金属-分子-金属结器件研究进展

有机功能分子是新型纳光电器件研究热门材料之一, 多用金属-分子-金属结方法研究其荷电输运特性.本文从无损制备、微纳尺度及可寻址性等方面, 综述了金属-分子-金属结器件研究进展. 将制备方法归为软接触法、扫描探针显微镜法、对电极法、交叉线法、角沉积法和纳米孔法等六大类, 并分析了不同方法及实验参数对荷电输运特性的影响. 总的来说, 扫描探针法可用于分子电学特性的快速统计分析, 但可寻址性差; 纳米孔分子结具有良好的可寻址性, 可用于分子输运特性的变温研究, 但上电极沉积可导致分子层破坏或界面特性不确定; 角度沉积法和软接触法可有效减少电极热沉积对分子层的烧蚀, 但器件尺度较大; 对电极法可获得纳米级可寻址分子结, 若结合模板压印交叉纳米线法制备电极, 则在无损分子器件研究及其集成方面有很好的前景.     

单分子结的构筑及分子电导性质的测试

分子电子学已成为21世纪研究的热点. 通过将具有特定功能的分子连接在纳米尺度金属电极之间从而构筑包括分子导线、开关、整流器在内的各种分子尺度电子器件, 这引起了科学家们广泛的研究兴趣. 在分子电子学研究中, 构筑金属/分子/金属(MMM)分子结是研究分子器件中电子传输性质的关键. 尽管已经取得了很大的进展, 目前在纳米尺度下构筑稳定可靠的MMM分子结并测试单个分子的电学性质仍然面临很多挑战. 本文着重对单分子电学性质的测试技术和相关理论研究的最新进展以及存在的挑战做了概述.     

基于单壁碳纳米管的功能分子电子器件研究

单壁碳纳米管具有完美的一维纳米结构、良好的导电性和电子弹道输运特性, 被认为是新一代电子学器件的重要基础材料. 作者介绍了两种构筑基于单壁碳纳米管的功能化场效应晶体管的策略, 使用纳米刻蚀法可以制备稳定的功能化单分子器件, 使用表面化学修饰法则提供了发展新型纳米传感器件的简易途径. 针对分子与电极间的非欧姆接触问题, 作者着重介绍了制备羧基功能化单壁碳纳米管点电极的普适性方法, 并将导电分子通过酰胺键共价嵌入碳纳米管电极之间, 从而制备稳定的单分子电子器件. 这一体系为发展无需标记、高选择性的快速单分子检测方法提供了机会, 在实际的工业应用及基础科学研究中都具有广阔的应用前景.     

简易方法制备交叉碳纳米管-石墨烯异质结

发展了一种通过两次高分子辅助转移和选择性氧等离子体刻蚀技术大量制备交叉碳纳米管-石墨烯异质结的无损方法. 拉曼光谱和导电性测试证明, 制备的单层石墨烯薄片在大面积范围内质量均一、导电性好. 而且, 本文所讨论的单层石墨烯的生长和随后的器件制备也提供了大面积制备石墨烯薄片图案化的可重复性方法. 该方法与传统的薄膜技术兼容, 只需简易的几步便可把图案化的石墨烯集成到大规模的微电子器件回路中, 有望实现流线型和自动化的石墨烯微电子器件的大量生产. 这些研究结果为进一步制备分子整流器和其它功能纳米/分子器件提供了技术基础.     

人工细胞膜上天然酶与人工受体的分子间通讯

在集成的分子系统中,分子间的通讯联系是设计分子器件和分子机械的重要方式[1].在水相介质中自组装形成的脂质体可以作为分子间通讯的平台,各种分子可以依靠弱作用力,按照设计思路有组织、有计划地排布其上,构成一个功能化的超分子体,即纳米器件(nanodevice).在脂质体上模拟生物膜上发生的细胞信号转导,成为在分子和超分子水平上开发具有仿生特征的新型纳米器件的重要方法和手段,近年来成为关注的热点[2-6].     

分子尺度电致发光器件

近年来,有机单分子电致发光研究在材料和器件方面取得了突破,是分子电子学新兴的研究方向之一。本文综述了扫描隧道显微镜法、纳米间隙电极法等测量单分子尺度电致发光的研究进展。根据电致发光谱图,可以确定分子器件的发光类型,并得到单个分子的指纹信息。     

二维半导体材料纳米电子器件和光电器件

近年来,随着各领域对微电子器件集成度及性能要求的不断提高,发展基于二维半导体材料的新型高性能功能性器件成为了突破当前技术瓶颈的重要环节和关键方向。目前,作为新型二维半导体材料的代表,二维过渡金属二硫化物、二维黑磷以及范德瓦尔斯异质结凭借其在电学、热学、机械、光学等方面的优异性能已经成为了发展高性能纳米电子器件和光电器件的最具潜力的材料之一。在本综述中,首先概述了几种用于纳米器件的常见二维材料,分析了材料的结构、性能及其在纳米器件中的应用,其次重点对基于过渡金属二硫化物、黑磷以及由其衍生的范德瓦尔斯异质结的纳米电子器件和光电器件的最新研究进展进行讨论,最后对目前二维半导体纳米器件所面临的挑战以及未来的发展方向进行总结及分析,从而为未来发展高性能功能性纳米器件提供支持。     

纳米器件的分子动力学模拟

分子动力学广泛应用于分子体系, 但受限于计算能力, 一般难以用于纳米器件的研究. 本文采用自主开发的超大规模分子动力学仿真程序(NanoMD), 构建了原子级的纳米齿轮模型, 并以此为代表实现了对具有高速转动特性的纳米器件的模拟. 通过位错和缺陷分析, 确定了纳米器件在高速转动过程中的应力分布以及失效机制, 并明确了以极限弹性转速为依据的材料强度衡量模式. 研究发现纳米器件在极限转速方面存在明显的尺寸效应: 随着器件直径的减小而单调增大, 随着轴径的缩小而先增大后减小.     

石墨烯表界面化学修饰及其功能调控

石墨烯属于碳纳米材料家族中的一员,是一种单层的二维原子晶体,具有高硬度、高导热性、高载流子迁移率等诸多优良特性,被认为是新一代电子学器件的重要基础材料.近年来我们课题组利用石墨烯的这些优良特性在其表界面化学修饰及其功能调控方面开展了一系列研究工作.我们对石墨烯表界面进行了共价或非共价化学修饰,在一定程度上打开了石墨烯的带隙,并发展了具有传感功能的石墨烯器件.我们还制备了基于石墨烯的纳米电极,发展了新一代分子电子器件的普适性制备方法,实现了单分子器件的功能化.展望未来,以石墨烯为代表的碳基纳米材料将继续在纳电子器件研究领域发挥重要作用.     

pH-温度协同响应的纳米门控器件

自然界中的生物孔道在生命过程中具有重要的意义, 在人工制备的仿生纳米器件上模仿生物孔道的离子输运性质是一项具有挑战性的课题. 我们制备了一种基于人工聚合物薄膜的纳米门控器件,这种纳米门控器件的离子输运性质可以通过调节体系的pH和温度来调控. 通过在人工聚合物薄膜上修饰功能分子聚赖氨酸(poly-L-Lysine)得到的门控器件能够模拟生物体中生物孔道的典型离子输运行为, 其离子输运性能受体系pH的控制, 可以通过调节体系的pH而限制纳米门控器件的导通方向. 同时, 在一定pH条件下调整体系温度也能够对离子输运性能产生影响, 而在其他pH条件下, 温度则不会对体系的离子输运性能产生明显的影响, 即这种基于人工聚合物薄膜的纳米门控器件具有对pH和温度的协同响应性能.     

An introduction to molecular spintronics

We review the progress and future possibilities in the emerging area of molecular spintronics. We first provide an overview of the different transport regimes in which electronic nanodevices can operate, then briefly overview the important characteristics of molecular magnetic materials that can be useful for application in spintronics and we eventually present several schemes to include such systems into spintronic nanodevices. We hightlight the importance of a chemical approach to the area, and in the last section we showcase some approaches to the creation of hybrids made of carbon nanostructures and molecular magnets, which are gaining increasing attention.     

Nucleic acid based molecular devices

In biology, nucleic acids are carriers of molecular information: DNA's base sequence stores and imparts genetic instructions, while RNA's sequence plays the role of a messenger and a regulator of gene expression. As biopolymers, nucleic acids also have exciting physicochemical properties, which can be rationally influenced by the base sequence in myriad ways. Consequently, in recent years nucleic acids have also become important building blocks for bottom-up nanotechnology: as molecules for the self-assembly of molecular nanostructures and also as a material for building machinelike nanodevices. In this Review we will cover the most important developments in this growing field of nucleic acid nanodevices. We also provide an overview of the biochemical and biophysical background of this field and the major "historical" influences that shaped its development. Particular emphasis is laid on DNA molecular motors, molecular robotics, molecular information processing, and applications of nucleic acid nanodevices in biology.     

基于金纳米棒的生物检测、细胞成像和癌症的光热治疗

由于金纳米棒颗粒独特的可调的表面等离子共振特性,使得金纳米棒颗粒在纳米复合材料和功能化纳米器件的构建、纳米生物技术、生物医学等领域具有广泛而重要的应用前景。本文综述了金纳米棒颗粒的生物检测、细胞成像和癌症的光热治疗方面的最新研究进展,并介绍了金纳米棒颗粒的光学性质和金纳米棒颗粒和几种主要的表面修饰方法,对金纳米棒颗粒在生物应用过程中存在的主要问题进行了讨论。     

Amplified Self-Immolative Release of Small Molecules by Spatial Isolation of Reactive Groups on DNA-Minimal Architectures

Triggering the release of small molecules in response to unique biomarkers is important for applications in drug delivery and biodetection. Due to low quantities of biomarker, amplifying release is necessary to gain appreciable responses. Nucleic acids have been used for both their biomarker-recognition properties and as stimuli, notably in amplified small-molecule release by nucleic-acid-templated catalysis (NATC). The multiple components and reversibility of NATC, however, make it difficult to apply in vivo. Herein, we report the use of the hybridization chain reaction (HCR) for the amplified, conditional release of small molecules from standalone nanodevices. We couple HCR with a DNA-templated reaction resulting in the amplified, immolative release of small molecules. We integrate the HCR components into single nanodevices as DNA tracks and spherical nucleic acids, spatially isolating reactive groups until triggering. This could be applied to biosensing, imaging, and drug delivery.     

Amplified Self‐Immolative Release of Small Molecules by Spatial Isolation of Reactive Groups on DNA‐Minimal Architectures

Triggering the release of small molecules in response to unique biomarkers is important for applications in drug delivery and biodetection. Due to low quantities of biomarker, amplifying release is necessary to gain appreciable responses. Nucleic acids have been used for both their biomarker‐recognition properties and as stimuli, notably in amplified small‐molecule release by nucleic‐acid‐templated catalysis (NATC). The multiple components and reversibility of NATC, however, make it difficult to apply in vivo. Herein, we report the use of the hybridization chain reaction (HCR) for the amplified, conditional release of small molecules from standalone nanodevices. We couple HCR with a DNA‐templated reaction resulting in the amplified, immolative release of small molecules. We integrate the HCR components into single nanodevices as DNA tracks and spherical nucleic acids, spatially isolating reactive groups until triggering. This could be applied to biosensing, imaging, and drug delivery.     

Construction and Application of DNAzyme-based Nanodevices

The development of stimuli-responsive nanodevices with high efficiency and specificity is very important in biosensing, drug delivery, and so on. DNAzymes are a class of DNA molecules with the specific catalytic activity. Owing to their unique catalytic activity and easy design and synthesis, the construction and application of DNAzymes-based nanodevices have attracted much attention in recent years. In this review, the classification and properties of DNAzyme are first introduced. The construction of several common kinds of DNAzyme-based nanodevices, such as DNA motors, signal amplifiers, and logic gates, is then systematically summarized. We also introduce the application of DNAzyme-based nanodevices in sensing and therapeutic fields. In addition, current limitations and future directions are discussed.     

A Molecular Translator that Acts by Binding-Induced DNA Strand Displacement for a Homogeneous Protein Assay

Protein in, DNA out: A "binding-induced molecular translator" is able to convert an input target protein into an output DNA that can be readily detected and potentially be used to assemble DNA nanodevices. Successful molecular translation is mediated by binding-induced DNA assembly on a gold nanoparticle (AuNP) scaffold, thereby achieving efficient target-dependent strand displacement.     

Towards polyoxometalate-integrated nanosystems

Polyoxometalates represent a diverse range of molecular clusters with an almost unmatched range of physical properties and the ability to form structures that can bridge several length scales. The new building block principles that have been discovered are beginning to allow the design of complex clusters with desired properties and structures; several structural types and novel physical properties are examined herein. The overall message that is presented throughout is the possibility that polyoxometalate clusters could be excellent candidates to be exploited in the development of functional nanosystems or nanodevices. The concepts that underpin the development of nanoscale devices are discussed briefly, as are the considerable challenges that must be overcome to realise polyoxometalate-based functional nanosystems.     

Molecular heterogeneity analysis of poly(amidoamine) dendrimer-based mono- and multifunctional nanodevices by capillary electrophoresis

Poly(amidoamine) (PAMAM) dendrimer-based nanodevices are of recent interest in targeted cancer therapy. Characterization of mono- and multifunctional PAMAM-based nanodevices remains a great challenge because of their molecular complexity. In this work, various mono- and multifunctional nanodevices based on PAMAM G5 (generation 5) dendrimer were characterized by UV-Vis spectrometry, (1)H NMR, size exclusion chromatography (SEC), and capillary electrophoresis (CE). CE was extensively utilized to measure the molecular heterogeneity of these PAMAM-based nanodevices. G5-FA (FA denotes folic acid) conjugates (synthesized from amine-terminated G5.NH(2) dendrimer, approach 1) with acetamide and amine termini exhibit bimodal or multi-modal distributions. In contrast, G5-FA and bifunctional G5-FA-MTX (MTX denotes methotrexate) conjugates with hydroxyl termini display a single modal distribution. Multifunctional G5.Ac(n)-FI-FA, G5.Ac(n)-FA-OH-MTX, and G5.Ac(n)-FI-FA-OH-MTX (Ac denotes acetamide; FI denotes fluorescein) nanodevices (synthesized from partially acetylated G5 dendrimer, approach 2) exhibit a monodisperse distribution. It indicates that the molecular distribution of PAMAM conjugates largely depends on the homogeneity of starting materials, the synthetic approaches, and the final functionalization steps. Hydroxylation functionalization of dendrimers masks the dispersity of the final PAMAM nanodevices in both synthetic approaches. The applied CE analysis of mono- and multifunctional PAMAM-based nanodevices provides a powerful tool to evaluate the molecular heterogeneity of complex dendrimer conjugate nanodevices for targeted cancer therapeutics.