la7b00409_si_003.pdf (56.35 kB)
Capping of Mn-Doped ZnS Quantum Dots with DHLA for Their Stabilization in Aqueous Media: Determination of the Nanoparticle Number Concentration and Surface Ligand Density
journal contribution
posted on 2017-05-30, 00:00 authored by Marta Garcia-Cortes, Emma Sotelo González, María T. Fernández-Argüelles, Jorge Ruiz Encinar, José M. Costa-Fernández, Alfredo Sanz-MedelColloidal
Mn2+-doped ZnS quantum dots (QDs) were synthesized, surface
modified, and thoroughly characterized using a pool of complementary
techniques. Cap exchange of the native l-cysteine coating
of the QDs with dihydrolipoic acid (DHLA) ligands is proposed as a
strategy to produce nanocrystals with a strong phosphorescent-type
emission and improved aqueous stability. Moreover, such a stable DHLA
coating can facilitate further bioconjugation of these QDs to biomolecules
using established reagents such as cross-linker molecules. First,
a structural and morphological characterization of the l-cysteine
QD core was performed by resorting to complementary techniques, including
X-ray powder diffraction (XRD) and microscopy tools. XRD patterns
provided information about the local structure of ions within the
nanocrystal structure and the number of metal atoms constituting the
core of a QD. The judicious combination of the data obtained from
these complementary characterization tools with the analysis of the
QDs using inductively coupled plasma-mass spectrometry (ICP-MS) allowed
us to assess the number concentration of nanoparticles in an aqueous
sample, a key parameter when such materials are going to be used in
bioanalytical or toxicological studies. Asymmetric flow field-flow
fractionation (AF4) coupled online to ICP-MS detection proved to be
an invaluable tool to compute the number of DHLA molecules attached
to the surface of a single QD, a key feature that is difficult to
estimate in nanoparticles and that critically affects the behavior
of nanoparticles when entering the biological media (e.g., cellular
uptake, biodistribution, or protein corona formation). This hybrid
technique also allowed us to demonstrate that the elemental composition
of the nanoparticle core remains unaffected after the ligand exchange
process. Finally, the photostability and robustness of the DHLA-capped
QDs, critical parameters for bioanalytical applications, were assessed
by molecular luminescence spectroscopy.
History
Usage metrics
Categories
Keywords
Aqueous MediaDHLA-capped QDstechniquemetal atomsluminescence spectroscopyXRD patternsICP-MS detectiontoxicological studiesNanoparticle Number Concentrationprotein corona formationcross-linker moleculesnanocrystal structurecharacterization toolsX-ray powder diffractionl-cysteine coatingZnS quantum dotsnanoparticle coreplasma-mass spectrometryDHLA moleculesl-cysteine QD coreMn-Doped ZnS Quantum Dotsdihydrolipoic acidDHLA coatingligand exchange processAsymmetric flow field-flow fractionationcap exchangephosphorescent-type emissionAFmicroscopy toolsnumber concentrationbioanalytical applications
Licence
Exports
RefWorks
BibTeX
Ref. manager
Endnote
DataCite
NLM
DC