Supramolecular Click Chemistry for Surface Modification of Quantum Dots Mediated by Cucurbit[7]uril

Abstract

Cucurbiturils (CBs), barrel-shaped macrocyclic molecules, are capable of self-assembling at the surface of nanomaterials in their native state, via their carbonyl-ringed portals. However, the symmetrical two-portal structure typically leads to aggregated nanomaterials. We demonstrate that fluorescent quantum dot (QD) aggregates linked with CBs can be broken-up, retaining CBs adsorbed at their surface, via inclusion of guests in the CB cavity. Simultaneously, the QD surface is modified by a functional tail on the guest, thus the high affinity host–guest binding (logK a > 9) enables a non-covalent, click-like modification of the nanoparticles in aqueous solution. We achieved excellent modification efficiency in several functional QD conjugates as protein labels. Inclusion of weaker-binding guests (logK a = 4–6) enables subsequent displacement with stronger binders, realising modular switchable surface chemistries. Our general “hook-and-eye” approach to host–guest chemistry at nanomaterial interfaces will lead to divergent routes for nano-architectures with rich functionalities for theranostics and photonics in aqueous systems.

Regulation of microtubule dynamics and function in living cells via cucurbit[7]uril host–guest assembly

“…The high binding affinities of CB[7]·guest complexes facilitate the expansion of host–guest chemistry to dilute and complex environments, which is typically the case in biological settings. 27–39 In addition, the emergence of high-affinity recognition from monovalent complexation decreases the need to exploit the structural and combinatorial complexity of multivalency, thereby providing a straightforward design approach for developing reconfigurable multi-component systems. In recent years, these properties have been strategically exploited to design high-fidelity biomimetic systems for the regulation of proteins/enzymes, nanozymes, supramolecular antibiotics, and platinum-based drugs.…”