自组装与纳米技术

自组装技术是制备纳米结构的几种为数不多的方法之一.本文对最近几年自组装技术在纳米科技领域中的一些重大突破和成果进行较为系统地综述,主要包括以下几个方面:自组装单层膜、纳米尺度的表面改性、超分子材料、分子电子学与光子晶体.     

自组装与纳米技术

自组装技术是制备纳米结构的几种为数不多的方法之一。本文对最近几年自组装技术在纳米科技领域中的一些重大突破和成果进行较为系统地综述，主要包括以下几个方面：自组装单层膜、纳米尺度的表面改性、超分子材料、分子电子学与光子晶体。     

制备纳米多孔材料的模板自组装技术

纳米自组装技术的突出优点是:通过改变相应模板的形状和大小可以实现对不同材料形状、结构和大小的预先控制,从而拓展了它的应用范围。本文主要阐述了纳米多孔材料模板自组装技术的原理和工艺流程,介绍了这种技术的几种典型方法的最新进展,并比较了各种方法的优劣,同时展示了它的应用前景。     

电子纳米技术与应用

纳米技术是从二十世纪八十年代开始迅速发展的技术,纳米(nm)是一个长度单位,纳米体系大都被作为1~100nm的范围当中。它的主要原理是在纳米尺寸的范围中了解及改变自然,经过直接操作来对原子、分子进行安排,创造出新的物质。本文主要介绍了纳米技术的内涵以及对纳米技术的应用方面进行相应的探讨。     

Tile自组装模型理论研究

自组装的形式化研究最终使得Tile自组装模型得以定义,系统中的因子编码可以随意地由不同部分组成。这个计算利用了不确定性的优势,但是在理论上每一个不确定性的路径都是以平行的方式被执行的,所以为了高效率解决路径的问题,就要增加现行规模的投入。文章主要对自组装模型的理论部分加以证明,并以实际例来说明这个模型的正确性。     

自组装法合成导电聚吡咯纳米线

以多孔氧化铝为模板,合成导电聚吡咯纳米线。利用SEM对聚吡咯进行了表征,结果表明:在吡咯单体浓度为0.2 mol/L,电压1.0 V,时间1 600 s的条件下,制得的聚吡咯会有大量的微触手结构出现,且表面光滑,比表面积较大,并初步探究了聚吡咯微触手结构的形成机理。     

组装技术与环境保护

组装材料选择与环境保护在电子产品中，随着小型、轻型、薄型和高性能元器件使用量的剧增，组装技术的地位正日臻重要，组装材料与环境保护的关系也日益密切。从1995年起，组装衬底材料专用的清洗剂氟里昂和三氯乙醚会破坏地球的臭氧层，国际上就实行禁用。另外，在组装工艺中焊接用的铅（Ph）和挥发性有机物（VOC）、树脂系列布线板等组装材料都面临环境保护问题。某种意义上说，在组装材料与环境保护具体选择的实施过程中，环保在企业管理中的措施，会增加企业负担，因此带有一定的强制性。以Sn－Ph焊接为基础形成的细间距QFP为例，它…     

新型微元件组装技术--流体自组装

随着电子产品向便携式方向发展,其中元件的尺寸逐渐变小,组装密度迅速提高,这使得与组装系统材料表面相关的范德华力、表面张力和静电引力等成了主要作用力,它们阻止了传统的拾放装置对微元件进行的操作。目前新型的流体自组装技术有望解决微元件组装面临的困难,它具有对大批量微元件在三维空间上并行地、精确地对位组装的能力。根据微元件在基板组装位置上的对位方式,本文将流体自组装分为三类:外形匹配式对位的流体自组装、粘结剂导向式对位的流体自组装和混合对位模式的流体自组装,并分别对其做了详细的介绍,文章最后展望了流体自组装技术的发展趋势。     

自组装技术在MEMS中的应用

起源于生物化学领域的自组装技术正被广泛地应用到了化学、材料、生物、电子、机械等不同的学科中。在MEMS和NEMS中,自组装作为一种新型的“自下而上”的微(纳)结构制备和装配技术而得到积极的关注,并显示出良好的应用前景。在阐述自组装技术发展的基础上,介绍了该技术在MEMS中的典型应用,讨论一些待解决的关键问题,最后展望了自组装技术的发展趋势。     

纳米技术在克隆技术中的应用前景

纳米科技近年来的迅猛发展带动物理、化学、生物和医学等众多学科进入全新的领域,其前景是可以预见的。本文从生物医学的众多技术之一——克隆技术,展望了纳米技术的应用前景。     

Self‐Assembled Complexes of Horseradish Peroxidase with Magnetic Nanoparticles Showing Enhanced Peroxidase Activity

Bio‐nanocatalysts (BNCs) consisting of horseradish peroxidase (HRP) self‐assembled with magnetic nanoparticles (MNPs) enhance enzymatic activity due to the faster turnover and lower inhibition of the enzyme. The size and magnetization of the MNPs affect the formation of the BNCs, and ultimately control the activity of the bound enzymes. Smaller MNPs form small clusters with a low affinity for the HRP. While the turnover for the bound fraction is drastically increased, there is no difference in the H₂O₂ inhibitory concentration. Larger MNPs with a higher magnetization aggregate in larger clusters and have a higher affinity for the enzyme and a lower substrate inhibition. All of the BNCs are more active than the free enzyme or the MNPs (BNCs > HRP ? MNPs). Since the BNCs show surprising resilience in various reaction conditions, they may pave the way towards new hybrid biocatalysts with increased activities and unique catalytic properties for magnetosensitive enzymatic reactions.     

Single-bit digital comparator circuit design using quantum-dot cellular automata nanotechnology

The large amount of secondary effects in complementary metal–oxide–semiconductor technology limits its application in the ultra-nanoscale region. Circuit designers explore a new technology for the ultra-nanoscale region, which is the quantum-dot cellular automata (QCA). Low-energy dissipation, high speed, and area efficiency are the key features of the QCA technology. This research proposes a novel, low-complexity, QCA-based one-bit digital comparator circuit for the ultra-nanoscale region. The performance of the proposed comparator circuit is presented in detail in this paper and compared with that of existing designs. The proposed QCA structure for the comparator circuit only consists of 19 QCA cells with two clock phases. QCA Designer-E and QCA Pro tools are applied to estimate the total energy dissipation. The proposed comparator saves 24.00% QCA cells, 25.00% cell area, 37.50% layout cost, and 78.11% energy dissipation compared with the best reported similar design.     

Highly Emissive,Water‐Repellent,Soft Materials: Hydrophobic Wrapping and Fluorescent Plasticizing of Conjugated Polyelectrolyte via Electrostatic Self‐Assembly

Sulfonated poly(diphenylacetylene) (SPDPA) is used as an anionic conjugated polyelectrolyte to examine stoichiometric electrostatic self‐assembly with homologous cationic surfactants (octadecyl)_X(methyl)_Y ammonium bromides (O_XM_YABs) having different numbers of long hydrophobic tails. The SPDPA–O_XM_YAB complexes formed show significantly increased water contact angle and enhanced fluorescence (FL) emissions compared with the pristine SPDPA. The complexes exist in a gum state at room temperature owing to the plasticizer effect of the hydrophobic tails, hence they are very soft and highly stretchable. The hydrophobicity, softness, and FL quantum efficiency of the SPDPA–O_XM_YAB complexes increase as the number of hydrophobic tails increases. SPDPA adsorbs uniformly onto filter papers to produce fluorescent papers. The SPDPA‐adsorbed papers have many unique applications, including FL image writing, fingerprinting, stamping, and inkjet printing using the surfactant solutions as an ink to reveal high‐resolution FL images. In particular, multideposit inkjet‐printing using SPDPA and O_XM_YAB solutions as inks produces water‐resistant, embedded figures in paper currency.     

Self‐Assembly and Metallization of Resorcinarene Microtubes in Water

Amphiphilic resorcinarene‐based multiwalled microtubes, millimetres in diameter and centimetres in length, are generated in water. The thickness of the tube wall approaches 300 nm. Their self‐assembly properties are investigated using transmission electron microscopy, scanning electron microscopy, atomic‐force microscopy, dynamic light scattering, X‐ray diffraction, UV‐vis spectra, and Fourier transform IR techniques. From these studies, the structures critical for the self‐assembly of resorcinarene into microtubes in aqueous media are determined. Furthermore, the study manifests a feasible method that aims to completely change the structure from a microtube to a sheet‐like morphology by selectively eliminating key groups. Subsequently, resorcinarene‐capped water‐soluble gold nanoparticles (AuNPs) are fabricated. By utilizing the obtained microtubes as a template, a gold/organic microtubular composite is successfully prepared.     

Controlled Sequential Assembly of DNA Nanoparticles Inside Cells Enabling Mitochondrial Interference

Developing artificial material systems to rationally interfere with organelles is emerging as a promising route to regulate the behaviors and fate of cells, thus providing new therapeutic strategies. Herein, a DNA nanoparticles (DNPs)-based material system is reported, which achieves controlled sequential assembly inside cells, and realizes specific interference toward mitochondria. Two types of DNPs are synthesized via radical polymerization, followed with cascade hybridization chain reaction of hairpin DNA with Cyanine5 (Cy5) for mitochondrial targeting, and with complementary sequences for base pairing, respectively. DNPs with Cy5 (Cy5-DNPs) first entered cells to target mitochondria, and the other DNPs with complementary sequences entered cells after an interval to sequentially assemble with Cy5-DNPs into aggregates via base pairing. Mitochondrial interference is achieved, including increased reactive oxygen species, decreased membrane potential, abnormal elevation of Ca²⁺ level, decreased adenosine triphosphate, and attenuated cellular migration rate. In particular, by regulating the intervals of two types of DNPs entering cells, the mitochondrial interference degree is controllably modulated. This work achieves regulated organelles interference via the precise controlled self-assembly of DNA nanostructures inside cells, which is envisioned to have great potential in precision biomedicine.     

A Smart DNA Nanoassembly Containing Multivalent Aptamers Enables Controlled Delivery of CRISPR/Cas9 for Cancer Immunotherapy

CRISPR/Cas9 system is promising for the reversal of tumor immunosuppression in immunotherapy, but the controlled delivery of CRISPR/Cas9 remains challenging. Herein, the study reported a smart DNA nanoassembly containing multivalent aptamers, realizing the controlled delivery of Cas9/sgRNA ribonucleoprotein (RNP) for enhanced cancer immunotherapy. A single-stranded DNA complementary to sgRNA in the Cas9/sgRNA RNP can initiate a cascade-clamped hybridization chain reaction (C-HCR) to wrap the Cas9/sgRNA RNP up in the DNA nanoassembly. After selective internalization of DNA nanoassembly by cancer cells, Cas9/sgRNA RNP is released to cytoplasm in response to endogenous RNase H and enters the nuclei to knock out β-catenin. The expression of the programmed death-ligand one gene is effectively suppressed, and the immunosuppressive tumor microenvironment is reprogrammed. Meanwhile, the migration of cancer cells is inhibited, and the apoptosis of cancer cells is promoted. In a breast cancer mouse model, the administration of DNA nanoassembly effectively increased the infiltration of CD8⁺ T cells, eventually achieving high therapeutic efficacy.     

Self‐Assembled Conjugated Thiophene‐Based Rotaxane Architectures: Structural,Computational, and Spectroscopic Insights into Molecular Aggregation

A comparative study of the self‐assembly at a variety of surfaces of a dithiophene rotaxane 1 ?β‐CD and its corresponding dumbbell, 1, by means of atomic force microscopy (AFM) imaging and scanning tunneling microscopy (STM) imaging on the micrometer and nanometer scale, respectively. The dumbbell is found to have a greater propensity to form ordered supramolecular assemblies, as a result of π–π interactions between dithiophenes belonging to adjacent molecules, which are hindered in the rotaxane. The fine molecular structure determined by STM was compared to that obtained by molecular modelling. The optical properties of both rotaxane and dumbbell in the solid state were investigated by steady‐state and time‐resolved photoluminescence (PL) experiments on spin‐cast films and diluted solutions. The comparison between the optical features of the threaded and unthreaded systems reveals an effective role of encapsulation in reducing aggregation and exciton migration for the rotaxanes with respect to the dumbbells, thus leading to higher PL quantum efficiency and preserved single‐molecule photophysics for longer times after excitation in the threaded oligomers.