基于DNA自组装的金属纳米结构制备及相关纳米光子学研究

纳米光子学是研究光在纳米尺度下的行为以及光和纳米材料相互作用的一门科学.金属纳米材料凭借其独特的表面等离子体效应,可以在衍射极限以下对光进行传递和聚焦,因而是纳米光子学研究的重点.大量研究表明,通过调控金属纳米材料的形貌和成分可以控制表面等离子体的性质,从而对光进行可控调节.近年来,随着DNA纳米技术的发展,又为纳米光子学的发展带来了新的机遇.首先,人们发现不同的DNA序列可以调控金属纳米颗粒的成长,从而影响金属纳米颗粒的形貌和成分.此外,利用DNA自组装技术,可以将金属纳米颗粒组装成为有序可控的纳米结构.因此,基于DNA的纳米光子学研究近年来发展十分迅速.在此背景下,本文对相关研究进行归纳与总结,以期吸引更多研究人员的关注,推动该领域的进一步发展.本文首先介绍了金属纳米结构基于表面等离体实现突破光学衍射极限的原理,然后按照DNA对金属纳米结构的形貌或成分影响方式的不同分成若干部分,对基于DNA的纳米光子学做了系统的综述,最后展望了未来可能的发展方向.

DNA self-assembly-based fabrication of metallic nanostructures and related nanophotonics

Nanophotonics focuses on the study of the behavior of light and the interaction between light and matter on a nanometer scale. It has often involved metallic nanostructures which can concentrate and guide the light beyond the diffraction limit due to the unique surface plasmons (SPs). Manipulation of light can be accomplished through controlling the morphologies and components of metallic nanostructures to incur special surface plasmons. However, it is still a severe challenge to achieve exquisite control over the morphologies or components of metallic nanostructures: chemical methods can provide anisotropic but highly symmetric metallic nanostructures; lithographic methods have a limited resolution, especially for three-dimensional metallic nanostructures. By comparison, DNA self-assembly-based fabrication of metallic nanostructures is not restricted to these confinements. With the high-fidelity Waston-Crick base pairing, DNA can self-assemble into arbitrary shapes ranging from the simplest double strands to the most sophisticated DNA origami. Due to the electrostatic interactions between negatively charged phosphate backbones and positively charged metal ions, DNA of any shapes can affect the metal ions or atoms to a certain degree. Depending on the shape and base, DNA self-assembly nanostructures can exert different influences on the growth of metallic nanoparticles, which in turn gives rise to deliberately controllable metallic nanostructures. Besides, DNA self-assembly nanostructures can act as ideal templates for the organization of metallic nanoparticles to construct special metallic nanostructures. In this case, DNA-modified metallic nanoparticles are immobilized on DNA self-assembly nanostructures carrying complementary sticky ends. The geometry and component arrangements of metallic nanostructures both can be precisely dictated on the DNA nanostructures by programming the sticky end arrays. Complicated metallic nanostructures which can be hardly fabricated with conventional chemical or lithographic methods have been readily prepared with the DNA self-assembly-based fabrication method, thereby greatly promoting the development of nanophotonics. Therefore, the studies of DNA self-assembly-based fabrication of metallic nanostructures and related nanophotonics have received rapidly growing attention in recent years. This review first gives a brief introduction of the mechanism for breaking the diffraction limit of light with metallic nanostructures based on SPs. Then we give a systematic review on DNA self-assembly-based fabrication of metallic nanostructures and related nanophotonics, which is divided into several parts according to the different pathways by which DNA self-assembly can influence the morphologies or components of metallic nanostructures. Finally, the remaining problems and limitations for the existing DNA self-assembly-based fabrication of metallic nanostructures are presented and an outlook on the future trend of the field is given as well.