Particles with tunable functionality by a nonaqueous emulsion polymerization approach

Diese Dissertation demonstriert die Synthese von funktionalen organischen Partikeln mit einem anwendungsspezifischen Fokus. Der Startpunkt dieser Partikel stellte stets die nicht-wässrige Emulsionspolymerisation dar. Diese Art der Emulsion besteht aus zwei nicht-mischbaren organischen Lösungsmitteln. Zur Stabilisierung der auftretenden Grenzflächenspannung zwischen den beiden organischen Phasen musste ein amphiphiles Blockcopolymer als Emulgator eingesetzt werden. Der Vorteil gegenüber der klassischen wässrigen Emulsionspolymerisation liegt im breiteren Portfolio an anwendbarer Polymerisationstechniken (z.B. Polykondensation) und zu verwendenden Komponenten (wassersensitive Chemikalien). rnrnSo wurde auf Basis einer wassersensitiven ringöffnenden Polymerisation von L-Lactid ein Wirkstoffträger synthetisiert, welcher eine selektive Freisetzung eines Zytostatikums in Tumorgewebe zeigte. Die Wirkstofffreisetzung war auf eine selektive Spaltung eines im Partikel befindlichen Peptids, welches von tumorassoziierenden Enzymen erkannt wird, zurückzuführen.rnrnDas nicht-wässrige Emulsionssystem wurde zudem zur Synthese von porösen Poly(Urethan)-Partikeln verwendet. Die Porosität wurde präzise durch eine definierte Wassermenge im System eingestellt. Die Ethylen-Polymerisation nach Katalysator-Beladung demonstrierte die Abhängigkeit der Aktivität und des Fragmentierungsverhaltens von der Partikelporosität.rnrnZuletzt wurde ein amphiphiles Blockcopolymer synthetisiert, welches Partikel in unpolaren Lösungsmitteln und in Wasser stabilisieren kann. Die Polarität des unpolaren, hydrophoben Polymerblocks konnte durch UV-Bestrahlung und einer resultierenden Abtrennung unpolarer Gruppen vom polaren Polymerrückgrat umgekehrt werden. So gelangen eine Hydrophilisierung der Partikeloberfläche und eine Stabilisierung der Partikel in wässrigem Medium, ohne Zusatz weiterer Tenside.

Non-aqueous dispersions of particles and their applications

In the current work, three studies about non-aqueous dispersions of particles were carried out by using an amphiphilic block copolymer poly(isoprene)-block-poly(methyl methacrylate) (PI-b-PMMA) as stabilizer:rn1. Dispersions of polyurethane and polyurea porous particles for polymer compositesrn2. Dispersions of PMMA and PU particles with PDI dye for study of Single Molecule Spectroscopy Detectionrn3. Dispersions of graphene nanosheets for polymer compositesrnrnIn the first study, highly porous polyurethane and polyurea particles were prepared in a non-aqueous emulsion. The preparation of porous particles consisted of two parts: At first, a system was developed where the emulsion had high stability for the polymerization among diisocyanate, diol and water. In the second part, porous particles were prepared by using two methods fission/fusion and combination by which highly porous particles were obtained. In this study, the applications of porous particles were also investigated where polyurethane particles were tested as filling material for polymer composites and as catalyst carrier for polyethylene polymerization. rnrnIn the second study, PMMA and PU particles from one non-aqueous emulsion were investigated via single molecule fluorescence detection. At first the particles were loaded with PDI dye, which were detected by fluorescence microscopy. The distribution and orientation of the PDI molecules in the particles were successfully observed by Single Molecule Fluorescence Detection. The molecules were homogenously distributed inside of the particles. In addition they had random orientation, meaning that no aggregations of dye molecules were formed. With the results, it could be supposed that the polymer chains were also homogenously distributed in the particles, and that the conformation was relatively flexible. rnrnIn the third part of the study, graphene nanosheets with high surface area were dispersed in an organic solvent with low boiling point and low toxicity, THF, stabilized with a block copolymer PI-b-PMMA. The dispersion was used to prepare polymer composites. It was shown that the modified graphene nanosheets had good compatibility with the PS and PMMA matrices. rn

Axion-like particles and the 3.5 keV line in 4D string models

This work is focused on axions and axion like particles (ALPs) and their possible relation with the 3.55 keV photon line detected, in recent years, from galaxy clusters and other astrophysical objects. We focus on axions that come from string compactification and we study the vacuum structure of the resulting low energy 4D N=1 supergravity effective field theory. We then provide a model which might explain the 3.55 keV line through the following processes. A 7.1 keV dark matter axion decays in two light axions, which, in turn, are transformed into photons thanks to the Primakoff effect and the existence of a kinetic mixing between two U(1)s gauge symmetries belonging respectively to the hidden and the visible sector. We present two models, the first one gives an outcome inconsistent with experimental data, while the second can yield the desired result.

Small dense particles in the retina observable by spectral-domain optical coherence tomography in age-related macular degeneration

To observe detailed changes in neurosensory retinal structure after anti-VEGF upload in age-related macular degeneration (AMD), by using spectral domain optical coherence tomography (SD-OCT).

Cellular responses after exposure of lung cell cultures to secondary organic aerosol particles

The scope of this work was to examine in vitro responses of lung cells to secondary organic aerosol (SOA) particles, under realistic ambient air and physiological conditions occurring when particles are inhaled by mammals, using a novel particle deposition chamber. The cell cultures included cell types that are representative for the inner surface of airways and alveoli and are the target cells for inhaled particles. The results demonstrate that an exposure to SOA at ambient-air concentrations of about 10(4) particles/cm(3) for 2 h leads to only moderate cellular responses. There is evidence for (i) cell type specific effects and for (ii) different effects of SOA originating from anthropogenic and biogenic precursors, i.e. 1,3,5-trimethylbenzene (TMB) and alpha-pinene, respectively. There was no indication for cytotoxic effects but for subtle changes in cellular functions that are essential for lung homeostasis. Decreased phagocytic activity was found in human macrophages exposed to SOA from alpha-pinene. Alveolar epithelial wound repair was affected by TMB-SOA exposure, mainly because of altered cell spreading and migration at the edge of the wound. In addition, cellular responses were found to correlate with particle number concentration, as interleukin-8 production was increased in pig explants exposed to TMB-SOA with high particle numbers.

Macrophages and dendritic cells express tight junction proteins and exchange particles in an in vitro model of the human airway wall

The human airway epithelium serves as structural and functional barrier against inhaled particulate antigen. Previously, we demonstrated in an in vitro epithelial barrier model that monocyte derived dendritic cells (MDDC) and monocyte derived macrophages (MDM) take up particulate antigen by building a trans-epithelial interacting network. Although the epithelial tight junction (TJ) belt was penetrated by processes of MDDC and MDM, the integrity of the epithelium was not affected. These results brought up two main questions: (1) Do MDM and MDDC exchange particles? (2) Are those cells expressing TJ proteins, which are believed to interact with the TJ belt of the epithelium to preserve the epithelial integrity? The expression of TJ and adherens junction (AJ) mRNA and proteins in MDM and MDDC monocultures was determined by RT-PCR, and immunofluorescence, respectively. Particle uptake and exchange was quantified by flow cytometry and laser scanning microscopy in co-cultures of MDM and MDDC exposed to polystyrene particles (1 μm in diameter). MDM and MDDC constantly expressed TJ and AJ mRNA and proteins. Flow cytometry analysis of MDM and MDDC co-cultures showed increased particle uptake in MDDC while MDM lost particles over time. Quantitative analysis revealed significantly higher particle uptake by MDDC in co-cultures of epithelial cells with MDM and MDDC present, compared to co-cultures containing only epithelial cells and MDDC. We conclude from these findings that MDM and MDDC express TJ and AJ proteins which could help to preserve the epithelial integrity during particle uptake and exchange across the lung epithelium.

Biomechanical effects of environmental and engineered particles on human airway smooth muscle cells

The past decade has seen significant increases in combustion-generated ambient particles, which contain a nanosized fraction (less than 100 nm), and even greater increases have occurred in engineered nanoparticles (NPs) propelled by the booming nanotechnology industry. Although inhalation of these particulates has become a public health concern, human health effects and mechanisms of action for NPs are not well understood. Focusing on the human airway smooth muscle cell, here we show that the cellular mechanical function is altered by particulate exposure in a manner that is dependent upon particle material, size and dose. We used Alamar Blue assay to measure cell viability and optical magnetic twisting cytometry to measure cell stiffness and agonist-induced contractility. The eight particle species fell into four categories, based on their respective effect on cell viability and on mechanical function. Cell viability was impaired and cell contractility was decreased by (i) zinc oxide (40-100 nm and less than 44 microm) and copper(II) oxide (less than 50 nm); cell contractility was decreased by (ii) fluorescent polystyrene spheres (40 nm), increased by (iii) welding fumes and unchanged by (iv) diesel exhaust particles, titanium dioxide (25 nm) and copper(II) oxide (less than 5 microm), although in none of these cases was cell viability impaired. Treatment with hydrogen peroxide up to 500 microM did not alter viability or cell mechanics, suggesting that the particle effects are unlikely to be mediated by particle-generated reactive oxygen species. Our results highlight the susceptibility of cellular mechanical function to particulate exposures and suggest that direct exposure of the airway smooth muscle cells to particulates may initiate or aggravate respiratory diseases.

Virus-like particles induce robust human T-helper cell responses

Among synthetic vaccines, virus-like particles (VLPs) are used for their ability to induce strong humoral responses. Very little is reported on VLP-based-vaccine-induced CD4(+) T-cell responses, despite the requirement of helper T cells for antibody isotype switching. Further knowledge on helper T cells is also needed for optimization of CD8(+) T-cell vaccination. Here, we analysed human CD4(+) T-cell responses to vaccination with MelQbG10, which is a Qβ-VLP covalently linked to a long peptide derived from the melanoma self-antigen Melan-A. In all analysed patients, we found strong antibody responses of mainly IgG1 and IgG3 isotypes, and concomitant Th1-biased CD4(+) T-cell responses specific for Qβ. Although less strong, comparable B- and CD4(+) T-cell responses were also found specific for the Melan-A cargo peptide. Further optimization is required to shift the response more towards the cargo peptide. Nevertheless, the data demonstrate the high potential of VLPs for inducing humoral and cellular immune responses by mounting powerful CD4(+) T-cell help.

Vapor bubble generation around gold nano-particles and its application to damaging of cells

We investigated vapor bubbles generated upon irradiation of gold nanoparticles with nanosecond laser pulses. Bubble formation was studied both with optical and acoustic means on supported single gold nanoparticles and single nanoparticles in suspension. Formation thresholds determined at different wavelengths indicate a bubble formation efficiency increasing with the irradiation wavelength. Vapor bubble generation in Bac-1 cells containing accumulations of the same particles was also investigated at different wavelengths. Similarly, they showed an increasing cell damage efficiency for longer wavelengths. Vapor bubbles generated by single laser pulses were about half the cell size when inducing acute damage.

Quantum Energy Teleportation Between Spin Particles in a Gibbs State

Energy in a multipartite quantum system appears from an operational perspective to be distributed to some extent non-locally because of correlations extant among the system's components. This non-locality allows users to transfer, in effect, locally accessible energy between sites of different system components by local operations and classical communication (LOCC). Quantum energy teleportation is a three-step LOCC protocol, accomplished without an external energy carrier, for effectively transferring energy between two physically separated, but correlated, sites. We apply this LOCC teleportation protocol to a model Heisenberg spin particle pair initially in a quantum thermal Gibbs state, making temperature an explicit parameter. We find in this setting that energy teleportation is possible at any temperature, even at temperatures above the threshold where the particles' entanglement vanishes. This shows for Gibbs spin states that entanglement is not fundamentally necessary for energy teleportation; correlation other than entanglement can suffice. Dissonance-quantum correlation in separable states-is in this regard shown to be a quantum resource for energy teleportation, more dissonance being consistently associated with greater energy yield. We compare energy teleportation from particle A to B in Gibbs states with direct local energy extraction by a general quantum operation on B and find a temperature threshold below which energy extraction by a local operation is impossible. This threshold delineates essentially two regimes: a high temperature regime where entanglement vanishes and the teleportation generated by other quantum correlations yields only vanishingly little energy relative to local extraction and a second low-temperature teleportation regime where energy is available at B only by teleportation.