Nanomaterials with zwitterionic surfaces exhibit exceptional resistance to nonspecific binding of proteins and cells, but zwitterionic coatings for quantum dots (QDs) have not yet been widely explored. We designed new zwitterionic multidentate polymer ligands to produce colloidally stable, homogeneous, compact and non-fouling QDs with efficient conjugation to biomolecules. We modulated the structures of hydrophilic domains of these polymers surface by tuning linker lengths and chemistry, focusing on zwitterion groups such as lysine (lys) and oligo(ethylene glycol) (OEG) (Fig. 1a). In all cases, gel chromatography showed that the coated QDs were similar in hydrodynamic diameter (Fig. 1b). We directly compared the performance of these QDs in resisting nonspecific binding to globular proteins and cells using fluorescence correlation spectroscopy, flow cytometry, and fluorescence microscopy. We surprisingly discovered that QDs with a 1:1 combination lysine and OEG outperformed all others, including lysine or OEG alone. Furthermore, lysine residues allow facile conjugation with amine reactive biomolecules (Fig. 1d). We anticipate that these outcomes can help improve the use of zwitterionic coatings for QDs by further eliminating nonspecific binding in biomolecular imaging and detection applications.

Zwitterionic multidentate polymer coating for non-fouling quantum dots

2019 Spring National Meeting

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