Anisotropic Gold Nanoparticles: Synthesis, Properties, Applications, and Toxicity

TLDR

Anisotropic gold nanoparticles have attracted interest for over a century, but research accelerated since 2000 with many 1D, 2D, 3D, and hollow shapes whose anisotropy enables tunable plasmon absorption in the visible and near‑infrared, enabling applications in diagnostics, therapy, optical devices, and catalysis. This review surveys the history, synthesis, shapes, applications, and toxicity of anisotropic gold nanoparticles. The review summarizes synthetic methods, shape diversity, application areas, and toxicity concerns of these nanomaterials.

Abstract

Abstract Anisotropic gold nanoparticles (AuNPs) have attracted the interest of scientists for over a century, but research in this field has considerably accelerated since 2000 with the synthesis of numerous 1D, 2D, and 3D shapes as well as hollow AuNP structures. The anisotropy of these nonspherical, hollow, and nanoshell AuNP structures is the source of the plasmon absorption in the visible region as well as in the near‐infrared (NIR) region. This NIR absorption is especially sensitive to the AuNP shape and medium and can be shifted towards the part of the NIR region in which living tissue shows minimum absorption. This has led to crucial applications in medical diagnostics and therapy (“theranostics”), especially with Au nanoshells, nanorods, hollow nanospheres, and nanocubes. In addition, Au nanowires (AuNWs) can be synthesized with longitudinal dimensions of several tens of micrometers and can serve as plasmon waveguides for sophisticated optical devices. The application of anisotropic AuNPs has rapidly spread to optical, biomedical, and catalytic areas. In this Review, a brief historical survey is given, followed by a summary of the synthetic modes, variety of shapes, applications, and toxicity issues of this fast‐growing class of nanomaterials.