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Li Z.,Center for Nanotechnology ech | Huve J.,Center for Nanotechnology ech | Huve J.,Institute of Medical Physics and Biophysics | Krampe C.,Center for Nanotechnology ech | And 8 more authors.
Small | Year: 2013

Information about the mechanisms underlying the interactions of nanoparticles with living cells is crucial for their medical application and also provides indications of the putative toxicity of such materials. Here the uptake and intracellular delivery of disc-shaped zeolite L nanocrystals as porous aminosilicates with well-defined crystal structure, uncoated as well as with COOH-, NH2-, polyethyleneglycol (PEG)- and polyallylamine hydrochloride (PAH) surface coatings are reported. HeLa cells are used as a model system to demonstrate the relation between these particles and cancer cells. Interactions are studied in terms of their fates under diverse in vitro cell culture conditions. Differently charged coatings demonstrated dissimilar behavior in terms of agglomeration in media, serum protein adsorption, nanoparticle cytotoxicity and cell internalization. It is also found that functionalized disc-shaped zeolite L particles enter the cancer cells via different, partly not yet characterized, pathways. These in vitro results provide additional insight about low-aspect ratio anisotropic nanoparticle interactions with cancer cells and demonstrate the possibility to manipulate the interactions of nanoparticles and cells by surface coating for the use of nanoparticles in medical applications. Interaction of zeolite L nanocontainers with cancer cells. By inhibition and colocalization experiments, the route of uptake and the intracellular fate of functionalized zeolite L nanoparticles in Hela cancer cells are described. According to their surface charge, zeolites are selectively engulfed and intracellularly targeted. The results show how the destiny of nanoparticles in cancer cells can be altered by surface functionalization. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Boening D.,Max Planck Institute for Biophysical Chemistry | Boening D.,Institute of Medical Physics and Biophysics | Groemer T.W.,Max Planck Institute for Biophysical Chemistry | Groemer T.W.,Friedrich - Alexander - University, Erlangen - Nuremberg | And 2 more authors.
Optics Express | Year: 2010

In this work we systematically explored performance of an EMCCD as a detector for spatially resolved total internal reflection image correlation spectroscopy (TIR-ICS) with respect to adjustable parameters. We show that variations in the observation volume (pixel binning) can be well described by a simple structural term D. To test the sensitivity of camera-based TIR-ICS we measured diffusion coefficients and particle numbers (PN) of fluorescent probes of different sizes (Fluorospheres, GFP and labeled antibodies) at varying viscosities, concentrations, and sampling rates. TIR-ICS allowed distinguishing between different probe concentrations with differences in PN of 5% and differences of 6% in D by acquiring only 15 independent measurement runs. © 2010 Optical Society of America.

Shah B.,University of Munster | Lutter D.,University of Munster | Bochenek M.L.,Max Planck Institute for Molecular Biomedicine | Bochenek M.L.,University Medical Center Mainz | And 8 more authors.
PLoS ONE | Year: 2016

The establishment of a polarized morphology is essential for the development and function of neurons. During the development of the mammalian neocortex, neurons arise in the ventricular zone (VZ) from radial glia cells (RGCs) and leave the VZ to generate the cortical plate (CP). During their migration, newborn neurons first assume a multipolar morphology in the subventricular zone (SVZ) and lower intermediate zone (IZ). Subsequently, they undergo a multi-to-bipolar (MTB) transition to become bipolar in the upper IZ by developing a leading process and a trailing axon. The small GTPases Rap1A and Rap1B act as master regulators of neural cell polarity in the developing mouse neocortex. They are required for maintaining the polarity of RGCs and directing the MTB transition of multipolar neurons. Here we show that the Rap1 guanine nucleotide exchange factor (GEF) C3G (encoded by the Rapgef1 gene) is a crucial regulator of the MTB transition in vivo by conditionally inactivating the Rapgef1 gene in the developing mouse cortex at different time points during neuronal development. Inactivation of C3G results in defects in neuronal migration, axon formation and cortical lamination. Live cell imaging shows that C3G is required in cortical neurons for both the specification of an axon and the initiation of radial migration by forming a leading process. © 2016 Shah et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Yew J.Y.,Institute of Medical Physics and Biophysics | Yew J.Y.,Temasek Life Science Laboratory | Yew J.Y.,National University of Singapore | Soltwisch J.,Institute of Medical Physics and Biophysics | And 2 more authors.
Journal of the American Society for Mass Spectrometry | Year: 2011

We recently demonstrated that ultraviolet laser desorption ionization orthogonal time-of-flight mass spectrometry (UV-LDI o-TOF MS) could be used for the matrix-free analysis of cuticular lipids (unsaturated aliphatic and oxygen-containing hydrocarbons and triacylglycerides) directly from individual Drosophila melanogaster fruit flies (Yew, J.Y.; Dreisewerd, K.; Luftmann, H.; Pohlentz, G.; Kravitz, E.A., Curr. Biol. 2009, 19, 1245-1254). In this report, we show that the cuticular hydrocarbon, fatty acid, and triglyceride profiles of other insects and spiders can also be directly analyzed from intact body parts. Mandibular pheromones from the jaw of a queen honey bee are provided as one example. In addition, we describe analytical features and examine mechanisms underlying the methodology. Molecular ions of lipids can be generated by direct UV-LDI when non-endogenous compounds are applied to insect wings or other body parts. Current sensitivity limits are in the 10 pmol range. We show also the dependence of ion signal intensity on collisional cooling gas pressure in the ion source, laser wavelength (varied between 280-380 nm and set to 2.94 μm for infrared LDI), and laser pulse energy. © American Society for Mass Spectrometry, 2011.

Masing F.,University of Munster | Mardyukov A.,University of Munster | Doerenkamp C.,University of Munster | Eckert H.,University of Munster | And 4 more authors.
Angewandte Chemie - International Edition | Year: 2015

Gold nanoparticles (AuNPs) are subjects of broad interest in scientific community due to their promising physicochemical properties. Herein we report the facile and controlled light-mediated preparation of gold nanoparticles through a Norrish type I reaction of photoactive polymers. These carefully designed polymers act as reagents for the photochemical reduction of gold ions, as well as stabilizers for the in situ generated AuNPs. Manipulating the length and composition of the photoactive polymers allows for control of AuNP size. Nanoparticle diameter can be controlled from 1.5 nm to 9.6 nm. Instant preparation of Au nanoparticles! Mixing a photoactive polymer with HAuCl4 and NaOH in DMF/H2O and irradiating with light for a few minutes provides stable, spherical, polymer-coated Au nanoparticles with defined diameter. The diameter can be adjusted from 1.5 to 9.6 nm by varying the length and composition of the photoactive polymer. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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