| dc.contributor.advisor | Jovin, Thomas Prof. Dr. | |
| dc.contributor.author | Díaz, Sebastián Andrés | |
| dc.date.accessioned | 2013-12-20T09:12:53Z | |
| dc.date.available | 2013-12-20T09:12:53Z | |
| dc.date.issued | 2013-12-20 | |
| dc.identifier.uri | http://hdl.handle.net/11858/00-1735-0000-0022-60A5-2 | |
| dc.identifier.uri | http://dx.doi.org/10.53846/goediss-4152 | |
| dc.identifier.uri | http://dx.doi.org/10.53846/goediss-4152 | |
| dc.language.iso | eng | de |
| dc.publisher | Niedersächsische Staats- und Universitätsbibliothek Göttingen | de |
| dc.rights.uri | http://creativecommons.org/licenses/by-nc-nd/3.0/ | |
| dc.subject.ddc | 540 | de |
| dc.title | Water Soluble Photochromic Fluorescent Nanoprobes based on Diheteroarylethenes and Polymer Coated Quantum Dots | de |
| dc.type | doctoralThesis | de |
| dc.contributor.referee | Stalke, Dietmar Prof. Dr. | |
| dc.date.examination | 2013-07-02 | |
| dc.description.abstracteng | The rapidly growing field of fluorescence microscopy is dependent on the introduction of new, versatile probes. Quantum dots (QDs) are of great interest due to their brightness, fatigue resistance, large extinction coefficient, broad excitation, and narrow emission. In addition, fluorescent probes capable of a systematic modulation of emission intensity provide increased detection sensitivity due to the suppression of background contributions. Of particular interest are probes whose emission can be controlled by external stimuli such as irradiation. By satisfying certain spectroscopic and structural criteria, Förster resonance energy transfer (FRET) can be employed as an efficient means for generating modulation of fluorescence. The use of photochromic molecules, e.g. diheteroarylethenes (PC), as acceptors permits the FRET pair to be reversibly switched between transfer/ nontransfer states with light. This strategy introduced previously as photochromic FRET (pcFRET), was exploited in this thesis to develop photomodulatable fluorescent nanoparticle probes.
A photomodulatable comb-like amphiphilic polymer was synthesized containing lucifer yellow and PC groups as FRET donors and acceptors, respectively. The adopted nano-conformation of the polymer as well as its spectral and switching properties were characterized in organic and aqueous solutions, alone or in combination with a QD template. Self-assembly of the polymer on the surface of a red light emitting QD created a dual-color photoswitchable nanoparticle dispersible in an aqueous medium.
When a 550 nm emitting QD was coated with a photochromic comb-like amphiphilic polymer it was observed that the polymer conjugated PC molecules self-assembled within the hydrophobic microenvironment demarcated by the outer surface of the semiconductor QD and the polymer cap. This novel surface architecture generated a biocompatible and stable photoswitchable quantum dot (psQD). The psQDs were small (~15 nm diameter) and an emission modulation of up to 50% in steady state and 47% in time-resolved fluorescence was observed upon UV irradiation. The psQDs underwent multiple on-off cycles without fatigue in buffer solution with a complete recovery of the initial intensity upon 550 nm light irradiation. Versions of the psQDs were prepared in which Alexa647 was also conjugated to the polymer and acted as an internal reference, thereby adding ratiometric properties to the construct.
The ensemble psQDs were characterized with a multitude of techniques including single-particle microscopy. The single particle microscopy supports a model according to which the UV irradiation causes a fraction of the psQDs to enter into a long-lived dark state. Finally psQDs were functionalized by adding biological molecules on the surface, creating targetable psQDs. Preliminary fluorescence microscopy studies were realized on live cells labeled with psQDs. The unique properties of psQDs should lead to numerous applications in cellular imaging. | de |
| dc.contributor.coReferee | Jovin, Thomas Prof. Dr. | |
| dc.contributor.thirdReferee | Enderlein, Jörg Prof. Dr. | |
| dc.contributor.thirdReferee | Clever, Guido Prof. Dr. | |
| dc.contributor.thirdReferee | Vana, Philipp Prof. Dr. | |
| dc.contributor.thirdReferee | Outeiro, Tiago Fleming Prof. Dr. | |
| dc.subject.eng | Quantum Dots | de |
| dc.subject.eng | Photochromic | de |
| dc.subject.eng | FRET | de |
| dc.subject.eng | Amphiphilic Polymers | de |
| dc.identifier.urn | urn:nbn:de:gbv:7-11858/00-1735-0000-0022-60A5-2-4 | |
| dc.affiliation.institute | Fakultät für Chemie | de |
| dc.subject.gokfull | Chemie (PPN62138352X) | de |
| dc.identifier.ppn | 775146226 | |