Targeted gold nanoshells

Gold nanoshells, also known as gold nanospheres (AuNSs), have been intensively studied over the past decade owing to their inherent localized surface plasmon resonance. By changing the core size, gold shell thickness, and/or composition of the particles, the plasmomic resonance of AuNSs can be made to absorb from the visible region to the near-infrared (NIR) region of the spectrum. The NIR region is very attractive because water and naturally occurring fluorochromes have the lowest absorption coefficient in this region and therefore, light can penetrate deeper into the tissues. AuNSs can also be conjugated with imaging reporters and can carry drug payloads, genes, and other chemotherapeutic agents for theranostic applications. Although they can passively accumulate in tumors, AuNSs can be functionalized with active targeting ligands such as antibodies, aptamers, and peptides to increase the particles' specific binding to desired targets. This chapter provides an up-to-date review of targeted, NIR light-activatable AuNSs used in cancer theranostics and drug delivery systems and focuses on AuNSs conjugated with active targeting ligands.