Dokument: Analysis of molecular diffusion and photochemistry by quantitative fluorescence correlation spectroscopy
| Titel: | Analysis of molecular diffusion and photochemistry by quantitative fluorescence correlation spectroscopy | |||||||
| URL für Lesezeichen: | https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=41878 | |||||||
| URN (NBN): | urn:nbn:de:hbz:061-20170410-091156-8 | |||||||
| Kollektion: | Dissertationen | |||||||
| Sprache: | Englisch | |||||||
| Dokumententyp: | Wissenschaftliche Abschlussarbeiten » Dissertation | |||||||
| Medientyp: | Text | |||||||
| Autor: | M.Sc. Sandrin, Deborah [Autor] | |||||||
| Dateien: |
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| Beitragende: | Prof. Dr. Seidel, Claus A. M. [Betreuer/Doktorvater] Prof. Dr. Gilch, Peter [Betreuer/Doktorvater] | |||||||
| Dewey Dezimal-Klassifikation: | 500 Naturwissenschaften und Mathematik » 540 Chemie | |||||||
| Beschreibung: | Molecular diffusion in a hydrogel
This section of my thesis is a fundamental and comprehensive study on the diffusion of macromolecules (dextrans, guest) into hydrogels (polyacrylamide, host). It is provided for the first time a full time and length scale study combining Brownian Dynamics (BD) simulations and three experimental methods: multi-parameter fluorescence image spectroscopy MFIS, macroscopic transmission imaging (MTI) and nuclear magnetic resonance spectroscopy (NMR). The results on diffusion are consistent over a very wide time range, which also implies consistency on a correspondingly large length scale range. A crucial novel finding is the influence of attractive guest-host interactions on the guest diffusion. Quantitative characterization provides new insights that explain the change in guest diffusion upon changing pH and ionic strength. Indeed, FCS could for the first time detect temporarily trapped molecules with diffusion times above 10 ms, which was also confirmed by anisotropy analysis. This finding could further be supported by MTI. The experimental agreement was further corroborated by BD simulations supporting the importance of the attractive interactions between guest and host, whereas common models in the literature focus only on the hindrance by the hydrogel network (Ogston model). BD simulations provide also valuable estimates for the pore size under the different conditions (nm range). Photochemistry of a fluorophore The second part is a study on the photochemistry of dyes using fluorescence correlation spectroscopy (FCS that is part of MFIS) with the aim to stabilize Cy5 and to improve its fluorescence signal. For this purpose, have been used 4-(phenylazo)-benzoic acid (AZB-C) and Trolox like quenchers with two different approaches: (i) the usage of quenchers as additives dissolved in solution; (ii) the usage of quenchers covalently linked to Cy5: Cy5-AZB-C and Cy5-Trolox. For additives, the experiments show that AZB-C is a good triplet quencher and it can also reduce the production of R•+, Trolox shows quenching effect only for triplet state. The second method is introduced recently and has the advantage to overcome problems due to the biological toxicity of the additives. In Cy5-conjugates, the FCS experiments show that Cy5-AZB-C is the best way to suppress the production of R•+ in buffer saturated solution and it decreases the triplet state dramatically in argon experiments. In buffer Cy5-conjugates show lower fluorescence quantum yield compared to Cy5, demonstrating therefore that the additives still give higher fluorescence signal. In ethanol, the behavior of the additives and the conjugates are similar due to the decreasing of singlet quenching of these new compounds. The prevalent photobleaching pathway under air saturated comes mostly from the singlet state and in argon solution from triplet state. Therefore, a good strategy to improve the fluorescence signal is the removal of O2 in combination with triplet quencher. | |||||||
| Lizenz: |  Urheberrechtsschutz | |||||||
| Fachbereich / Einrichtung: | Mathematisch- Naturwissenschaftliche Fakultät » WE Chemie » Physikalische Chemie und Elektrochemie | |||||||
| Dokument erstellt am: | 10.04.2017 | |||||||
| Dateien geändert am: | 10.04.2017 | |||||||
| Promotionsantrag am: | 20.02.2017 | |||||||
| Datum der Promotion: | 24.03.2017 |
