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Issue 42, 2018
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A small heterobifunctional ligand provides stable and water dispersible core–shell CdSe/ZnS quantum dots (QDs)

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Abstract

We describe a simple method to prepare water dispersible core–shell CdSe/ZnS quantum dots (QDs) 1 by capping QDs with a new thiol-containing heterobifunctional dicarboxylic ligand 4 (DHLA-EDADA). This ligand, obtained on a gram scale through a few synthetic steps, provides a compact layer on the QDs, whose hydrodynamic size in H2O is 15 nm ± 3 nm. The colloidal stability is dramatically enhanced with respect to the well-known (±) α-lipoic acid (DHLA). The ligand affinity towards QDs and the water dispersibility of nanocrystals 1 are addressed by the dithiol groups of DHLA, which chelate the zinc of the shell, and by the dicarboxylic groups of the ethylenediamine-N,N-diacetic acid (EDADA) residue, respectively. The effects of pH, buffer solutions, and biological medium on the stability of QDs 1 were assessed by monitoring the photoluminescence (PL) and hydrodynamic size over time. Highly fluorescent QD dispersions, stable over extended periods of time and over broad pH ranges and buffer types, were obtained. Furthermore, we show that the DHLA-EDADA ligand 4 also endows QDs with functional groups suitable for further conjugation and for metal ion detection. As a case study to illustrate the potential of our approach, we report the preparation and characterization of a highly luminescent orange light emitting polymer-QD 1 composite film.

Graphical abstract: A small heterobifunctional ligand provides stable and water dispersible core–shell CdSe/ZnS quantum dots (QDs)

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Publication details

The article was received on 10 Jul 2018, accepted on 03 Sep 2018 and first published on 04 Sep 2018


Article type: Paper
DOI: 10.1039/C8NR05566A
Citation: Nanoscale, 2018,10, 19720-19732
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    A small heterobifunctional ligand provides stable and water dispersible core–shell CdSe/ZnS quantum dots (QDs)

    G. Salerno, S. Scarano, M. Mamusa, M. Consumi, S. Giuntini, A. Macagnano, S. Nativi, M. Fragai, M. Minunni, D. Berti, A. Magnani, C. Nativi and B. Richichi, Nanoscale, 2018, 10, 19720
    DOI: 10.1039/C8NR05566A

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