13 July 2017
SDG3: Good health and well-being, monolayer-protected nanoparticles, NMR chemosensing, molecular dynamics of gold nanoparticles, molecular recognition, self-organization, NMR relaxation, AuNP, NOE, molecular simulations
The self-assembly of a monolayer of ligands on the surface of noble-metal nanoparticles dictates the fundamental nanoparticle's behavior and its functionality. In this combined computational-experimental study, we analyze the structure, organization, and dynamics of functionalized coating thiols in monolayer-protected gold nanoparticles (AuNPs). We explain how functionalized coating thiols self-organize through a delicate and somehow counterintuitive balance of interactions within the monolayer itself and with the solvent. We further describe how the nature and plasticity of these interactions modulate nanoparticle-based chemosensing. Importantly, we found that self-organization of coating thiols can induce the formation of binding pockets in AuNPs. These transient cavities can accommodate small molecules, mimicking protein-ligand recognition, which could explain the selectivity and sensitivity observed for different organic analytes in NMR chemosensing experiments. Thus, our findings advocate for the rational design of tailored coating groups to form specific recognition binding sites on monolayer-protected AuNPs.
The functionalization of monolayer-protected nanoparticles is at the frontier of nanotechnology, such that innovative applications are emerging in fields such as nanomedicine, chemosensing, and even catalysis. Importantly, the nanoparticle's functionality is mainly defined by the nature of the ligands forming the coating monolayer. Here, we show how the self-organization of functionalized coating ligands in monolayer-protected gold nanoparticles (AuNPs) affects their solubility and molecular recognition abilities. We found that coating ligands form transient, protein-like binding pockets in functionalized AuNPs. Thus, we reveal that nanoparticle-based chemosensing operates through a recognition process that is similar to that for protein-ligand complex formation. These findings could now herald the arrival of the computational nanodesign of intelligent nanodevices with recognition abilities toward small molecules such as drugs, metabolites, illegal drugs, and small molecular markers for cancer.
Functionalized gold nanoparticles (AuNPs) can perform different tasks, which depend on the coating ligands that cover the metal core. By combining NMR experiments and molecular-dynamics simulations, De Vivo and colleagues reveal how different ligands can self-organize to modulate molecular recognition ability in AuNPs. Results show how the composition, organization, and plasticity of coating ligands affect the selectivity and sensitivity observed for different organic analytes in NMR chemosensing experiments. These findings offer a unique perspective for the rational design of intelligent nanodevices.