, colorimetric and gas-phase detection method for N2H4 in both aqueous solution and real water samples. In addition, CyOE is successfully utilized to visualize hydrazine in cells with low cytotoxicity and high cell permeability. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Nine decorated lead-tin glazed earthenwares, colloquially termed 'delftware', produced in c. 1770 in Bristol, Lancaster and Liverpool, England, have been analysed non-invasively by Raman spectroscopy and electron microscopy. The body paste used to manufacture these west coast wares was attained by the blending of highly dolomitic [CaMg(CO3)(2)] "blue" clay sourced from Carrickfergus, County Antrim, Ireland, with locally sourced clays. Thus, the resulting body fabric of these wares contains significant MgO enabling them to be differentiated from MgO-free London manufactured delftware. The glazes employed all contain arsenic, obtained as a cobalt impurity or by deliberate addition. The presence of this unvolatilised arsenic in the glaze has then reacted with the lead during firing at temperatures approaching 1000 degrees C and then further reacted with calcium and magnesium to form needle-like crystals of lead arsenates in the form of mimetite [Pb-5(AsO4)(Cl,OH)], schultenite [Pb (AsO3OH)], beta-roselite [Ca2Co(AsO4)(2)center dot 2H(2)O], hedyphane [Ca2Pb3(AsO4)(3)Cl], wendwilsonite [Ca2Mg (AsO4)(2)center dot 2H(2)O] and/or adelite [CaMgAsO4(OH)] during high temperature firing.
查看更多>>摘要：A novel fluorescent compound, named C-TPA, based on coumarin (acceptor) and triphenylamine (donor) was facilely designed and fabricated through a one-step Suzuki coupling reaction. As a donor group, triphenylamine can efficiently enhance the fluorescence intensity and photostability of coumarin, and thus improve the detection efficiency. C-TPA-S was obtained from C-TPA treated with Lawesson's reagent and C-TPA-S can be used for the turn-on detection of hypochlorite through oxidative desulfurization with a low detection limit of 0.12 mu M. Moreover, the intramolecular charge transfer process between the donor and acceptor group endows C-TPA with solvatochromism property and makes C-TPA a good candidate for polarity detection. The C-TPA with bright green fluorescence was highly efficient for imaging the microenvironment of polarity both in living cells and tissues with high selectivity and photostability, which can be applied in the diagnosis for the cancer cells.
查看更多>>摘要：Herein, a ratiometric fluorescent nanoprobe was strategically fabricated using pH-sensitive azamonardine (Aza) as a pH indicator and pH-insensitive AIZS QDs as a reference fluorescence signal for urea activity determination and pH sensing. As the pH changed from 9.7 to 11.7, the resorcinol could react with dopamine to form the cyclization product (Aza), producing a fluorescence signal at 455 nm. Meanwhile, the fluorescence intensity of AIZS QDs at 566 nm remained unchanged. Thus, the ratio of the fluorescence intensity (F-455/F-566) was able to quantify pH value. Our designed pH-sensing platform showed a linear respond to pH values in the range of 9.7 to 11.7 at intervals of 0.2. In addition, the hydrolysis of urea by urease caused an increase of the system pH value, which can be used to measure the concentration of urea. The developed method for urea determination exhibited a good linear relationship from 0.02 to 20 mM and the limit of detection was 0.0103 mM. Moreover, the practical application was confirmed by urea analysis in real water sample with high feasibility and accuracy, indicating the great application prospects of this sensing platform for urea activity analysis.
查看更多>>摘要：For the first time, the spectroscopy data of TeCl+ ion and the transition data between low excited states are systematically calculated. The potential energy curves of 22 A -S states and 51 omega states are calculated by the internally contracted multiconfiguration interaction and Davidson correction method. By solving the onedimensional radial Schrodinger equation, the spectroscopy data of A-S states and dl states are obtained. The phenomenon of avoided crossing in omega state is analyzed in detail, which is mainly concentrated in the region of 20000 cm(-1) to 35000 cm(-1). The Franck-Condon factors, Einstein coefficients and spontaneous radiative lifetimes of X-3 sigma(0)-> 2(1)sigma(+)(0) transitions are calculated. According to the calculation results, it is preliminarily judged that the direct laser cooling of TeCl+ ion is not feasible.
NSTL
Elsevier