DNA纳米机器

本文介绍了以DNA为基础的纳米机器的发展现状,强调了核酸作为一种材料在纳米科技领域的重要作用.着重阐述了利用链交换反应或环境因素变化可以驱动DNA二级结构的变化,从而可以构建出形式多样的纳米级核酸分子机器;评价了各类分子机器在效率、寿命和副产物方面的优缺点.在总结前人工作的基础上预测了核酸纳米技术在生命科学、材料科学以及计算科学等诸多方面可能的应用.     

DNA在氨基功能化偶氮苯自组装膜表面的固定

采用简单快速的方法制备出将DNA固定在其表面的单分子层敏感膜.首先采用表面自组装技术将硅氧烷基偶氮苯衍生物H2NAzoCONHC3Si(OCH3)3(APDA-N-TMSPBA)组装在硅表面,在详细考察单分子层薄膜的化学结构、表面浸润性和分子表面形貌之后,又通过紫外吸收光谱(UV)在位考察了硅氧烷基偶氮苯衍生物的光学异构特性.在DNA在自组装薄膜固定后,X光电子能谱仪(XPS)结果显示出现了明显的磷元素信号,表明DNA分子可以成功固定在自组装膜表面.     

偶氮苯聚合物（PAZOS）的合成及其三阶非线性光学特性

合成及表征了一种偶氮苯聚合物聚「３－甲基－４－二（Ｎ，Ｎ－氧亚乙基）氨基－４－硝基偶氮苯癸二酰」通过简并四波混频方法研究了这种聚合物膜的三阶非线性光学性质，测得三三阶非线性光学系数Ｘ＾（３）为６．６＊１０＾－６ｅｓｕ，并考察了其相位共轭光产生特性及光致异构动力学。     

偶氮苯高分子的光致可逆固液转变

偶氮苯化合物是一种极具吸引力以及较为常用的光响应材料,本文主要介绍偶氮苯的光响应性质以及一些偶氮苯高分子的合成方法,解析光化学反应导致偶氮苯高分子固液转变的机理,并介绍其在粘结性材料、光致动器、光致热导开关器件及非热纳米压印中的应用。     

偶氮苯双亲化合物的合成及在其DMF中的光谱特性

以4-氨基苯甲酸乙酯为原料,通过重氮化-偶合等反应,设计合成了4-（4-辛烷氧基苯偶氮）苯甲酸钾（AZO-a）和4-（4-十四烷氧基苯偶氮）苯甲酸钾（AZO-b）等偶氮苯双亲化合物,其结构经¹H NMR和FT-IR确证。采用UV-Vis考察合成产物在N, N-二甲基甲酰胺（DMF）溶剂中紫外吸收影响。      

偶氮苯类衍生物材料性质及其研究进展

光可在不接触的条件下作用于材料,因此光是一种理想的触发机制并可以选择性、非破坏性和远程激活的施加外部刺激.偶氮苯类化合物作为一种芳香偶氮化合物染料分子,能够在不同光照下产生异构效应,并且芳香偶氮化合物分子具有可逆的异构体,这种基于不同波长导致的构型变化可使偶氮苯类化合物产生微观与宏观上的运动.基于这种宏观机械变形和可逆...     

偶氮苯聚合物的光控图案化

将自组装得到的聚苯乙烯胶体晶体,利用反应离子刻蚀和软刻蚀法复形到偶氮苯聚合物膜表面,获得六方非紧密排列的偶氮苯聚合物半球状阵列微图案膜。采用场发射扫描电子显微镜(FESEM)、原子力显微镜(AFM)和接触角测量仪等对膜的微阵列结构和表面润湿性能进行了表征。研究了光照对膜微图案结构和润湿性能的影响。结果表明:基于偶氮苯基团的光致取向特性,偶氮苯聚合物膜的微图案在偏振光照射下,可由初始的半球状阵列微结构形变成纺锤状和椭球状等结构,这种微结构的改变可以改变膜表面润湿性,实现偶氮苯聚合物膜表面不同微图案和润湿性能的光照调控。     

偶氮苯聚合物(PGMAA-20)膜光栅结构的分子取向机制

设计合成及表征了一种含偶氮苯聚合物(PGMAA 20)材料.利用两束S偏振光作为泵浦光在PGMAA 20膜上刻写光栅并观察光栅的衍射信号;然后再用相衬显微镜直接观察偶氮苯薄膜上的光栅结构,并以分子取向机制为基础对光栅形成和消除过程提出了新解释,这种观点被实验观察结果进一步证实.     

偶氮苯衍生物探针在乏氧细胞成像中的应用

细胞不受控制的生长增殖和异常的血管系统导致肿瘤部位氧气供应不足,氧气浓度低于正常组织.细胞乏氧是大多数实体瘤的共同特征,可用作恶性组织和癌症进展的指标.准确的乏氧检测和成像对癌症患者的诊断和临床治疗至关重要.荧光成像具有高灵敏度、无创、实时等优点,常被用于癌症检查.偶氮基团由于其对荧光基团的荧光猝灭作用和还原断裂荧光恢...     

偶氮苯聚合物膜的光致高密度存储及其三维微结构的研究

设计、合成及表征了一种偶氮苯聚合物(PGMAA-20)。研究了该偶氮苯聚合物薄膜中的高密度光学存储和三维微结构,并成功地将20套光栅储存在样品中同一个点上,储存密度是已报道的两倍;用简单的2波混频光路在该材料中刻写出长方格子和六角星型的微结构,在制作多重不同周期不同角度的高密度光栅结构的实验过程中,观察到不同周期光栅的刻写顺序对整个微结构形成的最终结果具有决定性的影响。     

A Membrane Tension-Responsive Mechanosensitive DNA Nanomachine

Membrane curvature reflects physical forces operating on the lipid membrane, which plays important roles in cellular processes. Here, we design a mechanosensitive DNA (MSD) nanomachine that mimics natural mechanosensitive PIEZO channels to convert the membrane tension changes of lipid vesicles with different sizes into fluorescence signals in real time. The MSD nanomachine consists of an archetypical six-helix-bundle DNA nanopore, cholesterol-based membrane anchors, and a solvatochromic fluorophore, spiropyran (SP). We find that the DNA nanopore effectively amplifies subtle variations of the membrane tension, which effectively induces the isomerization of weakly emissive SP into highly emissive merocyanine isomers for visualizing membrane tension changes. By measuring the membrane tension via the fluorescence of MSD nanomachine, we establish the correlation between the membrane tension and the curvature that follows the Young-Laplace equation. This DNA nanotechnology-enabled strategy opens new routes to studying membrane mechanics in physiological and pathological settings.     

Programming Rotary Motions with a Hexagonal DNA Nanomachine

Biological macromolecular machines perform impressive mechanical movements. F-adenosine triphosphate (ATP) synthase uses a proton gradient to generate ATP through mechanical rotations. Here, a programmed hexagonal DNA nanomachine, in which a three-armed DNA nanostructure (TAN) can perform stepwise rotations in the confined nanospace powered by DNA fuels, is demonstrated. The movement of TAN can precisely go through a 60° rotation, which is confirmed by atomic force microscopy, and each stepwise directional rotating is monitored by fluorescent measurements. Moreover, the rotary nanomachine is used to spatially organize cascade enzymes: glucose oxidase (GOx) and horseradish peroxidase (HRP) in four different arrangements. The multistep regulations of the biocatalytic activities are achieved by employing TAN rotations. This work presents a new prototype of rotary nanodevice with both angular and directional control, and provides a nanoscale mechanical engineering platform for the reactive molecular components, demonstrating that DNA-based framework may have significant roles in futuristic nanofactory construction.     

Trans-cis photoisomerization of azobenzene by n →π^＊ excitation： A semiclassical dynamics study

A realistic dynamics simulation study is reported for the trans-cis photoisomerization of azobenzene triggered by the n →π^＊ excitation and the results show that the formation ofcis isomer follows the rotational motion around the N=N bond. The simulation find that the CNN bond angle bending vibrations also play a significant role in the vibronic coupling between the HOMO and LUMO, which essentially leads a nonadiabatic transition of the molecule to the electronic ground state.     

Trans-cis photoisomerization of azobenzene by n→π* excitation:A semiclassical dynamics study

A realistic dynamics simulation study is reported for the trans-cis photoisomerization of azobenzene triggered by the n→π*excitation and the results show that the formation of cis isomer follows the rotational motion around the N=N bond.The simulation find that the CNN bond angle bending vibrations also play a significant role in the vibronic coupling between the HOMO and LUMO,which essentially leads a nonadiabatic transition of the molecule to the electronic ground state.     

Photoinduced Reversible Solid-to-Liquid Transitions and Directional Photofluidization of Azobenzene-containing Polymers

Photoinduced reversible liquefaction and solidification of polymers enable processing and healing of polymers with light. Some azobenzene-containing polymers(azopolymers) exhibit two types of photoinduced liquefaction properties: photoinduced reversible solid-toliquid transition and directional photofluidization. For the first type, light switches the glass transition temperature(Tg) values of azopolymers and induces reversible solid-to-liquid transitions. For the second type, polarized light gu...     

DNA步行器调控的纳米粒子超晶格

作为一种精巧的DNA纳米机器, DNA步行器因其优异的可设计性及可编程性在众多研究领域中展示出强大的应用价值. 本工作通过将基于催化发夹组装的双足DNA步行器与DNA功能化的金纳米粒子(即球形核酸)组装相结合, 开发了一种具有时间依赖性的DNA步行器驱动球形核酸恒温有序组装的策略. 以单组分球形核酸组装体系为例, DNA步行器通过发夹催化组装反应驱动在球形核酸表面上随机行走并逐渐产生带有活性粘性末端的DNA杂交结构, 促使球形核酸表面粘性末端间的“键合”速率与其组装速率在时间尺度上保持同步, 从而得到面心立方(FCC)晶型的超晶格结构. 基于类似原理, 作者还构建了一种DNA步行器驱动的双组分球形核酸组装体系并以此得到氯化铯(CsCl)晶型的超晶格结构.     

Rational Engineering of a Dynamic,Entropy-Driven DNA Nanomachine for Intracellular MicroRNA Imaging

We rationally engineered an elegant entropy-driven DNA nanomachine with three-dimensional track and applied it for intracellular miRNAs imaging. The proposed nanomachine is activated by target miRNA binding to drive a walking leg tethered to gold nanoparticle with a high density of DNA substrates. The autonomous and progressive walk on the DNA track via the entropy-driven catalytic reaction of intramolecular toehold-mediated strand migration leads to continuous disassembly of DNA substrates, accompanied by the recovery of fluorescence signal due to the specific release of a dye-labeled substrate from DNA track. Our nanomachine outperforms the conventional intermolecular reaction-based gold nanoparticle design in the context of an improved sensitivity and kinetics, attributed to the enhanced local effective concentrations of working DNA components from the proximity-induced intramolecular reaction. Moreover, the nanomachine was applied for miRNA imaging inside living cells.     

Improved functionality and control in the isomerization of a calix[4]arene-capped azobenzene

An improved azobenzene core capped by two calix[4]arene units isomerizes readily between trans and cis configurations via photochemical and/or thermal means. In addition, the presence of acid (particularly HCl) increases the rate of thermal cis→trans conversion. These enhancements to the functional response, control, and understanding of calixarene-capped azobenzene isomerization are important for future application in the dynamic encapsulation of small chemical species.