Conjugation strategies of DNA to gold nanoparticles

DNA-modified gold nanoparticles (NPs) have been extensively explored in various applications including the construction of three-dimensional (3D) assembly architectures and biomedical applications. As ligand molecules, DNA strands can facilitate the building block function of gold NPs due to the inherent nature of DNA bonding, that is, Watson-Crick base pairing. In addition, the negative electrostatic character of DNA backbones renders colloidal gold NPs stability and robustness under various aqueous environments. Therefore, DNA conjugation to gold NP surfaces is a key step for stabilizing, controlling, and utilizing DNA-modified gold NPs, and the working conjugation strategy should be employed and implemented for a specific application. This review covers various DNA conjugation strategies to gold NPs with fundamental binding features of DNA strands with varying functional groups to gold NP surfaces. DNA grafting density and directional grafting strategies on gold NPs are also discussed, which is a key factor to construct 3D NP assembly architectures via DNA hybridization.