查看更多>>摘要：Luminescent metal-organic frameworks (LMOFs) and their functional materials with unique characteristics can provide the basis for the construction of new analytical techniques, which can meet the continuous demand for various fields. In this work, guanosine monophosphate (GMP), terbium ion (Tb-3(+)) and zeolitic imidazolate framework-8 (ZIF-8) are self-assembled to form a ZIF-8@GMP-Tb nanocomplex, which can be utilized as a ratiometric fluorescent probe to monitor alkaline phosphatase (ALP) activity. Specifically, with adding ALP, the fluorescence intensity at 547 nm (one of the characteristic emission peaks of Tb3+) obviously decreased. Meanwhile, the conjugated structure of GMP increased the fluorescence of ZIF-8 (located at 330 nm). The possible mechanism was proposed through the characterization of the materials. Based on the variation of the emission peaks at 330 and 547 nm, the ratiometric fluorescent sensor of ALP has a linear range of 0.25-20 U/L. Moreover, applying this sensing system to the detection of ALP in the human serum sample and ALP inhibitor investigation possesses satisfactory results. This work provides a new perspective for the utilization of ZIF-8 and lanthanide ions in manufacturing simple and sensitive sensors. (C) 2021 Published by Elsevier B.V.
查看更多>>摘要：Cerium, an abundant lanthanide element, is widely used in human industry. The accumulation of Ce4+ ion, however, will damage the environment and biological organism. Therefore, its facile detection is highly needed. Herein, we design a hybrid sensing platform consisting of carbon dots (C-dots) and bathophenanthroline-disulfonate-Fe2+ complex (Bphen-Fe2+) for trace-level determination of Ce4+. Based on inner filter effect (IFE), the red-colored Bphen-Fe2+ complex severely quenches the fluorescence of C-dots. After addition of Ce4+, Fe2+ is oxidized to Fe3+, and the colorless Bphen-Fe3+ complex generates, which weakens the IFE efficiency and leads to the fluorescence recovery of C-dots. Meanwhile, due to the decreasing amount of Bphen-Fe2+ upon Ce4+ addition, the red color of the solution gradually fades, which enables visual detection of Ce4+ by the naked eyes. Under the optimized conditions, the C-dots/Bphen-Fe2+ system realizes the fluorometric and colorimetric sensing of Ce4+ in the range of 0.5-100 and 1.9-80 mu M, with the limits of detection as low as 0.5 and 1.9 mu M, respectively. This method also shows high selectivity over other common ions, and has an excellent applicability for monitoring of Ce4+ in real water samples. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：A multimode responsive hypochlorite probe 1, based on Terbium (III)-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (Tb(III)-DO3A) and 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY), is described. We have shown that probe 1 can detect ClO- by absorption, fluorescence, and phosphorescence simultaneously. The multimode response makes probe 1 a versatile ClO- probe for practical applications. We have found that probe 1 can be used in naked-eye colorimetric and fluorogenic detection of NaOCl in solution. Also, we have constructed a colorimetric test paper for visual sensing of NaOCl. Furthermore, fluorescence imaging studies indicated that probe 1 was a versatile tool for in vitro imaging of NaOCl in living cells. Thus, to the best of our knowledge, probe 1 represents one of the rare examples of multimode responsive ClO- probes. (C) 2021 Elsevier B.V. All rights reserved.
Pereira, Jorge L. G. F. S. CostaPais, Alberto A. C. C.Azevedo, Julio Cesar R.Knapik, Heloise G....
21页
查看更多>>摘要：Fluorescence EEM spectra provide the "fingerprint" of water contamination and is a very efficient way to access the quality of water bodies. These multivariate datasets correspond to complex mixtures and are very rich in information. Graphical approaches have been used for decades to characterize and quantify different contamination sources. It is very important to resolve mixed signals in raw EEM spectra in terms of signal sources and respective composition profiles - signal sources allow the identification of contamination type, while concentration profiles quantify the respective contribution inside the mixtures. In order to be able to use robust modeling algorithms, the first task is to accurately estimate the number of contributions that are present. We demonstrate the ability of Singular value Decomposition (SVD) in accessing this information content in raw EEM datasets. To decompose raw EEM information, several algorithms are tested: PARAFAC, MCR-ALS and ICA. In this work we suggest a systematic unsupervised algorithm to process raw EEM spectra of water samples. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Belonging to the Sartan family, antihypertensive drug - Valsartan (Val) had been found to possess antioxidant properties. Also, the zinc complex of Valsartan (VZn) has been recently recognized as inducing agents of the reductive stress effects thus possessing anticancer activity. Hence, in this work an attempt has been made to understand the interaction of Val and VZn with DNA using spectroscopic and in silico methods as DNA has been identified as the target for many anticancer drugs. VZn has been prepared in 2:1 M ratio and characterised by absorbance, FTIR, HRMS, NMR and Job's continuous variation method. VZn has been tested against human lungs cancer cell line which exhibited good anticancer activity (IC50 = 89 mu g/mL). Interaction of Val and VZn with ct-DNA under physiological conditions has been studied by spectroscopic techniques such as fluorescence, absorbance, FTIR, circular dichroism (CD) and in silico methods. Fluorescence quenching, DNA melting and viscometric studies confirmed that both ligand and complex bind to the grooves of the ct-DNA. The experimental results have revealed that VZn strongly bind with DNA compared to Val. Docking study suggested that, Val binds at major groove while VZn binds to both minor and major grooves of B-DNA. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Diabetes mellitus (DM) is associated with a high incidence of morbidity and mortality which, in many cases, is derived from the progressive kidney dysfunction due to diabetic nephropathy (DN). In this study, synchrotron-Fourier-transform infrared (SR-FTIR) microspectroscopy was used to identify molecular changes in the lipid and protein regions in the plasma of patients with different stages of DN (mild, moderate, severe and end-stage), and patients with type 2 diabetes mellitus (T2DM) without DN. Our results revealed different conformational changes in the proteins secondary structure between DN stages, and between DN and T2DM groups illustrated by peak shifts and intensity alterations. End-stage DN showed the highest CH2/CH3 ratio and intensity of the carbonyl group in protein-carbonyl region compared to other DN stages indicating high level of unsaturation and lipid peroxidation and oxidation conditions. Moreover, end-stage DN group was characterized by a decrease in amide I and amide II absorption signals which reflected a sign of hypoalbuminemia. When compared to T2DM, DN group demonstrated a higher oxidation state as confirmed via the high intensity of the carbonyl group and the high level of malondialdehyde. The current study highlights the promising role of SR-FTIR microspectroscopy as a new sensitive analytical approach that can be used to provide better understanding of the pathophysiology of DN, and guide the development of new preventive therapies and treatments. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Dapagliflozin (DAPA) is a selective sodium-glucose cotransporter-2 inhibitor that reduces renal glucose reabsorption. The drug has recently become a crucial milestone in the management of diabetes and heart failure. In this study, the interaction of DAPA with bovine serum albumin (BSA) was investigated for the first time using various fluorescence spectroscopic techniques, UV-absorption spectroscopy, molecular docking, and molecular dynamic (MD) simulation. The fluorescence spectroscopic titration study performed at different temperatures showed that DAPA quenched the fluorescence of BSA through a combination of dynamic and static mechanisms, which was confirmed by UV absorption, fluorescence-resonance energy transfer measurements, and MD simulation. The binding thermodynamic parameters demonstrated that the binding stoichiometry between BSA and DAPA was 1:1. Competitive binding experiments using site-specific markers as well as molecular docking studies showed that DAPA binds to site I on BSA. The positive values of enthalpy change (Delta H) and entropy change (Delta S) revealed that hydrophobic forces played a predominant role in the binding of DAPA to BSA, whereas the negative value of Gibbs free energy change (Delta G) indicated the spontaneity of the interaction. Moreover, the synchronous fluorescence spectroscopy has shown that DAPA binding to the protein molecule occurs in the vicinity of the tryptophan residue. These findings were confirmed by the molecular docking and MD simulation studies. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：In this paper, a simple and effective fluorescence turn-on approach for highly sensitive and selective monitoring He2+ ions was designed by using carbon dots (CDs) and silver nanoparticles (AgNPs). It reveals that the fluorescence of CDs solution can be quenched in the presence of AgNPs through inner filter effect (IFE) and the quenched CDs-AgNPs system is turned on after addition of Hg2+ ions, which is due to higher affinity of Hg2+ and AgNPs than that of CDs and AgNPs, thus resulting the disappearance of AgNPs from the CDs-AgNPs composites and leading to the fluorescence turn-on of CDs. The developed fluorescence turn-on approach exhibited high selectivity and sensitivity for detection of He2+. Under the optimum experimental conditions, good linearity was achieved over the range of 100-160 mu M and the limit of detection (LOD) was estimated to be 2.22 x 10(-8) M for Hg2+. The recoveries of Hg2+ spiked in real samples ranged from 98.4% to 101.6%. Results of this study suggest that the fluorescence turn-on approach can be used to the detection of Hg2+ in real water samples. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Based on the thiourea quenching of the chemiluminescence of Tb3+/ prulifloxacin (PUFX) sensitized KMnO4-Na2SO3 system, a convenient and rapid chemiluminescence method for the determination of thiourea was proposed. The reaction between KMnO4 and Na2SO3 brought only weak chemiluminescence, but the chemiluminescence increased sharply in the presence of sensitizer Tb3+/ PUFX. Addition of thiourea can prevent the reaction between KMnO4 and Na2SO3, thus the chemiluminescence intensity was significantly decreased. Under the optimum conditions, the calibration graphs for thiourea were linear in the range of 1.0 x 10(-7) to 4.0 x 10(-5) mol.L-1. The limit of detection was 6.4 x 10(-8) mol.L-1. The method was applied satisfactorily to the determination of thiourea in tap water, lake water and rice noodles and the spiked recoveries were between 104.7 similar to 113.4%. The possible mechanism of sensitization and quenching was also proposed. (C) 2021 Published by Elsevier B.V.
查看更多>>摘要：To obtain efficient pure organic thermally activated delayed fluorescence (TADF) materials, introducing non-metal heavy atoms is the common molecular design strategy, enhancing the intrinsically weak spin-orbit coupling (SOC) between singlet and triplet excited states by heavy-atom effect. However, the effect of heavy atom replacement sites is rarely explored. Herein, two series of molecules are investigated on the basis of different heavy atoms replacement sites to reveal the inherent structure-property relationships. The results show that DMSeC-DPS, which O is replaced with Se in periphery of donor units, could exhibit enhanced TADF performance. Because (i) sufficiently small singlet-triplet states energy gap (DEST) and enhanced SOC as well as mixed CT/LE character in T-1 state could facilitate reverse intersystem crossing process, and (ii) non-radiative consumption are decreased for S-1 -> S-0 transition. Additionally, replacement of As at the connection site between donor and acceptor units folds evidently the geometry, leading to much larger DEST and enhanced exponentially SOC between T-1 and S-0 state due to the great participation of heavy atoms of the frontier molecules orbitals and heavy-atom effect. The pure LE character leads to relative stability and slight non-radiative consumption in T-1 state. The luminescent way of DMOC-As-DPS would be transformed to phosphorescence. This work provides updated theoretical perspective for the effect of heavy atoms replacement sites and proposes a design strategy for the utilization of non-metal heavy atoms in efficiency organic lighting emitting diodes. (C) 2021 Elsevier B.V. All rights reserved.
NSTL
Elsevier