查看更多>>摘要：Adenosine triphosphate (ATP) is an energy molecule of significant importance, and, the monitoring of ATP in living cells is considerable for the clinical diagnosis of many related diseases, including cancer. Upconversion nanoparticles (UCNPs) have recently been attracting widespread interest in biomedical applications due to their chemical and thermal stability, high sensitivity, good biocompatibility, and excellent tissue penetration. Herein, a Cy3-aptamer-cDNA-UCNPs nanosensor was synthesized, based on the luminescence resonance energy transfer (LRET) between UCNPs and Cy3 for monitoring ATP in living cells. It showed a selective sensing ability for ATP levels by changes of fluorescence intensity of UNCPs at 536 nm. The investigated biosensor showed a precise, efficient detection with sufficient selectivity which was achieved through the optimization of conditions. In the range of 1-1000 mu M, the ATP induced changes of the fluorescence intensity were linearly proportional to the ATP concentrations. Furthermore, the cytotoxicity assay revealed that the UCNPs sensor exhibited favorable biocompatibility, implicating the use of UCNPs in vivo imaging. This study highlights the potential of using a combination of UCNPs and ATP-binding aptamer to design an ATP-activatable probe for fluorescence-mediated imaging in living cells. These results implied that the nanosensor can be applicable for the monitoring of intracellular ATP by fluorescence imaging and the quantitative analysis of biological liquids. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The spectroscopic parameters and anharmonic force fields of three isomers (c-H2C3O, HCCCHO and CH2CCO) of C3H2O have been calculated by Density Functional Theory (B3LYP, CAM-B3LYP, wB97XD) and second-order Moller-Plesset perturbation theory (MP2) combining with 6-311++G (3df, 3pd) and aug-cc-pVTZ basis sets. The equilibrium geometries, energies, rotational constants, harmonic and fundamental frequencies, and centrifugal distortion constants of three isomers of C3H2O are calculated and compared with the existed results. The anharmonic constants, vibration-rotation interaction constants, Coriolis coupling constants and force constants of three isomers of C3H2O are firstly predicted. The ingredients of complex vibration modes, and infrared spectral characteristics of three isomers as well as the relationship between structure and spectroscopic properties are detailedly discussed. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The catalytic amplification signal of polystyrene nanosphere (PN) is used to conveniently fabricate the resonance Rayleigh scattering (RRS)/surface-enhanced Raman scattering (SERS) dual-mode method to sensitively and selectively detect urea in food. PN has strong catalysis of the slow nanoreaction of citrate-Ag(I) to produce yellow silver nanoparticles (AgNP), which exhibit strong RRS effect and SERS effect with molecular probes. When aptamer (Apt) is present, the Apt is adsorbed on the PN surface, the catalysis is weakened, the AgNP is reduced, and the SERS/RRS signal is weakened. After adding urea to exhibit specific Aptamer reaction, the Apt is desorbed from the PN surface and the catalysis is restored. As urea increase, the desorbed PNs increase to produce more AgNPs indicator to increase SERS/RRS signal. The increase value 4I of SERS/RRS is linearly to urea concentration. Therefore, a sensitive and selective SERS/RRS dual-mode method for urea is established based on aptamers-regulated the catalysis of PNs. This method is applied to the detection of urea in milk with satisfactory results. The relative standard deviation is 3.9-6.8% and the recovery rate is 94.5-102%. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：A feasibly constructed novel pyridine based receptor (S) has been reported for the selective detection of copper ion over other metal ions. The metal sensing ability of receptor with diverse metal ions were studied by colorimetry, absorption and emission spectroscopic systems in CH3CN/H2O (7:3, v/v). This receptor reveals a drastic color converts from vapid to yellow and cyan under normal light and UV light with copper ion. Further, S-Cu2+ complex exhibits new UV-Visible band at 419 nm and intense fluorescence band at 494 nm upon the excitation at 388 nm. The stoichiometric binding ratio of receptor with metal ion was confirmed with Job's method and ESI-Mass also further supported the complexation. Besides, limits of detection of Cu2+ were calculated to be 0.25 mu M. The limiting capacity of receptor with Cu2+ ion was additionally explored by quantum chemical calculation. Moreover, this receptor was effectively utilized for the measurement of Cu2+ ion in various water tests. (C) 2021 Published by Elsevier B.V.
查看更多>>摘要：A highly stable heterometallic MOF, {[(Me2NH2)(2)]center dot[Cd2K2(L)(2)(H2O)]}(n) (H4L = terphenyl-2, 2', 4, 4'-tetracarboxylic acid) (1), was synthesized. 1 featuring one-dimensional channels can efficiently detect Aspartic acid with a low limit of detection (LOD) value (2.5 mu M). More interestingly, 1 can encapsulate Eu3+ and sensitize the visible-emitting characteristic fluorescence of Eu3+ in aqueous solution. Then, Eu3+@CdK-MOF is found to be an excellent fluorescence sensor for the detection of Ornidazole (ODZ) and the portable ODZ test paper is also successfully designed. Eu3+@CdK-MOF can also be used as fluorescent ink to write some words. The words can be hidden when treated with acid vapor and then the words can be restored when treated with alkaline vapor. More importantly, the hidden information can be read repeatedly. Therefore, this reversible light-emitting and reusable property have great potential for development in information encryption and decryption and information storage. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Plasmon has been widely investigated and applied, because it can greatly enhance molecular Raman spectral intensity. In this study, the resonance Raman effect of the tetra-tert-butylnaphthalocyanine (TTBN) is analyzed, including the Raman wave number shift and enhancement factor, resulting from light of different incident wavelengths. Furthermore, the optical properties of TTBN are obtained, such as charge transfer, the electronic circular dichroism (ECD) spectrum, etc. Lastly, we study the tipenhanced Raman spectroscopy (TERS) by adjusting the parameters of the metal tip to achieve the highest electromagnetic enhancement at different incident wavelengths. Combining the resonance excitation effect and the tip enhanced Raman effect, the enhancement factor of TERS can reach up to 10(8)-10(9). This study provides significant help for a profound understanding of the TERS mechanism. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Chemiluminescent (CL) reaction between hydrogen peroxide (H2O2) and luminol was dramatically enhanced by sodium molybdate (Na2MoO4) for 284-fold. CL mechanism investigation indicated that Na2MoO4 increased the production of hydroxyl radical ((OH)-O-center dot) and superoxide anion (O-center dot(2)) in the H2O2 luminol system, which could attribute to the enhanced-CL intensity and gave us new insights into the CL-enhanced property of Na2MoO4. The CL intensity of Na2MoO4-H2O2-luminol system increased with the concentration of H2O2, based on which, a convenient and sensitive CL determination method could be developed for H2O2 in the concentration ranging from 0.5 to 60 mu mol/L, with a detection limit of 0.25 mu mol/L. Combining with glucose oxidase, the Na2MoO4-H2O2-luminol system could also be applied for glucose detection. Glucose in human serum has been successfully detected with satisfied recoveries in the range of 96.7 % to 105.4 %. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The structure of water, especially around the solute is thought to play an important role in many biological and chemical processes. Water-peptide and cosolvent-peptide interactions are crucial in determining the structure and function of protein molecules. In this work, we present the H-bonding analysis for model peptides like glycyl-glycine (gly-gly), glycine-L-valine (gly-val), glycyl-L-leucine (gly-leu) and triglycine (trigly) and triethylammonium based carboxylate protic ionic liquids (PILs) in aqueous solutions as well as for peptides in similar to 0.2 mol-L-1 of aqueous PIL solutions in the spectral range of 7800-5500 cm(-1) using Fourier transform near-infrared (FT-NIR) spectroscopy at 298.15 K. The hydration numbers for peptides and PILs were obtained using NIR method of simultaneous estimation of hydration spectrum and hydration number of a solute dissolved in water. The H-bond of water molecules around peptides and PILs are found to be stronger and shorter than those in pure liquid water. We observe that the hydration shell around zwitterions is a clathrate-like cluster of water in which ions entrap. Watery network analysis confirms that singly H-bonded species or NHBs changes to partial or distorted ice-like structures of water in the hydration shell of PILs. The overall water H-bonding in the hydration sphere of PILs increases in the order TEAF < TEAA < TEAG < TEAPy approximate to TEAP < TEAB. The influence of PILs on hydration behavior of peptides is explored in terms of H-bonding, cooperativity, hydrophobicity, water structural changes, ionic interactions etc. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：This paper reports on the setting up and calibration of a portable NIR fluorimeter specifically developed for quantitative direct detection of the highly reactive singlet oxygen (O-1(2)) chemical specie, of great importance in Photodynamic therapies. This quantification relies on the measurement of fluorescence emission of O-1(2), which is peaked in the near-infrared (NIR) at lambda = 1270 nm. In recent years, several nanostructures capable of generating reactive oxygen species (ROS) when activated by penetrating radiation (X-rays, NIR light) have been developed to apply Photodynamic Therapy (PDT) to tumours in deep tissue, where visible light cannot penetrate. A bottleneck in the characterization of these nanostructures is the lack of a fast and reliable technique to quantitatively assess their performances in generating ROS, and in particular O-1(2). For instance, the widely used PDT "Singlet Oxygen Sensor Green" kit suffers from self-activation under X-ray irradiation. To solve this difficulty, we propose here direct detection of O-1(2) by spectroscopic means, using an apparatus developed by us around a recent thermoelectrically-cooled InGaAs single photon avalanche photodiode (SPAD). The SPAD is coupled to a custom-made integrating sphere designed for use under irradiation with high-energy X-ray beams from clinical Radiotherapy sources. We determine the detection threshold for our apparatus, which turns to be similar to 9.10(8) O-1(2) in realistic experimental condition and for measurements extending to 1 min of integration. After calibrations on standard photosensitizers, we demonstrate the potentiality of this instrument characterizing some photosensitizing nanostructures developed by us. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Single crystal of tin selenide (SnSe) was studied by micro-Raman spectroscopy under atmosphere conditions. The effect of varying the incident laser power on the sample up to 2 mW was analyzed. The Raman spectra showed that the number of all vibrational modes have not decreased or increased, but all peaks red-shifted and softened obviously as the laser power increased to the threshold value. The temperature dependent micro-Raman study of the single crystal was carried out for illustrating thermal effect due to the high incident laser power. A new SnSe2 phase appeared at high temperature without vacuum and become the dominant phase at the surface of the crystal gradually because of oxidation. Detecting few amounts of SnSe2 crystals on the surface of single crystal shows the high sensitivity of Raman spectroscopy. High resolution transmission electron microscopy (HRTEM) was also used to confirm that the newly generated SnSe2 phase is precipitated by SnSe under high temperature oxidation conditions. To study the Raman spectra of low thermal conductivity materials under high temperature and non vacuum conditions, lower incident laser power should be used to avoid the influence of additional thermal effects. (C) 2021 Elsevier B.V. All rights reserved.
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