ABSTRACT
The emergence of plasmonic nanostars with their attractive properties and unique versatility has enabled a wide range of advanced technologies critical to human health, safety, energy, and environmental remediation with vast potential for further exploration. In addition to their superior surface-to-volume ratios compared to those of other plasmonic nanostructures, plasmonic nanostars arguably possess the largest numbers of hotspots with intensely amplified electric fields when they are subjected to suitable electromagnetic waves to trigger localized surface plasmon resonance (LSPR). These outstanding characteristics make plasmonic nanostars ideal for many applications that benefit from the plasmonic enhancement effect of LSPR and/or the large surface area. Over the past decade, an increasing number of research endeavors has been reported on the synthesis and application of plasmonic nanostars to advance the state-of-the-art for various existing technologies. These contributions are pertinent to real-time image-guided multifunctional anticancer theranostics, the ultrasensitive on-site detection of the devastating virus SARS-CoV-2, multimodal multiplexed brain imaging, greatly enhanced catalysts for energy and environmental processes, or more efficient and stable solar cells. In addition to the enhancement of important but familiar technologies, plasmonic nanostars have also been employed to push the technological frontiers in multiple fields to enable applications such as maskless write-on lithography, nanosized field electron emitters, coherent random lasers, neural activity modulation, and optically controlled electrical currents. Despite great performance in various fields since their introduction, the nascency of this unique class of plasmonic nanostructures and the rise of unique types of plasmonic nanostars, in addition to the dominance of gold nanostars in recent years, indicate that there are still many opportunities for study, exploration, and development. This Review outlines a comprehensive picture of the current state of plasmonic nanostar research with a focus on their technological and scientific applications. We hope this Review will enlighten future collective endeavors to develop more effective plasmonic nanostars and incorporate them into mainstream technologies so that these stars can truly shine.