DNALB膜的AFM形貌观察

DNA分子本身所具有的独特性质使其在生物学、医学和遗传学等领域占有极其重要的位置 ,近年来 ,人们意识到利用 DNA作为模板剂建造具有特殊结构和功能的纳米材料的可行性 [1] ,如 Braun等 [2 ]将寡聚核苷酸连接在两个金电极之间 ,用 DNA分子作为模板剂生长出 1 2 μm长、直径 1 0 0 nm的银纳米线 ;Mirkin等 [3]将 3 和 5 端连有巯基的寡聚核苷酸与金纳米粒子结合 ,通过互补的碱基形成介观尺寸的组装体 ;Alivisatos等 [4]利用 DNA的特点 ,使其与之相连的金纳米粒子按预计的形式排布形成人造分子 .我们尝试利用 LB技术将 DNA分子复合到…     

活体生物膜控制合成纳米半导体硫化镉

目前 ,用于合成和制备纳米材料的方法除化学和物理方法[1～ 4] 外 ,还有仿生法[5～ 7] ,但尚未见到利用活体生物膜来合成无机纳米材料的报道 .本文利用绿豆芽通过生物膜控制合成了纳米ＣｄＳ .1　实验部分将市售新鲜绿豆芽用去离子水洗净后放入盛有 0 .1ｍｏｌ·Ｌ- 1 Ｎａ2 Ｓ水溶液的试管中 ,浸没茎部 ,露出叶片 .2 4ｈ后取出 ,用去离子水冲洗掉豆芽外部的Ｎａ2 Ｓ溶液 ,转放到盛有ＣｄＣｌ2 水溶液的试管中 ,用同法浸泡 2 4ｈ .取出豆芽 ,小心用玻璃棒将豆芽茎外的黄色ＣｄＳ转入无水乙醇中 .取少量ＣｄＳ乙醇溶液 ,经超声振荡后上铜网 ,…     

手性模板合成CdS纳米棒

由于纳米材料具有量子尺寸效应及大的比表面积等性质而使其在电子学[1]、光学[2]、催化[3]和陶瓷[4]等领域显示出诱人的应用前景. 近年来纳米材料的制备及纳米技术发展迅速, 特别是具有特殊光电活性的新型无机纳米材料的制备已引起人们的普遍关注. 现在合成纳米材料的方法主要包括反相胶束法[5]、 LB膜法[6]、嵌段共聚物法[7]和模板合成法[8]. 其中模板合成技术不仅可以通过设计新型的模板分子, 还可通过模板分子的不同自组装行为来调控纳米材料的尺寸和形貌. Stupp等[9]曾利用溶致液晶的六方中间相作为模板, 在其纳米孔隙中成功地合成了具有六方排列超晶格纳米结构的材料. 本文以双亲性丙氨酸衍生物为模板, 在不同的化学微环境下合成了结构不同的CdS纳米棒.     

利用侧链修饰寡聚DNA组装CdS有序纳米结构

由于 DNA分子具有特殊的结构和碱基配对特性 ,人们已经意识到利用 DNA分子将无机纳米粒子 (量子点 )组装成各种不同的有序纳米结构的可行性 [1～ 5] .如 Mirkin等 [6 ,7]利用端基修饰的寡聚 DNA将金纳米粒子组装成有序的六方堆积的层状结构 .Alivisatos等 [8]利用单链 DNA为模板 ,通过在 3′和5′端修饰巯基的互补 DNA将两个或三个金纳米粒子连接起来形成“人造分子”.本文中我们首次报道通过在侧链 ( 5′端 C1和 C2之间的磷酸根 )上修饰巯基的寡聚胞嘧啶 ( Oligo C10 - SH )和寡聚鸟嘌呤( Oligo G10 - SH)复性过程将 Cd S纳米…     

纳米级SiO_2填充PVC/CPE复合材料研究

80年代以后发展起来的纳米材料被称为“2 1世纪最有前途的材料” ,已成为材料学中跨世纪的研究热点[1 ] 。纳米级无机粒子 /聚合物复合材料是纳米材料中的一种具有重要价值的新型材料 ,可广泛应用于橡胶、塑料、纤维三大合成材料之中[2 ] 。其中 ,纳米级ＳｉＯ2 是纳米材料中的重要一员 ,它被称作跨世纪的高科技材料[3] 。因此 ,本文就纳米级ＳｉＯ2 填充ＰＶＣ/ＣＰＥ复合材料进行探讨。1　实验部分自制 纳米级 (和普通超细 )ＳｉＯ2 ,平均粒径约为 5 0ｎｍ ,比表面积约为 30 0ｍ2 /ｇ ,经过特殊表面处理 ,再用偶联剂、分散剂处理 ,1 2 0…     

高分子模板法合成特殊形态的氧化锌纳米结构材料

利用超分子模板法的形态花样复制制备具有复杂形态的无机超细材料已引起越来越多人的兴趣[1,2].模板与无机物之间的协同作用可制得有内部通道的新型中空分子筛[3,4],但无机材料合成在纳米尺度及亚微米尺度上的形态花样仍落后于生物矿化.生物矿化的独特之处在于可以通过自组合的有机集体或超分子模板通过材料复制而转变为有序的无机结构(如骨,壳,齿),这一合成原理也引导了我们利用高分子模板合成具有复杂形态的无机材料. 作者利用不同分子量的非离子型聚合物PEG作为大分子表面活性剂,在特定的胶束浓度范围和介质体系中形成超分子模板,以之作为"微反应器”并利用PEG与无机物之间的协同作用,控制模板水核中的水解反应;在特定的试剂浓度与比例、温度等条件下,除制备了具有球形、针/棒状纳米氧化锌粒子外,还制得了均匀分散的六角形、片状、螺旋棒状的氧化锌纳米、亚微米材料.     

利用室温固态反应制备球霰石型CaCO3粒子

合成形态、大小及结构可人为调控的无机材料是现代材料科学的重要研究方向[1]. 借助于各类有机添加剂及模板剂的调控作用, 可利用溶液合成方法制备出形貌与结构受到有效调控的无机粒子[2,3]. 室温固态化学反应已被成功地应用于多种无机纳米粒子[4]及纳米线[5]的合成, 并显示出高效、节能、无污染和操作简便等优点, 因而在材料合成领域具有应用前景[6].     

CdS纳米粒子的表面修饰及其对光学性质的影响

用反胶束法合成了用表面活性剂分子磺基焉珀酸双－２－乙基已酯钠盐（ＡＯＴ）进行表面修饰的ＣｄＳ纳米粒子（记为ＣｄＳ／ＡＯＴ－ＳＯ３＾－）,研究了这种纳米粒子在正庚烷（ｈｅｐｔａｅ）和吡啶（Ｐｙ）溶剂中的荧肖及光解行为,发现其在正庚烷中荧光很强,而Ｐｙ却强烈地猝灭ＣｄＳ纳一子的荧光,用电荷转移猝灭机制进行了解释,这种解释为ＣｄＳ纳米粒子在Ｐｙ中光解实验进一步证实。     

LB型Q态CdS复合膜构象有序性研究

报道了在较高膜压及高沉积速度下硬脂镉ＬＢ膜与Ｈ２Ｓ反应制备纳米有序的机分子／ＣｄＳ纳米粒子复合膜,该膜反应后仍能保持良好的－ＣＨ２－全反式排列,即形成纵向有机－无机复合超晶格材料。     

利用胶体碳球为模板制备SiO2、TiO2、SnO2空心球

介观尺度的氧化物空心球材料在许多领域都有着潜在的应用价值[1],因此近年来受到人们的广泛关注。其制备方法包括:模板法[2],声化学法[3],水热法[4]等。其中胶体粒子模板合成是制备氧化物空心球材料的一条最为有效的途径。常见的胶体粒子有金、银、CdS的纳米粒子,介观尺度的SiO     

Study on the Interaction between Gatifloxacin Mesylate and Salmon Sperm DNA by Fluorescence Method

The interaction between gatifloxacin mesylate (GM) and salmon sperm DNA was studied by fluorescence spectrometry and ultra‐violet (UV) spectrometry. Additions of salmon sperm DNA to GM solution resulted in its strong fluorescence quenching and UV absorbance decrease due to the strong interaction between GM and salmon sperm DNA. Both the maximum fluorescence emission wavelength and the maximum UV absorbance wavelength of GM did not change with the increasing concentration of salmon sperm DNA, indicating no intercalative binding existed between them. The Stern‐Volmer plot indicated that the fluorescence‐quenching constant at different temperatures or different salmon sperm DNA concentration ranges was different. Effects of ionic strength and I^? on the fluorescence quenching of GM by salmon sperm DNA indicated that electrostatic interaction and groove binding coexisted between them.     

A Novel Method to Determine DNA by Use of Molecular “Light Switch” of Ru(phen)2(dppz)

A novel fluorimetric method was developed for selective determination of DNA with the molecular “light switch” complex of Ru(phen)₂(dppz)²⁺. The maximum fluorescence intensity was produced in the pH range 9.3–11.5, with the maximum excitation and emission wavelength of 453.0 and 598.0 nm, respectively. Under the optimum conditions, the fluorescence intensity was in proportion to the concentration of DNA. The linear range for calfthymus DNA, salmon sperm DNA, and herring sperm DNA are 0–0.9 μg/mL. The limits of detection for calfthymus DNA, salmon sperm DNA, and herring sperm DNA are 2.0, 1.8, and 5.4 ng/mL, separately. When the proposed method was used to determine DNA in the presence of some coexisting substances, a satisfactory result was obtained.     

利用鲑鱼精DNA为模板构建CdS纳米线

以鲑鱼精DNA为模板合成了CdS纳米粒子，透射电子显微观察表明所生成的CdS是一种直径约为3nm的线形结构，紫外-可见吸收光谱，拉曼光谱和X-射线光电子能谱结果表明，CdS纳米粒子的生长点为DNA中的磷酸根，并且在这一体系中可能存在从CdS到DNA中碱基的电子转移。     

十六烷基三甲基溴化铵对DNA热稳定性的影响

研究十六烷基三甲基溴化铵(CTAB)对DNA分子热稳定性的影响对于认识阳离子表面活性剂与DNA二者之间的相互作用具有重要的意义。用差示扫描量热法和变温紫外光谱法研究了CTAB对鲑鱼精DNA及降解的鲱鱼精DNA热稳定性的影响，发现CTAB使鲑鱼精DNA的热稳定性降低，但降低程度随CTAB浓度的增大而先增大后减小；CTAB使鲱鱼精DNA发生了两阶段熔解行为。     

Determination of DNA by Use of the Molecular “Light Switch” Complex of Ru(bipy)2(dppz)2+

 A novel fluorimetric method has been developed for selective determination of DNA with the molecular “Light Switch” complex of Ru(bipy)₂(dppz)²⁺. The maximum fluorescence intensity was produced in the pH range of 9.3–11.5, with the maximum excitation and emission wavelength of 471.8 nm and 599.8 nm, respectively. Under the optimum conditions, the fluorescence intensity was in proportion to the concentration of DNA. The linear range for calf thymus DNA salmon sperm DNA and herring sperm DNA reaches from the limit of determination to 1.5 μg/mL. The limits of determination for calf thymus DNA salmon sperm DNA and herring sperm DNA are 3.3 ng/mL, 2.8 ng/mL and 4.4 ng/mL, respectively. When the proposed method was used to determine DNA in the presence of some coexisting substances, a satisfactory result was obtained. Received December 29, 1998. Revision June 28, 1999.     

反相微乳液介质中Nd2(CO3)3·8H2 O的可控合成

以十六烷基三甲基溴化铵(CTAB)/正丁醇/正辛烷/硝酸钕[Nd(NO3)3]溶液(碳酸钠溶液)所组成的反相微乳液为反应介质, 采用微乳液溶剂热法合成了Nd2(CO3)3·8H2O, 并考察了水/核比([H2O]/[CTAB])和Nd(NO3)3的浓度对其形貌和尺寸的影响. 利用X射线衍射(XRD)、 热分析(DSC-TGA)、 扫描电子显微镜(SEM)和透射电子显微镜(TEM)等对Nd2(CO3)3·8H2O的晶型、 形貌及尺寸进行了表征, 并提出了不同形貌Nd2(CO3)3·8H2O形成的可能机理. 结果表明, 随着水/核比的增大, Nd2(CO3)3·8H2O的形貌从多面体变成鱼尾状, 再变成针状; 随着Nd(NO3)3浓度的增大, 针状Nd2(CO3)3·8H2O的尺寸逐渐减小.     

pH对十二烷基二甲基氧化胺与DNA相互作用的影响

pH对十二烷基二甲基氧化胺与DNA相互作用的影响;DNA;十二烷基二甲基氧化胺;相互作用     

Construction of a DNA-Based Supramolecular Nanosheet That Emits Bluish-White Light from Charge-Transfer Excited States of the Nucleobases

1,ω-Inosinic acid-bearing bolaamphiphiles dI(18), dI(19), and dI(20) with a 3′-phosphorylated inosine as a universal base connected to each end of an oligomethylene chain were synthesized for the first time. Single-component self-assemblies of these bolaamphiphiles and their binary self-assemblies with salmon sperm DNA were studied by AFM; temperature-dependent UV absorption, fluorescence, and circular dichroism spectroscopy; and gel electrophoresis. The binary self-assembly of dI(20) and salmon sperm DNA (dI(20)-DNA) had a nanosheet structure with a homogeneous thickness of about 6 nm and widths of several micrometers. Interestingly, an aqueous solution of the nanosheets showed a broad absorption band originating from the charge-transfer (CT) states of the nucleobase in the long-wavelength region (>300 nm), and the molar absorptivity per nucleobase was calculated to be approximately 150 times that of single-stranded (dT20 and dA20) and double-stranded (dT20-dA20) oligonucleotides. In addition, a continuous and broad emission band originating from CT excited states of the nucleobases was observed in the visible region. These observations indicate that CT states of the nucleobases were formed and stabilized in the supramolecular nanosheet and that bluish white light was emitted from CT excited states of the nucleobases.     

Cd2+离子诱导的DNA构象变化

近年来,Cd^2 由于其在生物化学、临床医学、环境和农业科学等领域的重要性而受到了极大的关注^[1]。同其它金属离子一样,Cd^2 离子能与蛋白和其它生物分子反应从而影响动物和人类的器官,如肺、前列腺、睾丸、心脏、肝和肾等的正常生理活动^[2-4]。日本的痛痛病就是由于Cd^2 引起的骨软化和肾小管功能障碍造成的。但是从分子水平上对Cd^2 与生物大分子的相互作用机制的研究还较少。本文对Cd^2 与鲑鱼精DNA的相互作用及其对DNA构象的影响进行了初步研究。结果表明,Cd^2 可与DNA发生作用,并且使DNA构象发生变化。     

Light and host-guest inclusion mediated salmon sperm DNA/surfactant interactions

DNA/cationic surfactant interaction is relevant from the viewpoint of gene therapy, where the complexation and resulting compaction are essential to protect DNA from nuclease, and to allow entry of DNA into cells. In this work, light input and host-guest inclusion controlled DNA complexation by a novel cationic surfactant 1-[6-(4-phenylazo-phenoxy)-hexyl]-3-methylimidazolium bromide (AzoC6Mim) is reported. The surfactant is covalently attached with an azobenzene group, which undergoes reversible photoisomerizations by changing light input. Under visible light, trans-AzoC6Mim can bind to salmon sperm DNA through electrostatic attraction and hydrophobic interaction, resulting into DNA compaction. Under UV light, although cis-AzoC6Mim still binds to DNA chain, DNA/surfactant complex is decompacted owing to the decrease of surfactant hydrophobicity. On the other hand, azobenzene group can form an inclusion complex with α-CD through host-guest interaction, which removes AzoC6Mim from DNA chain and decompacts the DNA/surfactant complex.