Hydrazone exchange in nanoparticle monolayers : a dynamic covalent approach for controlling nanomaterial properties

Abstract

This Thesis reports the synthesis, purification and characterisation of gold nanoparticles (NPs) functionalised with a monolayer of hydrazone ligands in order to perform post-synthetic manipulations of the NP-bound monolayer exploiting dynamic covalent chemistry. NP post-synthetic manipulation based on reversible non-covalent interactions between oligonucleotides represents a promising approach to achieve functionalisation and self-assembly for potential applications in biology and medicine. However, the stability of these nanosystems is ensured only in a narrow window of environmental conditions. On the other hand, irreversible covalent strategies potentially allow the full range of synthetic chemistry to be exploited but they provide poor control over the manipulation of the NP-bound monolayer and can only produce kinetically controlled amorphous NP aggregates. Dynamic covalent chemistry represents an interesting and an attractive alternative approach because it would combine the reversibility of non-covalent interactions with the stability of covalent bonds. By this way, ligand-functionalised NPs could be manipulated in order to introduce a large variety of molecular functionalities on the NP surface not only to subtly tune the NP physicochemical properties but also to access an entire range of novel nanomaterials.