TY  - JOUR
A1  - Casse, Olivier
A1  - Shkilnyy, Andriy
A1  - Linders, Jürgen
A1  - Mayer, Christian
A1  - Häussinger, Daniel
A1  - Völkel, Antje
A1  - Thünemann, Andreas F.
A1  - Dimova, Rumiana
A1  - Cölfen, Helmut
A1  - Meier, Wolfgang P.
A1  - Schlaad, Helmut
A1  - Taubert, Andreas
T1  - Solution behavior of double-hydrophilic block copolymers in dilute aqueous solution
JF  - Macromolecules : a publication of the American Chemical Society
N2  - The self-assembly of double-hydrophilic poly(ethylene oxide)-poly(2-methyl-2-oxazoline) diblock copolymers in water has been studied. Isothermal titration calorimetry, small-angle X-ray scattering, and analytical ultracentrifugation suggest that only single polymer chains are present in solution. In contrast, light scattering and transmission electron microscopy detect aggregates with radii of ca. 100 nm. Pulsed field gradient NMR spectroscopy confirms the presence of aggregates, although only 2% of the polymer chains undergo aggregation. Water uptake experiments indicate differences in the hydrophilicity of the two blocks, which is believed to be the origin of the unexpected aggregation behavior (in accordance with an earlier study by Ke et al. [Macromolecules 2009, 42, 5339-5344]). The data therefore suggest that even in double-hydrophilic block copolymers, differences in hydrophilicity are sufficient to drive polymer aggregation, a phenomenon that has largely been overlooked or ignored so far.
Y1  - 2012
U6  - https://doi.org/10.1021/ma300621g
SN  - 0024-9297
VL  - 45
IS  - 11
SP  - 4772
EP  - 4777
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Haase, Andrea
A1  - Rott, Stephanie
A1  - Mantion, Alexandre
A1  - Graf, Philipp
A1  - Plendl, Johanna
A1  - Thünemann, Andreas F.
A1  - Meier, Wolfgang P.
A1  - Taubert, Andreas
A1  - Luch, Andreas
A1  - Reiser, Georg
T1  - Effects of silver nanoparticles on primary mixed neural cell cultures: Uptake, oxidative stress and acute calcium responses
JF  - Toxicological sciences
N2  - In the body, nanoparticles can be systemically distributed and then may affect secondary target organs, such as the central nervous system (CNS). Putative adverse effects on the CNS are rarely investigated to date. Here, we used a mixed primary cell model consisting mainly of neurons and astrocytes and a minor proportion of oligodendrocytes to analyze the effects of well-characterized 20 and 40 nm silver nanoparticles (SNP). Similar gold nanoparticles served as control and proved inert for all endpoints tested. SNP induced a strong size-dependent cytotoxicity. Additionally, in the low concentration range (up to 10 mu g/ml of SNP), the further differentiated cultures were more sensitive to SNP treatment. For detailed studies, we used low/medium dose concentrations (up to 20 mu g/ml) and found strong oxidative stress responses. Reactive oxygen species (ROS) were detected along with the formation of protein carbonyls and the induction of heme oxygenase-1. We observed an acute calcium response, which clearly preceded oxidative stress responses. ROS formation was reduced by antioxidants, whereas the calcium response could not be alleviated by antioxidants. Finally, we looked into the responses of neurons and astrocytes separately. Astrocytes were much more vulnerable to SNP treatment compared with neurons. Consistently, SNP were mainly taken up by astrocytes and not by neurons. Immunofluorescence studies of mixed cell cultures indicated stronger effects on astrocyte morphology. Altogether, we can demonstrate strong effects of SNP associated with calcium dysregulation and ROS formation in primary neural cells, which were detectable already at moderate dosages.
KW  - silver nanoparticles
KW  - neurons
KW  - oxidative stress
KW  - protein carbonyls
KW  - calcium
Y1  - 2012
U6  - https://doi.org/10.1093/toxsci/kfs003
SN  - 1096-6080
VL  - 126
IS  - 2
SP  - 457
EP  - 468
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Haase, A.
A1  - Mantion, A.
A1  - Graf, P.
A1  - Plendl, J.
A1  - Thünemann, Andreas F.
A1  - Meier, Wolfgang P.
A1  - Taubert, Andreas
A1  - Luch, A.
T1  - A novel type of silver nanoparticles and their advantages in toxicity testing in cell culture systems
JF  - Archives of toxicology : official journal of EUROTOX
N2  - Silver nanoparticles (SNPs) are among the most commercialized nanoparticles worldwide. Often SNP are used because of their antibacterial properties. Besides that they possess unique optic and catalytic features, making them highly interesting for the creation of novel and advanced functional materials. Despite its widespread use only little data exist in terms of possible adverse effects of SNP on human health. Conventional synthesis routes usually yield products of varying quality and property. It thus may become puzzling to compare biological data from different studies due to the great variety in sizes, coatings or shapes of the particles applied. Here, we applied a novel synthesis approach to obtain SNP of well-defined colloidal and structural properties. Being stabilized by a covalently linked small peptide, these particles are nicely homogenous, with narrow size distribution, and form monodisperse suspensions in aqueous solutions. We applied these peptide-coated SNP in two different sizes of 20 or 40 nm (Ag20Pep and Ag40Pep) and analyzed responses of THP-1-derived human macrophages while being exposed against these particles. Gold nanoparticles of similar size and coating (Au20Pep) were used for comparison. The cytotoxicity of particles was assessed by WST-1 and LDH assays, and the uptake into the cells was confirmed via transmission electron microscopy. In summary, our data demonstrate that this novel type of SNP is well suited to serve as model system for nanoparticles to be tested in toxicological studies in vitro.
KW  - Silver nanoparticles
KW  - Peptide coating
KW  - Nanotoxicity
Y1  - 2012
U6  - https://doi.org/10.1007/s00204-012-0836-0
SN  - 0340-5761
VL  - 86
IS  - 7
SP  - 1089
EP  - 1098
PB  - Springer
CY  - Heidelberg
ER  -