偶氮苯类DNA纳米机器

具备光致异构性及乏氧响应性的偶氮苯为构建DNA纳米机器提供了动态响应元件. 然而, 受限于偶氮苯类化合物有限的光异构化反应, 偶氮苯类DNA纳米机器的构建与应用仍然面临着巨大的挑战. 本文梳理了基于偶氮苯的DNA纳米机器的构建方式及相应优缺点, 总结了可见光响应的偶氮苯类DNA纳米机器的设计规则, 并进一步综合评述了偶氮苯类DNA纳米机器在调控酶活性、 物质运输和机械运动等方面的应用. 本文有望推动开发更灵活的偶氮苯与DNA的偶联方式, 并为偶氮苯类DNA纳米机器在生物医学上的应用带来一定启示.     

Caging-Decaging Strategies to Realize Spatiotemporal Control of DNAzyme Activity for Biosensing and Bioimaging

DNAzymes with RNA-cleaving activity have been widely used as biosensing and bioimaging tools for detection of metal ions. Despite the achievements, DNAzyme-based biosensors sometime suffer from false positive signals and unexpected off-target turn-on in biological environments, which are likely due to the unstable nature of the RNA site. Ways to control DNAzyme activity in order to improve the sensing performance remain a significant challenge. To meet the challenge, there is growing interest to develop synthetic strategies that can cage native DNAzyme under undesired conditions and reactivate it in target environment in order to function in a controlled manner. A variety of caging-decaging strategies have been developed to realize spatiotemporal control of the DNAzyme activity, improving its specificity and sensitivity as well as extending its application regimes. In this review, we focus on strategies to regulate the catalytic activity of DNAzyme, highlight the nucleic acid modification chemistries, and summarize three strategies to cage DNAzyme functions. Examples of using caged DNAzyme for bio-applications have also been reviewed in detail. Finally, we provide our perspectives on the potential challenges and opportunities of this emerging research topic that could advance the DNAzyme field.     

DNA‐Mediated Proximity‐Based Assembly Circuit for Actuation of Biochemical Reactions

Smart nanodevices that integrate molecular recognition and signal production hold great promise for the point‐of‐care (POC) diagnostic applications. Herein, the development of a DNA‐mediated proximity assembly of biochemical reactions, which was capable of sensing various bio‐targets and reporting easy‐to‐read signals is reported. The circuit was composed of a DNA hairpin‐locked catalytic cofactor with inhibited activity. Specific molecular inputs can trigger a conformational switch of the DNA locks through the mechanisms of toehold displacement and aptamer switching, exposing an active cofactor. The subsequent assembly of an enzyme/cofactor pair actuated a reaction to produce colorimetric or fluorescence signals for detecting target molecules. The developed system could be potentially applied to smart biosensing in molecular diagnostics and POC tests.     

Enhanced catalytic DNAzyme for label-free colorimetric detection of DNA

A DNAzyme-based label-free method for the colorimetric detection of DNA is introduced, with a supramolecular hemin-G-quartet complex as the sensing element and a 36-mer single-strand DNA as the analyte that is detected at 10 nM.     

基于功能性纳米材料的新型电化学界面的构筑以及相关应用(英文)

由于独特的光、电、磁以及催化性质,功能性纳米材料的研究已经渗透到各个学科并在不同领域展示出潜在的应用前景,尤其是利用纳米材料构建功能性电极界面、研究其电化学行为并发展新颖的电化学纳米器件引起了了人们的广泛关注. 本篇综述中,主要介绍作者研究小组在以功能性纳米材料构建新颖的电化学界面的最新进展,集中关注其在电化学传感器、燃料电池以及光谱电化学中的应用. 这些纳米材料的应用极大地增强了电子转移、提高了电化学传感器的灵敏度以及燃料电池的催化效率. 作者也通过合成一些光谱匹配的荧光以及电致变色纳米材料构建新颖的荧光光谱电化学器件,同时在材料的合成组装、多重刺激响应体系以及多功能化进行探索. 最后,作者对这类基于纳米材料的电化学器件的发展和应用予以展望.     

Single-chain antibodies against DNA aptamers for use as adapter molecules on DNA tile arrays in nanoscale materials organization

Complex DNA nanostructures have been developed as structural components for the construction of nanoscale objects. Recent advances have enabled self-assembly of organized DNA nanolattices and their use in patterning functional bio-macromolecules and other nanomaterials. Adapter molecules that bind specifically to both DNA lattices and nanomaterials would be useful components in a molecular construction kit for patterned nanodevices. Herein we describe the selection from phage display libraries of single-chain antibodies (scFv) for binding to a specific DNA aptamer and their development as adapter molecules for nanoscale construction. We demonstrate the decoration of various DNA tile structures with aptamers and show binding of the selected single-chain antibody as well as the self-assembly of mixed DNA-protein biomolecular lattices.     

Microwave synthesis of electrically conductive gold nanowires on DNA scaffolds

Biological molecules, in particular DNA, have shown great potential to be used as interconnects of nanodevices and computational elements. In this research, we synthesized electrically conductive gold nanowires for the first time exploiting an electroless and microwave heating method for 120-180 s. Our results indicate that DNA serves as a reducing and nonspecific capping agent for the growth of nanowires. The current voltage ( I- V) characteristics of the Au nanowires are continuous, exhibiting Ohmic behavior having low contact resistance with the gold electrodes. The nanowires have a diameter of 10-15 nm in solution and of 20-30 nm in immobilized DNA with resistivity comparable to pure metals. The method is highly selective with deposition confined to the DNA itself. The nanowires we fabricated can be used as building blocks for functional nanodevices, sensors, and optoelectronics.     

Colorimetric Cu2+ detection with a ligation DNAzyme and nanoparticles

Using a Cu(2+)-dependent DNA ligation DNAzyme, a colorimetric sensor for Cu2+ has been developed based on directed assembly of DNA-functionalized gold nanoparticles by the ligation product, and such ligation DNAzyme-based sensors are intrinsically more sensitive than cleavage DNAzyme systems due to the lack of background.     

Self-Assembly of Nanoparticles into Two-Dimensional Arrays for Catalytic Applications

Self-assembly of nanoparticles (NPs) is at the heart of nanotechnology, and has shown many potential applications in fabricating nanodevices with highly controlled functionality. Two-dimensional (2D) arrays of NPs can provide a thin and uniform NP array with each NP being exposed on the surface to maximize NP catalysis. This minireview summarizes the recent progress on the fabrication and application of 2D NP arrays. It conveys the important message to readers that creation of libraries of NP arrays with varying catalytic strengths is an exciting direction in catalysis. This approach can be used to solve complicated catalytic problems in which multiple chemical reactions need to be catalyzed in a single reaction vessel.     

Enzyme-regulated activation of DNAzyme: a novel strategy for a label-free colorimetric DNA ligase assay and ligase-based biosensing

The DNA nick repair catalyzed by DNA ligase is significant for fundamental life processes, such as the replication, repair, and recombination of nucleic acids. Here, we have employed ligase to regulate DNAzyme activity and developed a homogeneous, colorimetric, label-free and DNAzyme-based strategy to detect DNA ligase activity. This novel strategy relies on the ligation-trigged activation or production of horseradish peroxidase mimicking DNAzyme that catalyzes the generation of a color change signal; this results in a colorimetric assay of DNA ligase activity. Using T4 DNA ligase as a model, we have proposed two approaches to demonstrate the validity of the DNAzyme strategy. The first approach utilizes an allosteric hairpin-DNAzyme probe specifically responsive to DNA ligation; this approach has a wide detection range from 0.2 to 40?U?mL(-1) and a detection limit of 0.2?U?mL(-1). Furthermore, the approach was adapted to probe nucleic acid phosphorylation and single nucleotide mismatch. The second approach employs a "split DNA machine" to produce numerous DNAzymes after being reassembled by DNA ligase; this greatly enhances the detection sensitivity by a signal amplification cascade to achieve a detection limit of 0.01?U?mL(-1).     

Robust charge transport in DNA double crossover assemblies

BACKGROUND: Multiple-stranded DNA assemblies, encoded by sequence, have been constructed in an effort to self-assemble nanodevices of defined molecular architecture. Double-helical DNA has been probed also as a molecular medium for charge transport. Conductivity studies suggest that DNA displays semiconductor properties, whereas biochemical studies have shown that oxidative damage to B-DNA at the 5'-G of a 5'-GG-3' doublet can occur by charge transport through DNA up to 20 nm from a photo-excited metallointercalator. The possible application of DNA assemblies, in particular double crossover (DX) molecules, in electrical nanodevices prompted the design of a DNA DX assembly with oxidatively sensitive guanine moieties and a tethered rhodium photo-oxidant strategically placed to probe charge transport. RESULTS: DX assemblies support long-range charge transport selectively down the base stack bearing the intercalated photo-oxidant. Despite tight packing, no electron transfer (ET) crossover to the adjacent base stack is observed. Moreover, the base stack of a DX assembly is well-coupled and less susceptible than duplex DNA to stacking perturbations. Introducing a double mismatch along the path for charge transport entirely disrupts long-range ET in duplex DNA, but only marginally decreases it in the analogous stack within DX molecules. CONCLUSIONS: The path for charge transport in a DX DNA assembly is determined directly by base stacking. As a result, the two closely packed stacks within this assembly are electronically insulated from one another. Therefore, DX DNA assemblies may serve as robust, insulated conduits for charge transport in nanoscale devices.     

Dynamic allosteric control of noncovalent DNA catalysis reactions

Allosteric modulation of catalysis kinetics is prevalent in proteins and has been rationally designed for ribozymes. Here, we present an allosteric DNA molecule that, in its active configuration, catalyzes a noncovalent DNA reaction. The catalytic activity is designed to be modulated by the relative concentrations of two DNA regulator molecules, one an inhibitor and the other an activator. Dynamic control of the catalysis rate is experimentally demonstrated via three cycles of up and down regulation by a factor of over 10. Unlike previous works, both the allosteric receptor and catalytic core are designed, rather than evolved. This allows flexibility in the sequence design and modularity in synthetic network construction.     

A ligation-triggered DNAzyme cascade for amplified fluorescence detection of biological small molecules with zero-background signal

Many types of fluorescent sensing systems have been reported for biological small molecules. Particularly, several methods have been developed for the recognition of ATP or NAD(+), but they only show moderate sensitivity, and they cannot discriminate either ATP or NAD(+) from their respective analogues. We have addressed these limitations and report here a dual strategy which combines split DNAzyme-based background reduction with catalytic and molecular beacon (CAMB)-based amplified detection to develop a ligation-triggered DNAzyme cascade, resulting in ultrahigh sensitivity. First, the 8-17 DNAzyme is split into two separate oligonucleotide fragments as the building blocks for the DNA ligation reaction, thereby providing a zero-background signal to improve overall sensitivity. Next, a CAMB strategy is further employed for amplified signal detection achieved through cycling and regenerating the DNAzyme to realize the true enzymatic multiple turnover (one enzyme catalyzes the cleavage of several substrates) of catalytic beacons. This combination of zero-background signal and signal amplification significantly improves the sensitivity of the sensing systems, resulting in detection limits of 100 and 50 pM for ATP and NAD(+), respectively, much lower than those of previously reported biosensors. Moreover, by taking advantage of the highly specific biomolecule-dependence of the DNA ligation reaction, the developed DNAzyme cascades show significantly high selectivity toward the target cofactor (ATP or NAD(+)), and the target biological small molecule can be distinguished from its analogues. Therefore, as a new and universal platform for the design of DNA ligation reaction-based sensing systems, this novel ligation-triggered DNAzyme cascade method may find a broad spectrum of applications in both environmental and biomedical fields.     

Construction of biomimetic smart nanochannels with polymer membranes and application in energy conversion systems

Learning from nature has inspired the creation of intelligent devices to meet the increasing needs of the advanced community and also to better understand how to imitate biology. As one of biomimetic nanodevices, nanochannels or nanopores aroused particular interest because of their potential applications in nanofluidic devices, biosensing, filtration, and energy conversions. In this review we have summarized some recent results mainly focused on the design, construction and application in energy conversion systems. Like biological nanochannels, the prepared smart artificial nanochannels fabricated by ion track-etched polymer membranes and smart molecules show a great potential in the field of bioengineering and biotechnology. And these applications can not only help people to know and understand the living processes in nature, but can also inspire scientists to study and develop novel nanodevices with better performance for the mankind.     

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.     

G-四链体-氯化血红素DNA酶在传感器设计中的应用

G-四链体-氯化血红素(hemin)DNA酶是一种由特定的核酸G-四链体与hemin结合后形成的具有过氧化物酶活性的人工模拟酶。作为一类重要的DNA酶,G-四链体-hemin DNA酶近年来在分析化学领域受到了越来越多的关注。目前这类DNA酶已被用在了多种传感器,包括金属离子传感器、适配体传感器、酶传感器、DNA传感器及药物传感器的设计当中。本文对G-四链体-hemin DNA酶在传感器设计中的应用进行了系统的介绍和评述,并对其未来的发展进行了初步的展望。     

外光驱动的纳米材料和器件的研究进展

近红外光由于具有良好的生物组织穿透性且对组织几乎无损伤等优点, 在生物医学领域展现了光明的应用前景。进入生物体内的近红外光要发挥诊疗作用, 其前提是需要可吸收/转换近红外光的纳米材料或器件。本文综述了近红外光驱动的纳米材料和器件的研究进展, 主要包括稀土上转换发光纳米材料、980 nm激光驱动的发电机以及光热转换纳米材料, 重点介绍了它们的生物应用进展;最后指出了目前存在的问题和发展方向。     

介电力显微术：一种观察纳米材料中电荷行为的新方法

功能纳米器件中组成材料间的电荷转移输运过程对于器件中的物理化学过程以及由此引发的器件功能会有重大影响,因此,深入理解器件工作过程中的电子／离子行为机理对于优化器件功能以及进一步开发纳米材料的应用潜力具有重要意义．传统场效应晶体管对于纳米材料的电输运测量表征反映了载流子在整个器件中的统计行为,但难以检测电荷具体的转移输运过程．同时,由于纳米材料的尺寸和分散性,基于纳米材料的场效应晶体管面临着制备困难、电极／纳米材料接触复杂和制作成本高等问题．因此,本课题组发展了介电力显微术（dielectricforcemicroscopy,DFM）方法并实现了对纳米材料电学性质的无接触、高空间分辨率和快速表征．本文介绍了介电力显微术的基本原理,列举了其在探究一维纳米材料、纳米颗粒以及有机半导体薄膜电学性质上的一些应用实例．这些实例验证了介电力显微术对纳米材料电学性质的表征能力,并展现了这一技术在纳米材料物理化学性质和纳米器件功能研究上的广阔前景．     

Mechanisms,Methods of Tracking and Applications of DNA Walkers: A Review

In recent years, DNA nanotechnology expanded its scope from structural DNA nanoarchitecture towards designing dynamic and functional nanodevices. This progress has been evident in the development of an advanced class of DNA nanomachines, the so-called DNA walkers. They represent an evolution of basic switching between distinctly defined states into continuous motion. Inspired by the naturally occurring walkers such as kinesin, research on DNA walkers has focused on developing new ways of powering them and investigating their walking mechanisms and advantages. New techniques allowing the visualization of walkers as single molecules and in real time have provided a deeper insight into their behavior and performance. The construction of novel DNA walkers bears great potential for applications in therapeutics, nanorobotics or computation. This review will cover the various examples and breakthrough designs of recently reported DNA walkers that pushed the limits of their performance. It will also mention the techniques that have been used to investigate walker nanosystems, as well as discuss the applications that have been explored so far.     

Small-molecule-triggered manipulation of DNA three-way junctions

DNA three-way junctions are frequently used in nanoarchitectures. Ligand-dependent designs that provide well-characterized building blocks for structure-switching DNA nanodevices are presented.