Interaction of water-soluble calix[4]arene with l-tryptophan studied by fluorescence spectroscopy

The complexing ability of water-soluble calix[4]arene for l-tryptophan (l-try) was investigated by a variety of techniques. The spectrofluorometry titrations were performed at different temperatures to determine stability constants, as well as to evaluate the thermodynamic parameters of the obtained complex. The effect of pH on the complexation process was quantitatively assessed. Moreover, to obtain information about the binding mechanism of the interaction, ¹H NMR studies were carried out. Molecular modeling showed that water-soluble calix[4]arene accommodated part of l-amino acid in its cavity meanwhile the aliphatic chain of l-tryptophan stuck out of the cavity. Based on the experiment data, the association process of complexes was established. The water-soluble calix[4]arene was found to be able to adjust its conformation to fit the size of aromatic l-tryptophan, and the benzene ring of amino acid penetrated into the hydrophobic cavity of calix[4]arene.     

高效液相色谱法测定食品中纳他霉素

提出了高效液相色谱法测定食品中纳他霉素的方法,样品经甲醇-水(3+1)溶液提取净化后,用高效液相色谱配紫外检测器在305 nm波长处测定.纳他霉素的检测采用保留时间定性,外标法定量.方法的回收率在95.7%～102.0%之间,相对标准偏差均小于3%.方法的检出限(3S/N)为0.50 μg·g-1(固体样品),0.25 mg·L-1(液体样品).     

p-HPcZn与CT DNA相互作用

在检测β-四(羧基苯氧基)锌酞菁(p-HPcZn)光敏性能的基础上,利用吸收光谱和荧光光谱分析技术研究了p-HPcZn与小牛胸腺脱氧核糖核酸(CT DNA)的相互作用机理.研究结果表明,p-HPcZn能以嵌插的形式与CT DNA发生作用;无论是在有氧或是在无氧的条件下,p-HPcZn对CT DNA的光敏损伤能力均高于血卟咻.     

氨基酸配位聚合物[Co(L-trp)(D-trp)]n

The coordination polymer [Co(L-trp)(D-trp)]_n (where L-trp is L-tryptophan or (S)-2-Amino-3-(3-indolyl)propionic acid and D-trp is D-tryptophan or (R)-2-Amino-3-(3-indolyl)propionic acid) was prepared by hydro-thermal method. The structure and physicochemical properties were characterized by single-crystal X-ray diffraction structure determination, infrared spectroscopy, elemental analysis and cyclic vohammogram. The crystal data for the title compound: Monoclinic, P2₁/c, β=98.024(2)°, a=1.959 5(3) nm, b=0.546 45(7) nm, c=0.905 54(17) nm, Z=2, μ=0.934 mm^-1, R₁=0.063 2, wR₂=0.155 3. The crystal structure shows a two-dimensional double chain plane structure feature. The cyrstallized coordination polymer has a centrosymmetric space group. Each Co²⁺ is coordinated with a pair of racemes, and the complex is a mesomer. CCDC: 651088.     

Study on the absorption and fluorescence and resonance Rayleigh scattering spectra of Cu (II)-fluoroquinolone chelates with erythrosine and their applications

In pH 4.2-5.0 Britton-Robinson buffer solution medium, fluoroquinolone antibiotics (FLQs), such as ciprofloxacin (CIP), norfloxacin (NOR), ofloxacin (OF), levofloxacin (LEV), lomefloxacin (LOM), and sparfloxacin (SPA), react with Cu (II) to form chelate cations, which further bind with erythrosine to form the ion association complexes. They can result in the changes of the absorption spectra. Simultane- ously, erythrosine fades obviously and the maximum fading wavelength is located at 526 nm. The fad- ing reactions have high sensitivities. Thus, new spectrophotometries of determination for these drugs are developed. The ion-association reactions result in the quenching of fluorescence, which also have high sensitivities. The detection limits for six antibiotics are in the range of 7.1-12.2 μg·L?1. Furthermore, the reactions can result in the enhancement of resonance Rayleigh scattering (RRS). The maximum scattering peaks of six ion-association complexes are located at 566 nm, and there are two small RRS peaks at 333 nm and 287 nm. The detection limits for fluoroquinolone antibiotics are in the range of 1.70 -3.10 μg·L?1 for RRS method. Among the above three methods, the RRS method has the highest sen- sitivity. In this work, we investigated the spectral characteristics of the absorption, fluorescence and RRS, the optimum conditions of the reactions, and the properties of the analytical chemistry. In addi- tion, the mechanism of reactions were discussed by density function theory (DFT) and AM1 methods.     

微囊藻毒素-LR免疫亲和层析柱的研制和应用

用CNBr-activated Sepharose4B和微囊藻毒素-LR的单克隆抗体制备了免疫亲和层析柱,测得抗体偶联率在75.7%~94.1%之间。制得的免疫亲和层析柱最大柱容量在76~95ng之间,柱空白为0,回收率在90.8%~105.1%之间。柱子再生重复使用6次后,回收率不低于75%。建立了免疫亲和层析柱-高效液相色谱测定水样中的微囊藻毒素-LR的方法。该法检出限为5ng/L;线性定量范围为10~500ng/L。实验结果显示,免疫亲和层析柱特异性好,一次净化能除去绝大部分干扰物,净化效果明显优于现有的固相萃取柱。     

直流电弧自催化合成β-SiC纳米线

采用C,Si和SiO₂为反应原料,利用直流电弧法制备出长直的β-SiC纳米线。纳米线的直径为100～200 nm,长度为10～20 μm,并且沿着<111>方向生长。通过X射线衍射(XRD)、扫描电子显微术(SEM)、透射电子显微术(TEM)、拉曼光谱等手段,对β-SiC纳米线进行表征。探讨了β-SiC纳米线自催化气-液-固(VLS)生长机制。     

新型纳米金直接修饰玻碳电极的制备及其电催化活性

在不使用交联剂的情况下,借助种子媒介纳米金属生长法将纳米金直接修饰到玻碳电极表面.试验发现纳米金粒子在电极表面覆盖率为5.4×10-10 mol·cm-2,[Fe(CN)6]3-/[Fe(CN)6]4-氧化还原电子探针的试验证明,纳米金修饰玻碳电极表面的电子传递速率是使用交联剂制备电极的四倍.与裸玻碳电极相比,抗坏血酸在该电极表面的氧化峰电位负移150 mV,峰电流提高2.2μA,同时与尿酸的氧化峰电位差达到186 mV,可用于抗坏血酸和尿酸的同时检测.     

溶剂和溶液酸碱性对碳酸钙晶型和形状影响研究

<正>CaCO3主要有三种晶型:方解石,文石和球霰石[1-3],方解石是CaCO3晶体最稳定的晶型,球霰石是最不稳定的,文石的稳定性介于两者之间。在生物矿物中经常发现有文石和方解石的存在,具有结构功能和光学等性能[4],是生物体硬组织中的主要无机成份之一。在珍珠、贝壳、甲壳、动物骨骼等生物组织中CaCO3与少量有机基质(生物大分子)结合,形成具有特定性质的有机/无机杂化材料[5],例如,方解石存在于骨头,牙齿等硬组织中,另外还具有在神经束中的光聚焦功能;     

聚甲基丙烯酸甲酯在纳米氧化铝表面的吸附和氢键作用

研究了聚甲基丙烯酸甲酯(PMMA)在纳米氧化铝表面的吸附行为, 采用透射红外光谱研究了吸附的PMMA中的羰基和纳米氧化铝表面羟基之间的氢键作用. 结果表明, PMMA在纳米氧化铝表面的吸附曲线为典型的Langmuir曲线, 饱和吸附值为1.2 mg/m2, 受氢键作用影响, 键合羰基在红外光谱中的吸收峰向低波数方向移动. 根据计算, 羰基的最大键合值(即含键合羰基的甲基丙烯酸甲酯单元的总质量)为0.36 mg/m2, 其余为自由羰基. 随着吸附量的增加, 羰基的键合比例逐渐降低. 吸附达到饱和时, 羰基键合比例为0.30, 说明PMMA主要以平铺的方式覆盖在纳米氧化铝的表面.