查看更多>>摘要：A new fluorescence coordination polymer [Zn(Py2TTz)(5-OH-IPA)]n (1) (Py2TTz = 2,5-bis(4-pyridyl)thia zolo[5,4-d]thiazole, 5-OH-IPA = 5-hydroxyisophthalic acid dianion) was synthesized, which exhibited the characteristics of fluorescence quenching and bathochromic shift toward Hg(II) in aqueous solution at pH 7.00. Mechanism study showed that the interactions between Hg(II) ions and Py2TTz ligands in 1 were responsible for the fluorescence emission change. Thanks to the specific interactions between 1 and Hg(II), excellent selectivity was achieved both in aqueous solution and in solid test paper. The detec-tion limit of 1 for Hg(II) sensing was 125.76 nmol L-1 and a linear rang was 1.00-10.00 lmol L-1. More importantly, satisfactory recovery and accuracy of 1 for Hg(II) sensing were also obtained in buffer-free real water samples. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Infrared spectra for the beta and gamma phases of oleic acid were obtained at room temperature (similar to 25 degrees C) under pressures of up to 5 and 10 GPa, respectively. Density functional theory (DFT) calculations were performed to examine the changes in the infrared spectra and crystal lattices of the beta and gamma phases that occur under pressure. Mode assignments for peaks that were observed to have a low-wavenumber shift with pressure were made based on the DFT-calculated infrared spectra. The C=O stretching and O-H stretching vibration peaks shifted to a lower wavenumber with pressure in both the beta and gamma phases because the hydrogen bonds became stronger with pressure and the C=O and O-H bonds weakened. The difference in the shift amount between the two phases was related to anisotropic compression in the crystal lattice. (C) 2021 Elsevier B.V. All rights reserved.
Baddini, Ana Luisa de QueirozSantos, Jorge Luiz Victor de PaulaTavares, Raquel Reinerde Paula, Leticia Silva...
9页
查看更多>>摘要：In this work samples of historical pigments of green hue were brushed on a canvas and studied by Visible Reflectance, X-Ray Fluorescence and Fourier Transform Infrared Spectroscopy. One hundred samples were investigated, all with green hue, these prepared from pigments themselves green, such as chromium oxide (Cr2O3) or from a mixture of pigments that result in green, for example, chrome yellow (PbCrO4) and Prussian blue (Fe-4[Fe(CN)(6)](3)). Because every sample investigated through the spectroscopic techniques were of green hue, the characterization of the pigments present in the mixtures through the visual inspection of spectra has become a complex task in some cases, also, due the large number of recorded spectra. In this work, classification models were developed using the multivariate statistical method Partial Least Squares Discriminant Analysis (PLS-DA) to automate the characterization of the pigments present in the mixtures. The models were developed to classify chromium oxide (Cr2O3), chrome yellow (PbCrO4), cerulean blue (CoO center dot nSnO(2)) and yellow ochre (Fe2O3.H2O + clay + silica). The models were developed from the fusion of data from the three spectroscopic techniques. However, before data fusion, pre-treatments of the spectral data were tested for their influence on the PLS-DA models. The models developed with data from the three techniques made it possible to classify the pigments of interest in the samples with up to 100% effectiveness. The results also indicate that fusion of the data from the three techniques allows to obtain fingerprints of the pigments of interest, which is not always possible using data from only one or two of the techniques applied in this work. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Hg(II) is one of the most toxic heavy metal ions. The bioconcentration and degradation-resistant of Hg(II) bring about serious harm to the ecosystem and humans. Therefore, the establishment of an accurate and effective method for detecting mercury ions is of great significance to environmental protection, food safety and human health. In this work, a new fluorescent nanoprobe was presented using nitrogendoped carbon quantum dots (N-CQDs) for Hg(II) sensing with high stability and selectivity. On this basis,a paper-based chip was innovatively developed for visualization detection of Hg(II). The N-CQDs were prepared through a one-step hydrothermal reaction using catechol and ethylenediamine as carbon and nitrogen sources, respectively. As-prepared N-CQDs exhibit the strong green fluorescence at the excitation/emission wavelength of 370/511 nm. In aqueous solution, a rapid and highly sensitive detection method of Hg(II) was established by the joint of dynamic and static quenching effect of Hg(II) on NCQDs fluorescence. Under the optimized conditions, there was a stable correlation between the fluorescence intensity change of N-CQDs and the concentrations of Hg(II) in the range of 15 ti 104 nM, and the detection limit was down to 8 nM (S/N = 3). The recoveries of water, sorghum and rice were 91.60 to 102.46%, which was consistent with ICP-MS. More importantly, the N-CQDs nanoprobe was further integrated in nitrocellulose membrane to develop paper-based chip for Hg(II) visualization detection, and the detection performance was also excellent. This strategy had significant implications for achieving lowcost, on-site real-time monitoring of mercury (II) in the environment and food. (c) 2021 Published by Elsevier B.V.
查看更多>>摘要：Glutathione (GSH) as an essential biothiol maintains redox homeostasis in human body, the aberrant level of it has been related to various diseases. In this work, we constructed a facile and environment-friendly strategy by using Ce based metal-organic frameworks and gold nanoparticles (AuNPs) for detection of GSH. The fluorescence intensity of the Ce-MOF was quenched by AuNPs, which is ascribed to the existence of fluorescence resonance energy transfer (FRET) and electrostatic interaction between Ce-MOFs and AuNPS. Because of the formation of Au-SH between AuNPs and GSH, the addition GSH induced the Ce-MOF/AuNPs and prevented the occurrence of FRET and electrostatic interaction between Ce-MOFs and AuNPS, which futher recovered the fluorescence of Ce-MOF. Under the optimized conditions, this "turn-on" sensing process revealed a high selectivity toward GSH and displayed good linearity in range of 0.2-32.5 lM with low detection limit of 58 nM. In addition, the practicability of the strategy was testified through analyzing GSH in real human serum samples. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Owing to the attractive biological and pharmacological activities, sensitive and selective detection of cur cumin is of great significance. Nanomaterials possessing unique optical properties exhibit potential applications in the fluorescent detection of curcumin. This review first discussed the detection strategies of fluorescent nanosensors. In the subsequent section, we highlighted the recent advances of different nano materials for fluorescent detection of curcumin, including semiconductor QDs, lanthanide upconversion nanoparticles, fluorescent metal nanoclusters, and carbon quantum dots. And we further provided the merits of fluorescent nanosensors for curcumin. Lastly, the challenges and further directions were presented. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：In recent years, fluorescent probes based on chemical reactions have been widely investigated as a powerful and noninvasive method for the diagnosis of diseases. beta-Galactosidase (beta-gal), a typical lysosomal glycosidase, over expressed in senescent cells and primary ovarian cancer cells, which has been considered as an important biomarker cell senescence and primary ovarian cancers. Fluorescent probes for the determination of beta-gal provide an excellent choice for visualization of cell senescence. In this work, a turn on fluorescent probe (HBT-gal) for beta-gal activity was developed based on the enzymatic hydrolysis of glycosidic bonds. HBT-gal showed little fluorescence in aqueous buffer excited at 415 nm, while emitted green fluorescence centered at similar to 492 nm upon incubated with beta-gal. The sensing scheme showed high selectivity and sensitivity for beta-gal activity with a limit of detection calculated as low as 0.19 mU/mL. Moreover, HBT-gal was successfully applied to image beta-gal activity in senescent Hep G2 cells treated with H2O2. Therefore, probe HBT-gal demonstrated a potential usage for the determination of cell senescence using beta-gal as a biomarker. (C) 2021 Elsevier B.V. All rights reserved.
Vega Canamares, MariaMieites-Alonso, Maria GorettiLeona, Marco
8页
查看更多>>摘要：Alkannin is the main coloring matter of Alkanet, a natural red dye extracted from the root of Alkanna tinc-toria L. Shikonin, the optical isomer of alkannin, is extracted from Lithospermum erythrorhizon. As both red dyes are only slightly soluble in water, the application of ordinary Raman spectroscopy is limited. Thus, Surface-enhanced Raman spectroscopy (SERS) can be successfully applied to the study of the red dyes solutions. Solid alkannin and shikonin were characterized by ordinary Raman spectroscopy. Density Functional Theory (DFT) methods were used to calculate the Raman spectrum of the dyes and to assign the experimental Raman bands to their vibrational normal modes. Different pH conditions were tested in order to determine the optimal conditions for the SERS detection of alkannin and shikonin. Based on the previous results, a perpendicular orientation of the red dyes on the Ag substrate was deducted. Finally, shikonin was identify by SERS spectroscopy in a dyed paper sample from an 8th cen-tury handscroll from Japan. (c) 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
查看更多>>摘要：Sulfur dioxide (SO2) is an important signal molecule in living systems, and plays a wide range of physiological functions. Real-time and in situ detection of the dynamic balance of SO2 in mitochondria is of great significance to in-depth study its biological roles. Herein, we have developed a mitochondria-targeted fluorescent probe Nap-L based on the FRET mechanism to detect SO2 in living cells. The probe Nap-L employed naphthalimide and positively charged benzopyridine as the donor and acceptor in the FRET system, and emitted green and red fluorescence under excitation. In respond to SO2, the nucleophilic addition of bisulfite to benzopyridine and then interrupted the FRET process from naphthalimide to benzopyridine fluorophore, thereby triggering an obvious change in the fluorescence ratio. The probe Nap-L showed high selectivity to SO2 over the biothiols (Hcy, GSH, Cys) and other biologically related species. Biological experiments suggested that the probe Nap-L mainly distributed in mitochondria, and can be successfully used to detect mitochondrial endogenous SO2 in living cells. (C) 2021 Elsevier B.V. All rights reserved.
Goncalves, Helena M. R.Tavares, Isabel S.Neves, Susana A. F.Fontes, Rui...
9页
查看更多>>摘要：The pressing need to develop a specific analytical sensor that can identify and quantify Fe(II) without a cytotoxic response was the major motivation drive in this work. The turn-on fluorescent sensor here described can successfully detect Fe(II) and discriminate this ion from other analytes that commonly act as interferents in biological media. Moreover, this reduced fluoresceinamine-based sensor has a high photostability and high dissociation constant, which is an indication that the complex obtained between reduced fluoresceinamine (RFL) and Fe(II) is highly stable. This fluorescence-based sensor has a binding mechanism of 1:1 and a positive cooperativity was found between analyte and sensor. The detection, quantification and sensitivity parameters of the sensor were determined: 21.6 +/- 0.1 lM; 65.6 +/- 0.1 lM and 48 +/- 3 (x10(7)) lM, respectively. To evaluate a possible cytotoxicity effect an erythrocyte assay was performed and the obtained data were evaluated considering CdTe Quantum Dots (QDs) passivated with mercaptoacetic acid has experimental control. According to the resulting data RFL is not cytotoxic even when used in high concentrations, 660 mM. On the other hand QDs are quite different. Indeed it was proven that these heavy metal-based nanoparticles are responsible for 40% erytrocytes hemolysis in concentrations of 600 mM. (C) 2021 Elsevier B.V. All rights reserved.
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