查看更多>>摘要：A new long-wavelength fluorescent probe 1 that could specifically identify H2S has been successfully synthesized and applied for imaging H2S in zebrafish. Probe 1 was readily prepared by featuring nitroben-zene as the recognition unit coupled to resorufin. The fluorescence off-on response is based on the fact that H2S can reduce the nitro group to an amino group, followed by the 1,6-rearrangement-elimination and the release of resorufin. By evaluating the application abilities of probe 1 in vivo and vitro, it is shown that probe 1 has high sensitivity and selectivity to H2S, low background fluorescence interference, with a low detection limit of 17.30 lM. Notably, the occurrence of the reaction can be observed by the naked eye, and the color of the solution changes from yellow to pink. More importantly, it is the first time that using paper chips as carrier to detect H2S, which lays a foundation for the practical application of detect-ing H2S. The excellent analysis and application capabilities of probe 1 make it an effective tool for further application in practice. (c) 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).
查看更多>>摘要：In this work, we report in situ nonlinear microscopic images on plasmon-enhanced coherent anti-Stokes Raman scattering (CARS) and plasmon-Induced two-photon excited fluorescence (TPEF)of non-fluorescent microorganism. Our unique synthesized Au@Ag nanorods provide with two distinct surface-plasmon resonance (SPR) at 400 and 800 nm, respectively, which can efficiently induce linear fluorescence signals of E. coli but also enhance the nonlinear optical spectroscopy signals of TPEF, and coherent anti-Stokes Raman scattering (CARS) imaging of E. coli and S. aureus. Furthermore, calculations with complete active space self-consistent field (CASSCF) reveals the hot electrons of SPs can efficiently induce the biological fluorescence of non-fluorescent flavin nucleotides on the surface of E. coli. This novel mechanism is expected to guide the development and application of new microbial detection reagents. Gram-negative and Gram-positive bacteria can be well distinguished by nonlinear microscopic imaging of the CARS signal at 1589 cm(-1). Benefit by the strong penetrability of non-linear optical signals, it is expected to realize in situ real-time detection and classification of pathogenic microbial infections in vivo. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Fibril formation of globular proteins is driven by attaining an appropriate partially-unfolded conformation. Excluded volume effect exerted by the presence of other macromolecules in the solution, as found in the cellular interior, might affect the conformational state of proteins and alter their fibril formation process. The change in structure, stability and rate of fibril formation of aggregation-prone partially-unfolded states of lysozyme (Lyz) and alpha-lactalbumin (ALA) in the presence of different sizes of polyethylene glycol (PEG) is examined using spectroscopic methods. Thermal denaturation and far-UV CD studies suggest that Lyz is stabilized by PEGs and the stability increases with increasing concentration of PEGs. However, the stability of ALA depends on the size and concentration of PEG. The change in enthalpy of unfolding indicates the existence of soft-interactions between the proteins and PEG along with excluded volume effect. Fibrillation rate of Lyz is not significantly altered in the presence of lower concentrations of PEGs suggesting that the crowding effect dominates the viscosity-induced retardation of protein association whereas at higher concentrations the rates are reduced. In case of ALA, the rate of fibrillation is drastically reduced; however, there is a marginal increase with the increasing concentration of PEG. The results suggest that the fibril formation is influenced by change in initial conformation of the partially-unfolded states of the proteins and their stability in the presence of the crowding agent. Further, the size and concentration of the crowding agent, and the soft-interaction between the proteins and PEG also affects the fibrillation. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Dicofol, a broad-spectrum acaricide, has garnered considerable attention because of the potential harm to the environment and various organisms. Herein, this study applied spectroscopic and in silico methods to understand the interaction between human serum albumin (HSA) and dicofol. Fluorescence experiments demonstrated that dicofol formed a stable complex and the binding process occurred in Suldow's site I of HSA. Its binding constant was 2.26 x 10(5) M-1 at 298 K. Van der Waals forces and hydrogen bond were primarily facilitated the interaction between dicofol and HSA (Delta H < 0, Delta S < 0) according to thermodynamic experiments. Additionally, 3D fluorescence and circular dichroism (CD) spectra revealed a few conformational changes in HSA due to dicofol. Molecular docking analysis indicated that dicofol interacted with Ser192, G1n196, Leu481, Arg218, Leu238, and Phe211 via van der Waals forces and formed a hydrogen bond with His242. Molecular dynamics (MD) simulation showed that Lys195 and Arg218 residues contributed greater energy for forming the HSA-dicofol complex. MD simulation analysis also showed that dicofol can affect the HSA structure with a reduction in alpha-helix. This research is desired to facilitate a new perspective on the toxicity mechanism of dicofol in the human body. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Three isostructural lanthanide coordination polymers (LnCPs), [Ln(L)(6)(DMF)](n) {HL = 2-(2-formylphenoxy) acetic acid, Ln = Sm(1); Eu (2); Tb (3)} have been synthesized by solvothermal reaction and characterized. Single crystal analyses revealed that the architectures of these LnCPs own one dimensional chain which can be further packed into two-dimensional architectures by hydrogen bonds. Moreover, these LnCPs can offer strategically placed uncoordinated formyl groups, which may act as hydrogen-bond acceptor in the sensing of nitro explosives. Luminescence measurements reveal that LnCPs 2 and 3 exhibit strong luminescence in solid states. LnCP 2 shows quick, highly selective and sensitive detection of 2,4,6-trinitrophenol (TNP) with the high quenching constant (2.6 x 10(4) M-1) and low detection limit (3.39 mu M), which indicates that LnCP 2 is more efficient than most of Eu-based coordination polymers for the sensing of TNP. Furthermore, LnCP 2 represents the first example of one-dimensional Eu-based sensors with formyl group as hydrogen-bonding site in the detection of TNP. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：In order to improve the accuracy of spectral analysis of complex solutions, based on the "M + N" theory, this paper proposes to use single (365 nm +/- 5 nm) ultraviolet LED as emission light to detect transmission spectrum and excited fluorescence spectrum. Taking the total bilirubin in serum as the measurement object, the dual-mode spectrum of transmission and fluorescence about serum is collected, which increases the amount of information. In order to verify the effectiveness of the method proposed in this paper, the transmission and fluorescence spectra of the samples were also collected. Then three models of total bilirubin concentration are established by transmission spectrum, fluorescence spectrum and dual-mode spectrum of transmission and fluorescence respectively. Through the comparison of the parameters of the three models, the model established by dual-mode spectrum of transmission and fluorescence is good. The Rc of the model is 0.91 and the RMSEC is 3.00 (mu mol/L). The Rp is 0.92, the RMSEP is 3.53 (mu mol/L). Compared with transmission spectrum modeling and fluorescence spectrum modeling, the RMSEP of dual-mode spectrum modeling was reduced by 34.8% and 22.6% respectively. The experimental results show that the measurement method of dual-mode spectrum of transmission and fluorescence by using a single ultraviolet light source proposed in this paper based on the "M + N" theory increases the information of solution composition, which provides a new method for the analysis of the same characteristic components. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：An in-depth understanding of reaction processes is beneficial to the development and quality control of chemical products. In this work, the mechanism and kinetics of the Paal-Knorr reaction for pyrrole derivatives are thoroughly studied using in-situ Fourier transform infrared (FTIR) spectroscopy. The hemiacetal amine intermediate, reactants, and products were identified and quantified by the treatment of real-time infrared spectra via chemometrics method and two-dimensional correlation spectroscopy (2DCOS) technique. Based on the IR quantitative models, influences of operating conditions on reaction processes were investigated, and the reaction kinetic model was built with kinetic parameters of two rate-limiting reaction steps calculated. This approach of analysis on the in-situ FTIR data demonstrated the ability to extract useful information on reaction components, especially the intermediate spectrum, from the confounding real-time IR data. The in-situ FTIR monitoring combined with the IR analysis methods is proved as a powerful tool for revealing the reaction mechanism and kinetics. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：An analytical formula that relates the molecular constants of the Herzberg expression and experimental transition lines is developed herein with a difference algebraic approach (DAA) model. Based on the datadriven strategy, the DAA model is able to deal with the tiny uncertainties that exhibit behind the experimental transition lines, which is applied to the P branch emission spectra of some first overtone bands of the ground electronic state of (CO)-C-12-O-16. The relationship can be used to generate transition lines with sufficient accuracy, as evident from the high J of agreement with the HITRAN database, Velichko data, Goorvitch data and quantum-mechanical data. In addition, line intensities, absorption oscillator strengths and Einstein A coefficients of these lines, which are introduced to enhance the dataset and are in good agreement with those of other authors, are also reported to validate our results. These various comparative results show that the proposed data-driven strategy based on the DAA model is expecting to be a good algorithm that relies on relatively limited data for training. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Antibiotic resistant bacteria pose an increasing threat to global public health, and it is essential that effective detection methods for identifying these organisms. This study assesses the ability of three different analytical approaches that were developed using surface-enhanced Raman spectroscopy (SERS) to differentiate between antibiotic sensitive and resistant bacteria based on their responses to ampicillin exposure, using Escherichia coli O157:H7 as a model bacterium. The approaches tested in this study included a conventional SERS approach of mixing a droplet of bacterial culture with gold nanoparticles, extracellular matrix analysis, and in situ mapping of bacterial cells on a filter membrane. All three of the SERS techniques were able to differentiate between the sensitive and resistant bacterial strains based on peak intensity changes associated with compounds released by the bacteria in response to antibiotic exposure, with extracellular matrix analysis and filter mapping both observed to be more effective than the conventional approach. However, there were significant differences between the spectra obtained from the different techniques and the potential advantages and disadvantages of each approach should be considered when used in the future. This study shows that SERS can be an effective technique for rapid and efficient assessment of ampicillin sensitivity in E. coli, and more work should be done to explore these analytical approaches with other types of bacterial samples. (c) 2021 Published by Elsevier B.V.
查看更多>>摘要：An entropy driven catalytic reaction powered DNA motor was proposed for simultaneous detection of ochratoxin A (OTA) and chloramphenicol (CAP) in food. The dumbbell hairpin structure was formed by the two aptamers of OTA and CAP. The dumbbell hairpin can be opened by the interaction of OTA and CAP with their aptamers. The tails of the end of dumbbell hairpin sequence can induce the entropy driven catalytic reactions on the AuNPs, causing the sustained releasing of the fluorophore labeled DNA sequences. The recovery of fluorescent intensities can be used for quantitative detection of OTA and CAP. The limit of detection reached 2 pM for OTA and 6 pM for CAP respectively, which was great improved by entropy driven amplification of the self-powdered DNA motor. This strategy is simple and sensitive and only needs one-step operation. It exhibits promising potentiality in food quality control and food security supervision. (c) 2021 Published by Elsevier B.V.
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