For use in biological applications, semiconductor quantum dots (QDs) must be transferred from their native organic phase into aqueous media. Polymeric or small molecule ligands facilitate water solubility while conferring colloidal stability through either steric hinderance or charge repulsion. We demonstrate a novel polymer functionalization that produces a carboxybetaine-like coating for QDs. This polymer formulation takes advantage of the high stability observed in nanoparticles exhibiting both positive and negative charges on their surface without requiring the synthesis or handling of small molecule zwitterions. This polymer coating uses readily available reagents to functionalize commercially available poly(anhydride maleic-<i>alt</i>-isobutylene) (PIMA) with a quaternary amine to balance charges from carboxylic acids on the polymer backbone, avoiding the synthetic and solubility challenges typically associated with working with zwitterionic moieties. The resulting particle surface charge is much closer to neutral than the similar, but more complicated, materials that inspired this work. In addition to the charge-based stabilization, the polymer also provides copper-free click-chemistry handles for subsequent biofunctionalization. As a demonstration of the ease with which this subsequent functionalization proceeds, we demonstrate the grafting of DNA oligomers to the surface of the QDs with &gt;95 % efficiency, reducing the amount of DNA used for conjugation and eliminating the need to remove unbound DNA prior to use of the QD-DNA conjugate. The simplicity of the polymer preparation ensures that the coating approach will be accessible to a range of chemistry and biological research.

Click chemistry-ready zwitterionic quantum dots exhibiting high DNA grafting efficiency

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.