查看更多>>摘要：A portable m-chip-based colorimetric device was developed for the determination of Cr3+ and Al3+ ions. The silver nanoparticles were modified with pyrrolidine-1-dithiocarboxylic acid ammonium salt as a novel ligand for the first time. The color of modified AgNPs in the test zone immediately changes after the addition of Cr3+ and Al3+ ions. The resulting color changes were detected by the naked eye or were taken by a smartphone camera. The obtained images were analyzed by RGB software to assay the Cr3+ and Al3+ ions concentration. Under optimized experimental conditions, the linear ranges are 0.1-220 and 0.01-250 mM for Cr3+ and Al3+ ions, respectively. The probe has a limit of detections of 10.66 and 3.55 nM for Cr3+ and Al3+ in an aqueous solution. In the case of m-chip, the concentration ranges are 0.1-200 mu M and 0.01-220 mu M for Cr3+ and Al3+ ions, with detection limits of 9.18 and 2.30 nM, respectively. The mu-chip showed great potential as a fast detection tool for the monitoring of Cr3+ and Al3+ ions in real samples such as river water samples.(c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Three-dimensional (TD) deoxyribonucleic acid (DNA) tweezers were programmed for one-step identification and detection of ochratoxin A (OTA) and zearalenone (ZEN). The unfolding of the TD-DNA tweezers by aptamers specific to these two mycotoxins "turned " the fluorescent signals "on. " The bonding of the aptamers to their corresponding targets in OTA and ZEN "turned " the fluorescent signals and the DNA tweezers "off. " The detection limit of the TD-DNA tweezers for OTA and ZEN was 0.032 and 0.037 ng mL(-1), respectively. The feasibility of this method was tested using two samples. Detection via this method increased the recovery of OTA and ZEN from 95.8% to 110.2%. Spike recovery and certified food products were used to detect applicability in actual situations. Analyte detection in complex samples using TD-DNA tweezers is rapid, as the process involves a single operational step. This proposed design has considerable potential for application in mycotoxin detection. (c) 2022 Elsevier B.V. All rights reserved.
Marques, Flavia C.Azevedo, Gustavo C.Senna, Carlos A.Archanjo, Braulio S....
9页
查看更多>>摘要：The preparation of metal@(dielectric or semiconductor) core@shell hybrid materials have been shown promising for both SERS and SEF applications due to improved stability in the presence of ions and the adsorbate compared to non-covered metallic nanoparticles. However, fine control over the thickness of the covering layer is essential to maximize the intrinsic trade-off between the plasmonic enhancement and the chemical stability improvement. Here, the preparation of manganese dioxide ultrathin layers covered gold nanorods (AuNR@MnO2) with varying thicknesses of the MnO(2 )layer is reported, and the characterization and evaluation of the resulting materials as SERS and SEF substrate. The MnO2 layer over the AuNR was prepared by reducing potassium permanganate by sodium oxalate in a basic medium. The AuNR@MnO2 hybrid material was characterized by UV-Vis spectroscopy, transmission electron microscopy, X-ray powder diffraction, and cyclic voltammetry. It was studied the SEF effect of the cyanine dye IR-820 excited at 785 nm with high performance for several thicknesses of the MnO2 ultrathin film. The enhancement factor increased for thicker oxide layers. The SERS effect of the IR-820 dye excited at 633 nm showed the most significant enhancement factor for thinner layers. The seemly opposite behavior of the two plasmonic effects may be assigned to the distance dependence of the electromagnetic field generated in the AuNR, which results in decreasing SERS performance. For SEF, the thinner layers resulted in the Au nanoparticles' emission quenching, so a more significant distance was necessary to observe enhancement.(C) 2022 Elsevier B.V. All rights reserved.
Ladarevic, Jelena M.Bozic, Bojan D.Vitnik, Vesna D.Matovic, Luka R....
8页
查看更多>>摘要：In order to improve the performance of theoretical UV-Vis spectra predictions, a theoretical and experimental study of solvatochromic properties of ten azo pyridone dyes has been performed. For quantitative estimation of intermolecular solvent-solute interactions, a concept of the linear solvation energy relationships has been applied using Kamlet-Taft and Catalan models. Theoretical UV-Vis spectra for all dyes have been calculated using four TD-DFT methods in nine different solvents with the aim to define the most reliable model. Finally, new polylinear equations for more accurate theoretical prediction of UV-Vis maxima are developed using empirical Kamlet-Taft and Catalan solvent parameters as additive corrections for specific and nonspecific solvent-solute interactions. CO 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Simeprevir and sofosbuvir are direct-acting antiviral drugs approved for the treatment of chronic HCV infection. Reports demonstrate the similarities between HCV and SARS-CoV-2 in terms of structure and replication mechanism. Therefore, it is suggested that a combination of simeprevir and sofosbuvir may be considered for COVID-19 patients. To date, no spectrophotometric methods have been published for quantitative analysis of simeprevir and sofosbuvir in combination. In this work, two simple spec-trophotometric methods allowed quantitative analysis of the studied drugs in the mixed form. The zero-order direct method allowed quantitative analysis of simeprevir at 333 nm, with sofosbuvir showing zero absorbance values. The dual wavelength method allowed quantitative analysis of sofosbuvir by mea-suring the difference in absorbance values at 259.40 and 276 nm, where the difference in absorbance val-ues of simeprevir was zero. With the applied methods, the investigated drugs in the mixtures and tablets prepared in the laboratory were successfully analyzed quantitatively with acceptable results.(c) 2022 Published by Elsevier B.V.
查看更多>>摘要：This article reports a new type of dicyanisophorone-based near-infrared fluorescent probe for the rapid detection of mercaptophenol by introducing 2,4-dinitrobenzene sulfonate group as a specific recognition group for thiophenol. The probe has a significant large Stokes shift (185 nm). At the same time, it exhibits rapid response, high selectivity and high sensitivity to thiophene. In addition, the fluorescence of the probe at 650 nm has a good linear relationship with the concentration of thiophenol in the range of 0-100 lM, and the detection limit is as low as 65 nM. The probe has been successfully applied to the detection of thiophenol in actual water samples, and has good live cell imaging effects, and at the same time shows the superiority of its low cell toxicity. (c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：We demonstrate a novel ratio fluorescence nanoprobe for dipicolinic acid (DPA) as an anthrax biomarker based on layered rare-earth hydroxide (LRH). 3-Amino-benzenesulfonic acid (AS) was intercalated into layered terbium hydroxide to form composite and then delaminated into nanosheets in formamide. The monolayer nanosheets were beneficial to expose the Ln3+ luminescence centers to the environment more completely, contributing a high sensitive detection to the environment. With the increase of DPA concentration, the emission intensity of AS kept constant which worked as a stable internal reference, while the fluorescence of Tb3+ was enhanced obviously due to the antenna effect. In the 0.05-5.0 lM concentration range, the I544/I360 fluorescence ratio changed with the DPA concentration, which exhibited a good linear relationship (R2 = 0.999) and an ultralow detection limit of 3.8 nM. In addition, the probe showed high selectivity and sensitivity to the DPA detection as an anthrax biomarker, which can be applied in real tap water with good performances. This work could extend the applications of LRH nanosheets in detection and offer an extremely effective and easy technique for detecting DPA.(c) 2022 Elsevier B.V. All rights reserved.
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