查看更多>>摘要：The level of L-kynurenine (L-kyn) can reflect the health state of human body, and the determination of Lkyn can be used for the medical diagnosis of several cancers and neurological diseases. In this work, a series of air-, water-, and thermo-stable dinuclear lanthanide nanoclusters [Ln(2)(2,5-DFBA)(6)(phen)(2)] (Tb 1, Eu 2, Gd 3, 2,5-DFBA = 2,5-difluorobenzoic acid, phen = 1,10-phenanthroline) are obtained by a facial method. 1 and 2 show very high luminescence quantum yields (QYs) of 71.7% and 81.8%, respectively. Interestingly, investigation reveals that 1 is a quick, highly sensitive and selective sensor for L-kyn in real samples of urine and serum. Furthermore, transmission electron microscope (TEM) results reveal that nanocluster 1 is stable in solution and can be uniform distributed on the base, suggesting it can be deposited on various supports to fabricate sensing devices. Thus, 1 is fabricated into a sensitive test paper for the eye-readable detection of L-kyn in real samples of human urine and serum. The limit of detection (LOD) as low as 0.3 mu M, which is enough to rapidly determine L-kyn in human body liquor (usually 5 mu M in healthy human body). (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Near-Infrared Spectroscopy (NIRS) has shown to be helpful in the study of rice, tea, cocoa, and other foods due to its versatility and reduced sample treatment. However, the high complexity of the data produced by NIR sensors makes necessary pre-treatments such as feature selection techniques that produce compact profiles. Supervised and unsupervised techniques have been tested, creating different subsets of features for classification, which affect the performance of the classifiers based on such compact profiles. In this sense, we propose and test a new covering array feature selection (CAFS) algorithm coupled to the naive Bayes classifier (NBC) to discriminate among Amazonian cacao nibs from six cacao clones. The CAFS wrapper approach looks for the wavebands that maximize the F-1-score, and then, are more relevant for classification. For this purpose, cacao pods of six varieties were collected, and their grains were extracted and processed (fermented, dried, roasted, and milled) to obtain cacao nibs. Then from each clone NIR spectral profiles in the range of 1100-2500 nm were extracted, and relevant wavebands were selected using the proposed CAFS algorithm. For comparison, two standard feature selection techniques were implemented the multi-cluster feature selection MCFS and the eigenvector centrality feature selection ECFS. Then, based on the different selected variables, three NBCs were built and compared among them through statistical metrics. The results showed that using the wavebands selected by CAFS, the NBC performed an average accuracy of 99.63%; being this superior to the 94.92% and 95.79% for ECFS and MCFS respectively. These results showed that the wavebands selected by the proposed CAFS algorithm allowed obtaining a better fit concerning other feature selection methods reported in the literature. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：A novel photoluminescent Hcy-AuNCs has been developed through one-pot reduction method, to establish a tobramycin sensing by second-order scattering (SOS). Hcy-AuNCs could spontaneously assemble to small-scaled aggregation, resulting in remarkable intensity enhancement of scattered luminescence signals. The luminescence of Hcy-AuNCs could be clearly observed under ultraviolet lamp, when excited at 365 nm, a significant luminescent intensity at 741 nm was monitored in SOS spectra. The introduction of AuNPs would cause large-scaled aggregation of Hcy-AuNCs that was rapidly settled in the solution, resulting in the decrease of SOS intensity. Besides, the non-radiative energy transfer between AuNPs and Hcy-AuNCs would also reduce the luminescent intensity. However, the addition of tobramycin would cause the aggregation of AuNPs due to the electrostatic and covalent bonding between AuNPs and tobramycin, thus eliminating the interference of AuNPs. The luminescence of Hcy-AuNCs reappeared, exhibiting an optical response toward tobramycin. The good linearity was obtained in a wide range from 4 nM to 300 nM with a low detection limit of 0.27 nM. The selectivity was acceptable toward different types of antibiotics. Finally, the proposed method was successfully applied to the widely used tobramycin eye drops. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：The irrational use of tetracycline (TC) poses a serious threat to human health, which calls for the development of efficient and reliable detection methods. Herein, an ideal sensor based on luminescence resonance energy transfer (LRET) between aptamer modified up-conversion nanoparticles as signal probes (donors) and manganese dioxide (MnO2) nanosheets (acceptors) was developed for TC detection in food samples. As a result of van der Waals forces between the nucleobases of the aptamer and the basal plane of MnO2 nanosheets, the distance of the donors and acceptors was shortened. The emission spectrum of the signal probes and the absorption spectrum of MnO2 nanosheets overlapped, resulting in LRET, and quenching of up-conversion luminescence. The TC-specific aptamer could fold into a complex conformational structure to provide recognition sites for TC. In the presence of TC, the aptamer was found to preferentially combine with TC due to the stacking of planar moieties, hydrogen bonding interactions and molecular shape complementarity, causing the separation of signal probes and nanosheets, and luminescence recovery. Consequently, a low detection limit of 0.0085 ng/mL was achieved with a wide detection range of 0.01-100 ng/mL. Moreover, the ability of the sensor to detect TC was confirmed in actual food samples and compared with the traditional ELISA with satisfactory results (p > 0.05). (C) 2022 Published by Elsevier B.V.
查看更多>>摘要：A new ratiometric fluorescence sensor is prepared for selective detection of chlorotetracycline (CTC) through dual-mode fluorescence method. The sensor is composed of carbon dots (CDs) with blue emission and carboxyl-modified CuInS2/ZnS quantum dots (QDs) with dark-red emission. Usually QDs are used as fluorescent probes or signal sources, but it is interesting in this strategy that CuInS2/ZnS QDs innovatively work as quenching agent to reduce the fluorescence of CDs, mainly due to the fluorescence resonance energy transfer (FRET). After the addition of CTC, the interaction between CDs and CuInS2/ZnS QDs is restrained, resulting in the fluorescence recovery of CDs, whilst the QDs' fluorescence remains unaffected. In this work, CTC is detected in the range of 0-50 mu M by conventional fluorescence and synchronous fluorescence methods under an excitation wavelength of 360 nm or Delta lambda = 90 nm, and the detection limits of the two methods are 0.46 mu M and 0.36 mu M, respectively. The designed sensor displays good selectivity compared with other tetracycline drugs with similar structure to CTC, different ions and various natural - amino acids. And the sensor can also be applied to determine CTC in tap water and milk. (C) 2022 Elsevier B.V. All rights reserved.
Ghoniem, Nermine S.Hussien, Emad M.Atta, Madonna Y.Hegazy, Maha A....
13页
查看更多>>摘要：Simple, accurate, and precise four spectrophotometric methods were developed and validated for simultaneous determination of glimepiride and pioglitazone hydrochloride in their pharmaceutical formulation. The first spectrophotometric method was the dual-wavelength which determined glimepiride at 219.0 and 228.0 nm and pioglitazone hydrochloride at 268.0 nm. The second one is the first derivative of ratio spectra (DD1) spectrophotometry in which the peak amplitudes were used at 238.0 nm and 268.0 nm for glimepiride and pioglitazone hydrochloride, respectively. The third method is ratio subtraction in which glimepiride was determined at 228.0 nm in the presence of pioglitazone hydrochloride which was determined by extended ratio subtraction at 268.0 nm. The fourth method was the ratio difference to determine glimepiride and pioglitazone hydrochloride. Beer's law was confirmed in the concentration range 2.50-15.00 mu g mL-1, and 10.00-50.00 mu g mL-1 for glimepiride and pioglitazone respectively for the four methods. The proposed methods were used to determine both drugs in their pure powdered form with mean percentage recoveries of 99.91 +/- 1.117% for glimepiride and 99.76 +/- 0.911% for pioglitazone hydrochloride in method (A). In method (B), the mean percentage recoveries were 100.12 +/- 0.89% for glimepiride and 100.02 +/- 1.06% for pioglitazone hydrochloride. In method (C) glimepiride was 100.01 +/- 0.592% and 99.85 +/- 0.845% for pioglitazone hydrochloride by extended ratio subtraction. And finally, in method (D) the mean percentage recoveries were 100.66 +/- 0.670% for glimepiride and 99.92 +/- 0.988% for pioglitazone hydrochloride. The developed methods were successfully applied for the determination of glimepiride and pioglitazone hydrochloride in pure powder and dosage form. The suggested methods were also used to determine both compounds in laboratory-prepared mixtures. The accuracy, precision, and linearity ranges of the developed methods were determined. The results obtained were compared statistically with the official method, and there was no significant difference between the proposed methods and the official method for accuracy and precision. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：In this article, Density Functional Theory based calculations, including dispersion corrections, PBEO (D3BJ)/Def2-TZVP(-f), were performed to elucidate the photophysics of the [Ru(bpy)(2)(HAT)](2+) complex in water. In addition, the thermodynamics of the charge and electron transfer excited state reactions of this complex with oxygen, nitric oxide and Guanosine-5'-monophosphate nucleotide (GMP) were investigated. The first singlet excite state, S-1, strongly couples with the second and third triplet excited states (T-2 and T-3) giving rise to a high intersystem crossing rate of 6.26 x 10(11) s(-1) which is similar to 10(6) greater than the fluorescence rate decay. The thermodynamics of the excited reactions revealed that all electron transfer reactions investigated are highly favorable, due mainly to the high stability of the triply charged radical cation (PS)-P-2.(3+) species formed after the electron has been transferred. Excited state electron transfer from the GMP nucleotide to the complex is also highly favorable (Delta G(sol) = -92.6 kcal/mol), showing that this complex can be involved in the photooxidation of DNA, in line with experimental findings. Therefore, the calculations allow to conclude that the [Ru(bpy)(2)(HAT)](2)(+) complex can act in Photodynamic therapy through both mechanisms type I and II, through electron transfer from and to the complex and triplet-triplet energy transfer, generating ROS, RNOS and through DNA photooxidation. In addition, the work also opens a perspective of using this complex for the in-situ generation of the singlet nitroxyl ((NO)-N-1 ) species, which can have important applications for the generation of HNO and may have, therefore, important impact for physiological studies involving HNO. (C) 2022 Elsevier B.V. All rights reserved.
AbdElgawad, HamadaAl-ghamdi, Abdullah A.Thomas, Ajith M.Raju, Lija L....
9页
查看更多>>摘要：Novel Ag@Ni nanosphere decorated with CdS NPs (Ag@Ni-CdS NCs) was synthesized by one step chemical synthesis method. The fabricated NCs were characterized by transmission electron microscope (TEM), scanning electron microscope (SEM), fourier transfer infra-red spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), zeta sizer and particle size analyzer. TEM and XRD confirmed the Ag in core and Ni in shell for the effective formation of Ag@Ni core shell nanosphere. EDAX and XPS spectra of NCs confirms the formation of Ag@Ni-CdS NCs. Zeta potential and particle size of the NCs was found to be 29.5 +/- 1.5 mV and 24 +/- 1 nm respectively. The complete loss in the peak intensity of Ag@Ni-CdS NCs (localized surface plasmon resonance (LSPR)) at similar to 410 nm in presence of S2- ions was observed which indicates its selective detection towards S2- ions. The sulfide ion sensing by Ag@NiCdS NCs was due to the successive oxidation of Ag results in the formulation of Ag2+ ions in the system, which causes the diminishing of LSPR band of NCs. The limit of detection (LOD) of S2- ions by Ag@Ni-CdS NCs was calculated to be of 2.66 nM. The combination of CdS NPs with core-shell Ag@Ni nanosphere guides a promising strategy for S2- ions detection from environmental polluted samples. (C) 2021 Elsevier B.V. All rights reserved.
Abdelhameed, Ali SaberBakheit, Ahmed H.Hassan, Eman S.Alanazi, Amer M....
9页
查看更多>>摘要：Enasidenib (EDB) is a new therapeutic agent for the treatment of adult patients with relapsed or refractory acute myeloid leukemia (AML) with an isocitrate dehydrogenase-2 (IDH2) mutation. This research aimed at utilizing experimental and theoretical approaches to characterize the binding mechanism between EDB and human serum albumin (HSA). Formation of an EDB-HSA static complex was demonstrated by quenching of the HSA intrinsic fluorescence by EDB. Using well known mathematical relations (e.g. Stern-Volmer and Lineweaver-Burk equations), the recorded EDB-HSA fluorescence data were interpreted and revealed binding constants in the magnitude order of 10(4) M-1 for the different investigated temperatures. These determined results were taken into further mathematical calculations to reveal the thermodynamic properties of EDB-HSA binding. Results demonstrated that spontaneous EDB and HSA binding takes place led by electrostatic forces. Computational docking studies have further confirmed the latter finding showing that EDB fits into the HSA Sudlow site I. Molecular dynamic simulation was performed to calculate the root mean square deviation (RMSD), root mean square fluctuation (RMSF), radius of gyration (R-g) and hydrogen bond parameters for the EDB-HSA complex. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Effective outcome from dynamic live-cell-imaging requires utilization of a probe with high emission intensity and low photobleaching. It would be preferable to achieve such properties at a low power of the applied laser to avoid any probable damage to biological cells or tissue. Most of the used small-molecule fluorophores have been reported to show significant photobleaching in a time-dependent manner and require high laser power to gain significant intensity for bioimaging. Carbon nanoparticles have recently been successfully used for cell imaging with low bleaching characteristics but require high laser power and lack optical nonlinearity at low power levels. Here, we report the preparation, characterization, and application of a Nanoscale Carbon (NC) which, on being surface decorated with crescent-shaped poly-lysine (PLNC), provides two-photon fluorescence (TPF) and low bleaching properties. PLNC was found to stain the cytoplasm of C2C12 muscle cells in the first four-hours of incubation with high TPF in the infrared range and can be useful for deep tissue imaging with further improvements. (C) 2021 Elsevier B.V. All rights reserved.
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