title: Dual-Colour STED-microscopy on the Nanoscale creator: Donnert, Gerald subject: 530 subject: 530 Physics description: Stimulated emission depletion (STED) microscopy was the first concept for breaking Abbe's diffraction barrier in optical far-field microscopy verified in biological applications. However, the theoretically infinite resolution was limited due to photobleaching of the fluorescent species. In this thesis, dark-state relaxation (D-Rex) has been traced in a comprehensive study on one- and two-photon excitation to crucially reduce photobleaching in general thus leading to a major signal increase per excitation pulse. This facilitated a successful combination of this illumination strategy with STED-microscopy making a 10-fold increase of STED-power feasible. The expansion of STED-microscopy to D-Rex conditions at 250 kHz leads to a yet unattained focal plane resolution ~20 nm, equivalent to an approximate 12-fold multilateral increase of resolution below the diffraction limit. This macromolecular resolution was exemplified in a variety of biological samples, including proteins of cell-junction and focal adhesion, or a neurofilamental protein from the human brain. Finally, the extension to a Dual-colour STED-microscope was achieved to provide nanoscale precise colocalization ability of individual protein clusters in cell biology, thereby sustainably widening the application range of STED-microscopy. The method proved to resolve hitherto uncovered nanopatterns of vesicle proteins on endosomes, as well as localized different proteins in mammalian mitochondria. date: 2007 type: Dissertation type: info:eu-repo/semantics/doctoralThesis type: NonPeerReviewed format: application/pdf identifier: https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/7338/1/Dissertation_Gerald_Donnert.pdf identifier: DOI:10.11588/heidok.00007338 identifier: urn:nbn:de:bsz:16-opus-73389 identifier: Donnert, Gerald (2007) Dual-Colour STED-microscopy on the Nanoscale. [Dissertation] relation: https://archiv.ub.uni-heidelberg.de/volltextserver/7338/ rights: info:eu-repo/semantics/openAccess rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html language: eng