TY - JOUR A1 - Morgner, Frank A1 - Lecointre, Alexandre A1 - Charbonniere, Loic J. A1 - Löhmannsröben, Hans-Gerd T1 - Detecting free hemoglobin in blood plasma and serum with luminescent terbium complexes JF - Physical chemistry, chemical physics : a journal of European Chemical Societies N2 - Hemolysis, the rupturing of red blood cells, can result from numerous medical conditions (in vivo) or occur after collecting blood specimen or extracting plasma and serum out of whole blood (in vitro). In clinical laboratory practice, hemolysis can be a serious problem due to its potential to bias detection of various analytes or biomarkers. Here we present the first "mix-and-measure' method to assess the degree of hemolysis in biosamples using luminescence spectroscopy. Luminescent terbium complexes (LTC) were studied in the presence of free hemoglobin (Hb) as indicators for hemolysis in TRIS-buffer, and in fresh human plasma with absorption, excitation and emission measurements. Our findings indicate dynamic as well as resonance energy transfer (FRET) between the LTC and the porphyrin ligand of hemoglobin. This transfer leads to a decrease in luminescence intensity and decay time even at nanomolar hemoglobin concentrations either in buffer or plasma. Luminescent terbium complexes are very sensitive to free hemoglobin in buffer and blood plasma. Due to the instant change in luminescence properties of the LTC in presence of Hb it is possible to access the concentration of hemoglobin via spectroscopic methods without incubation time or further treatment of the sample thus enabling a rapid and sensitive detection of hemolysis in clinical diagnostics. Y1 - 2015 U6 - https://doi.org/10.1039/c4cp04206a SN - 1463-9076 SN - 1463-9084 VL - 17 IS - 3 SP - 1740 EP - 1745 PB - Royal Society of Chemistry CY - Cambridge ER - TY - GEN A1 - Morgner, Frank A1 - Lecointre, Alexandre A1 - Charbonnière, Loic J. A1 - Löhmannsröben, Hans-Gerd T1 - Detecting free hemoglobin in blood plasma and serum with luminescent terbium complexes N2 - Hemolysis, the rupturing of red blood cells, can result from numerous medical conditions (in vivo) or occur after collecting blood specimen or extracting plasma and serum out of whole blood (in vitro). In clinical laboratory practice, hemolysis can be a serious problem due to its potential to bias detection of various analytes or biomarkers. Here we present the first ‘‘mix-and-measure’’ method to assess the degree of hemolysis in biosamples using luminescence spectroscopy. Luminescent terbium complexes (LTC) were studied in the presence of free hemoglobin (Hb) as indicators for hemolysis in TRIS-buffer, and in fresh human plasma with absorption, excitation and emission measurements. Our findings indicate dynamic as well as resonance energy transfer (FRET) between the LTC and the porphyrin ligand of hemoglobin. This transfer leads to a decrease in luminescence intensity and decay time even at nanomolar hemoglobin concentrations either in buffer or plasma. Luminescent terbium complexes are very sensitive to free hemoglobin in buffer and blood plasma. Due to the instant change in luminescence properties of the LTC in presence of Hb it is possible to access the concentration of hemoglobin via spectroscopic methods without incubation time or further treatment of the sample thus enabling a rapid and sensitive detection of hemolysis in clinical diagnostics. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 288 Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-99485 ER - TY - JOUR A1 - Morgner, Frank A1 - Bennemann, Mark A1 - Cywiński, Piotr J. A1 - Kollosche, Matthias A1 - Górski, Krzysztof A1 - Pietraszkiewicz, Marek A1 - Geßner, André A1 - Löhmannsröben, Hans-Gerd T1 - Elastic FRET sensors for contactless pressure measurement JF - RSC Advances : an international journal to further the chemical sciences N2 - Contactless pressure monitoring based on Forster resonance energy transfer between donor/acceptor pairs immobilized within elastomers is demonstrated. The donor/acceptor energy transfer is employed by dispersing terbium(III) tris[(2-hydroxybenzoyl)-2-aminoethyl] amine complex (LLC, donor) and CdSe/ZnS quantum dots (QD655, acceptor) in styrene-ethylene/buthylene-styrene (SEBS) and poly(dimethylsiloxane) (PDMS). The continuous monitoring of QD luminescence showed a reversible intensity change as the pressure signal is alternated between two stable states indicating a pressure sensitivity of 6350 cps kPa(-1). Time-resolved measurements show the pressure impact on the FRET signal due to an increase of decay time (270 ms up to 420 ms) for the donor signal and parallel drop of decay time (170 mu s to 155 mu s) for the acceptor signal as the net pressure applied. The LLC/QD655 sensors enable a contactless readout as well as space resolved monitoring to enable miniaturization towards smaller integrated stretchable opto-electronics. Elastic FRET sensors can potentially lead to developing profitable analysis systems capable to outdo conventional wired electronic systems (inductive, capacitive, ultrasonic and photoelectric sensors) especially for point-of-care diagnostics, biological monitoring required for wearable electronics. Y1 - 2017 U6 - https://doi.org/10.1039/c7ra06379b SN - 2046-2069 VL - 7 SP - 50578 EP - 50583 PB - RSC Publishing CY - Cambridge ER - TY - THES A1 - Morgner, Frank T1 - Quantenpunktbasiertes spektroskopisches Lineal mit Terbium-Komplexen als Donoren für optische FRET-Multiplexmessungen T1 - Quantum-dot based spectroscopic ruler with terbium-complexes as donors for multiplexed optical FRET measurements N2 - Der Förster-Resonanzenergietransfer (FRET) liefert einen wichtigen Beitrag bei der Untersuchung kleinskaliger biologischer Systeme und Prozesse. Möglich wird dies durch die r-6-Abhängigkeit des FRET, die es erlaubt Abstände und strukturelle Änderungen weit unterhalb der Beugungsgrenze des Lichts mit hoher Sensitivität und geringem Aufwand zu bestimmen. Die besonderen photophysikalischen Eigenschaften von Terbiumkomplexen (LTC) und Quantenpunkten (QD) machen sie zu geeigneten Kandidaten für hochsensitive und störungsarme Multiplex-Abstandsmessungen in biologischen Systemen und Prozessen. Die Abstandsbestimmungen setzen jedoch eine genaueste Kenntnis des Mechanismus des Energietransfers von LTC auf QD ebenso voraus, wie das Wissen um Größe und Gestalt letzterer. Quantenpunkte haben im Vergleich zu biologischen Strukturen ähnliche Dimensionen und können nicht als punktförmig betrachtet werden, wie es bei einfacheren Farbstoffen möglich ist. Durch ihre Form kommt es zu einer Abstandsverteilung innerhalb des Donor-Akzeptorsystems. Dies beeinflusst den Energietransfer und damit die experimentellen Ergebnisse. In dieser Arbeit wurde der Energietransfer von LTC auf QD untersucht, um zu einer Aussage hinsichtlich des Mechanismus der Energieübertragung und der dabei zu berücksichtigenden photophysikalischen und strukturellen Parameter von LTC und QD zu gelangen. Mit der Annahme einer Abstandsverteilung sollten die Größen der Quantenpunkte bestimmt und der Einfluss von Form und Gestalt auf den Energietransfer betrachtet werden. Die notwendigen theoretischen und praktischen Grundlagen wurden eingangs dargestellt. Daran schlossen sich Messungen zur photophysikalischen Charakterisierung der Donoren und Akzeptoren an, die Grundlage der Berechnung der FRET-Parameter waren. Die Förster-Radien zeigten die für den FRET von LTC auf QD typischen extrem hohen Werte von bis zu 11 nm. Zeitaufgelöste Messungen der FRET-induzierten Lumineszenz der Donoren und Akzeptoren in den beiden biomolekularen Modellsystemen Zink-Histidin und Biotin-Streptavidin beschlossen den praktischen Teil. Als Donor wurde Lumi4Tb gebunden an ein Peptid bzw. Streptavidin genutzt, Akzeptoren waren fünf verschiedene, kommerziell erhältliche Quantenpunkte mit Carboxyl- bzw. Biotinfunktionalisierung. Bei allen Donor-Akzeptor-Paarungen konnte FRET beobachtet und ausgewertet werden. Es konnte gezeigt werden, dass die gesamte Emission des Terbiums zum Energietransfer beiträgt und der Orientierungsfaktor ² den Wert 2/3 annimmt. Die Charakterisierung der Bindungsverhältnisse innerhalb der FRET-Paare von LTC und QD über Verteilungsfunktionen bietet über die Form der Verteilungskurve die Möglichkeit Aussagen über die Gestalt der FRET-Partner zu treffen. So war es möglich, die mittlere Form der Quantenpunkte als Sphäre zu bestimmen. Dies entsprach, insbesondere bei den in z-Richtung des Kristallgitters elongierten Quantenpunkten, nicht den Erwartungen. Dieser Befund ermöglicht daher bei zukünftigen Messungen eine Verbesserung der Genauigkeit bei Abstandsbestimmungen mit Quantenpunkten. Neben der Ermittlung der die FRET-Verteilung bestimmenden Gestalt der Quantenpunkte konnte im Rahmen dieser Arbeit anhand vergleichender Messungen die Dicke der Polymerhülle der QD bestimmt und so gezeigt werden, dass FRET-Paare aus lumineszenten Terbiumkomplexen und Quantenpunkten in der Lage sind, Abstände im Nano- bis Sub-Nanometerbereich aufzulösen. N2 - Förster resonance energy transfer (FRET) plays an important role in the study of small-scale biological systems and processes. This is made possible by the r-6-dependence of FRET, which allows for determination of distances and structural changes far below the diffraction limit of light with high sensitivity and low costs. The unique photophysical properties of terbium complexes (LTC) and quantum dots (QDs) make them suitable candidates for high-sensitivity, low-noise multiplex distance measurements in biological systems and processes. Estimating distances with these FRET-pairs requires a precise knowledge of the mechanism of energy transfer from LTC to QD as well as the knowledge of size and shape of the latter. Quantum dots have, compared to biological structures, similar dimensions and therefore can not be considered as point-like, as it is possible with smaller dyes. Due to their shape, there is a distance distribution within the donor-acceptor system. This influences the energy transfer and hence the experimental results. In this work, the energy transfer from LTC to QD was examined to come to a conclusion regarding the mechanism of energy transfer and the photophysical and structural parameters of LTC and QD to be considered. The adoption of a FRET-distance distribution due to a size distribution of quantum dots should yield to a size estimation of the nanoparticles as well as a conclusion of the influence of shape and form on energy transfer. The necessary theoretical and practical principles were described at the outset of this work. This description of the basic concepts was followed by the photophysical characterization of the donors and acceptors and the calculation of FRET parameters. The calculated Förster radii were typical for the FRET from LTC to QD and showed extremely high values of up to 11 nm. Time-resolved measurements of the FRET-induced luminescence of donors and acceptors in two biomolecular model binding systems namely zinc-histidine and biotin-streptavidin binding rounded the practical part. FRET-donors used were commercially available Lumi4Tb complexes bound to streptavidin or a peptide, respectively. As FRET-acceptors five different commercially available quantum dots with carboxyl- or biotin-functionalisation were used. For all donor-acceptor pairs FRET could be observed and evaluated. It could be shown that the whole emission of terbium contributes to energy transfer. Furthermore the orientation factor ² was estimated to have a value of 2/3 when using LTC as FRET-donors and QD as FRET-acceptors. The characterization of the bonding within the FRET pairs of LTC and QD with distribution functions allows for statements about the shape of the FRET partners via shape of the distribution curves. It was possible to determine the average shape of the quantum dots as a sphere. This outcome was, especially for (in z-direction of the crystal lattice) elongated quantum dots, in the contrary to the expectations. This finding therefore allows for improving the accuracy of distance determinations with quantum dots. Based on comparative measurements it was also possible to determine the thickness of the polymer shell of the QD demonstrating that FRET pairs of luminescent terbium complexes and quantum dots are capable of determining distances in the nanometer to sub-nanometer range. KW - Quantenpunkte KW - Lanthanoidkomplexe KW - FRET KW - Abstandsverteilungen KW - spektroskopisches Lineal KW - quantum dots KW - lanthanide complexes KW - FRET KW - distance distribution KW - spectroscopic ruler Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-63576 ER - TY - JOUR A1 - Morgner, Frank A1 - Stufler, Stefan A1 - Geissler, Daniel A1 - Medintz, Igor L. A1 - Algar, W. Russ A1 - Susumu, Kimihiro A1 - Stewart, Michael H. A1 - Blanco-Canosa, Juan B. A1 - Dawson, Philip E. A1 - Hildebrandt, Niko T1 - Terbium to quantum dot FRET Bioconjugates for clinical diagnostics influence of human plasma on optical and assembly properties JF - Sensors N2 - Forster resonance energy transfer (FRET) from luminescent terbium complexes (LTC) as donors to semiconductor quantum dots (QDs) as acceptors allows extraordinary large FRET efficiencies due to the long Forster distances afforded. Moreover, time-gated detection permits an efficient suppression of autofluorescent background leading to sub-picomolar detection limits even within multiplexed detection formats. These characteristics make FRET-systems with LTC and QDs excellent candidates for clinical diagnostics. So far, such proofs of principle for highly sensitive multiplexed biosensing have only been performed under optimized buffer conditions and interactions between real-life clinical media such as human serum or plasma and LTC-QD-FRET-systems have not yet been taken into account. Here we present an extensive spectroscopic analysis of absorption, excitation and emission spectra along with the luminescence decay times of both the single components as well as the assembled FRET-systems in TRIS-buffer, TRIS-buffer with 2% bovine serum albumin, and fresh human plasma. Moreover, we evaluated homogeneous LTC-QD FRET assays in QD conjugates assembled with either the well-known, specific biotin-streptavidin biological interaction or, alternatively, the metal-affinity coordination of histidine to zinc. In the case of conjugates assembled with biotin-streptavidin no significant interference with the optical and binding properties occurs whereas the histidine-zinc system appears to be affected by human plasma. KW - FRET KW - quantum dots KW - terbium KW - luminescence lifetime KW - blood KW - plasma KW - clinical diagnostics KW - biotin KW - streptavidin KW - histidin KW - immunoassay Y1 - 2011 U6 - https://doi.org/10.3390/s111009667 SN - 1424-8220 VL - 11 IS - 10 SP - 9667 EP - 9684 PB - MDPI CY - Basel ER -