1. Functional CdSe/CdS@SiO2 Nanoparticles for Bioimaging Applications
Tangi Aubert, Daniel Wassmuth, Stefaan J. Soenen, Rik Van Deun, Kevin Braeckmans, Zeger Hens
Ghent University, Belgium

2. Functional silica NPs for biotechnologies
- Biocompatible
- High colloidal stability
- Versatile surface chemistry
- …
luminescent
magnetic
plasmonic
Burns A.A., Wiesner U. et al., Nano. Lett. 2009, 9 (1), 442
Lu C.H. et al., Nano. Lett. 2007, 7 (1), 150
Sokolov K. et al., Cancer Res. 2003, 63, 1999

3. Semiconductor colloidal QDs
- Sharp and tunable emission
- High quantum yields
- Large absorption cross section
- …

4. Outline ● ‘Flash’ CdSe/CdS core-shell quantum dots
- synthesis, properties and low blinking
● nanoparticles
- synthesis and photostability
● Potential for bioimaging applications
- toxicity, cell uptake and labeling

5. ‘Flash’ CdSe/CdS QDs synthesis
● SILAR CdSe/CdS synthesis (successive ion layer adsorption and reaction)
→ highly time consuming Li et al., J. Am. Chem. Soc. 2003, 125, 12567
● FLASH CdSe/CdS synthesis: adapted from synthesis of CdSe/CdS
dot-in-rods Carbone et al., Nano Lett. 2007, 7 (10), 2942
T = 330°C
CdO
oleic acid
TOPO N2
CdSe
+ TOP-S
3 min reaction !!
M. Cirillo, T. Aubert, R. Gomes, R. Van Deun, P. Emplit, A. Biermann, H. Lange, C. Thomsen, E. Brainis, Z. Hens, Chem. Mater. 2014, 26,

6. ‘Flash’ CdSe/CdS QDs synthesis
Morphology, size control and optical properties
sharp emission
high quantum yield (>80%)
Ø = 16 nm
tunable CdS thickness
→ up to 20 monolayers of CdS shell in no more than 3 minutes
M. Cirillo, T. Aubert, R. Gomes, R. Van Deun, P. Emplit, A. Biermann, H. Lange, C. Thomsen, E. Brainis, Z. Hens, Chem. Mater. 2014, 26,

7. ‘Flash’ CdSe/CdS QDs synthesis
Raman analysis
→ low blinking
→ interfacial alloying
M. Cirillo, T. Aubert, R. Gomes, R. Van Deun, P. Emplit, A. Biermann, H. Lange, C. Thomsen, E. Brainis, Z. Hens, Chem. Mater. 2014, 26,

8. CdSe/CdS@SiO2 nanoparticles
Synthesis by water-in-oil microemulsion
inverted micelle
amphiphilic ligand
hydrolyzed TEOS
hydrophobic NP

9. CdSe/CdS@SiO2 nanoparticles
Morphology
→ high control on the thickness of the silica shell
T. Aubert, S.J. Soenen, D. Wassmuth, M. Cirillo, R. Van Deun, K. Braeckmans, Z. Hens, submitted

10. CdSe/CdS@SiO2 nanoparticles
Optical properties
under continuous UV irradiation
in water
CdSe/CdS QDs
in toluene
→ long term stability in water
→ improved photo-stability
T. Aubert, S.J. Soenen, D. Wassmuth, M. Cirillo, R. Van Deun, K. Braeckmans, Z. Hens, submitted

11. CdSe/CdS@SiO2 for bioimaging
Toxicity tests on human umbilical vein endothelial cells (HUVECs)
24 hrs exposition
*: p < 0.05
**: p < 0.01 * **
QD first significant effect at 10 nM
→ low toxicity (first significant effect at [NPs] = 100 nM)
T. Aubert, S.J. Soenen, D. Wassmuth, M. Cirillo, R. Van Deun, K. Braeckmans, Z. Hens, submitted

12. CdSe/CdS@SiO2 for bioimaging
HUVECs cell labeling ([NPs] = 50 nM, 30 min)
red channel (NPs)
green channel (dye)
merged (NPs + dye)
40 µm
→ rapid endosomal uptake of high levels of NPs
T. Aubert, S.J. Soenen, D. Wassmuth, M. Cirillo, R. Van Deun, K. Braeckmans, Z. Hens, submitted

13. CdSe/CdS@SiO2 for bioimaging
Long term cell visualization (HUVECS, [NPs] = 50 nM, 24 hrs)
0 cell division
3 cell divisions
7 cell divisions
→ nanoparticles visible in more than 50% of cells after 9 cell divisions
T. Aubert, S.J. Soenen, D. Wassmuth, M. Cirillo, R. Van Deun, K. Braeckmans, Z. Hens, submitted

14. Conclusion tangi.aubert@ugent.be ● ‘Flash’ CdSe/CdS synthesis
- fast and tunable
● nanoparticles
- good morphology
- high stability in water
● High potential for bioimaging
- low toxicity
- fast and high uptake
- long term visualization

15. Thanks for your attention !
Acknowledgement
Max Kade
Foundation
Thanks for your attention !