查看更多>>摘要：Hypoxia plays an important role in cancer progression, which is a characteristic feature of the tumor micro-environment and reflects the invasiveness of tumor cells. Nitroreductase (NTR) is overexpressed in hypoxic tumors, which making it an efficient target for detecting the hypoxic state in tumor. In this work, a new type of nitro-based fluorescent probe, named HNT-NTR, has been proposed, HNT-NTR could detect specifically and rapidly the NTR degree, which reflects the level of hypoxia in bidimensional (2D) tumor cells, three-dimensional (3D) tumor spheres and even the real tumors in vivo without biological toxicity. Most importantly, according to the research, HNT-NTR even could distinguish tumor cells from other normal cells in vivo and reflect the invasiveness of tumor cells by the near-infrared fluorescence intensity, which provides a new way of clinical pathologic diagnosis. All in all, HNT-NTR not only is proven to be an ideal probe for detecting solid tumors in vivo, but also has great potential to distinguish if cells are benign or malignant and even guide therapeutic applications in the clinic. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：In this work, carbon dots-doped terbium phosphonate coordination polymers (CDs-GMP/Tb) were designed and prepared as ratiometric fluorescent probes for the detection of citrate. The as-prepared CDs-GMP/Tb are prepared and have the merits of high photostability, low toxicity, and excellent biocompatibility. The as-prepared CDs-GMP/Tb as ratiometric fluorescent probes also have better anti-interference ability and stability compared with the traditional single fluorescent probe. The surface morphology, fabrication, and spectroscopy were characterized through a variety of instruments. It confirms that the probes exhibited network structure doping carbon dots. With the addition of citrate, the fluorescence of GMP/Tb at 545 nm was significantly quenched, contrasting to the enhancement of fluorescence of CDs at 454 nm. Under optimum conditions, the detection limit for citrate was 0.47 mu M, with a linear range of 0-200 mu M between citrate concentrations and I-545/I-454. It has high sensitivity, selective, and rapid detection for citrate. The as-prepared CDs-GMP/Tb as ratiometric fluorescent probes were also used for imaging citrate in living cells. These experiment results showed that CDs-GMP/Tb as ratiometric fluorescent probes could be applied to trace citrate detection in the environmental and biological fields. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：In this project, poly (citric acid) (PCA) functionalized on nano Ag/Cu was synthesized by chemical analysis method. The nano probe was applied to detection of cysteine by using the magnesium (II) ions as a cross linker. The characterization of Ag/Cu/PCA nano probe was studied by using the UV-visible, morphological microscopy, dynamic light scattering, and zeta potential analyzer. The zeta potential and size of Ag/Cu/ PCA were -38.0 mV and 18.0 nm, respectively. The prepared nano probe shows rapid response for detection of cysteine. The detection limit of Ag/Cu/PCA nano probe was 0.07 nM. Additional, the Ag/Cu/PCA nanoparticles was applied to cysteine detection from real samples in the presence of amino acids compounds. Rapidly and sensitive determination of Streptococcus pneumoniae is substantial for food safety and human health. The DNA-Ag/Cu/PCA were prepared as a template in chemical method and experimented as a bio-receptor for the cell bacteria detection as peroxidase-like catalytic process. The DNAAg/Cu/PCA nano probe shows a linear dynamic concertation range of Streptococcus pneumoniae via detection limit about 65 CFU/mL. The project presents that the DNA-Ag/Cu/PCA could detect the biolog-ical and bacterial samples via high accuracy. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：In this work, the effects of atomic electronegativity (O, S, and Se atoms) on the competitive double excited-state intramolecular proton transfer (ESIPT) reactions and photophysical characteristics of uralenol (URA) were systematically explored by using the density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. The calculated hydrogen bond parameters, infrared (IR) vibrational spectra, reduced density gradient (RDG) scatter plots, interaction region indicator (IRI) isosurface and topology parameters have confirmed the six-membered intramolecular hydrogen bond (IHB) O4AH5...O3 is the stronger one in all the three studied compounds. Subsequently, frontier molecular orbitals (FMOs) and natural bond orbital (NBO) population analysis essentially uncover that the electron redistribution has induced the ESIPT process. Besides, the constructed potential energy curves (PECs) have indicated that the ESIPT process prefers to occur along the O4AH5...O3 rather than the O1AH2...O3 and the protontransfer energy barrier is gradually decreased with the weakening of atomic electronegativity from URA to URA-S and URA-Se. In a conclusion, the attenuating of atomic electronegativity has enhanced the IHBs of URA and thereby promoting the ESIPT reaction, which is helpful for further developing novel fluorophores based on ESIPT behavior in the future. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The nest of Eumeninae wasp is one of nature's creations, revealing the mysterious architectural beauty through its composition and nanostructuring. The present study unveils the compositional mystery of Eumeninae nest through the signal processing of the laser-induced breakdown spectrum (LIBS). The structure, morphological, and optical characterisations of the nest sample shows nanoparticles of oxides of silicon, aluminium, and iron with an optical bandgap of 2.5 eV, giving a fluorescence emission in the blue region upon ultraviolet excitation. Though, the energy dispersive spectroscopic study confirms the major elements present in the sample, the more elements are revealed through LIBS analysis. The intriguing properties of nest is attributed to the elemental compositions - oxygen, silicon, iron, manganese, chromium, cobalt, calcium and carbon - which necessitate deconvolution of peaks in the spectra for estimating the plasma temperature (4300-5045 K) and electron density (1.13 119 cm3). (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Despite the adequacy of the endogenous steroid (progesterone) levels in biological functioning, elevated levels of progesterone hormone have several physiological effects that are amplified due to its direct and indirect uptake from the environment, food products, and medical therapy. So, it is much needed to evaluate the progesterone levels in environmental samples as well as for biological fluids. In this work, we focused on the development of the nano sensing probe for the selective detection of progesterone among the library of steroid hormones belonging to the class of female sex hormones. Herein, functionalization of dipeptide is carried out at N-terminal to produce N-functionalized dipeptide (SS3), and simultaneously, its self-assembly properties are explored. Furthermore, HR-TEM imaging was also performed to examine the morphology of the self-assembled architectures before and after the addition of the steroid hormone. To investigate the binding mechanism of the sensing probe, Fluorescence spectroscopy, Circular Dichroism (CD), MD-Simulation, and DFT studies were performed and studied in detail. Moreover, to check the potency of the real-time application of the developed nanoprobe, we have successfully determined the spiked concentration of progesterone levels in pharmaceutical and biological fluid samples with functional percentage recovery. Also, the stability and other competitive binding studies of the probe with the coexisting substances are performed to check the rationality of the sensing probe at physiological conditions. (C) 2021 Elsevier B.V. All rights reserved.
Ramachandran, R.Pavithraa, S.Meka, J. K.Rahul, K. K....
4页
查看更多>>摘要：Isoprene and its oligomers, terpenes, are expected to be present, along with other complex organic molecules in the diverse environments of the ISM and in our solar system. Due to insufficient spectral information of these molecules at low temperature, detection and understanding the importance of these molecules has been rather incomplete. For this purpose, we have carried out the vacuum ultraviolet (VUV) photoabsorption measurements on pure molecular ices of isoprene and a few simple terpenes: limonene, a-pinene and fl-pinene by forming icy mantles on cold dust analogs. From these experiments, we report the first low temperature (10 K) VUV spectra of isoprene and its oligomers limonene, a-pinene and fl-pinene. VUV photoabsorption spectra of all the molecules reported here reveal similarities in the ice and gas phase as expected, with an exception of isoprene where a prominent red shift is observed in the ice phase absorption. This unqiue property of isoprene along with distinctive absorption at longer wavelengths supports its candidature for detection on icy bodies. (c) 2021 Elsevier B.V. All rights reserved.
Anwer, Ebtehal F.El-Deen, Deena A. M. NourDerayea, Sayed M.Omar, Mahmoud A....
6页
查看更多>>摘要：6-Aminocaproic acid is one of the most widely used antihemorrhagic and antifibrinolytic agent, therefore, it is essential to create a novel, sensitive, low cost and straightforward spectrofluorimetric method for its determination. The nucleophilic substitution interaction between the primary amine of 6-aminocaproic acid with 4-chloro-7-nitro benzofurazan (NBD-Cl) generated a yellow product. The reaction proceeded in borate buffer (pH 9) and its fluorescence has been measured at 525 nm after excitation at 472 nm. All of the parameters that have impact on the performance of the developed method were investigated and optimized. The range of linearity was 0.1-0.7 mu g/mL while, the quantitation limit was down to 0.101 mu g/mL and limit of detection was 0.033 mu g/mL. This approach was effectively employed to evaluate the content of 6-aminocaproic acid in laboratory prepared dosage form with average percentage recovery of 100.19 +/- 0.72% without any interference from basic excipients. Moreover, the proposed method was extended to determine 6-aminocaproic acid in spiked human plasma and urine. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：A novel D-A-D chromophore TBQM based on triphenylamine, acylhydrazone and dimethylamino was synthesized, and the emission properties of TBQM was studied in solutions as well as in aggregated state. TBQM showed obvious solvatochromism in different solutions. In addition, the reversible multicolor fluorescence switching properties under the stimulation of external forces and acid were also obtained. The fluorescence of TBQM changed from blue to bright blue, and finally to blue-green as the degree of grindning increased, which would recover after being fumigated by CH2Cl2. Meanwhile, TBQM could undergo twice protonation after fumigated by TFA. The fluorescence color changed from blue to bright blue, blue-green, and yellow-green until the fluorescence was quenched with the increasing of TFA fumigation time, which can be restored automatically or by TEA fumigation. Moreover, TBQM could be used as an advanced fluorescent anti-counterfeiting ink. (C) 2021 Elsevier B.V. All rights reserved.
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