查看更多>>摘要：ETC (3,3'-di(3-sulfopropyl)-4,5,4',5'-dibenzo-9-ethylthiacarbocyanine triethylammonium salt), as a derivative of thiazole, is capable of forming various aggregates by the short-range noncovalent interaction forces under specific conditions, accompanying with significant absorbance and fluorescence characteristics. In this work, a label-free probe (ETC) for the detection of Cys (Cysteine) and Hg2+ was developed based on transformation between monomers and J-aggregations by AGRO100. AGRO100 can transform between single-stranded DNA and G-quadruplex to realize recognition of Cys and Hg2+ in dual-channel mode. These recognitional signals can be captured by UV-visible absorption spectra and fluorescence spectroscopy. ETC exhibits high sensitivity and selectivity with the detection limit of 0.197 nM in a wide range of 0-15 mu M, which can apply of Cys and Hg2+ detection in human serum. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Ascorbic acid has recently been extensively used due to its role in the management of COVID-19 infections by stimulating the immune system and triggering phagocytosis of the corona virus. The currently used spectrofluorometric methods for determination of ascorbic acid require using derivatizing agents or fluorescent probes and suffer from a number of limitations, including slow reaction rates, low yield, limited sensitivity, long reaction times and high temperatures. In this work, we present a highly sensitive spectrofluorometric method for determination of ascorbic acid by switching-on the fluorescence of salicylate in presence of iron (III) due to a reduction of the cation to iron (II). The addition of ascorbic acid resulted in a corresponding enhancement in the fluorescence intensity of iron (III)-salicylate complex at emission wavelength = 411 nm. The method was found linear in the range of 1-8 mu g/mL with a correlation coefficient of 0.9997. The limits of detection and quantitation were 0.035 mu g/mL and 0.106 mu g/mL, respectively. The developed method was applied for the determination of ascorbic acid in the commercially available dosage form; Ruta C60 (R) tablets. The obtained results were compared with those obtained by a reported liquid chromatographic method at 95% confidence interval, no statistically significant differences were found between the developed and the reported methods. Yet, the developed spectrofluorometric method was found markedly greener than the reference method, based on the analytical Eco-scale and the green analytical procedure index. This work presents a simple, rapid and sensitive method that can possibly be applied for determination of ascorbic acid in pharmaceuticals, biological fluids and food samples. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Gestational diabetes mellitus (GDM) is a common complication during pregnancy. It could cause severe side-effect on the mother's and newborn's heath in the short- and long-term. Prevalence has been increasing over time, likely due to increases in mean maternal age and body weight. However, how GDM affects the placenta structure and function are still unclear. Fourier transform infrared microspectroscopy is well suited to study biological samples, such as tissues and cells. Biomolecules of human tissues have characteristic absorptions in mid-infrared range. In this study, Fourier transform infrared microspectroscopy was used to measure unfixed placental tissue sections from women with GDM and matched controls. The molecular composition of different type of placental tissue sections were further analyzed with principle component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA). The major spectral characteristic of biomolecules in GDM placental tissue and control group were compared. The conformational change of lipid chains and higher level of lipid oxidation were found for placental tissues from GDM pregnancies. The increase of proteins beta-sheet structures relative to the alpha-helix structures in the GDM placental tissues were also found. The fingerprint region showed the variances of carbohydrates, nucleic acids and phospholipids between GDM and control group placental tissues. These findings are helpful for understanding how GDM affects placenta's biochemical composition and how GDM causes maternal and fetal metabolism changes. This study also provides a new approach to investigating biomolecular composition of samples from GDM pregnancy through spectroscopic method. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The solid-state reaction was employed as a suitable method to produce orthorhombic Yb3+/Er3+ co-doped La2Ti2O7 phosphors. The pump power and temperature dependencies of spectra of the Yb3+/Er3+ co-doped La2Ti2O7 were studied for color tunability and optical thermometry. The pump power significantly affected the color coordinates of the phosphors. The upconversion green light transformed to the broad white light at higher pump power. A two-photon transition was proposed to explain the upconversion energy transfer process. The fluorescence intensity ratio technique was used to calculate the optical temperature sensor sensitivities. The Delta E energy difference obtained from the intensity ratios of the thermally coupled H-2(11/2) and I-4(15/2) energy levels of Er3+ are 763.64 +/- 76.62 cm(-1), 777.77 +/- 44.62 cm(-1), 640.71 +/- 137.39 cm(-1) for La1.95Yb0.04Er0.01Ti2O7, La1.94Yb0.04Er0.02Ti2O7, and La1.93Yb0.04Er0.03Ti2O7, respectively. Absolute temperature sensitivities of the phosphors decreased with increasing Er a-1 concentration. The maximum absolute sensitivity was determined to be 0.51x10(-2) K-1 at 553 K for La1.95Yb0.04Er0.01Ti2O7, 0.64x10(-2) K-1 at 571 K for La1.94Yb0.04Er0.02Ti2O7, and 0.38x10(-2) K-1 at 457 K for La1.93Yb0.04Er0.03Ti2O7. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：A benzothiazole-based fluorescent and colorimetric chemosensor BZD ((E)-2-(benzo[d]thiazol-2-yl)-5-((4-(diethylamino)-2-hydroxybenzylidene)amino)phenol) was applied for detecting ClO-. BZD showed fluorescence quenching and color variation for ClO- via oxidative reaction between ClO- and the imine bond. It could effectively detect ClO- over various competitive analytes. Detection limit for ClO- was calculated to be 1.74 mu M by fluorescent method and 16.44 mu M by colorimetric one, respectively. Additionally, BZD could be utilized for sensing ClO- in zebrafish, real water sample and paper strip. The photophysical characteristics and sensing mechanism of BZD to ClO- were studied by fluorescent and UV-visible spectroscopy, NMR titration, and ESI-mass spectrometry. (C) 2021 Elsevier B.V. All rights reserved.
Mayerhoefer, Thomas G.Ivanovski, VladimirPopp, Juergen
9页
查看更多>>摘要：Since about 60 years, it is possible to determine the set of optical constants from reflectance measurements by the Kramers-Kronig relations. Unfortunately, the potential of the method seems to be limited in practice by the need to extend measured data into unknown regions by extrapolation, which is prone to error and leads to deviations from the true values in the known region depending on the method of extension. With the advent of infrared refraction spectroscopy, which uses reflectance measurements at normal or near normal incidence, the development of a fast method to determine the complex index of refraction function reliably for these cases has become an even more interesting goal. In this work, we introduce a way to perform a Kramers-Kronig analysis of such reflectance spectra without the need to extrapolate the measured data for higher wavenumbers beyond the measurement range. Furthermore, we introduce and compare very simple and reliable material-independent ways to extrapolate the measured data for lower wavenumbers. As a result, we devise fast and sufficiently accurate methods, which are easily implementable into existing spectrometer software, to extract quantitative spectral information from reflectance measurements at near normal incidence. (C) 2021 Elsevier B.V. All rights reserved.
Tusek, Ana JurinjakJurina, TamaraCulo, IvanaValinger, Davor...
10页
查看更多>>摘要：In this study, the potential of microfluidic systems with different microchannel geometries (microchannel with teardrop micromixers and microchannel with swirl micromixers) for the preparation of oil-inwater (O/W) emulsions using two different emulsifiers (2 % and 4 % Tween 20 and 2% and 4 % PEG 2000) at total flow rates of 20-280 mu L/min was investigated. The results showed that droplets with a smaller average Feret diameter were obtained when a microfluidic device with tear drop micromixers was used. To predict the average Feret diameter of O/W emulsion droplets, near-infrared (NIR) spectra of all prepared emulsions were collected and coupled with partial least squares (PLS) regression and artificial neural network modelling (ANN). The results showed that PLS models based on NIR spectra can ensure acceptable qualitative prediction, while highly non-linear ANN models are more suitable for predicting the average Feret diameter of O/W droplets. High R-2 values (R-2 validation greater than 0.8) confirm that ANNs can be used to monitor the emulsification process. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：A fluorescent probe based on glutathione-capped copper nanoclusters (GSH-CuNCs) was developed for the detection of dual targets, human serum albumin (HSA) and creatinine, in human urine. The GSH-CuNCs were synthesized by a one-pot green method using ascorbic acid as a reducing agent. The detection of HSA was in a turn-on mode via electrostatic interaction in a basic condition while the detection of creatinine was in a turn-off mode via non-covalent bonding in an acidic condition. Under optimal conditions, the linear range and detection limit of HSA were 5.0 nM to 150 nM and 1.510 +/- 0.041 nM, while those of creatinine were 30 mu M to 1000 mu M and 13.0 +/- 1.0 mu M. This easily fabricated nanocluster probe provided a fast response with high sensitivity, and good selectivity. Recoveries from urine samples were in the range of 81.44 +/- 0.25 to 109.22 +/- 0.57% for HSA and 80.57 +/- 0.16 to 109.0 +/- 0.10% for creatinine. The urinary analytical results from the fluorescent probe were in good agreement (P > 0.05) to those obtained from immunoturbidimetric and enzymatic methods, signifying the excellent performance of this sensing system. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The detection of intracellular nitroreductase (NTR) activity is important for the study of hypoxia in organisms. In the present study, a Rhodol-derived fluorescent chemosensor (Rhod-NO2) was synthesized in a one-step procedure. Rhod-NO2 exhibits 110-fold fluorescence enhancement in the presence of NTR. Moreover, Rhod-NO(2 )demonstrates high NTR selectivity and sensitivity (LOD, 0.6 ng/mL). The mode of Rhod-NO2 binding to NTR was also revealed by molecular docking. In addition, the reaction and luminescence mechanisms were evaluated by MS and TDDFT theoretical calculations, respectively. Finally, Rhod-NO2 was successfully applied to monitor NTR production during Escherichia coli (E. coli) growth, and to visually analyze NTR production in malignant oral cancer cells under hypoxia. Thus, Rhod-NO(2 )represents a new molecular tool to further understanding of the biological function of NTR. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Although biomimetic surface enhanced Raman scattering (SERS) substrate which makes use of naturally existing raw materials have been fully utilized, it remains challenging to achieve credible quantitative detection. Herein, nanoimprint technology was exploited to engineer internal standard (IS) enabled quantitative flexible biomimetic SERS substrates, in which polydimethylsiloxane (PDMS) with intrinsic Raman signal was utilized as a tool to reversely duplicate surface structures from different agriculture products and then deposited with Ag nanoparticles. The resultant four kinds of biomimetic SERS substrates with different surface geometries all permit highly sensitive assay with enhancement factors (EFs) of about 10(6) in both drop-dry and in situ SERS detection modes. Moreover, the quantitative degree in the SERS detection was effectively corrected based on the IS strategy. Finally, an ingenious interactive in situ SERS detection was conducted. Interestingly, the maximum recovery rate was achieved when the template food was used as target surface compared with other foods, indicating the significance of manufacturing the highly conformed SERS-active structure from the surface to be tested. The proposed quantitative biomimetic SERS substrate is expected to be widely used in the field of biochemical supervision. (C) 2021 Elsevier B.V. All rights reserved.
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