查看更多>>摘要：Functional composite fibers were prepared by a wet-spinning method and used for pH sensing based on surface enhanced Raman scattering (SERS). Alginate solution with gold nanoparticles (AuNPs) was spun to fibers that acting as active substrate showed distinct SERS enhancement for low concentrations of dyes (1.0 x 10(-9) M for rhodamine 6G and 1.0 x 10(-8) M for crystal violet). After AuNPs were modified with 4-mercaptopyridine (4-MPY), the as-synthesized composite fibers (AuNPs@4-MPY/Ca-ALG fibers) displayed pH dependent SERS spectra due to the changes of chemical structures of 4-MPY under different pH conditions. The AuNPs@4-MPY/Ca-ALG fibers achieved fast response to the pH changes between 1.00 and 13.00. The flexible composite fibers were woven to a wearable "wrist band", which has potential applications in health monitoring involving pH variation. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Hydrogen polysulfides (H2Sn) as an important member of reactive sulfur species is closely relevant to many physiological functions in redox homeostasis and metabolism. Dual-channel monitor the changes of H(2)S(n)level in vivo is highly desired. Herein we design a simple ratiometric fluorescent probe based on flavone skeleton for highly selective detection of H2Sn. The probe HF-NA-MC bearing 2-fluoro-5-nitrobenzoic acid group inhibited the intramolecular ESIPT process, which show the blue fluorescence of adjacent naphthalene unit. In the presence of H2Sn, the enol form of probe is converted to conjugated keto form, resulted in a 90 nm red-shift of fluorescence emission from 450 nm to 540 nm. The ratiometric intensity (I540/I450) of the probe exhibits a good linear relationship toward H2Sn in the range of 0-120 lM, and the detection limit is estimated to be 0.63 lM. The ratiometric fluorescent probe shows high speci-ficity and anti-interference ability for H(2)S(n)over other related reactive sulfur species. The probe HF-NA-MC shows promising outlook and could be applied to the confocal imaging of H(2)S(n)by dual emission channels in Hela cells. (C)& nbsp;2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：In this study, rare-earth-doped self-activated LiCa3ZnV3O12 (LCZV) vanadate phosphors were preparation by a high-temperature solid-state reaction. Their crystal structure, non-contact temperature sensing, and luminescence properties were studied deeply. Excited by ultraviolet light at 340 nm, the emission of [VO4](3-) group and the Eu3+ ions were monitored. The highest strength emission peaks at 470 nm and 610 nm for [VO4](3-) and Eu3+, respectively, provide favorable signal identification for estimating temperature. Due to thermal quenching behavior and energy transfer, the FIR (Fluorescence Intensity Ratio) from Eu3+ to [VO4](3-) exhibits excellent sensitivity performance at 303 K - 523 K. In the meantime, the maximum absolute and relative sensitivities of the obtained phosphors are 0.0068 K-1 and 1.18 % K-1, which are overtopped to those reported previously. Furthermore, for the luminescent color of the CIE diagram with a strong temperature effect, the color coordinate could be verified from (0.2871, 0.3416) to (0.4121, 0.3420), which was matched well with the linear equation. Consequently, the Eu3+ doped LCZV phosphor not only can be used for high-temperature environmental safety signals but also is an extraordinary viable material in the field of optical sensing. (C) 2022 Elsevier B.V. All rights reserved.
Youssef, Rasha M.Abdelhafez, Aya M.Hassan, Ekram M.Gawad, Dina A....
8页
查看更多>>摘要：A fixed-dose combination therapy of tamsulosin and tadalafil is now available for treatment of lower urinary tract symptoms associated with benign prostatic hyperplasia. The decrease in sexual performance which is a side-effect of tamsulosin can be compensated by using tadalafil. This study is the first to develop and optimize a synchronous spectrofluorimetric method coupled with derivative and derivative ratio mathematical tools for the determination of tamsulosin and tadalafil in their newly released dosage form. The method successed in quantification of tadalafil by measuring the second-order derivative synchronous spectrofluorimetric amplitude at 278 nm (corresponding to zero-crossing of tamsulosin) using Delta(sic)=11 nm. On the other hand, first derivative ratio synchronous spectrofluorimetric peak amplitude was measured at 260 nm for determination of tamsulosin, using Delta(sic)=15 nm and divisor concentration of 0.1 mu g mL(-1). The method validation was performed using ICH guidelines. The linear responses of tamsulosin and tadalafil were from 0.04 to 0.5 and 0.05-0.5 mu g mL(-1), respectively. High sensitivity was achieved as represented by slope values of 0.32 and 608.4 for tamsulosin and tadalafil, respectively. The method is sensitive enough to detect concentration as low as 0.024 for both drugs. The proposed integrated spectrofluorimetric method showed good simplicity, selectivity and greenness. It can be successfully applied for analysis of both drugs in dosage form. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：The feasibility of identifying geographical origin and storage age of tangerine peel was explored by using a handheld near-infrared (NIR) spectrometer combined with machine learning. A handheld NIR spectrometer (900-1700 nm) was used to scan the outer surface of tangerine peel and collect the corresponding NIR diffuse reflectance spectra. Principal component analysis (PCA) combined withMahalanobis distance were used to detect outliers. The accuracies of all models in the anomaly set were much lower than that in calibration set and test set, indicating that the outlierswere effectively identified. After removing the outliers, in order to initially explore the clustering characteristics of tangerine peels, PCA was performed on tangerine peels from different origins and the same origin with different storage ages. The results showed that the tangerine peels from the same origin or the same storage age had the potential to cluster, indicating that the spectral data of the same origin or the same storage age had a certain similarity, which laid the foundation for subsequent modeling and identification. However, there were quite a fewsamples with different origins or different storage ages overlapped and could not be distinguished from each other. In order to achieve qualitative identification of origin and storage age, Savitzky-Golay convolution smoothing with first derivative (SGFD) and standard normal variate (SNV) were used to preprocess the raw spectra. Random forest (RF), K-nearest neighbor (KNN) and linear discriminant analysis (LDA) were used to establish the discriminant model. The results showed that SGFD-LDA could accurately distinguish the origin and storage age of tangerine peel at the same time. The origin identification accuracy was 96.99%. The storage age identification accuracy was 100% for Guangdong tangerine peel and 97.15% for Sichuan tangerine peel. This indicated that the near-infrared spectroscopy (NIRS) combine with machine learning can simultaneously and rapidly identify the origin and storage age of tangerine peel on site. (C) 2022 Elsevier B.V. All rights reserved.
Priyadharshini, R. DurgaPonkarpagam, S.Vennila, K. N.Elango, Kuppanagounder P....
7页
查看更多>>摘要：Binding of voglibose (VOG), an alpha glucosidase inhibitor, with CT-DNA has been investigated using various spectroscopic techniques including UV-Vis, fluorescence and circular dichroism (CD) coupled with relative viscosity. Isothermal titration calorimetric studies have been used to calculate the thermodynamic parameters such as Delta H (0.0188 cal/mol), Delta S (63.3 cal/mol/K) and Delta G (-18.8 kcal/mol), which reveal that the binding is a spontaneous process and hydrophobic and H-bonding interactions play major roles in the binding process. Effect of ionic strength confirms the existence of hydrophobic interaction between VOG and CT-DNA. Competitive displacement assays with ethidium bromide (EB) and Hoechst 33258 suggest that VOG possibly binds on the surface of CT-DNA. Viscosity measurements also disclose that the binding could be mainly surface binding. Corroborating the experimental observations, metadynamics molecular simulation studies confirm that VOG binding on the surface of the DNA molecule through hydrophobic interactions and direct and water molecule mediated H-bonding. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：The widespread use of Hydrazine (N2H4) in many areas of the chemical industry, brings potential risks to human health and environmental pollution. To detect N2H4 effectively, a simple ratio fluorescence probe (QMM), designed and synthesized through Vilsmeier reaction and Knoevenagel reaction, was prepared for the specific response of N2H4 based on the irreversible chemical reaction. The ratiometric fluorescence chemodosimeter displayed a response for hydrazine with high selectivity, sensitivity and anti-interference ability. The measured detection limit is 38.30 nm (0.122 ppb), which is far lower than the maximum allowable level of the U.S. Environmental Protection Agency (10 ppb). Moreover, test paper and TLC plates loading QMM had been made, which could be utilized to detect hydrazine both in aqueous solution samples and in gas phase samples. Thus QMM could serve as an easily manufactured, low-cost, efficient and portable solid-state optical probe to detect hydrazine in field measurements. (C) 2022 Elsevier B.V. All rights reserved.
Bastidas, Camila Y.Castillo, Rosario del P.Manuel Amigo, Josevon Plessing, Carlos...
7页
查看更多>>摘要：Fourier Transform Mid Infrared with Attenuated Total Reflection Imaging (FTIR-ATR imaging) and Multivariate Curve Resolution with Alternating Least Squares (MCR-ALS) were used in a multiblock fashion to study the presence, distribution and penetration depth of very low concentrations of florfenicol (FF) in a complex matrix like feed pellets for salmonids. Images from the surface, at 150 mu m deep and 200 mu m deep from the surface were analyzed to certify the penetration power of FF added by surface coating methodology. Besides, the unique homogeneity index was calculated in order to evaluate the distributional homogeneity of each component. The results demonstrated the reliability of MCR-ALS in studying the distributional homogeneity of FF. It was demonstrated that FF remains mostly on the surface of the pellets with almost no penetration. The rest of the components of the pellets (oil, protein and carbohydrates) were also analyzed. These three nutrients are distributed on the three layers analyzed with a relatively homogeneous location, being carbohydrates (%H = 51 +/- 3) the component with the best homogeneous distribution, unlike protein (%H = 45 +/- 5), and oil (%H = 40 +/- 7). This is the first publication where the penetration of an antibiotic, added with surface-coating to feed pellets, was analyzed with FTIR-ATR imaging and multivariate analysis, showing the contribution these analytical tools can make to the medicated feed industry. (C) 2022 Elsevier B.V. All rights reserved.
Ivanovski, VladimirPiwonski, IreneuszGuziejewski, DariuszMayerhoefer, Thomas G....
13页
查看更多>>摘要：In case of thin films of siloxane obtained from different organo-silane derivatives (alkoxy and chloro) on soda lime silica glass substrates, IR-ATR and IR-SR could not detect the organic functional groups of the coating. This becomes even more problematic for the case of tetraethoxysilane (when fully hydrolyzed), the coating of which possesses the same functional groups as the glass substrate. In this work we propose to employ the so-called ratio-reflectance spectra in the v(Si-O) wavenumber region, where both glass and the siloxane coating give most prominent bands, important for the evaluation of the quality of coating formation and qualitative knowledge on its structure. We show that the reflectance-absorbance spectra obtained from the ratio-reflectance spectra are in direct connection to the structure of the siloxane network which depends not only on the chemical nature of the parent silane, but also on the dipping time and the solvent composition. Some characteristics of the reflectance-absorbance spectra, like the appearance of a two well defined bands at 1110 and 975 cm(-1), can be correlated to the film morphology and bridging oxygen number. We support our conclusions using principal component analysis of reflectance spectra, contact angle, AFM and SEM measurements. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Rapid detection of mercaptans in materials and the environment is of great help to material analysis and pollutant monitoring. Gold (Au) shows a high affinity to mercaptans. The coordination and steric effect of mercaptans to Au may be used for the development of new fluorescent sensors. It is possible to distinguish simple mercaptans (such as, HS-, thioglycolic acid) from glutathione (GSH) using Au as a coordinator of dye. Herein, a water-soluble fluorescent sensor of an imidazole conjugated 4,4-difluoro-4-bora3a,4a-diaza-s-indacene (BODIPY) derivative (BIM) was characterized by spectroscopic methods. BIM showed a large Stokes shift and high affinity to metals. Especially, Au-combined BIM produced a new complex BIMAu showing improved fluorescence emission, which can be quenched by thioglycolic acid and sodium hydrosulfide, but less affected by GSH. The detection limit of thioglycolic acid was 0.014 mM. Both NaSH and thioglycolic acid coordinated with BIMAu, while GSH took Au3+ away from BIMAu. These results indicate that the gold coordination competition between imidazole-substituted dyes and mercaptans is a good method for the development of new fluorescence chemosensors. (C) 2022 Elsevier B.V. All rights reserved.
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