Fawzy, Michael GamalHassan, Wafaa ElsayedMostafa, Alaa AhmedSayed, Rania Adel...
10页
查看更多>>摘要：Simultaneous measurement of saxagliptin hydrochloride (SAG) and dapagliflozin propanediol monohy-drate (DAG) in bulk powder, laboratory-prepared mixtures, and pharmaceutical dosage form were applied by utilizing three precise and sensitive spectrophotometric techniques which were developed and validated. The first method was the induced dual-wavelength approach (IDW), which relied primar-ily on the use of alternative equality factors (F) to abolish the effect of DAG when determining SAG and vice versa. The ratio difference method (RDM) was the second method, which used 25 mu g/ml of DAG and 20 mu g/ml of SAG as divisors to determine the amplitude difference on the ratio spectrum of SAG and DAG, respectively. SAG was determined at lambda(max) 221 nm after plateau subtraction followed by multiplication by the divisor of DAG 25 lg/ml using the third method, ratio subtraction coupled with extended ratio sub-traction method (RSER). Subsequently, using an extension ratio subtraction of the spectra, DAG was determined at lambda(max) 225 nm was determined. The developed methods were effectively used to estimate SAG and DAG in laboratory-prepared mixtures and pharmaceutical dosage forms, with satisfactory recov-eries. The methodologies were assessed for their environmental friendliness using the analytical eco-scale, analytical GREEnness calculator, and green analytical procedure index (GAPI). These methodologies were validated following the International Conference on Harmonisation (ICH) requirements. A statistical comparison of the obtained findings to those of the published method revealed no significant differences in precision and accuracy. Because of their high precision and cost-effectiveness, the developed methods can be used in quality control laboratories to determine the binary mixture. (c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：The selectivity and sensitivity of amino-functionalized tetraphenylethene probes (namely Z-N2TPE and E-N2TPE) for ssDNA detection in aqueous solution were investigated. Both Z-N2TPE and E-N2TPE showed high selectivity to guanine-rich ssDNA. The sensitivity was found to be positively related to the DNA length, indicating the longer DNA could binding more probes to cause aggregation induced fluorescence. Z-N2TPE and E-N2TPE could detect guanine-rich ssDNA as short as 5 nt and 10 nt respectively. Theoretical simulation calculation shows that the amino group of the probe could simultaneously bind with guanine and phosphate ester, which contribute to high selectivity. And the cis probe could bind DNA with higher affinity than the trans one, since the two amino groups of Z-N2TPE could synergistically bind DNA while E-N2TPE could bind DNA with only one amino group.(c) 2022 Elsevier B.V. All rights reserved.
Ramirez-Perez, Javier ChristianReis, Tatiana A.Olivera, Cristiano L. P.Rizzutto, Marcia A....
10页
查看更多>>摘要：Using the proper size of nanoparticles as an active substrate, Surface-enhanced Raman scattering (SERS) can provide a reliable technique for detecting and identifying fungi, including Alternaria alternata, Aspergillus flavus, Fusarium verticilliodes, and Aspergillus parasiticus that have been associated to biodeterioration and biodegradation of cultural heritage materials. In this research spherical silver nanoparticles (AgNPs) of average size of 10, 30 and 60 nm were synthesized using the wet chemical method with good yield and their size and shape distributions were examined using small-angle X-ray scattering (SAXS). The protocol for fungi sample preparation proved to be critical for producing high-quality and reproducible SERS spectra. We found that the effect of AgNPs on SERS signal enhancement is size dependent under the same experimental conditions; the SERS intensity of fungal strains using 60 nm achieved up to 2.3x105 enhancement, about twice as intense as those produced with 30 nm, and 10 nm produced a minor broad weak peak barely discernible around 1400 cm-1, similar to the NR spectra profile in the 550-1700 cm-1 spectral region, and the SERS signals using 60 nm showed high reproducibility, with less than 20% variance. Furthermore, we used principal component analysis (PCA) to statistically classify the SERS spectrum into four separate clusters with 99 percent variability so that the four fungal strains could be clearly detected and identified. The SERS technique, in combination with the PCA developed in this study, provides a simple, rapid, accurate, and cost-effective analytical tool for detecting and identifying filamentous fungal strains.(c) 2022 Published by Elsevier B.V.
查看更多>>摘要：In the current work, we have reported a fast and easy method based on gold nanoparticles for the deter-mination of uric acid in urine samples. In the first stage, gold nanoparticles were synthesized using the chemical reduction method and then applied as a sensor to measure uric acid concentration based on its strong reducing property. The main parameters affecting response signals such as pH, reagent concen-tration, and time are optimized using the multivariate method. Under the optimum conditions, the cal-ibration graphs were linear in the range of 0.5 - 10.0 mg.L-1 with limits of detection of 0.2 mg.L-1 and RSD% of 1.2% These results show that this nano-based method is a very sensitive and simple method for the determination of uric acid in urine samples. (C) 2022 Elsevier B.V. All rights reserved.
Mary, PriyaSherin, D. R.Manojkumar, T. K.Nampoori, V. P. N....
11页
查看更多>>摘要：Linear and nonlinear optical properties of near-infrared laser grade dye LDS 821 in different solvents and Salmon Deoxyribonucleic acid (DNA) were studied using spectroscopic and Z-scan techniques. UV-Vis absorption spectrum of the dye shows a bathochromic shift with a decrease in the solvent polarity parameter, and in DNA, the dye exhibits a hypochromic shift. The fluorescence spectrum of the dye does not show any notable correlation with the solvent polarity parameter, but in DNA, the fluorescence intensity of the dye decreases with the incremental addition of DNA. Molecular docking studies reveal that the dye intercalates on the major grooves of DNA. Nonlinear optical properties of the dye in different solvents and phosphate buffer solution with varying DNA concentrations were studied using the Z-scan technique using a Q-switched Nd: YAG laser operating at fundamental and second harmonics. A closed and open aperture Z-scan of dye in different solvents was carried out to estimate the nonlinear refractive index, excited-state absorption cross-section, and two-photon absorption coefficient (TPA). The variation in nonlinear optical properties of the dye in different solvents was due to solvent-induced structural modifications. Theoretical investigation on nonlinear optical properties of the dye in different solvents was carried out using density function theory. The theoretical first and second-order hyperpolarizability was calculated using B3LYP functional. The predicated nonlinear optical parameters of the dye in different solvents does not show any direct correlation with solvent polarity. Nonlinear absorption of the dye in phosphate buffer solution (PBS) and DNA were estimated. The nonlinear absorption of the dye in PBS decreases with the addition of DNA. Molecular docking studies were carried out to determine the structural changes induced in dye due to the intercalation with DNA.(c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Cysteine is an essential biothiol that plays various functions in the human body. Decrease or exceeding of this excellent antioxidant from the expected range will lead to so many problems. Thus, appropriate sens-ing of it would be of great importance. Sulfur-doped carbon Dots (S-CDs) owe excellent fluorescence emission. Therefore, designing a Fluorescence resonance energy transfer (FRET) system between S-CDs as donor and Au nanoparticles (AuNPs) decorated tungsten disulfide nanosheet (WS2 NSs) would be a perfect strategy for cysteine detection. Excitation at 340 nm will give the maximum quantum yield of S-CDs (21%) and fluorescence emission peak at 460 nm. In the presence of cysteine, the FRET mechanism inhibited through the affinity of cysteine's functional groups (-SH and-NH2) toward AuNPs and S-CDs fluorescence emission was recovered. To find the best efficiency of the system, optimization of pH, tem-perature, and time was investigated. Here the linear range of 3-275 mM and limit of detection of 0.01 mM was obtained. Finally, the fluorescence method was applied to the analysis of cysteine in human blood serum, which poses the potential of rapid and sensitive sensing. It can detect both lower and higher amounts of serum cysteine. (c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：In this paper, we theoretically investigated the electronic and optical properties of monolayer borophene, including the electronic energy band, density of states (DOS), dielectric function, and absorption spectra and the charge distribution. The calculated phonon spectra and phononic DOS confirm that the four kinds of monolayer borophene structures can stably exist. Two-dimensional (2D) borophene exhibits apparent optical anisotropy in visible and near infrared (NIR) regions. Our results provide a reliable theoretical base for the application of monolayer borophene in optoelectronic devices.(c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：The interaction mechanisms of nimodipine with pepsin, trypsin, a-chymotrypsin, lysozyme and human serum albumin were investigated by multispectral and molecular docking methods. Vitamin C and naringin were the main active components of grapefruit juice, and nimodipine was the typical drug that interacts with this juice. Fluorescence spectroscopy was used to study the interaction of nimodipine with five proteinases (pepsin, trypsin, alpha-chymotrypsin, lysozyme and human serum albumin) and the effects of vitamin C and naringin on these interactions. The fluorescence quenching results showed that nimodipine can quench the intrinsic fluorescence of these five proteinases by a static quenching procedure. Nimodipine binds to pepsin and alpha-chymotrypsin, through hydrogen bonding and van der Waals forces, whereas it binds to trypsin, lysozyme and human serum albumin mainly by hydrophobic interactions. The microenvironment of the five proteinases changed. The probability of nonradiative energy transfer between the five proteinases and nimodipine was high. Both vitamin C and naringin reduced the binding constant of nimodipine to the four proteinases (except a-chymotrypsin) and might increase the concentration of free nimodipine. Thus, vitamin C or naringin in fruits or foods could increase the blood concentration of free nimodipine and perhaps a reduction in nimodipine dose was needed. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：An efficient colorimetric sensor was developed using a high-density deep eutectic solvent (HD-DES) for the trace detection and speciation of iron in various milk samples. A liquid colorimetric probe was fabricated by dissolving ferrozine (FZ) in HD-DES prepared from TBABr and PBA. The prederivatization of Fe2+ via complexation with FZ on the HD-DES/FZ probe provided the [Fe(FZ)(3)](4- )complex, which led to a color change from pale yellow to purple before it was simultaneously extracted by HD-DES. The Fe3+ content was calculated by subtracting the amount of Fe2+ from the total Fe content following the reduction of Fe3+ to Fe2+ by L-ascorbic acid in an acid buffer. Under the optimized conditions, the proposed colorimetric sensor exhibited appreciable linearity in the concentration range of 0.003-0.04 mg L-1, a low limit of detection (0.95 mg L-1), high enrichment factor (50), and outstanding repeatability. The liquid colorimetric probe was successfully applied for the determination and speciation of iron in milk samples, and the results were compared with those obtained using the standard atomic absorption spectrometry method. Moreover, quantitative analysis was performed on a smartphone using the Image J application to estimate the color intensity change, which eliminated the requirement of sophisticated scientific instruments. (c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：We synthesized a new pH-dependent meso-captor/sensor for the visual monitoring and selective sequestering of Ag(I) ions from wastewater. The SBA-16 microspheres were successfully synthesized via a direct hydrothermal treatment through surfactant-assisted cooperative self-assembly. The meso-captor/sensor was designed via the direct immobilization of the chromogenic Acid Blue 90 (AB90) chelate into cubical large, open mesoporous SBA-16 carriers and investigate of its ability to detect and retain silver ions from aqueous solutions. Results show that the synthesized SBA-16 microspheres were retained after modification and the AB90 functional groups were immobilized hierarchically inside the mesopore channels. This was evidenced by the N-2 adsorption, X-ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared (FTIR), Scanning Electron Microscope (SEM), High-Resolution Transmission Electron Microscope (HR-TEM), and elemental analyses. Batch adsorption experiments were carried out and the effects of various parameters on Ag(I) ions removal and detection were determined. The optimum adsorption/detection of Ag(I) ions were recorded at a pH of 6.2 within 30 min with color change from a brilliant blue to a pale blue-gray. The spectral response for [SBA-16@AB90 -> Ag(I)] complex showed a maximum reflectance at lambda(max) = 385 nm within 2.5 min response time (t(R)); the LOD was close to 3.87 mu g/L while the LOQ approached 12.83 mu g/L, this was attributed to the concentration range at which a linear signal has been observed against Ag(I) analyte concentration (i.e., 5 to 1000 mu g/L) at pH 6.2 with standard deviation (SD) of 0.077 (RSD% = 9.5 at n = 8). (c) 2022 Elsevier B.V. All rights reserved.
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