查看更多>>摘要：A new Lanthanum-based luminescent metal-organic framework, {[La(H2O)(4)(HL)]center dot H2O} (1), has been successfully synthesized by employing 3,3',5,5'-azodioxybenzenetetracarboxylic acid (H4L) as a rigid organic linker through the solvothermal reactions. 1 exhibits a two-dimensional (2D) layered structure and a three-dimensional (3D) supramolecular structure is formed by hydrogen bonds between the layers. Stability studies indicate that 1 has good chemical stability and thermostability. Meanwhile, the K-sv values for TNP is 4.61 x 10(4) M-1 with the LOD of 4.13 x 10(-6) M and the K-sv value for Fe3+ is 1.22 x 10(4) M-1 with the LOD of 1.72 x 10(-5) M, respectively, which demonstrated that 1 exhibits high sensitivity and excellent selectivity for the detection of TNP and Fe3+ via fluorescence quenching. Significantly, 1 shows high regenerability after five recycling progress for sensing Fe3+. The possible mechanisms associated with the luminescent quenching are discussed in detail through some relevant experiments and tests, as well as the DFT calculations. Based on the above excellent properties of 1, it will have extremely potential to be used as a dual functional sensor for both detecting TNP and Fe3+ in aqueous solution, simultaneously. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Globally, the environmental pollution is one of the major issues causing toxicity towards human and aquatic life. We have developed a facile and innovative sensing approach for detection of sulphide ions (S-2) present in the aqueous media using Ag-0 decorated Cr2S3 NPs embedded on PVP matrix (Ag/Cr2S3-PVP). Based on the SPR phenomena, the detection of S-2 ions was established. The nanohybrid was characterized using various techniques such as UV-vis spectrophotometer, High-Resolution Transmission Electron Microscopy (HR-TEM), Thermal Gravimetric Analysis (TGA), X-ray diffraction analysis (XRD), Energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The yellowish colour of Ag/ Cr2S3-PVP nanohybrid turned to brown colour in presence of S-2 ions. The selectivity and sensitivity of the prepared probe was studied against the other interfering metal ions. In addition, the effect of different concentration of S-2 ions in the nanohybrid solution was investigated and the Limit of detection (LOD) was found to be 6.6 nM. The good linearity was found over the range of 10 nM to 100 mu M with R-2 value of 0.981. The paper strip based probe was developed for rapid onsite monitoring of S-2 ions. The proposed method is found to be cost-effective, rapid, and simple. We have validated the practical applicability of the prepared probe for determining the concentration of S-2 ions in real water samples. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Surface-enhanced Raman scattering (SERS) has been applied in many fields, but still has the limitation of widespread applications on semiconductor substrates. In this work, a series of antimony-doped tin oxide (ATO) nanoparticles (NPs) have been synthesized by a hydrothermal method and were used as SERS substrates for the first time. Interestingly, a charge transfer (CT) effect was revealed between the probing molecules of 4-mercaptobenzoic acid (4-MBA) and the substrates of ATO NPs, which accounts for the SERS enhancement and shows dependence to the Sb ions doping ratios in ATO NPs. By considering the energy level diagram of the ATO-MBA complexes and the doping theory of semiconductors, this phenomenon is believed to connect to the variance of the optical band gap energy (E-g), which is accompanied with the changes of free charge carrier densities in conduction bands (CBs) of ATO NPs due to different doping contents. The study of the E-g- or free-charge-carrier-density-dependent property of the semiconductor-based SERS provides a new point of view for the development of new semiconductor SERS substrates and also contributes to the SERS CT mechanism. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：A new Schiff base probe (QT) consisting of 8-aminoquinoline (Q) and thiophene-2-carboxaldehyde (T) moieties has been synthesized. QT undergoes chelation-enhanced fluorescence quenching when exposed to Hg2+ due to coordination by the sulfur and nitrogen atoms of QT thus forming a facile "turn-off" sensor. The formation of the chelation complex was confirmed by UV-visible absorption and emission spectral measurements, H-1 NMR titration and density functional theory calculations. These studies revealed that the probe exhibits high selectivity and sensitivity towards Hg2+ in the presence of other common metal ions. A low detection limit of 23.4 nM was determined and a Job plot confirmed a 2:1 stoichiometry between QT and Hg2+. The potential utility of QT as a sensor for Hg2+ ions in human HeLa cells was determined by confocal fluorescence microscopy, and its suitability for use in the field with environmental samples was tested with Whatman filter paper strips. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Rapid and accurate detection of fluoroquinolones (FQs) antibiotics residues in food substrate are of great significance to food safety. In this study, terahertz spectroscopy was employed to conduct the spectral and imaging analysis to explore its feasibility for detection concentrations of FQs in fish meal feeds (FMF). Four methods (frequency of maximum difference in frequency-domain, characteristic absorption peak, successive projections algorithm and stepwise regression) were used to selected characteristic frequencies of sample. Terahertz imaging was formed at selected characteristic frequency and back propagation neural network was used to establish quantitative evaluation models to select optimal characteristic imaging frequency. Finally, relationship between concentrations of FQs and their gray values was revealed, and each data had a small range of error bar. The results showed that terahertz spectral and imaging technique can visualize norfloxacin and enrofloxacin concentrations in FMF precisely. This study explored a brand-new visualization method for quantitative detection of FQs in FMF based on terahertz spectral and imaging technology. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Amphibians are a natural source of a large number of peptides with a wide range of functional activities. Here, a complex of spectroscopic methods including NMR-, FTIR-, CD-, and UV-spectroscopy was applied to characterize the structure and functional activity of megin-1, a peptide isolated from amphibian skin. The three-dimensional structure of two forms of the peptide was determined using solution NMR spec-troscopy. Thermodynamic characteristics of the process of peptide transformation from linear to cyclic form were obtained. Antibacterial and antimycotic properties of the peptide, as well as its protease inhi-bitory activities, were analyzed. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Hydrogen sulfide (H2S) is an important gasotransmitter in biological system, and plays a crucial role in varied physiological and pathological processes. Exogenous H2S is widely employed as a positive control in H2S related biological study. Herein, we develop a reactive oxygen species (ROS) triggered donor HSD545 that delivers H2S and simultaneously generates a fluorophore to real-time monitoring the process of H2S release in vitro and in vivo. The donor exhibits low cytotoxicity and strong cytoprotection against ROS-induce oxidative stress. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Spectroscopic rotational characterization of two upsilon' = 0 and upsilon' = 1 vibrational components of the E-3 Sigma(+)(1)(5s6s S-3(1)) Rydberg state of CdNe van der Waals (vdW) complex has been performed using specially designed approach. In optical-optical double resonance (OODR) process, a selective J-excitation has been realized using the E-3 Sigma(+)(1) <- A(3)Pi(0+)(5s5p P-3(1)) transition, with upsilon '' = 0 level of the A(3)Pi(0+) state as an intermediate in the excitation from upsilon = 0 of the X-1 Sigma(0+)(5s(2) S-1(0)) state. As a result, B-upsilon=0' and B-upsilon=1' rotational constants have been determined as well as the R-e' equilibrium internuclear separation in the E-3 Sigma(+)(1) - state potential well. (C) 2021 Elsevier B.V. All rights reserved.
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