Authors:	Bernhardt, Max
Title:	Mikroskopische Analyse des transmembranen Transports von Nanopartikeln in Polymersome, riesige unilamellare Vesikel und Erythrozyten
Online publication date:	25-Jan-2016
Year of first publication:	2016
Language:	german
Abstract:	This thesis focuses on two main points. The first concentrates on the improvement of a recently developed artificial minimal model of a membrane system with which we were able to understand and control the uptake behavior of nanoparticles into polymeric vesicles (polymersomes). The second point aimes at transferring the acquired knowledge step by step to a natural system - red blood cells. The membrane of the minimal model system consists of the amphiphilic poly(dimethylsiloxane)- poly(2-methyloxazoline) block copolymer (PDMS-b-PMOXA). At the beginning of this work the synthesis of this block-copolymer (BC) was optimized. By variing the length of the PMOXA-block it was possible to gain information about the influence of the block length on the mechanical properties of the polymersomes produced. To develop the system further, gold particles were used instead of silica and polystyrene particles as Jaskiewicz et al. had done. Gold particles can easily be modified and they show an intrinsic cristallinity, which gives access to new experiments in light scattering and plasmonics. By using immobilized, differently modified gold particles in atomic force microscopy (AFM) measurements (= colloidal probe technique), information about the interactions between those particles and polymersomes could be gained. It was found that the dominant interactions are weak electrostatic interactions. By mixing polymersomes and gold-nanoparticles with a diameter of 44nm, modified in the same different ways as for AFM experiments, their behavior towards polymersomes could be controlled. We were able to set different scenarios: uptake of particles into polymersomes, attachment of particles to the polymersomes and coexistence of particles and polymersomes. Those findings were proven by cryogenic transmission electron microscopy (Cryo-TEM). From these images one could also understand how the membrane is built up at the molecular level. Furthermore, modified gold-nanorods were used to study the influence of the nanoparticles’s shape on the uptake into polymersomes. It was found that shape does not influence the uptake of particles into polymersomes. The insight gained through an understanding of this minimal model system was transferred to a more natural model system. For this purpose, giant unilamellar vesicles (GUVs) were prepared and mixed with differently modified XX particles (made of silica and polystyrene). These mixtures were analyzed with confocal laser scanning microscopy (CLSM). It was observed that here, too, the dominant interactions are elctrostatic ones. In a last step, experiments with red blood cells were carried out to transfer the knowledge gained from the model to a natural system, which confirmed some of the findings of the model systems. Furthermore, some very interesting behavior of silica particles was observed. Within the scope of this thesis the existing model system was developed further and the interacting forcees between particles and model system were uncovered. For the first time, information gained from a minimal model system was successively transferred to a model system and compared to a similar natural system - a line was drawn between a minimal model and nature. Sonderzeichen im Text wurden teilweile gelöscht um den Text übertragbar zu machen.
DDC:	540 Chemie 540 Chemistry and allied sciences
Institution:	Johannes Gutenberg-Universität Mainz
Department:	FB 09 Chemie, Pharmazie u. Geowissensch.
Place:	Mainz
ROR:	https://ror.org/023b0x485
DOI:	http://doi.org/10.25358/openscience-4214
URN:	urn:nbn:de:hebis:77-diss-1000000971
Version:	Original work
Publication type:	Dissertation
License:	In Copyright
Information on rights of use:	https://rightsstatements.org/vocab/InC/1.0/
Appears in collections:	JGU-Publikationen