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

McGuire, Katie; He, Suhang; Gracie, Jennifer; Bryson, Charlotte; Zheng, Dazhong; Clark, Alasdair W; Koehnke, Jesko; France, David J et al. · ACS Nano · 2023

basic_science · Level V

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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 (log<i>K</i><sub>a</sub> > 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 (log<i>K</i><sub>a</sub> = 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.