ABSTRACT
This chapter discusses the use of polaritonic resonances in chiral nanostructures for biosensing applications. It describes how chiral optics emerged, including natural optical activity and the observed chiroptical effects. The chapter then addresses the chiroptical effects in flat chiral nanostructures and discusses the application of chiral nanostructures in the realm of biosensing for detection of chiral biomolecules. Optical activity was first observed in the colors of sunlight that passed through the optical axis of a quartz crystal placed between crossed polarizers. Flat chiral nanostructures are the most studied systems that provide a high dissymmetry factor together with wide coverage critical for sensing applications. Superchirality in such structures has been demonstrated in many designs of single and multi-layer systems made of metallic and dielectric materials. The nanoengineering strategies developed for chiral structures can be related to the concepts originated in chiral molecules. Many of the concepts associated with chirality initially developed for molecules are also applicable to nanostructures.
