@misc{LopezdeGuerenuBastianWessigetal.2019, author = {L{\´o}pez de Guere{\~n}u, Anna and Bastian, Philipp and Wessig, Pablo and John, Leonard and Kumke, Michael Uwe}, title = {Energy transfer between tm-doped upconverting nanoparticles and a small organic dye with large stokes shift}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe}, number = {961}, issn = {1866-8372}, doi = {10.25932/publishup-47224}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-472240}, pages = {19}, year = {2019}, abstract = {Lanthanide-doped upconverting nanoparticles (UCNP) are being extensively studied for bioapplications due to their unique photoluminescence properties and low toxicity. Interest in RET applications involving UCNP is also increasing, but due to factors such as large sizes, ion emission distributions within the particles, and complicated energy transfer processes within the UCNP, there are still many questions to be answered. In this study, four types of core and core-shell NaYF4-based UCNP co-doped with Yb3+ and Tm3+ as sensitizer and activator, respectively, were investigated as donors for the Methyl 5-(8-decanoylbenzo[1,2-d:4,5-d ']bis([1,3]dioxole)-4-yl)-5-oxopentanoate (DBD-6) dye. The possibility of resonance energy transfer (RET) between UCNP and the DBD-6 attached to their surface was demonstrated based on the comparison of luminescence intensities, band ratios, and decay kinetics. The architecture of UCNP influenced both the luminescence properties and the energy transfer to the dye: UCNP with an inert shell were the brightest, but their RET efficiency was the lowest (17\%). Nanoparticles with Tm3+ only in the shell have revealed the highest RET efficiencies (up to 51\%) despite the compromised luminescence due to surface quenching.}, language = {en} } @article{LopezdeGuerenuBastianWessigetal.2019, author = {L{\´o}pez de Guere{\~n}u, Anna and Bastian, Philipp and Wessig, Pablo and John, Leonard and Kumke, Michael Uwe}, title = {Energy Transfer between Tm-Doped Upconverting Nanoparticles and a Small Organic Dye with Large Stokes Shift}, series = {Biosensors : open access journal}, volume = {9}, journal = {Biosensors : open access journal}, number = {1}, publisher = {MDPI}, address = {Basel}, issn = {2079-6374}, doi = {10.3390/bios9010009}, pages = {17}, year = {2019}, abstract = {Lanthanide-doped upconverting nanoparticles (UCNP) are being extensively studied for bioapplications due to their unique photoluminescence properties and low toxicity. Interest in RET applications involving UCNP is also increasing, but due to factors such as large sizes, ion emission distributions within the particles, and complicated energy transfer processes within the UCNP, there are still many questions to be answered. In this study, four types of core and core-shell NaYF4-based UCNP co-doped with Yb3+ and Tm3+ as sensitizer and activator, respectively, were investigated as donors for the Methyl 5-(8-decanoylbenzo[1,2-d:4,5-d ']bis([1,3]dioxole)-4-yl)-5-oxopentanoate (DBD-6) dye. The possibility of resonance energy transfer (RET) between UCNP and the DBD-6 attached to their surface was demonstrated based on the comparison of luminescence intensities, band ratios, and decay kinetics. The architecture of UCNP influenced both the luminescence properties and the energy transfer to the dye: UCNP with an inert shell were the brightest, but their RET efficiency was the lowest (17\%). Nanoparticles with Tm3+ only in the shell have revealed the highest RET efficiencies (up to 51\%) despite the compromised luminescence due to surface quenching.}, language = {en} } @phdthesis{LopezdeGuerenu2020, author = {L{\´o}pez de Guere{\~n}u, Anna}, title = {Tm3+-doped NaYF4 nanoparticles}, doi = {10.25932/publishup-47559}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-475593}, school = {Universit{\"a}t Potsdam}, pages = {119}, year = {2020}, abstract = {Lately, the integration of upconverting nanoparticles (UCNP) in industrial, biomedical and scientific applications has been increasingly accelerating, owing to the exceptional photophysical properties that UCNP offer. Some of the most promising applications lie in the field of medicine and bioimaging due to such advantages as, among others, deeper tissue penetration, reduced optical background, possibility for multicolor imaging, and lower toxicity, compared to many known luminophores. However, some questions regarding not only the fundamental photophysical processes, but also the interaction of the UCNP with other luminescent reporters frequently used for bioimaging and the interaction with biological media remain unanswered. These issues were the primary motivation for the presented work. This PhD thesis investigated several aspects of various properties and possibilities for bioapplications of Yb3+,Tm3+-doped NaYF4 upconverting nanoparticles. First, the effect of Gd3+ doping on the structure and upconverting behaviour of the nanocrystals was assessed. The ageing process of the UCNP in cyclohexane was studied over 24 months on the samples with different Gd3+ doping concentrations. Structural information was gathered by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS), and discussed in relation to spectroscopic results, obtained through multiparameter upconversion luminescence studies at various temperatures (from 4 K to 295 K). Time-resolved and steady-state emission spectra recorded over this ample temperature range allowed for a deeper understanding of photophysical processes and their dependence on structural changes of UCNP. A new protocol using a commercially available high boiling solvent allowed for faster and more controlled production of very small and homogeneous UCNP with better photophysical properties, and the advantages of a passivating NaYF4 shell were shown. F{\"o}rster resonance energy transfer (FRET) between four different species of NaYF4: Yb3+, Tm3+ UCNP (synthesized using the improved protocol) and a small organic dye was studied. The influence of UCNP composition and the proximity of Tm3+ ions (donors in the process of FRET) to acceptor dye molecules have been assessed. The brightest upconversion luminescence was observed in the UCNP with a protective inert shell. UCNP with Tm3+ ions only in the shell were the least bright, but showed the most efficient energy transfer. In the final part, two surface modification strategies were applied to make UCNP soluble in water, which simultaneously allowed for linking them via a non-toxic copper-free click reaction to the liposomes, which served as models for further cell experiments. The results were assessed on a confocal microscope system, which was made possible by lesser known downshifting properties of Yb3+, Tm3+-doped UCNP. Preliminary antibody-staining tests using two primary and one dye-labelled secondary antibodies were performed on MDCK-II cells.}, language = {en} }