Synthesis and functionalization of core/shell CuInS2/ZnS quantum
dots for cancer cells imaging
Martyna Michalska1,2, Raphaël Schneider2, Stefan Jurga1
1
NanoBioMedical Centre and Department of Macromolecular Physics, Adam Mickiewicz University,
Umultowska 85, 61-614 Poznan, Poland
2 Université de Lorraine, Laboratoire Réactions et Génie de Procédés (LRGP), CNRS UMR 7274,
1 Rue Grandville, 54001 Nancy Cedex, France
m.mich@amu.edu.pl
Quantum dots (QDs) are semiconductor nanocrystals that possess unique optical properties attributed
to the quantum confinement effect. Thanks to their broad absorption profiles the simultaneous excitation
of multiple colors of QDs is possible unlike the conventional organic dyes. Moreover, the QDs surface
can be functionalized by conjugation with various molecules enabling the nanoparticles to be dispersed
in water and to be specifically addressed for biological applications (1-2).
During the last decade, low band gap II-VI and IV-VI semiconductors have been a major focus in the
form of size and shape-controlled nanocrystals (NCs). Many synthetic pathways have been developed
to obtain highly emissive CdSe or CdTe core QDs, especially for biological labeling. However, despite
their appealing optical properties, the intrinsic toxicity of Cd, Te or Se elements and the production of
reactive oxygen species (ROS) from these nanocrystals shed a doubt on the future applicability of these
QDs, particularly in view of recent environmental regulations (3-4). Thus, there is a big interest in
developing new synthetic pathways for production of highly fluorescent Cd–free QDs. One of a possible
alternative materials are ternary I-III-VI NCs, including CuInS2 (CIS), which possess much lower toxicity,
high absorption coefficient, high stability, and tunable emissions from visible to NIR region (2).
Here, we report a new synthesis of core/shell CuInS2/ZnS QDs with PL emission at ca. 610 nm, and
photoluminescence quantum yield (QY) up to 65%. The successful transfer of these dots into water was
achieved via overcoating with the amphiphilic polymer, poly(maleic anhydride-alt-1-octadecene)
(PMAO). The products were characterized by means of UV–vis and fluorescence spectroscopies, X–ray
diffraction (XRD), dynamic light scattering (DLS) and high resolution transmission electron microscopy
(HRTEM) (Fig. 1). The PMAO-coated QDs emit at ca. 640 nm with QY of 35%. Such prepared QDs
were subsequently functionalized with a peptide which is known to have an affinity to HER2-postive
cancer cells. The binding of NCs to the targeted cancer cells was assessed by flow cytometer.
(B)
Absorbance (a.u.) / PL Intensity (a.u.)
(A)
200
300
400
500
600
700
800
Wavelength (nm)
Fig.1 Absorption and PL emission spectra (A) and (B) high resolution micrograph
of PMAO-coated CuInS2/ZnS QDs.
References
[1] Kim, Y.-K., Ahn, S.-H., Chung, K., Cho, Y.-S. & Choi, C.-J., Journal of Materials Chemistry, 22 (2012)
1516.
[2] Nam, D.-E., Song, W.-S., & Yang, H., Journal of Materials Chemistry, 21 (2011), 18220.
[3] Park, J., & Kim, S.-W., Journal of Materials Chemistry, 21 (2011) 3745.
[4] Shi, A., Wang, X., Meng, X., Liu, X., Li, H., & Zhao, J., Journal of Luminescence, 132 (2012) 1819–
1823.
[5]