Biofunctionalization of gold nanorods

Gold nanorods (NRs) are promising nanomaterials for biotechnology innovations that include photoassisted drug delivery, gene therapy, noninvasive cancer detection, and ultrasensitive biodetection. Owing to their unique geometry, Au NRs exhibit surface plasmon (SP) modes in the near-infrared (IR) wavelength range-ideal for carrying out optical measurements in biological fluids and tissue. Because NR interactions highly depend on the chemical nature of their solvent-accessible interface, it is necessary to carry out specific post-synthetic chemical modifications of the Au surface to create NRs that are biocompatible and biofunctional. In this review, we discuss various NR surface chemistries that have successfully enabled the integration of Au NRs into biological environments, as well as current challenges in designing the biofunctional NR interface for in vivo applications.