TY - THES A1 - López de Guereñu, Anna T1 - Tm3+-doped NaYF4 nanoparticles T1 - Tm3+-dotierte NaYF4 Nanopartikel BT - upconversion properties and bioimaging BT - Aufkonversionseigenschaften und Biologische Bildgebung N2 - 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. Förster 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. N2 - In letzter Zeit hat sich die Integration von hochkonvertierenden Nanopartikeln (UCNP) in industriellen, biomedizinischen und wissenschaftlichen Anwendungen aufgrund der außergewöhnlichen photophysikalischen Eigenschaften, die UCNP bieten, zunehmend beschleunigt. Einige der vielversprechendsten Anwendungen liegen auf dem Gebiet der Medizin und des Bioimaging, der Bildgebung in biologischen Proben, unter anderem aufgrund vieler Vorteile wie einer tieferen Gewebedurchdringung, einem verringerten optischen Hintergrund, der Möglichkeit einer mehrfarbigen Bildgebung und einer geringeren Toxizität im Vergleich zu vielen bekannten Luminophoren. Einige Fragen, die nicht nur die grundlegenden photophysikalischen Prozesse betreffen, sondern auch die Wechselwirkung der UCNP mit anderen Lumineszenzreportern, die häufig für das Bioimaging verwendet werden, und die Wechselwirkung mit biologischen Medien bleiben jedoch offen. Diese Themen waren die Hauptmotivation für die vorgestellte Arbeit. Diese Doktorarbeit untersuchte verschiedene Aspekte verschiedener Eigenschaften und Möglichkeiten für die Bioanwendung von Yb3+,Tm3+-dotierten NaYF4-hochkonvertierenden Nanopartikeln. Zunächst wurde der Einfluss verschiedener Gd3+-Dotierungen auf die Struktur und das Hochkonvertierungsverhalten der Nanokristalle untersucht. Der Alterungsprozess des UCNP in Cyclohexan wurde über 24 Monate an Proben mit unterschiedlichen Gd3+-Dotierungskonzentrationen untersucht. Strukturinformationen wurden mittels Röntgenbeugung (XRD), Transmissionselektronenmikroskopie (TEM) und dynamischer Lichtstreuung (DLS) gesammelt und in Bezug auf die spektroskopischen Ergebnisse diskutiert, die durch Multiparameter-Hochkonversion-Lumineszenz-Experimenten bei verschiedenen Temperaturen (von 4 K bis 295 K) erhalten wurden. Zeitaufgelöste und stationäre Emissionsspektren, die über diesen weiten Temperaturbereich aufgezeichnet wurden, ermöglichten ein tieferes Verständnis der photophysikalischen Prozesse und ihrer Abhängigkeit von strukturellen Änderungen des UCNP. Ein neues Protokoll unter Verwendung eines im Handel erhältlichen hochsiedenden Lösungsmittels ermöglichte eine schnellere und kontrolliertere Herstellung von sehr kleinen und homogenen UCNP mit besseren photophysikalischen Eigenschaften. Weiterhin wurden die Vorteile einer passivierenden NaYF4-Hülle gezeigt. Der Förster-Resonanzenergietransfer (FRET) zwischen vier verschiedenen Spezies der NaYF4:Yb3+,Tm3+ UCNP (synthetisiert unter Verwendung des verbesserten Protokolls) und einem kleinen organischen Farbstoff wurde untersucht. Der Einfluss der UCNP-Zusammensetzung und die Nähe von Tm3+-Ionen (Donoren im FRET-Prozess) zu Akzeptorfarbstoffmolekülen wurden untersucht. Die effizienteste Hochkonversionslumineszenz wurde bei dem UCNP mit einer schützenden inerten Hülle beobachtet. Die UCNP mit den nur in der Schale dotierten Tm3+-Ionen leuchteten am schlechtesten, zeigten jedoch den effizientesten Energietransfer. Im letzten Teil wurden zwei Oberflächenmodifizierungsstrategien angewendet, um die UCNP wasserlöslich zu machen. Dadurch wurde es gleichzeitig möglich, die UCNP mittels einer ungiftigen kupferfreien Klickreaktion mit den Liposomen zu verbinden, die als Modelle für weitere Zellexperimente dienten. Die Ergebnisse wurden mit einem konfokalen Mikroskopsystem untersucht, das durch weniger bekannte Abwärtsumwandlungseigenschaften von Yb3+,Tm3+-dotiertem UCNP ermöglicht wurde. Vorläufige Antikörperfärbungstests wurden unter Verwendung von zwei primären Antikörpern und einem farbstoffmarkierten sekundären Antikörper an MDCK-II-Zellen durchgeführt. KW - upconverting nanoparticles KW - core-shell UCNP KW - resonance energy transfer KW - time-resolved luminescence KW - antibody staining KW - Antikörper-Färbung KW - Kern-Schale Aufkonvertierende Nanopartikel KW - Resonante Energie Transfer KW - Zeitaufgelöste Lumineszenz Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-475593 ER - TY - GEN A1 - López de Guereñu, Anna A1 - Bastian, Philipp A1 - Wessig, Pablo A1 - John, Leonard A1 - Kumke, Michael Uwe T1 - Energy transfer between tm-doped upconverting nanoparticles and a small organic dye with large stokes shift T2 - Postprints der Universität Potsdam : Mathematisch Naturwissenschaftliche Reihe N2 - 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. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 961 KW - resonance energy transfer KW - DBD dye KW - core shell UCNP KW - time-resolved luminescence Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-472240 SN - 1866-8372 IS - 961 ER - TY - JOUR A1 - López de Guereñu, Anna A1 - Bastian, Philipp A1 - Wessig, Pablo A1 - John, Leonard A1 - Kumke, Michael Uwe T1 - Energy Transfer between Tm-Doped Upconverting Nanoparticles and a Small Organic Dye with Large Stokes Shift JF - Biosensors : open access journal N2 - 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. KW - resonance energy transfer KW - DBD dye KW - core shell UCNP KW - time-resolved luminescence Y1 - 2019 U6 - https://doi.org/10.3390/bios9010009 SN - 2079-6374 VL - 9 IS - 1 PB - MDPI CY - Basel ER - TY - JOUR A1 - López de Guereñu Kurganova, Anna A1 - Klier, Dennis Tobias A1 - Haubitz, Toni A1 - Kumke, Michael Uwe T1 - Influence of Gd3+ doping concentration on the properties of Na(Y,Gd)F-4 BT - Yb3+, Tm3+ upconverting nanoparticles and their long-term aging behavior JF - Photochemical & photobiological sciences / European Society for Photobiology N2 - We present a systematic study on the properties of Na(Y,Gd)F-4-based upconverting nanoparticles (UCNP) doped with 18% Yb3+, 2% Tm3+, and the influence of Gd3+ (10-50 mol% Gd3+). UCNP were synthesized via the solvothermal method and had a range of diameters within 13 and 50 nm. Structural and photophysical changes were monitored for the UCNP samples after a 24-month incubation period in dry phase and further redispersion. Structural characterization was performed by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) as well as dynamic light scattering (DLS), and the upconversion luminescence (UCL) studies were executed at various temperatures (from 4 to 295 K) using time-resolved and steady-state spectroscopy. An increase in the hexagonal lattice phase with the increase of Gd3+ content was found, although the cubic phase was prevalent in most samples. The Tm3+-luminescence intensity as well as the Tm3+-luminescence decay times peaked at the Gd3+ concentration of 30 mol%. Although the general upconverting luminescence properties of the nanoparticles were preserved, the 24-month incubation period lead to irreversible agglomeration of the UCNP and changes in luminescence band ratios and lifetimes. KW - Upconversion luminescence KW - Lanthanides KW - Near infra-red KW - Ultra-low KW - temperature KW - Time-resolved spectroscopy Y1 - 2022 U6 - https://doi.org/10.1007/s43630-021-00161-4 SN - 1474-905X SN - 1474-9092 VL - 21 IS - 2 SP - 235 EP - 245 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Bastian, Philipp U. A1 - Yu, Leixiao A1 - de Guereñu Kurganova, Anna Lopez A1 - Haag, Rainer A1 - Kumke, Michael Uwe T1 - Bioinspired confinement of upconversion nanoparticles for improved performance in aqueous solution JF - The journal of physical chemistry : C, Nanomaterials and interfaces N2 - The resonance energy transfer (RET) from NaYF4:Yb,Er upconverting nanoparticles (UNCPs) to a dye (5-carboxytetramethylrhodamine (TAMRA)) was investigated by photoluminescence experiments and microscale thermophoresis (MST). The dye was excited via RET from the UCNPs which was excited in the near-infrared (NIR). The change of the dye diffusion speed (free vs coupled) was investigated by MST. RET shows significant changes in the decay times of the dye as well as of the UCNPs. MST reveals significant changes in the diffusion speed. A unique amphiphilic coating polymer (customized mussel protein (CMP) polymer) for UCNP surface coating was used, which mimics blood protein adsorption and mussel food protein adhesion to transfer the UCNP into the aqueous phase and to allow surface functionalization. The CMP provides very good water dispersibility to the UCNPs and minimizes ligand exchange and subsequent UCNP aging reactions because of the interlinkage of the CMP on the UCNP surface. Moreover, CMP provides N-3-functional groups for dick chemistry-based functionalization demonstrated with the dye 5-carboxytetramethylrhodamine (TAMRA). This establishes the principle coupling scheme for suitable biomarkers such as antibodies. The CMP provides very stable aqueous UCNP dispersions that are storable up to 3 years in a fridge at 5 degrees C without dissolution or coagulation. The outstanding properties of CMP in shielding the UCNP from unwanted solvent effects is reflected in the distinct increase of the photoluminescence decay times after UCNP functionalization. The UCNP-to-TAMRA energy transfer is also spectroscopically investigated at low temperatures (4-200 K), revealing that one of the two green Er(III) emission bands contributes the major part to the energy transfer. The TAMRA fluorescence decay time increases by a factor of 9500 from 2.28 ns up to 22 mu s due to radiationless energy transfer from the UCNP after NIR excitation of the latter. This underlines the unique properties of CMP as a versatile capping ligand for distinctly improving the UCNPs' performance in aqueous solutions, for coupling of biomolecules, and for applications for in vitro and in vivo experiments using UCNPs as optical probes in life science applications. Y1 - 2020 U6 - https://doi.org/10.1021/acs.jpcc.0c09798 SN - 1932-7447 SN - 1932-7455 VL - 124 IS - 52 SP - 28623 EP - 28635 PB - American Chemical Society CY - Washington, DC ER - TY - JOUR A1 - Schimka, Selina A1 - Klier, Dennis Tobias A1 - de Guerenu, Anna Lopez A1 - Bastian, Philipp A1 - Lomadze, Nino A1 - Kumke, Michael Uwe A1 - Santer, Svetlana T1 - Photo-isomerization of azobenzene containing surfactants induced by near-infrared light using upconversion nanoparticles as mediator JF - Journal of physics : Condensed matter N2 - Here we report on photo-isomerization of azobenzene containing surfactants induced during irradiation with near-infrared (NIR) light in the presence of upconversion nanoparticles (UCNPs) acting as mediator. The surfactant molecule consists of charged head group and hydrophobic tail with azobenzene group incorporated in alkyl chain. The azobenzene group can be reversible photo-isomerized between two states: trans- and cis- by irradiation with light of an appropriate wavelength. The trans-cis photo-isomerization is induced by UV light, while cis-trans isomerization proceeds either thermally in darkness, or can be accelerated by exposure to illumination with a longer wavelength typically in a blue/green range. We present the application of lanthanide doped UCNPs to successfully switch azobenzene containing surfactants from cis to trans conformation in bulk solution using NIR light. Using Tm-3(+) or Er-3(+) as activator ions, the UCNPs provide emissions in the spectral range of 450 nm < lambda(em) < 480 nm (for Tm-3(+), three and four photon induced emission) or 525 nm < lambda(em) < 545 nm (for Er-3(+), two photon induced emission), respectively. Especially for UCNPs containing Tm-3(+) a good overlap of the emissions with the absorption bands of the azobenzene is present. Under illumination of the surfactant solution with NIR light (lambda(ex) = 976 nm) in the presence of the Tm-3(+)-doped UCNPs, the relaxation time of cis-trans photo-isomerization was increased by almost 13 times compared to thermally induced isomerization. The influence of thermal heating due to the irradiation using NIR light was shown to be minor for solvents not absorbing in NIR spectral range (e.g. CHCl3) in contrast to water, which shows a distinct absorption in the NIR. KW - upconversion nanoparticles KW - azobenzene containing surfactants KW - kinetic of cis-trans isomerization Y1 - 2019 U6 - https://doi.org/10.1088/1361-648X/aafcfa SN - 0953-8984 SN - 1361-648X VL - 31 IS - 12 PB - IOP Publ. Ltd. CY - Bristol ER -