【作者】 王振兴；

【导师】 侯建国； 王晓平；

【作者基本信息】 中国科学技术大学 ， 凝聚态物理， 2009， 博士

【摘要】 随着纳米科技的发展,“自上而下”（Top-Down）和“自下而上”（Bottom-up）技术已经成为构建基于低维纳米结构的各种功能纳米器件或分子器件的主要方法。在构建纳米或分子器件过程中,如何实现高效、可靠、可重复的各功能单元或分子的定位、组装和连接,是人们必须解决的关键挑战之一。伴随纳米器件尺寸的不断减小,“Top-Down”技术将不得不面对工艺复杂、成本高昂和各种物理效应等因素的限制,因此进一步发展和完善基于自组装为特征的“Bottom-up”技术,并拓展其同“Top-Down”技术的结合,已成为纳米器件研究领域关注的焦点。由于具有纳米尺度的分子直径、分子内和分子间的特异识别特性、良好的力学性能、负电性的磷酸骨架结构等特质,DNA分子在自组装技术和功能纳米器件的构建中已经扮演了十分重要的角色。本论文以发展纳米器件的设计、制备和组装为研究目标,充分发挥DNA的上述特性,较为细致地开展了基于DNA为模板的金属半导体一维纳米结构的制备和纳米器件的设计与组装技术的探索。主要内容分述如下:第一章,首先简要介绍了同纳米材料和纳米器件相关的纳米技术的发展历程,随后概述介绍了纳米技术和生物技术的交叉融合及焕发勃勃生机的纳米生物学,最后总结了本论文的研究内容和目的。第二章,开展了以DNA为模板的CdS纳米线的制备与物性表征。我们结合DNA梳理技术、纳米转移印刷技术和光化学反应技术,发展出一种基于PDMS转移法的半导体CdS纳米线制备方法。通过对反应时间、反应浓度的优化控制,可以获得高产率、高密度并且整齐排列的纳米线结构。该方法制备的CdS纳米线呈现结构致密、形貌和尺寸可控、衬底表面杂散颗粒少等特点,并且这一方法还具有产率高、重复性好、通用性强的优势。第三章,侧重基于DNA模板的金属Pd纳米线的制备与物性研究。分别利用常规法、水相UV法、乙醇还原PDMS转移法三种方法,完成了Pd纳米线的制备。通过对三种方法制备的纳米线的形貌、直径、密度等主要参数的对比研究发现乙醇还原PDMS转移法是最优化的方法。这种方法合成的纳米线具有连续度佳、直径大、长度长、衬底杂散颗粒少等优点。此外,我们还着重讨论了乙醇还原PDMS转移法的制备反应机理,以及纳米线的电学性质等。第四章,我们分别讨论了Pd（NH₃）₄Cl_·H₂O和CdS两种纳米线的自组装特性。对于Pd（NH₃）₄Cl₂·H₂O纳米线,通过控制反应时间,能够实现纳米线高度和长度的可控生长。通过选择合适的衬底,并借助外延生长要求晶格匹配的限制生长条件,我们还实现了Pd（NH₃）₄Cl₂·H₂O纳米线在云母表面的六方取向排列的规则生长。对于CdS纳米线,通过TAA分子自组装形成的“模板”作用,发现可通过Cd（Ac）₂和IAA的反应形成几十纳米直径的CdS纳米线,并且这种纳米线具有很好的发光性质。第五章,提出了一种利用Biotin-Streptavidin体系组装DNA的方法.我们采用深紫外光刻术完成了金电极的制备,通过PCR技术实现了Biotin-DNA的扩增,用分子膜组装技术分别实现了Streptavidin的组装和Biotin-DNA的组装。此外,我们还借助QCM方法,较系统地研究了上述分子的组装过程及相关机理。更多还原

【Abstract】 A significant challenge in integrating nanoscale building blocks into functional nanodevices or circuits is finding parallel,cost-effective,and simple methods of assembling the nanostructures,such as nanoparticle,nanowire and nanotube.With the size of nanodevices shrinking,it has become quite clear that the conventional "top-down" approaches are beset with many difficulties,such as more complicated techniques,higher cost and even some fundamental physical limitations.This state of affairs has led to great interest in the development of new methodologies based on "bottom-up" approaches.In particular,DNA has already been extensively used to construct various nanostructures and nanodevices recently,due to its unique properties including intermolecular and intramolecular recognition,special chemical structure,mechanical rigidness and nanoscale diameter.The self-assembly technology of nanowires based on the DNA template has been widely demonstrated by a great deal of researchers and their potential applications for the functional nanodevices or circuits were also been explored.The main contents of the dissertation can be summarized as follows:In ChapterⅠ,we first introduced briefly the development history of nanomaterials and nanodevices.Then,we described some important applications of nanotechnologies in biology area.Finally,the motivation and main contents of this dissertation were summarized.In ChapterⅡ,we have developed a simple,yet highly effective and reliable, poly（dimethylsiloxane）（PDMS） transfer method to fabricate highly dense and well-aligned CdS nanowires on silica substrates,following DNA templates.This method combined DNA combing technique,nanotransfer-printing and photochemical reaction techniques.CdS nanoparticles are selectively deposited and confined on DNA strings aligned on a PDMS sheet to form CdS nanowires.The nanowires are then transferred to the substrate with a low occurrence of parasitic CdS nanoparticles. The width and length of the nanowires can be controlled by adjusting the incubation time on the PDMS sheet.Lastly,theⅠ-Ⅴmeasurement of the CdS nanowire was also performed.In ChapterⅢ,we fabricated Pd nanowires respectively by three different methods:direct method on mica surface,photochemical method in aqueous solution and PDMS-transfer method in ethanol solution.The morphologies,diameters,density and continuity of the Pd nanowires synthesized by three methods were carefully investigated and characterized.It was found that the Pd nanowires fabricated by the PDMS-transfer method in ethanol solution had thick diameter,long length,dense density,low numbers of parasitic CdS nanoparticles on the surface and high conductance.In addition,the growth mechanics related to the method was also proposed.In ChapterⅣ,we demonstrated that a palladium chloride aqueous solution, mixed with a proper ammonia solution,could produce Tetra-amminepalladous chloride（Pd（NH₃）₄Cl₂·H₂O） nanowires.These nanowires can spontaneously form the two-dimensional hexagon-oriented Pd（NH₃）₄Cl₂·H₂O arrays on mica surfaces.We can control the length and height of these nanowires by adjusting their deposit time on the mica substrate.In addition,we developed a simple,effective method,based on the self-assembly of TAA on Cd（Ac）₂ film,to fabricate thick,luminescent CdS nanowires on mica surface.In ChapterⅤ,we proposed a method to construct DNA-templated nanodevice based on the interaction between biotin and streptavidin.Au microelectrodes with 4μm gap were fabricated by deep UV lithography and the biotin labeled DNA with about 20k b.p.length was synthesized by PCR method.Through self-assembly approach,the streptavidin molecules were first assembled on the Au film and then the biotin-DNA molecules were assembled on the streptavidin layer.The assembly processes were carefully characterized by QCM-D technique and the corresponding mechanisms were also discussed.更多还原