碳量子点荧光猝灭法检测药物中的异鼠李素

以L-天冬氨酸为碳源,尿素为氮源,采用微波加热法制备荧光碳量子点(CDs),得到的CDs具有球形结构和单一分散性,平均粒径约为5 nm。红外光谱、X射线光电子能谱、紫外和荧光光谱的表征结果表明,合成的CDs具有较高的荧光稳定性,良好的水溶性和对异鼠李素(ISOR)高的选择性。在优化条件下,ISOR浓度在0.22～180 nmol/L范围内时与CDs荧光猝灭程度(I_(F_0)/I_F)呈良好的线性关系,检出限(LOD)为1.32 nmol/L,回收率为90.8%～107%。结果表明,该CDs可用于ISOR的快速、高效、灵敏检测。     

高效液相色谱法同时测定不同产地及不同药用部位景天三七中4种黄酮类成分的含量北大核心CSCD

建立了同时测定不同产地及不同药用部位景天三七中槲皮素、木犀草素、山奈酚和异鼠李素含量的高效液相色谱(HPLC)法。采用TOP ODS-AQ色谱柱(250×4.6mm,5μm),以甲醇-0.1%磷酸溶液为流动相梯度洗脱,检测波长为365nm。结果表明,槲皮素、木犀草素、山奈酚和异鼠李素的浓度分别在1.90~189.90μg·mL-1(r=0.99996),1.12~112.00μg·mL-1(r=0.99998),3.71~370.56μg·mL-1(r=0.99995)和0.98~97.60μg·mL-1(r=0.99996)范围内与其色谱峰面积呈良好线性关系;平均加标回收率分别为99.79%、100.06%、100.19%和100.00%,且不同产地及不同药用部位的4个黄酮类成分在数量上或质量上有明显差异。该方法快速、准确,重现性好,可用于同时测定景天三七中槲皮素、木犀草素、山奈酚和异鼠李素含量。     

HPLC法同时测定24种花中的5种活性成分含量

建立了高效液相色谱法(HPLC)同时测定24种花中绿原酸、金丝桃苷、槲皮素、木犀草素和异鼠李素含量的方法。采用C18柱(250 mm×4.6 mm,5μm),流动相为甲醇-0.2%冰乙酸溶液梯度洗脱,检测波长350 nm,柱温35℃,流速0.8 mL/min。绿原酸、金丝桃苷、槲皮素、木犀草素和异鼠李素分别在0.0208~104.00μg/mL(r=0.99993),0.017~85.00μg/mL(r=0.99998),0.0172~86.00μg/mL(r=0.99997),0.0304~152.00μg/mL(r=0.99997),0.0168~84.00μg/mL(r=0.99986)范围内与峰面积呈良好的线性关系,平均加标回收率(n=9)92.26%~99.09%,仪器精密度(n=6)RSD均小于3.1%,方法重复性(n=6)的RSD均小于3.6%。方法可同时测定这24种花中绿原酸和黄酮类物质的含量,可作为花中活性成分定量分析的方法。     

一种不对称菁染料及其与不同结构DNA的相互作用

为考察小分子配基与不同核酸结构的结合机理,发展新的核酸探针分子,合成了一种新型一次甲基不对称菁染料(MTP).吸收光谱、荧光光谱及圆二色光谱研究结果表明,MTP可与平行和混合平行G-四链体DNA(如c-myc和22AGK+)较强地结合,并引起130~180倍的荧光增强;其与单/双链DNA作用较弱,导致40~60倍荧光增强;而与反平行G-四链体DNA(如TBA和22AGNa+)的作用最弱,只引起15~25倍荧光增强;以上结果表明MTP可作为荧光探针分子用于区别不同结构的核酸分子.结合机理研究表明,平行和混合平行G-四链体DNA优先通过沟槽结合模式结合1分子MTP,再通过末端堆积模式结合另1分子MTP.     

Ru(phen)2dppx2+光谱探针法研究道诺霉素与脱氧核糖核酸的相互作用

以核酸分子“光开关”Ru(phen)2dppx2 为探针,分别采用紫外-可见吸收光谱法和荧光光谱法研究了抗癌药物道诺霉素(daunomycin,DNM)与小牛胸腺DNA之间的作用方式,结果表明:DNM是以插入的方式与DNA相互作用。Scatchard方程的研究表明,Ru(phen)2dppx2 与小牛胸腺DNA的结合比为1∶4~1∶5;表观结合常数为2.58×107L/mol。DNM加入后,表观结合常数大大降低,这也表明道诺霉素主要是以插入方式与DNA结合。作为研究核酸分子的荧光探针,与溴化乙锭相比,Ru(phen)2dppx2 具有灵敏度高、毒性低、稳定性好、选择性好、使用方便等优点。     

天然植物体中与稀土元素结合的DNA

利用分子活化分析方法 ,初步研究了稀土矿区植物铁芒萁叶中稀土元素(REE)与核酸的结合状态 .铁芒萁叶经过提取和生化分离纯化后 ,得到了与稀土元素结合的DNA(REE DNA) .用紫外光谱法鉴定DNA的纯度 ;用考马斯亮兰G 2 5 0光度法测定DNA中的蛋白质 ;并用琼脂糖凝胶电泳分离和检测DNA .同时 ,用仪器中子活化法 (INAA)测定了REE DNA中 8个稀土元素 (La ,Ce ,Nd ,Sm ,Eu ,Tb ,Yb ,Lu)的含量 .研究结果表明 ,用本生化分离流程及琼脂糖凝胶电泳可从铁芒萁叶中提取出纯度比较高的REE DNA ,并证明了稀土元素与DNA的结合是紧密的 .由琼脂糖凝胶电泳图谱可在分子量 2 2kb处得到一条清晰的REE DNA谱带     

二芳基乙烯衍生物与DNA结合的分子动力学研究

基于分子动力学方法, 对2种旋转异构的二芳基乙烯(DTE, dithienylethene)衍生物(DTE1和DTE2)与不同分子结构DNA结合过程的热力学与动力学特征进行模拟, 结果发现, DTE1, DTE2与DNA分子采用小凹槽结合(MiGB)的模式结合时所需能量最低, 存在的分子间库仑能与范德华相互作用能最小, 说明该结合模式最稳定; 由于空间位阻作用, 互为旋转异构体的2个DTE衍生物与DNA作用表现出截然不同的结合行为, DNA对DTE衍生物具有明显的对映异构体选择性; DTE衍生物与DNA分子作用位点的选择性直接与构成位点的碱基对相关.     

四甲基吡啶卟啉与核酸相互作用的稳态和时间分辨光谱

采用稳态吸收和荧光光谱、圆二色谱和皮秒时间分辨荧光光谱手段, 研究了5,10,15,20-四[4-(N-甲基吡啶)]卟啉(TMPyP4)与腺嘌呤(A)、鸟嘌呤(G)、胸腺嘧啶(T)和胞嘧啶(C)等4种碱基, 以及相应的核苷、核苷酸和单链DNA的结合能力和光谱学性质. 研究结果发现, 嘌呤与TMPyP4的结合能力比嘧啶的强. 对于某一碱基系列, 结合能力强弱顺序依次为: 碱基~核苷<核苷酸<单链DNA. 时间分辨荧光谱研究发现, 除鸟嘌呤外, 核酸和TMPyP4复合物的荧光动力学均含有快(1~2 ns)和慢(约10 ns)两个衰减过程, 它们分别是由激基复合体和环境极性对激发态TMPyP4分子的影响所致. 单链DNA能诱导TMPyP4产生诱导圆二色信号, 而单分子(碱基、核苷、核苷酸)则无此功能.     

硫堇与DNA分子相互作用的电化学方法研究

采用交流阻抗技术和循环伏安法 ,研究了在硫堇自组装膜修饰金电极上 ,以及在硫堇或DNA吸附修饰的玻碳电极上 ,硫堇与DNA分子的相互作用;硫堇自组装膜修饰金电极与DNA分子作用后 ,阻抗增大 ,表明它们之间发生了作用 ;吸附在玻碳电极上的硫堇 (DNA)与DNA(硫堇 )作用后 ,峰电位和峰电流均发生了变化 ,结合光谱测定结果 ,表明硫堇与DNA分子间存在着嵌插、静电等作用 ,二者作用的反应速度与分子在电极上固定的位置有关;在PBS缓冲液中硫堇 -DNA的表观结合常数为4.9×104L·mol -1 ;交流阻抗技术和循环伏安法是研究小分子与DNA分子间相互作用的经济、快速、简便的方法     

HPLC法测定不同施肥模式栽培的金线莲中黄酮类成分

HPLC法测定不同施肥模式栽培的金线莲中3种黄酮类成分:槲皮素、山奈酚和异鼠李素.超声-微波协同提取法提取4种不同施肥模式下金线莲中的黄酮类成分.HPLC-电喷雾离子化法/质谱(HPLC-ESI-MS)对黄酮类化合物进行定性分析.HPLC分析得槲皮素在0.25~20.0μg/m L(r=0.999 2)、山奈酚在0.25~20.0μg/m L(r=0.999 5)、异鼠李素在1.0~80.0μg/m L(r=0.999 0)范围内峰面积与浓度呈良好的线性关系,不同栽培方法的金线莲药材中槲皮素、山奈酚、异鼠李素的质量分数分别在151.8~240.0、47.2~88.2、16.8~29.8μg/g之间.方法简单、精确,快速,可为科学评价不同培养模式金线莲质量提供依据.栽培过程施加氮、磷、钾(NPK)复合肥及添加腐植素和微量元素,能提高金线莲中3种黄酮类成分的含量.栽培过程施加硫、磷(SP)复合肥,槲皮素、山奈酚和异鼠李素的质量分数分别下降了2.3%、17.2%和18.8%.结果表明采用不同施肥模式直接影响到药材中的药效物质的含量.     

Furyl- and thienyl-silatranes and germatranes

We review our research on the synthesis and study of the physical and biological properties of furyl- and thienylgermatranes and -silatranes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 725–732, June, 1992.     

Review and patents and literature

The use of the insect cell/baculovirus expression system for producing recombinant proteins of bacterial, plant, insect, and mammalian origin has become widespread. The popularity of this eukaryotic expression system is due to many factors, including (1) potentially high protein expression levels, (2) ease and speed of genetic engineering, (3) ability to accommodate large DNA inserts, (4) protein processing similar to higher eukaryotic cells (e.g., mammalian cells), and (5) ease of insect cell growth (e.g., suspension growth). The following review of the literature discusses two engineering aspects of recombinant protein synthesis by insect cell cultures: bioreactor scale-up and insect cell line selection. Following this review patent abstracts and additional literature pertaining to expression of recombinant proteins in insect cell culture are listed.     

Hard and soft acids and bases: structure and process

Under investigation is the structure and process that gives rise to hard-soft behavior in simple anionic atomic bases. That for simple atomic bases the chemical hardness is expected to be the only extrinsic component of acid-base strength, has been substantiated in the current study. A thermochemically based operational scale of chemical hardness was used to identify the structure within anionic atomic bases that is responsible for chemical hardness. The base's responding electrons have been identified as the structure, and the relaxation that occurs during charge transfer has been identified as the process giving rise to hard-soft behavior. This is in contrast the commonly accepted explanations that attribute hard-soft behavior to varying degrees of electrostatic and covalent contributions to the acid-base interaction. The ability of the atomic ion's responding electrons to cause hard-soft behavior has been assessed by examining the correlation of the estimated relaxation energies of the responding electrons with the operational chemical hardness. It has been demonstrated that the responding electrons are able to give rise to hard-soft behavior in simple anionic bases.     

Ground- and excited-state aromaticity and antiaromaticity in benzene and cyclobutadiene

The aromaticity and antiaromaticity of the ground state (S 0), lowest triplet state (T 1), and first singlet excited state (S 1) of benzene, and the ground states (S 0), lowest triplet states (T 1), and the first and second singlet excited states (S 1 and S 2) of square and rectangular cyclobutadiene are assessed using various magnetic criteria including nucleus-independent chemical shifts (NICS), proton shieldings, and magnetic susceptibilities calculated using complete-active-space self-consistent field (CASSCF) wave functions constructed from gauge-including atomic orbitals (GIAOs). These magnetic criteria strongly suggest that, in contrast to the well-known aromaticity of the S 0 state of benzene, the T 1 and S 1 states of this molecule are antiaromatic. In square cyclobutadiene, which is shown to be considerably more antiaromatic than rectangular cyclobutadiene, the magnetic properties of the T 1 and S 1 states allow these to be classified as aromatic. According to the computed magnetic criteria, the T 1 state of rectangular cyclobutadiene is still aromatic, but the S 1 state is antiaromatic, just as the S 2 state of square cyclobutadiene; the S 2 state of rectangular cyclobutadiene is nonaromatic. The results demonstrate that the well-known "triplet aromaticity" of cyclic conjugated hydrocarbons represents a particular case of a broader concept of excited-state aromaticity and antiaromaticity. It is shown that while electronic excitation may lead to increased nuclear shieldings in certain low-lying electronic states, in general its main effect can be expected to be nuclear deshielding, which can be substantial for heavier nuclei.     

Determination and study on residue and dissipation of benazolin-ethyl and quizalofop-p-ethyl in rape and soil

A QuEChERS (quick, easy, cheap, effective, rugged, and safe) method for the determination of benazolin-ethyl and quizalofop-p-ethyl in rape and soil by high-performance liquid chromatography-tandem mass spectrometry has been developed in this study. The residue and dissipation of benazolin-ethyl and quizalofop-p-ethyl in rape and soil were determined with the developed method. The half-lives of benazolin-ethyl in rape straw and soil were 3.7–5.1 days and 14.3–26.3 days, respectively. The half-lives of quizalofop-p-ethyl in rape straw and soil were 5.0-6.1 days and 0.3–9.7 days, respectively. The residue of benazolin-ethyl and quizalofop-p-ethyl in rapeseed and soil were below the detection limit (i.e., 0.5?mg?kg^?1, the maximum residue level of European Union for quizalofop-p-ethyl).