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Synthesis of functionalized amphiphilic polymers for coating quantum dots

Abstract

Quantum dots (QDs) need to be attached to other chemical species if they are to be used as biomarkers, therapeutic agents or sensors. These materials also need to disperse well in water and have well-defined functional groups on their surfaces. QDs are most often synthesized in the presence of ligands such as trioctylphosphine oxide, which render the nanoparticle surfaces hydrophobic. We present a complete protocol for the synthesis and water solubilization of hydrophobic CdSe/ZnS QDs using designer amphiphilic polymeric coatings. The method is based on functionalization of an anhydride polymer backbone with nucleophilic agents. Small functional groups, bulky cyclic compounds and polymeric chains can be integrated into the coating prior to solubilization. We describe the preparation of acetylene- and azide-functionalized QDs for 'click' chemistry. The method is universal and applicable to any type of nanoparticle stabilized with hydrophobic ligands able to interact with the alkyl chains in the coating in water.

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Figure 1: Synthesis of the amphiphilic polymers.
Figure 2: Scheme of the phase-transfer procedure.
Figure 3
Figure 4
Figure 5: Fixed and live samples of mammalian cancer cells C-6 imaged with red light–emitting QDs coated with polymer 2a; the cell nucleus was stained blue with 4,6-diamidino-2-phenylindole.

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Acknowledgements

We are grateful to the Institute of Materials Research and Engineering of A*STAR, Singapore, for providing financial support.

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Authors

Contributions

All authors contributed extensively to the work presented in this paper. D.J. and N.T. designed the experiments, tested the protocols, carried out the synthetic procedures and edited the paper. M.-Y.H. and G.J.V. designed the experiments, analyzed data and wrote the manuscript. All authors discussed the results and implications and commented on the manuscript at all stages.

Corresponding author

Correspondence to G Julius Vancso.

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The authors declare no competing financial interests.

Supplementary information

Supplementary Fig. 1

Photograph taken during step 5 of the quantum dot synthesis. (JPG 2455 kb)

Supplementary Fig. 2

Diagram showing the quantum dot synthesis setup. (PDF 131 kb)

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Jańczewski, D., Tomczak, N., Han, MY. et al. Synthesis of functionalized amphiphilic polymers for coating quantum dots. Nat Protoc 6, 1546–1553 (2011). https://doi.org/10.1038/nprot.2011.381

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