Clicking DNA to gold nanoparticles: poly-adenine-mediated formation of monovalent DNA-gold nanoparticle conjugates with nearly quantitative yield

Abstract

Monovalent DNA–gold nanoparticle (mDNA–AuNP) conjugates hold great promise for widespread applications, especially the construction of well-defined, molecule-like nanosystems. Previously reported methods all rely on the use of thiolated DNA to functionalize AuNPs, resulting in relatively low yields. Here, we report a facile method to rapidly prepare mDNA–AuNPs using a poly-adenine (polyA)-mediated approach. As polyA can selectively bind to AuNPs with high controllability of the surface density of DNA, we can use a DNA strand with a sufficiently long polyA to wrap around the surface of an individual AuNP, preventing further the adsorption of additional strands. Based on this observation, we obtained mDNA–AuNPs with a nearly quantitative yield of ~90% using 80 As, as confirmed by both gel electrophoresis and transmission electron microscope observation. The yields of mDNA–AuNPs were insensitive to the stoichiometric ratio between DNA and AuNPs, suggesting the click chemistry-like nature of this polyA-mediated reaction. mDNA–AuNPs exhibited rapid kinetics and high efficiency for sequence-specific hybridization. More importantly, we demonstrated that AuNPs of fixed valences could form well-defined heterogenous oligomeric nanostructures with precise, atom-like control. An easy, one-step, high-yield (~90%) way of preparing gold nanoparticles functionalized with monovalent DNA is reported by a team in China. Monovalent DNA–gold nanoparticle conjugates have many uses, such as acting as building blocks for the bottom-up construction of nanosystems. Common synthesis methods, however, use thiolated DNA and suffer from low yields. The method reported here, which was developed by researchers at Sichuan University and the Chinese Academy of Sciences, employs a new strategy that uses polyadenine to mediate the functionalization of gold nanoparticles. It involves wrapping the surfaces of the gold nanoparticles with DNA strands attached to sufficiently long lengths of polyadenine, which prevents additional DNA strands being adsorbed. The researchers show the potential of their method by using gold nanoparticles of fixed valences to form oligomeric nanostructures with precise, atom-level control. PolyA can selectively bind to AuNPs with similar affinity to thiolated DNA and better control of the surface density of DNA, which results in the formation of monovalent DNA-gold nanoparticle conjugates . mDNA–AuNPs with in a click chemistry-like manner.