TY  - GEN
A1  - Schneider, Ralf
A1  - Weigert, Florian
A1  - Lesnyak, Vladimir
A1  - Leubner, Susanne
A1  - Lorenz, Tommy
A1  - Behnke, Thomas
A1  - Dubavik, Aliaksei
A1  - Joswig, Jan-Ole
A1  - Resch-Genger, Ute
A1  - Gaponik, Nikolai
A1  - Eychmüller, Alexander
T1  - pH and concentration dependence of the optical properties of thiol-capped CdTe nanocrystals in water and D2O
N2  - The optical properties of semiconductor nanocrystals (SC NCs) are largely controlled by their size and surface chemistry, i.e., the chemical composition and thickness of inorganic passivation shells and the chemical nature and number of surface ligands as well as the strength of their bonds to surface atoms. The latter is particularly important for CdTe NCs, which – together with alloyed CdxHg1−xTe – are the only SC NCs that can be prepared in water in high quality without the need for an additional inorganic passivation shell. Aiming at a better understanding of the role of stabilizing ligands for the control of the application-relevant fluorescence features of SC NCs, we assessed the influence of two of the most commonly used monodentate thiol ligands, thioglycolic acid (TGA) and mercaptopropionic acid (MPA), on the colloidal stability, photoluminescence (PL) quantum yield (QY), and PL decay behavior of a set of CdTe NC colloids. As an indirect measure for the strength of the coordinative bond of the ligands to SC NC surface atoms, the influence of the pH (pD) and the concentration on the PL properties of these colloids was examined in water and D2O and compared to the results from previous dilution studies with a set of thiol-capped Cd1−xHgxTe SC NCs in D2O. As a prerequisite for these studies, the number of surface ligands was determined photometrically at different steps of purification after SC NC synthesis with Ellman's test. Our results demonstrate ligand control of the pH-dependent PL of these SC NCs, with MPA-stabilized CdTe NCs being less prone to luminescence quenching than TGA-capped ones. For both types of CdTe colloids, ligand desorption is more pronounced in H2O compared to D2O, underlining also the role of hydrogen bonding and solvent molecules.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 332 
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-395143
ER  - 
TY  - JOUR
A1  - Koshkina, Olga
A1  - Westmeier, Dana
A1  - Lang, Thomas
A1  - Bantz, Christoph
A1  - Hahlbrock, Angelina
A1  - Würth, Christian
A1  - Resch-Genger, Ute
A1  - Braun, Ulrike
A1  - Thiermann, Raphael
A1  - Weise, Christoph
A1  - Eravci, Murat
A1  - Mohr, Benjamin
A1  - Schlaad, Helmut
A1  - Stauber, Roland H.
A1  - Docter, Dominic
A1  - Bertin, Annabelle
A1  - Maskos, Michael
T1  - Tuning the Surface of Nanoparticles: Impact of Poly(2-ethyl-2-oxazoline) on Protein Adsorption in Serum and Cellular Uptake
JF  - Macromolecular bioscience
N2  - Due to the adsorption of biomolecules, the control of the biodistribution of nanoparticles is still one of the major challenges of nanomedicine. Poly(2-ethyl-2-oxazoline) (PEtOx) for surface modification of nanoparticles is applied and both protein adsorption and cellular uptake of PEtOxylated nanoparticles versus nanoparticles coated with poly(ethylene glycol) (PEG) and non-coated positively and negatively charged nanoparticles are compared. Therefore, fluorescent poly(organosiloxane) nanoparticles of 15 nm radius are synthesized, which are used as a scaffold for surface modification in a grafting onto approach. With multi-angle dynamic light scattering, asymmetrical flow field-flow fractionation, gel electrophoresis, and liquid chromatography-mass spectrometry, it is demonstrated that protein adsorption on PEtOxylated nanoparticles is extremely low, similar as on PEGylated nanoparticles. Moreover, quantitative microscopy reveals that PEtOxylation significantly reduces the non-specific cellular uptake, particularly by macrophage-like cells. Collectively, studies demonstrate that PEtOx is a very effective alternative to PEG for stealth modification of the surface of nanoparticles.
KW  - cellular uptake
KW  - nanoparticles
KW  - poly(2-ethyl-2oxazoline)
KW  - poly(ethylene glycol)
KW  - protein adsorption
Y1  - 2016
U6  - https://doi.org/10.1002/mabi.201600074
SN  - 1616-5187
SN  - 1616-5195
VL  - 16
SP  - 1287
EP  - 1300
PB  - Wiley-VCH
CY  - Weinheim
ER  -