查看更多>>摘要：Atypical luminescent compounds that do not contain conventional chromophores emit light due to clustering and have important basic research value and a broad range of potential applications. To date, most atypical luminescent compounds are small molecules or polymers containing groups such as cyano, carbonyl and hydroxyl. In this work, driven by some sporadic and accidental luminescence phenomena observed for cucurbit[n]urils (Q[n]s), the luminescent properties and mechanism of Q[n]s in the solid and solution-state were systematically studied and the clustering emission of Q[n]s confirmed. Our experiments have revealed that the self-induced outer-surface interactions of Q[n]s (OSIQ) are the most important driving force resulting in the clustering emission of Q[n]s. Substances that can weaken the effect of self-induced OSIQ, such as the presence of various aromatic compounds and anions, may weaken or quench the clustering emission of Q[n]s. This not only reveals the new characteristics and mechanism of the clustering emission of Q[n]s, but also provides new insights on how to utilize the clustering emission of Q[n]s and construct new types of macrocyclic luminescence systems.(c) 2022 Elsevier B.V. All rights reserved.
Abd Elhaleem, Shymaa M.Elsebaei, F.Shalan, ShBelal, F....
11页
查看更多>>摘要：Nitrogen and sulfur carbon quantum dots(N,S-CQDs) as effective fluorescent nanoprobes were synthe-sized through one-step-hydrothermal method using thiosemicarbazide (as nitrogen and sulfur source) and citric acid (as carbon source). The highly fluorescent N,S-CQDs were subjected to various character-ization techniques. The fluorescence of the synthesized N,S-CQDs is characterized by maximum fluores-cence emission at 415 nm after excitation at 345 nm and a high quantum yield of 0.58. The native N,S-CQDs fluorescence is quantitatively quenched upon addition of imatinib (IMA), so they are used for its spectrofluorimetric determination in its pharmaceutical formulations and biological fluids. Under optimal conditions, N,S-CQDs exhibited a "turn-off" fluorescence response to IMA over the range of 1.0 to 15.0 mg/mL with a limit of quantification of 0.42 mg/mL anda lower detection limit of 0.14 mg/mL. Stern-Volmer equation was used to study the mechanism of quenching and it was found to occur through static quenching mechanism. The method was extended to the in-vitro determination of the drug in spiked human urine and plasma samples and the percent recoveries were satisfactory.(c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Hydrogen sulfide (H2S) has been regarded as the third endogenous gas signaling molecule. The development of suitable tools for H2S detection in vitro and in vivo has always been a focus of research. In this work, three BODIPY-NBD dyads (o/m/p-BNP) were designed and synthesized using BODIPY and NBD as the fluorophore and quencher, respectively. The position of the NBD moiety in the probe showed different fluorescence quenching abilities. All probes showed highly selective to H2S. Probe o-BNP displayed the maximum fluorescence enhancement (c.a. 1300-fold) and the lowest detection limit (105 nM). Probe o-BNP can visualize the production of endogenous H2S in HeLa cells and zebrafish. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：The measurement of NH(4)(+ )has attracted considerable attention with the increase of NH4+ emissions in sewage caused by human activities. So far, a variety of photometric and fluorescence methods for the detection of NH4+ have been researched and summarized, but there is no report about the use of liquid crystals (LCs) cholesteryl benzoate (CB) as a resonance Rayleigh scattering (RRS) probe to determine ammonium ions. In the NaAc-HAc buffer solution with pH = 4.80, the yellow compounds 3,5 diacetyl-1,4 dihydrolutidine (DDL) generated by the reaction of NH4+ with acetylacetone (AT) and formaldehyde (HCHO) act as the energy receiver and CB as the donor. Because the RRS spectrum of CB overlaps with the DDL absorption spectrum, resonance Rayleigh scattering energy transfer (RRS-ET) occurs. When the NH4+ concentration increased, the generated DDL increased, and the RRS-ET also increased, so the RRS intensity of the system at 395 nm decreased. For this reason, a fast and sensitive CB RRS-ET method was established to apply to the detection of NH4+ in water. The detection range was 1.00 x 10(-3) -4.66 lg/mL, and the detection limit was 6.62 x 10(-3) lg/mL. Using this method to analyze and detect NH4' in environmental water samples, the precision and recovery rate were between 1.30-9.30% and 95.5-109.9%, respectively. Therefore, this method has the advantages of sensitivity and simplicity. (c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：The versatility and importance of chiral compounds make it urgent to develop fast and efficient methods to detect the absolute configuration, enantiomeric excess(ee), and concentration of chiral compounds. In this study, we demonstrate that commercially available diethyl squarate can rapidly react with various types of chiral amino compounds and exhibit characteristic ultraviolet (UV) and circular dichroism (CD) signals. The UV and CD signals can determine the total concentration of the two enantiomers and ee value of the sample, respectively. The probe showed a broad substrate scope, applicable to 39 tested chiral amino compounds, including chiral amino acids, amino alcohols, and amines. Additionally, the probe accurately detected 10 samples of phenylalanine, phenylglycinol, and phenethylamine with the error range less than 8%, demonstrating the practicability of this method.(c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Hyperspectral imaging was attempted to evaluate the internal and external quality of 'Feicheng' peach by providing the spectral and spatial data simultaneously. Mask-image was created from hyperspectral image at 810 nm and used to segment the fruit region where the average spectrum, after area normalization, was obtained for soluble solids content (SSC) and firmness evaluation. Pixel size and area were used for diameter and weight estimation. Then effective wavelengths were selected by competitive adaptive reweighted sampling (CARS) and random frog (RF), and employed to develop multiple linear regression (MLR) models. The more effective prediction performances emerged from CARS-MLR model withR(V)(2) = 0.841, RMSEV = 0.546, RPD = 2.51 for SSC andR(V)(2) = 0.826, RMSEV = 1.008, RPD = 2.401 for firmness, followed by creating pixel-wise and object-wise visualization maps for quantifying SSC and firmness. Furthermore, peach diameter was estimated by calculating the minimum bounding rectangle with an average percentage error of 1.01 %, and the MLR model for weight prediction achieved a good performance ofR(V)(2) = 0.957, RMSEV = 9.203, and RPD = 4.819. The overall results showed that hyperspectral imaging could be used as an effective and non-destructive tool for evaluating the internal and external quality attributes of 'Feicheng' peach, and provided a holistic approach to develop online grading systems for quality tiers identification. (c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：In this study, the interaction between gold nanoparticles (AuNPs) and proteins (including lysozyme, trypsin, pepsin, gamma-globulin and hemoglobin) was investigated by UV-visible absorption spectroscopy, fluorescence spectroscopy, circular dichroism (CD) spectroscopy and protein activity assay. AuNPs was synthesized using reduction of HAuCl4 with sodium citrate. The formation of AuNPs was confirmed from the characteristic surface plasmon resonance band at 521 nm and transmission electron microscopy revealed the average particle size was about 10 nm. The results reveal that AuNPs can interact with proteins to form a "protein corona (PC) ", but the protein concentration required to form a relatively stable PC is not the same. The quenching mechanism of proteins by AuNPs is arisen from static quenching. The binding constants of AuNPs with proteins are in the range from 10(6) to 10(10) L mol(-1), and the order is pepsin > gamma-globulin > hemoglobin > trypsin > lysozyme at 298 K. Van der Waals forces and hydrogen bonds are the main forces for the lysozyme-AuNPs system. The interaction between trypsin/pepsin/gamma-globulin/hemoglobin and AuNPs is mainly by hydrophobic interaction. The addition of AuNPs has an effect on the secondary structure of proteins as confirmed from CD spectra. The change in secondary structure of different proteins is different and seems to have little relation with the binding constant. The activity of lysozyme/trypsin/pepsin decreases with the addition of AuNPs. (c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：In this study, we developed an innovative approach that combines solid phase microextraction (SPME) with surface-enhanced Raman spectroscopy (SERS) to detect pesticide ferbam rapidly. An Au nano-glass capillary was fabricated by coating template-freely synthesized three-dimensional network Au nanostructures (3D-NW AuNSs) on the roughened surface of glass capillary and used for SPME and SERS respectively. Significant Raman signals were obtained by the SPME-SERS method, followed by detection of ferbam in water and orange juice samples with only 1 min SPME process. Results showed that Au nano-glass capillaries could achieve the detection of ferbam with limit of detection of 0.05 mu g/L, and coefficient of determination (R-2) of 0.9913. The recovery of predicted results was in the range of 88.46-103.29% and the relative standard deviation (RSD) was 3.5-8.2%. This study demonstrated potential capability of the SPME-SERS method for rapid (within 1 min) and sensitive detection of organic compounds in complex matrices. The SERS-active Au nano-glass capillary is easy to carry and operate, and is expected to play a role in the detection of trace pollutants. (c) 2022 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：In this study, we prepared nitrogen-doped carbon dots (xNCDs) using hydrothermally-treated bitter tea oil residue with urea for the detection of metal ions by monitoring the photoluminescence quenching. The quantum yields of the xNCDs increased from approximately 3.85% (CDs) to 5.5% (3NCDs) and 7.2% (1NCDs), revealing that nitrogen doping effectively increases the fluorescence emission. The increased emission of the xNCDs can be attributed to radiative recombination resulting from the pi -pi* transition of the C=C or the n-pi* transition between the C=O or N=O of sp(3) units. Moreover, the CDs have abundant surface-attached phenolic and hydroxyl groups that coordinate with Fe3+ ions and quench the fluorescence. Conversely, Hg2+ ions preferentially adsorb on nitrogen-containing groups, such as amide-carbonyl groups (O=C-NH2) and pyridinic and pyrrolic functionalities, on the surface of the NCDs owing to their strong affinity, quenching the substantial photoluminescence emissions. Our results suggest that bitter tea oil residue-derived carbon dots can be used to selectively detect metal ions, such as Fe3+ and Hg2+, by doping with nitrogen using urea as a nitrogen precursor. (c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Cholangiocarcinoma (CCA) is a type of cancer, which 5-year survival is lower than 20 %, and which is detected mostly in advanced stage of the disease. Unfortunately, there are no diagnostic tools, which could show changes in the body indicating the development of the disease. Therefore, in this study, we investigate Raman spectroscopy as a promising analytical tool in medical diagnostics and as a method, which would allow to distinguish between healthy patients and patients suffering from cholangiocarcinoma. The obtained Raman spectra showed, that lower intensities of peaks corresponding to amino acids and proteins, as well as higher intensities of peaks originating from lipids vibrations were observed in healthy individuals in comparison with cancer patients. Moreover, Partial Last Square (PLS), Principal Component Analysis (PCA) and Hierarchical Component Analysis (HCA) of Raman spectra indicate that the ranges between 800 cm(-1) and 1800 cm(-1), 3477 cm(-1) -3322 cm(-1) and 1394 cm(-1) - 1297 cm(-1) allow to distinguish cancer patients from healthy ones. The obtained results showed, that Raman spectroscopy is a good candidate, to become in future one of the diagnostic tools of Cholangiocarcinoma. (c) 2022 Elsevier B.V. All rights reserved.
NSTL
Elsevier