Advanced Review DNA-based plasmonic nanoarchitectures: from structural design to emerging applications Yi Chen 1,2 and Wenlong Cheng 1,2∗ Plasmonic nanoarchitectures refer to the well-deﬁned groupings of elementary metallic nanoparticle building blocks. Such nanostructures have a plethora of technical applications in diagnostics, energy-harvesting, and nanophotonic circuits, to name a few. Nevertheless, it remains challenging to construct plasmonic nanoarchitectures at will inexpensively. Bottom-up self-assembly is promising to overcome these limitations, but such methods often produce defects and low-yields. For these purposes, DNA has emerged as a powerful nanomaterial beyond its genetic function in biology to either program or template synthesis of plasmonic nanostructures, or act as a ligand to mediate large-area self-assembly. In conjunction with top-down lithography, DNA-based strategies can afford excellent control over internal and overall structures of plasmonic nanoarchitectures. In this review, we outline the representative methodologies for building various well- deﬁned plasmonic nanoarchitectures and cover their recent exciting applications. © 2012 Wiley Periodicals, Inc. How to cite this article: WIREs Nanomed Nanobiotechnol 2012. doi: 10.1002/wnan.1184 INTRODUCTION I t is an essential task in modern nanoscience and nanotechnology to understand light–matter interactions at the nanoscale as well as to develop the capability to precisely manipulate light by nanomaterials. Construction of well-deﬁned plasmonic nanoarchitectures from elementary metallic nanoparticle building blocks constitutes an exciting route to control light propagation below the diffraction limit. Such plasmonic structures can precisely concentrate, guide and switch light at the nanoscale, 1,2 which is leading to the development of next-generation technologies for a broad spectrum of applications, such as in miniaturized optical 2 and electronic devices, 3,4 sensors 5 and photonic circuits, 6 and medical diagnostics and therapeutics 7,8 Thanks to the worldwide efforts in developing synthetic approaches with wet chemical techniques, ∗ Correspondence to: wenlong.cheng@monash.edu 1 Department of Chemical Engineering, Monash University, Clayton, Victoria, Australia 2 The Melbourne Centre for Nanofabrication, Clayton, Victoria, Australia a wide range of recipes are available to control the key morphological parameters of metallic nanoparticles. 9–14 In general, a particle’s speciﬁc size and shape produces a unique optical signa- ture, allowing it to serve as ‘artiﬁcial plasmonic atom’. 15 The following task, then, is to ﬁnd an efﬁcient way to group these artiﬁcial atoms into well-deﬁned plasmonic architectures including vecto- rial (or directional) grouping of ﬁnite numbers of nanoparticle, 16,17 one-dimensional regularly-spaced nanoparticle chains, 18,19 two-dimensional ordered arrays 20–22 and three-dimensional ordered nanoparti- cle assemblies, 23–28 which we term in this review ‘plas- monic molecules’, ‘plasmonic polymers’, ‘plasmonic sheets’, and ‘plasmonic crystals’, respectively. The recently developed plasmon hybridization theory 29 justiﬁes the need to construct plasmonic nanoarchitec- tures to substantially expand the scope of plasmonics to spur various technical applications. 30 Nevertheless, it is nontrivial to rationally group nanoparticles together due to complex nanoscale forces at different spatial and temporal scales. Unless precise control can be exercised over these forces, particularly to achieve high ﬁdelity of vectorial © 2012 Wiley Periodicals, Inc.