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Capillary electrophoresis-frontal analysis is one of the most frequently used approaches for the study of plasma protein-drug interactions as a substantial part of new drug development. However, the capillary electrophoresis-frontal analysis typically combined with ultraviolet-visible detection suffers from insufficient concentration sensitivity, particularly for substances with limited solubility and low molar absorption coefficient. The sensitivity problem has been solved in this work by its combination with an on-line sample preconcentration. According to the knowledge of the authors this combination has never been used to characterize plasma protein-drug binding. It resulted in a fully automated and versatile methodology for the characterization of binding interactions. Further, the validated method minimalizes the experimental errors due to a reduction in the manipulation of samples. Moreover, employing an on-line preconcentration strategy with capillary electrophoresis-frontal analysis using human serum albumin-salicylic acid as a model system improves the drug concentration sensitivity 17-fold compared to the conventional method. The value of binding constant (1.51 ± 0.63) · 104 L/mol obtained by this new capillary electrophoresis-frontal analysis modification is in agreement with the value (1.13 ± 0.28) ·104 L/mol estimated by a conventional variant of capillary electrophoresis-frontal analysis without the preconcentration step, as well as with literature data obtained using different techniques. 相似文献
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A colorimetric sensor has been developed in this work to sensitively detect α-glucosidase activity and screen α-glucosidase inhibitors (AGIs) utilizing unmodified gold nanoparticles (AuNPs). The sensing strategy is based on triple-catalytic reaction triggered by α-glucosidase. In the presence of α-glucosidase, aggregation of AuNPs is prohibited due to the oxidation of cysteine to cystine in the system. However, with addition of AGIs, cysteine induced aggregation of AuNPs occurs. Thus, a new method for α-glucosidase activity detection and AGIs screening is developed by measuring the UV–vis absorption or visually distinguishing. A well linear relation is presented in a range of 0.0025–0.05 U mL−1. The detection limit is found to be 0.001 U mL−1 for α-glucosidase assay, which is one order of magnitude lower than other reports. The IC50 values of four kinds of inhibitors observed with this method are in accordance with other reports. The using of unmodified AuNPs in this work avoids the complicated and time-consuming modification procedure. This simple and efficient colorimetric method can also be extended to other enzymes assays. 相似文献
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Pradip K. Bhowmik Tae S. Jo Jung J. Koh Jongwon Park Bidyut Biswas Ronald Carlo G. Principe Haesook Han Andrs F. Wacha Matti Knaapila 《Molecules (Basel, Switzerland)》2021,26(6)
A series of poly(pyridinium salt)s-fluorene main-chain ionic polymers with various organic counterions were synthesized by using ring-transmutation polymerization and metathesis reactions. Their chemical structures were characterized by Fourier Transform Infrared (FTIR), proton (1H), and fluorine 19 (19F) nuclear magnetic resonance (NMR) spectrometers. These polymers showed a number-average molecular weight (Mns) between 96.5 and 107.8 kg/mol and polydispersity index (PDI) in the range of 1.12–1.88. They exhibited fully-grown lyotropic phases in polar protic and aprotic solvents at different critical concentrations. Small-angle X-ray scattering for one polymer example indicates lyotropic structure formation for 60–80% solvent fraction. A lyotropic smectic phase contains 10 nm polymer platelets connected by tie molecules. The structure also incorporates a square packing motif within platelets. Thermal properties of polymers were affected by the size of counterions as determined by differential scanning calorimetry and thermogravimetric analysis measurements. Their ultraviolet-visible (UV-Vis) absorption spectra in different organic solvents were essentially identical, indicating that the closely spaced π-π* transitions occurred in their conjugated polymer structures. In contrast, the emission spectra of polymers exhibited a positive solvatochromism on changing the polarity of solvents. They emitted green lights in both polar and nonpolar organic solvents and showed blue light in the film-states, but their λem peaks were dependent on the size of the counterions. They formed aggregates in polar aprotic and protic solvents with the addition of water (v/v, 0–90%), and their λem peaks were blue shifted. 相似文献
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Journal of Radioanalytical and Nuclear Chemistry - Tritium and stable isotopes contents in precipitation were analyzed on a monthly base at Hongseung which was located middle west of Korea... 相似文献
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Predicting potential changes in groundwater salinity in low-lying coastal regions due to climate change is important, where coastal vegetation is abundant, succession competition between halophytes and glycophytes plays a significant role in the salinity budget. Sea level rise enhances salinity intrusion, contributing an additional dimension to vegetation competition. A new simulation model known as mangrove-hardwood hammock model coupled with saturated-unsaturated transport (MANTRA) has recently been developed by the authors to simulate groundwater salinity regimes in the presence of vegetation competition, subject to climate change. MANTRA is based upon linking two existing Unites States geological survey (USGS) simulation models known as mangrove-hardwood hammock model (MANHAM) and saturated-unsaturated transport (SUTRA). MANHAM simulates the evolution of vegetation succession subject to changing groundwater salinity. SUTRA simulates saturated and unsaturated transport of solutes and salinity in groundwater given sea salinity. MANTRA improves the simulation robustness to simultaneously simulate groundwater hydrology, salinity and coastal vegetation succession subject to sea level rise. Some simulation results will be presented to demonstrate the impact of sea level rise on coastal vegetation succession and groundwater salinity. 相似文献
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Hyuk Yoon Seunghyun Ahn Doseok Hwang Geunhyeong Jo Dong Woon Kim Sang Ho Kim Dongsoo Koh Yoongho Lim 《Magnetic resonance in chemistry : MRC》2012,50(11):759-764
Several types of chalcones containing 2H‐chromen group were synthesized. Claisen–Schmidt condensation of 2H‐chromen‐3‐carbaldehydes (I) with methoxy substituted acetophenones afforded (E)‐3‐(2H‐chromen‐3‐yl)‐1‐(methoxyphenyl)prop‐2‐en‐1‐ones (chromenylchalcones, 1–7). Other types of chromenylchalcone, (E)‐1‐(6‐methoxy‐2H‐chromen‐3‐yl)‐3‐(methoxyphenyl)prop‐2‐en‐1‐ones (8–13) were also obtained between reaction of methoxy substituted benzaldehydes and 1‐(6‐methoxy‐2H‐chromen‐3‐yl)ethanone (II). Dichromenylchalcones (14–16) were also synthesized through the same reaction between aldehydes (I) and ketone (II). Their complete 1H‐NMR and 13C‐NMR assignments are reported here and more polysubstituted chromenylchalcones synthesized or isolated from the natural sources in the future can be identified on the basis of the NMR data reported here. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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