Karuppiah, KrishnaveniAlam, M. MujahidNelson, MaliniSelvaraj, Manickam...
11页
查看更多>>摘要：A novel indole hydrazone tagged moiety, 2-((5-bromo-1H-indol-2-yl) methylene) hydrazono) methyl)-4, 6-diiodophenol (BHDL) has been developed for the selective and sensitive detection of biogenic tryptamine and F- ions. The binding dexterity of probe BHDL towards F-/tryptamine (TryptA) has been investigated by UV-visible/fluorescence spectroscopy. In the presence of TryptA, probe exhibits strong enhancement in the emission band at 433 nm and the band at 555 nm underwent a blue shift accompanied by a decrease in intensity by the inhibition of Excited State Intramolecular Proton Transfer (ESIPT) on BHDL. Excitingly, complexation with F- ions as well triggers an enhancement in a fluorescence band at 430 nm with the concomitant disappearance of the emission band at 555 nm due to the inhibition of ESIPT and deprotonation process initiated by the hydrogen bonding complex formation. Further, Density Functional Theoretical (DFT) calculations have been performed to support the mechanism functioned on the probe BHDL in the presence of TryptA/F-. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Structural changes of the n-alkanes (n = 18, 20, 21, 22) have been investigated by Raman spectroscopy during the melting from solid phase to the intermediate transition phase to the molten phase. With increasing temperature docosane (C-22) undergoes an orthorhombic-hexagonal (rotator, R) phase follow by an alpha (alpha) phase. In addition, the alpha phase as an intermediate transition between the solid and liquid phases is observed in heneicosane (C-21). For eicosane (C-20) and octadecane (C-18) the transition from solid to liquid phase is almost instantaneous unlike docosane (C-22) and heneicosane (C-21) where the intermediate transitions are observed. During freezing from the liquid phase, the even n-alkanes show the rotator phase (R) a few degrees lower than melting and just before the crystalline solid phase. The intermediate phase transition temperature can be spectrally determined with the 1100-1350 cm(-1 )Raman region of the CH2 band. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Beta 2 agonists are well known for their use in the treatment of asthma and COPD however in the last few years new indications of beta 2 agonist appeared like reduction of local fats and treatment of preterm labour which required the formulation of new dosage forms and administration strategies. The new developments require accurate, economic and feasible methods the determination of these drugs to facilitate testing the newly introduced dosage forms and to study the pharmacokinetics and pharmacodynamics regarding the modern uses. In this study two rapid, sensitive and economic colorimetric methods for the determination of salmeterol xinafoate and salbutamol in pharmaceutical dosage forms and spiked plasma were developed and validated. The developed methods depends on the optimized reaction of the studied drugs with two charge transfer reagents, 2,3-dochloro-5,6-dicyano-1,4-benzoquo none (DDQ) and chloranilic acid (CA) to produce coloured complexes measured at 460 and 529 nm for DDQ and CA respectively. The developed methods showed high accuracy of 99.52 +/- 1.108, 101.03 +/- 0.3 89, 100.04 +/- 1.520 and 100.3 +/- 0.951 for salmetrol xinafoate and salbutamol with DDQ and CA respectively. The proposed methods were successfully used for the determination of the studied drugs in their dosage forms and spiked plasma with high accuracy and precision and the results were compared to reported methods. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：A simple and portable colorimetric sensor for colorimetric detection of UO22+ in aqueous solution based on vinylphosphonic acid functionalized gold nanoparticles (VPA-AuNPs) has been developed. The VPA-AuNPs solution was prepared by sodium borohydride reduction in the presence of vinylphosphonic acid. The addition of UO22+ would induce aggregation of VPA-AuNPs, resulting in the color change from winered to blue, and red-shift of the ultraviolet-visible (UV-vis) spectra. The UO22+ assay based on VPA-AuNPs showed good selectivity and sensitivity, with a limit of detection to be approximately 2.0 mu M by naked eyes and 1.07 mu M by UV-vis (S/N = 3) respectively. Additionally, a smartphone with a free application named "PhotoMetrix" was employed to estimate the color intensities (red, green, blue value) of VPA-AuNPs in the presence of UO22+ with different concentrations, and the concentration of UO22+ samples could be conveniently exported by the calculated univariate calibration curves. This method shows good feasibility for on-site UO22+ detection in an aqueous solution. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：A novel aminoquinoline functionalized norbornene (1) and its ring-opening metathesis polymerization (ROMP) copolymer P1 have been designed and synthesized. The polymer probe P1 can self-assemble nano aggregation in aqueous solution. The fluorescent experiments revealed that both 1 and P1 show a ratiometric fluorescence response toward Zn2+ over other mental ions in Tris-HCl buffer solution, with the polymer probe P1 shows a better photostability and higher binding affinity than that of the small molecular probe 1. Furthermore, the in situ formed P1-Zn2+ ensemble was successfully used as the secondary sensor for ATP. P1 is also successfully used for monitoring intracellular Zn2+ and ATP in living cells. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Butyrylcholinesterase (BChE) is an important clinical diagnosing index for liver dysfunction and organophosphate toxicity. However, the current assays for BChE activity are suffering from the relative poor detection sensitivity. In this work, an ultrasensitive fluorescence assay for BChE activity was developed based on the self-polymerization modulated fluorescence of sulfur quantum dots (S-dots). The luminescence of S-dots can be quenched by the self-polymerized dopamine. The hydrolysate of substrates, thiocholine, under the catalysis of BChE can reduce dopamine, which results in the inhibition of self-polymerization and the fluorescence recovery of S-dots. BChE can be quantitatively detected by recording the recovered fluorescence of S-dots, and a linear relationship is observed between the ratio of fluorescence and the concentration of BChE in the range from 0.01 to 10 U/L. A limit of detection as low as 0.0069 U/L calculated, which is the lowest number so far. The assay also shows excellent selectivity towards various interference species and acetylcholinesterase. These features allowed the direct detection of BChE activity in human serum, demonstrating the great practical applications of our assay. (C) 2021 Published by Elsevier B.V.
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