【作者】 董强；

【导师】 吴晓静； 陈志宇；

【作者基本信息】 合肥工业大学 ， 材料工程（专业学位）， 2021， 硕士

【摘要】 DNA分子不仅是一种携带并传递遗传信息的重要生物大分子,也是一种可用于构建微纳尺度精巧结构的组装基元。二十世纪八十年代,Nadrian C.Seeman教授率先提出采用DNA分子作为组装基元构筑高级有序结构,开启了DNA纳米技术这一领域。DNA纳米技术的蓬勃发展为材料、化学、生物计算、医学等众多领域的交叉研究提供了各种机会。DNA功能化纳米金不仅具有纳米金颗粒的优良性质,而且拥有来自DNA的可编程组装能力,在纳米材料可控组装、基因调控和药物输送等诸多方面有着广泛的应用前景。本论文围绕DNA功能化纳米金寡聚结构的制备进行了以下两方面研究,阐述如下:1.发展了一种制备DNA功能化强偶联纳米金寡聚体的简便方法。在纳米金的DNA功能化过程中,我们通过改变巯基DNA浓度或者改变溶液p H值,以调控纳米金的DNA功能化过程动力学,一步法制备了DNA功能化的纳米金强偶联寡聚结构,并结合凝胶电泳分离方法获得了组成单一的寡聚产物,如二聚体、三聚体等。本工作中,我们首先以球形金纳米颗粒(Au NP)为构筑基元,通过改变DNA浓度制备了二聚体DNA-(Au NP)2、三聚体DNA-(Au NP)3。常规透射电镜及冷冻电镜结果证实了纳米金寡聚组装结构,统计分析表明所得二聚体和三聚体的纯度分别高达89%和76%。吸收光谱和拉曼散射光谱证实寡聚结构具有较强的等离激元强偶联性质。进一步,我们通过改变溶液p H值的方法,实现了DNA功能化强偶联Au NP寡聚体的快速制备。为了验证该策略的通用性,我们采用金纳米棒(Au NR)为构筑基元,利用改变溶液p H值的方法制备得到了DNA功能化的金纳米棒强偶联寡聚结构。结合透射电镜显微表征及吸收光谱,证实Au NR之间主要通过“肩并肩”方式形成了强偶联的二聚、三聚等结构。最后,我们基于DNA可编程组装特性,构筑了核-壳卫星组装结构;基于等离激元强偶联性质,探索了Au NP寡聚体的表面拉曼增强性质。该方法简单便捷,不需要使用其他交联分子,且适用多种调控手段以及不同纳米基元,有望为纳米等离激元材料的构筑及性质研究提供有力技术支持。2.发展了一种基于DNA模块构建纳米金手性结构的组装方法。首先利用DNA价态控制思路,制备一价Au NP-DNA复合物(一价:即Au NP表面只连接一条DNA分子),然后利用一价Au NP-DNA及其他短链DNA组装DNA三分支模块,通过设计调控三分支模块茎环T碱基不同长度(即调控模块分支不同柔性),构筑具有不同手性的纳米金六聚体组装结构。本工作中,我们已经结合凝胶电泳技术进行了组装产物分析及分离纯化,常规电镜结果显示纳米粒子组装产物主要为Au5NP六聚体。下一步,我们将结合圆二色散光谱表征金纳米粒子手性组装体光谱性质。基于DNA模块策略发展的组装方法简单高效,仅需较少的DNA链,便可实现复杂纳米组装结构的构筑。该方法有望为纳米器件(如手性超材料)构筑提供有效途径。更多还原

【Abstract】 DNA is not only an important biological macromolecule that carries and transmits genetic information,but also an assembly unit that can be used to construct micro nano scaled exquisite structure.In the 1980 s,Professor nadrian C.Seeman first proposed using DNA molecules as assembly units to construct advanced ordered structures,which opened the field of DNA nanotechnology.The vigorous development of DNA nanotechnology provides various opportunities for the cross development of materials,chemistry,biological computing,medicine and other fields.DNA functionalized gold nanoparticles not only has the excellent properties of gold nanoparticles,but also has the ability of programmable assembly from DNA,which has a broad application prospect in the controllable assembly of nanomaterials,gene regulation and drug delivery.Based on the theory and application of DNA functionalized gold nanoparticles,the following two aspects were studied in this paper:1.We have developed a method for the preparation of DNA functionalized gold nanoparticles with high DNA density and strong plasmonic coupling.In the process of DNA functionalization of gold nanoparticles,we changed the DNA concentration of the thiol or changed the p H value of the solution to regulate the kinetics of DNA’s functionalization process.In the one-step process,the DNA functionalized gold nanoparticles with strong plasmonic coupling was prepared.the single oligomers,such as dimer and trimer,were obtained by gel electrophoresis.In this work,we first prepared dimer(DNA-(Au NP)2)and trimer(DNA-(Au NP)3)by changing DNA concentration by using spherical gold nanoparticles(Au NP)as the construction unit.The results of transmission electron microscopy and freeze electron microscopy confirmed the assembly structure of gold oligomer.Statistical analysis showed that the purity of dimer and trimer were as high as 89% and 76% respectively.The absorption spectra showed that the oligomeric structure has strong coupling properties of plasmon.Furthermore,we realized the rapid preparation of DNA functionalized Au NP oligomers by changing the p H value of the solution.In order to verify the generality of this strategy,we used gold nanorod(Au NR)as building unit and prepared DNA functionalized gold nanorods with strong plasmonic coupling by changing the p H value of the solution.Combined with transmission electron microscopy and absorption spectrum,it was confirmed that the structure of strong coupling was formed into Au NRs side by side.Finally,we constructed the core-shell satellite assembly structure based on DNA programmable assembly capability.Based on the strong coupling properties of plasmon,the surface Raman enhancement properties of Au NP oligomers were investigated.The method is simple and convenient,and it does not need other crosslinking molecules,suitable for many kinds of regulatory methods and different nano radicals.It is expected to provide strong technical support for the construction and properties of the materials.2.An assembly method based on DNA module to construct chiral structure of gold nanoparticles was developed.First,based the idea of DNA valence state control to prepare univalent Au NP-DNA complex(univalent: only one DNA molecule is connected to the surface of Au NP),we used the principle of DNA module assembly to realize DNA assisted chiral structure controllable assembly of gold nanoparticles.we have tried to construct hexamer of gold nanoparticles with straight triangular prism conformation,and change the length of T base of three branch module stem rings to achieve the experimental purpose of controllable assembly of chiral structure.In this work,we have analyzed and purified the assembled products by gel electrophoresis.Combined with transmission electron microscopy,we characterized the products.The assembly method based on DNA module strategy is simple and efficient,which can realize the construction of complex nano assembly structure with less DNA strand.This method is expected to provide an effective way for the construction of nano devices,such as chiral metamaterials.更多还原