Potential influence on drug efficacy from interaction of tartrazine and trypsin

The extent to which drugs combine with trypsin is influenced by the interaction of tartrazine and trypsin, which may cause overdose or underdose of drugs. Therefore, the interaction of tartrazine and trypsin is investigated by methods of spectrometry in this paper. The binding rate of tartrazine to trypsin is 80.95–95.71% at 310?K, and Hill’s coefficients are almost 1. The effect of tartrazine on trypsin structure was studied by synchronous and circular dichroism. The results showed that the binding of tartrazine and trypsin induced the conformational change of trypsin, and quenched the endogenous fluorescence in trypsin. The results of molecular docking revealed that tartrazine is located in the catalytic active site of trypsin, and is consistent with that of experimental calculation.     

Viscous Shock Wave to an Inflow Problem for Compressible Viscous Gas with Large Density Oscillations

Acta Mathematicae Applicatae Sinica, English Series - This paper is concerned with the inflow problem for one-dimensional compressible Navier-Stokes equations. For such a problem, Huang, Matsumura,...     

Binding of caffeic acid to human serum albumin by the retention data and frontal analysis

A new mathematical model and frontal analysis were used to characterize the binding behavior of caffeic acid to human serum albumin (HSA) based on high‐performance affinity chromatography. The experiments were carried out by injecting various mole amounts of the drug onto an immobilized HSA column. They indicated that caffeic acid has only one type of binding site to HSA on which the association constant was 2.75 × 10⁴/m . The number of the binding site involving the interaction between caffeic acid and HSA was 69 nm . The data obtained by the frontal analysis appeared to present the same results for both the association constant and the number of binding sites. This new model based on the relationship between the mole amounts of injection and capacity factors assists understanding of drug–protein interaction. The proposed model also has the advantages of ligand saving and rapid operation. Copyright © 2014 John Wiley & Sons, Ltd.     

Multipolar Porphyrin-Triazatruxene Arrays for Two-Photon Fluorescence Cell Imaging

Two-photon excited fluorescent (TPEF) materials are highly desirable for bioimaging applications owing to their unique characteristics of deep-tissue penetration and high spatiotemporal resolution. Herein, by connecting one, two, or three electron-deficient zinc porphyrin units to an electron-rich triazatruxene core via ethynyl π-bridges, conjugated multipolar molecules TAT-(ZnP) _n (n=1–3) were developed as TPEF materials for cell imaging. The three new dyes present high fluorescence quantum yields (0.40–0.47) and rationally improved two-photon absorption (TPA) properties. In particular, the peak TPA cross section of TAT-ZnP (436 GM) is significantly larger than that of the ZnP reference (59 GM). The δ_TPA values of TAT-(ZnP)₂ and TAT-(ZnP)₃ further increase to 1031 and up to 1496 GM, respectively, indicating the effect of incorporated ZnP units on the TPA properties. The substantial improvement of the TPEF properties is attributed to the formation of π-conjugated quadrapole/octupole molecules and the extension of D -π-A-D systems, which has been rationalized by density function theory (DFT) calculations. Moreover, all of the three new dyes display good biocompatibility and preferential targeting ability toward cytomembrane, thus can be superior candidates for TPEF imaging of living cells. Overall, this work demonstrated a promising strategy for the development of porphyrin-based TPEF materials by the construction and extension of D -π-A-D multipolar array.     

A cinnamoyl substituted Nile Red-based probe to detect hydrazine

Herein we discovered that a Nile Red-based probe with a cinnamoyl unit was highly selective and sensitive to N₂H₄. Hydrazinolysis by N₂H₄ would release a hydroxyl substituted Nile Red and result in remarkable fluorescence quench. Importantly, Cys/Hcy would not interrupt the N₂H₄ recognition. This is because, for this probe, the combination of the π-π conjugate system can stabilize the ethylene union, which results in the nucleophilic addition of the thiol group of Cys/Hcy becomes non-effective.     

Cauchy-type integral formula and Plemelj formula of hypermonogenic functions on unbounded domains

In this paper, we discuss the Cauchy-type integral formula of hypermonogenic functions on unbounded domains in real Clifford analysis, then we extend the Plemelj formula and Cauchy–Pompeiu formula of hypermonogenic functions on bounded domains to unbounded domains. We also deal with the Green-type formula on unbounded domains and get several important corollaries.     

Fast Determination of Phenanthrene in Soil by Gas Chromatography-Mass Spectrometry Using Chemometric Resolution and Standard Addition Method

A method for fast determination of the component in complex samples by using gas chromatography‐mass spectrometry (GC‐MS) was developed and used for quantitative analysis of phenanthrene in soils. In the method, window independent component analysis (WICA) was used for resolving the mass spectrum and non‐negative immune algorithm (NNIA) was employed for obtaining the chromatographic profile. Therefore, spectral and chromatographic information of a specific component can be obtained from the measured GC‐MS data of overlapping and high background. Six soil samples collected from different places were analyzed. The tedious pretreatments in preparing the samples and the elution in the separation were simplified for speeding up the analysis. Due to the complexity of the matrix, standard addition method was adopted for the final quantification. The applicability of the method was validated with a spiked sample and the results of the six samples are reasonable.     

LC–MS/MS法测定动物性食品中万古霉素残留

建立液相色谱–串联质谱(LC–MS/MS)法检测动物性食品中万古霉素药物残留的方法。用磷酸盐缓冲溶液对动物性食品中的万古霉素进行提取,经HLB固相萃取柱净化,采用电喷雾离子源,以正离子检测方式进行质谱分析。实验结果表明,万古霉素质量浓度在1~500μg/L范围内与色谱峰面积呈良好的线性,相关系数r=0.998。低、中、高3个质量浓度添加水平的回收率为84.8%~118.2%,相对标准偏差为2.2%~7.2%(n=5),检出限为2μg/kg。