盐酸普罗帕酮与赤藓红相互作用的荧光光谱研究

在pH4.4～5.0的HAc-NaAc介质中,盐酸普罗帕酮(PPF)能与赤藓红(Ery)阴离子形成离子缔合物,引起荧光猝灭.赤藓红(Ery)体系用荧光猝灭法测定盐酸普罗帕酮的检出限分别为:0.045 μg·mL<'-1>而线性范围分别为:0.5～3.5 μg·mL<'-1>.本实验重点研究了荧光猝灭法的适宜反应条件.     

DNA对硫堇同步荧光光谱的猝灭原理及应用

研究了小牛胸腺脱氧核糖核酸(ctDNA)对硫堇(TH)荧光光谱的影响,发现DNA对TH的荧光有猝灭作用。对其猝灭机理进行了深入探讨,同时发现荧光猝灭度(ΔF)与DNA质量浓度(ρctDNA)之间存在线性关系。为消除Rayleigh散射干扰以建立良好的线性方程,选择TH荧光斯托克斯位移(4 nm)为Δλ进行同步荧光猝灭的研究,效果不佳。进一步考察了DNA对TH不同Δλ同步荧光的猝灭作用,分别选择λex/λem=627/638 nm和617/628 nm(Δλ=11 nm)作为参比溶液和样品溶液的工作波长,并建立了良好的线性方程,ctDNA的线性范围为0.015～1.260μg/mL,检出限为0.005μg/mL,回收率为96.5%～104.8%。该方法用于合成DNA样品的测定,结果满意。     

荧光分光光度法研究氯霉素与蛋白质的相互作用

用荧光分光光度法研究了在模拟人体生理条件pH=7.38下,氯霉素与牛血清蛋白结合反应特征,研究发现氯霉素对牛血清蛋白有较强的荧光猝灭作用,计算得到牛血清蛋白与氯霉素在17℃和37℃下静态猝灭的猝灭常数分别为1.41×10~(12)L·mol~(-1)·s~(-1)和1.35×10~(12)L·mol~(-1)·s~(-1),结合常数分别为1.29×10~5和2.54×10~5L·mol~(-1),结合点位数均为1。根据热力学参数说明了氯霉素与牛血清蛋白相互作用以疏水作用为主,同时也存在静电引力。     

荧光光谱法研究吲哚美辛与牛血清白蛋白结合作用的热力学特征

在模拟动物体生理条件下,用荧光猝灭光谱、同步荧光光谱和紫外可见吸收光谱,研究了不同温度下吲哚美辛(IDT)与牛血清白蛋白(BSA)结合作用的光谱行为.结果表明,IDT对BSA有较强的荧光猝灭作用.用Stern-Volmer方程、Lineweaver-Burk双倒数方程和热力学方程等处理实验数据,得到了在25℃、31℃和38℃下,结合反应的生成常数KLB平均值为2.081×105L·mol-1、热力学参数平均值ΔHθ、ΔGθ和ΔSθ分别为-10.43 kJ·mol-1、-31.13 kJ·mol-1和67.94 J·K-1;发现IDT与BSA结合可形成具有一定结构的复合物,其荧光猝灭作用更符合静态猝灭作用特征,作用力可能主要是静电力;同时探讨了IDT对BSA构象的影响.为研究IDT的毒理作用、生态环境效应和生物学效应等提供了重要信息.     

高分子半透膜中的荧光猝灭动力学

光学传感器是基于气体或液体猝灭剂对高分子半透膜中荧光分子的猝灭作用而构建的．为了表达它们之间的定量关系,本文从光化学反应动力学模型出发,推导出了一个荧光猝灭反应的动力学方程．该方程能够非常准确地拟合荧光猝灭反应的实验数据,并能很好地说明荧光猝灭的机理,是一个简单而又实用的动力学方程.     

离子型表面活性剂与牛血清白蛋白作用的比较研究

采用荧光光谱、紫外吸收光谱、动态光散射和Zeta电位法对比研究了十二烷基硫酸钠(SDS)和十二烷基三甲基溴化铵(DTAB)与牛血清白蛋白(BSA)的相互作用机理。结果表明：SDS和DTAB均能猝灭BSA内源荧光,298 K时的猝灭常数Ksv分别为2.64×104和304.21 L/mol。同步荧光光谱和三维荧光光谱显示SDS和DTAB对BSA的构象产生了影响。SDS对BSA荧光猝灭机理为动静联合猝灭机制;热力学计算表明,SDS与BSA的结合过程中,静电力起主导作用,并且能与BSA形成SDS/BSA超分子复合物;DTAB对BSA荧光猝灭机理为动态猝灭,作用力主要是疏水作用。SDS和DTAB与BSA的平均结合距离分别为2.77和4.73 nm。综合结合常数、粒径和Zeta电位等变化,在相同条件下具有较大电荷密度和较小体积极性头基的SDS与BSA具有更强的结合作用。     

荧光光谱法研究1-甲基-2,6-二苯基-哌啶酮-4与BSA的相互作用

用荧光光谱法和紫外吸收光谱法研究了1-甲基-2,6-二苯基-哌啶酮-4(MPP)与牛血清白蛋白(BSA)的相互作用,并计算了结合位点数(n)、结合常数(KA)和热力学参数如ΔHθ、ΔGθ、ΔSθ等.结果表明,荧光猝灭机理为动态猝灭,MPP与BSA以1:1结合,主要作用力是疏水力.根据Frster非辐射能量转移原理计算了MPP与BSA的结合距离.     

荧光猝灭法快速检测水样中的汞离子

快速、灵敏定量环境水样中的汞离子(Hg~(2+))对水质监测和人体健康有十分重要的意义。本研究利用富含胸腺嘧啶碱基(T)的DNA,发展了一种灵敏的荧光分析法,实现了Hg~(2+)的快速检测。首先,在DNA两端各修饰一个发光基团(6’-FAM)和猝灭基团(BHQ1)。在Hg~(2+)存在时,相对的两个T碱基与Hg~(2+)通过金属配位形成T-Hg~(2+)-T结构,从而使ss DNA形成ds DNA,DNA的结构变化会使发光基团和猝灭基团距离靠近,从而猝灭发光基团的荧光,实现对水样中Hg~(2+)的定量分析。对Hg~(2+)的检测浓度在10～100n M范围内呈线性相关,所用方法检出限为2.0n M(MDL=3σ/S)。     

苯甲酸与牛血清白蛋白相互作用的荧光光谱研究

采用荧光光谱、三维荧光光谱、同步荧光光谱研究了苯甲酸与牛血清白蛋白(BSA)分子之间的相互作用机制、特征及苯甲酸对牛血清白蛋白构象的影响。根据不同温度下苯甲酸对牛血清白蛋白的荧光猝灭作用,利用Stem-Volmer和Lineweaver-Burk方程和热力学方程分别处理实验数据,求得它们之间的结合常数K为1.096×103L/mol、结合位点数n为1.12(20℃),ΔH=-31.8 kJ/mol,ΔG=-17.1 kJ/mol,ΔS=-50.2 J.mol-1.K-1。研究发现苯甲酸对BSA内源性荧光的猝灭作用属于静态猝灭,苯甲酸与BSA分子之间的相互作用是一个吉布斯自由能降低的自发过程,两者之间的主要作用力类型为氢键力或范德华力。     

光谱法研究联苯双酯及其类似物与卵清白蛋白的相互作用

本课题旨在研究模拟生理条件下联苯双酯(DDB)及其类似物与卵清白蛋白(OVA)之间的相互作用,同时研究了DDB猝灭OVA荧光发射的机理。通过荧光光谱法、同步荧光光谱法、三维荧光光谱法结合紫外-可见吸收光谱法对其相互作用进行检测分析发现,DDB及其类似物对OVA内源性荧光具有猝灭作用,计算得到相应的猝灭常数。深入研究发现,它们之间主要作用力是疏水作用,DDB及其结构类似物与卵清白蛋白之间发生了非辐射能量转移,且OVA的构象发生了改变。     

水镁石、水菱镁石和斜方云石资源、加工与应用

对水镁石、水菱镁石和斜方云石资源及其加工和应用进行了评述。包括上述资源的发展历史、化学组成和物性参数、资源储量和矿石品位、生产加工以及在不同领域(如镁质阻燃剂、中和剂、重金属离子脱除剂、镁肥、饲料添加剂等)的应用,并对它们的发展前景进行了展望。     

Stable silyl, germyl, and stannyl cations, radicals, and anions: heavy versions of carbocations, carbon radicals, and carbanions

The rapidly growing chemistry of the cations, radicals, and anions based on the group 14 elements heavier than carbon (Si, Ge, Sn, and Pb) is one of the most important organometallic fields. Recent developments in this research area moved such species from the class of short-lived reactive intermediates to the class of easily accessible, isolable, and fully characterizable compounds. In this Account, we deal with the major accomplishments in the field of the stable representatives of "heavy" cations, radicals, and anions.     

Breaking, making, and twisting of chemical bonds in gas, liquid, and nanocavities

In this Account, we recount on our studies of 1'-hydroxy-2'-acetonaphthone (HAN, a proton transfer prototype molecule) in gas, solutions, and nanocavities. The internal H-bond photoreaction in HAN leads to a keto type structure, and following its formation, an internal twisting motion gives birth to keto rotamers. Theory, temperature, and solvent effects on its photodynamics show the involvement of efficient radiationless processes in both keto structures. When HAN is caged in a cyclodextrin nanocavity, the spectroscopy, photodynamics, and issues of twisting motion are strongly affected and could be tuned: a behavior relevant to those of many chemical and biological systems.     

Thermoplastic processing,rheology, and extrudate properties of wheat,soy, and pea proteins

Plant protein isolates (wheat gluten, soy, and pea protein) were treated in a thermoplastic extrusion process, yielding protein based bioplastic material. The application of glycerol as plasticizer in amounts of 50–67% of total mass and high temperatures above 140°C led to smooth and homogeneous extrudates. Viscosity measurements of the protein melt under extrusion conditions confirmed the thermoplastic behavior, obeying the power law with power law indices of 0.31‐0.4. Chemical changes in the material were qualitatively shown by amino acid analysis and fluorescence measurement. High moisture sensitivity and low mechanical stability of the extrudates, as determined by solubility, water vapor permeability, sorption isotherms, and tensile strength, can be partially ascribed to the high glycerol content. The application of pure protein bioplastics for technical purposes, e.g., as packing material, is discussed on basis of the presented data considering stability, appearance, and long time storage. POLYM. ENG. SCI., 55:1912–1919, 2015. © 2014 Society of Plastics Engineers     

Chemistry of Lipoquinones: Properties,Synthesis, and Membrane Location of Ubiquinones,Plastoquinones, and Menaquinones

Lipoquinones are the topic of this review and are a class of hydrophobic lipid molecules with key biological functions that are linked to their structure, properties, and location within a biological membrane. Ubiquinones, plastoquinones, and menaquinones vary regarding their quinone headgroup, isoprenoid sidechain, properties, and biological functions, including the shuttling of electrons between membrane-bound protein complexes within the electron transport chain. Lipoquinones are highly hydrophobic molecules that are soluble in organic solvents and insoluble in aqueous solution, causing obstacles in water-based assays that measure their chemical properties, enzyme activities and effects on cell growth. Little is known about the location and ultimately movement of lipoquinones in the membrane, and these properties are topics described in this review. Computational studies are particularly abundant in the recent years in this area, and there is far less experimental evidence to verify the often conflicting interpretations and conclusions that result from computational studies of very different membrane model systems. Some recent experimental studies have described using truncated lipoquinone derivatives, such as ubiquinone-2 (UQ-2) and menaquinone-2 (MK-2), to investigate their conformation, their location in the membrane, and their biological function. Truncated lipoquinone derivatives are soluble in water-based assays, and hence can serve as excellent analogs for study even though they are more mobile in the membrane than the longer chain counterparts. In this review, we will discuss the properties, location in the membrane, and syntheses of three main classes of lipoquinones including truncated derivatives. Our goal is to highlight the importance of bridging the gap between experimental and computational methods and to incorporate properties-focused considerations when proposing future studies relating to the function of lipoquinones in membranes.