TY - JOUR A1 - Wilhelm, Stefan A1 - Kaiser, Martin A1 - Würth, Christian A1 - Heiland, J. A1 - Carrillo-Carrion, C. A1 - Muhr, V. A1 - Wolfbeis, Otto S. A1 - Parak, W.J. A1 - Resch-Genger, Ute A1 - Hirsch, T. T1 - Water dispersible upconverting nanoparticles: effects of surface modification on their luminescence and colloidal stability JF - Nanoscale N2 - We present a systematic study on the effect of surface ligands on the luminescence properties and colloidal stability of β-NaYF4:Yb3+,Er3+ upconversion nanoparticles (UCNPs), comparing nine different surface coatings to render these UCNPs water-dispersible and bioconjugatable. A prerequisite for this study was a large-scale synthetic method that yields ~2 g per batch of monodisperse oleate-capped UCNPs providing identical core particles. These ~23 nm sized UCNPs display an upconversion quantum yield of ~0.35% when dispersed in cyclohexane and excited with a power density of 150 W cm-2, underlining their high quality. A comparison of the colloidal stability and luminescence properties of these UCNPs, subsequently surface modified with ligand exchange or encapsulation protocols, revealed that the ratio of the green (545 nm) and red (658 nm) emission bands determined at a constant excitation power density clearly depends on the surface chemistry. Modifications relying on the deposition of additional (amphiphilic) layer coatings, where the initial oleate coating is retained, show reduced non-radiative quenching by water as compared to UCNPs that are rendered water-dispersible via ligand exchange. Moreover, we could demonstrate that the brightness of the upconversion luminescence of the UCNPs is strongly affected by the type of surface modification, i.e., ligand exchange or encapsulation, yet hardly by the chemical nature of the ligand. KW - upconverting nanoparticles (UCNPs) KW - Luminescence KW - surface modification PY - 2015 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-324071 DO - https://doi.org/10.1039/c4nr05954a SN - 2040-3364 SN - 2040-3372 VL - 7 IS - 4 SP - 1403 EP - 1410 PB - RSC Publ. CY - Cambridge AN - OPUS4-32407 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lisy, M.-R. A1 - Goermar, A. A1 - Thomas, C. A1 - Pauli, Jutta A1 - Resch-Genger, Ute A1 - Kaiser, W.A. A1 - Hilger, I. T1 - In Vivo Near-infrared Fluorescence Imaging of Carcinoembryonic Antigen-expressing Tumor Cells in Mice JF - Radiology N2 - Purpose: To prospectively depict carcinoembryonic antigen (CEA)-expressing tumors in mice with a high-affinity probe consisting of a near-infrared (NIR) fluorochrome and the clinically used anti-CEA antibody fragment arcitumomab. Materials and Methods: This study was approved by the regional animal committee. By coupling a NIR fluorescent (NIRF) cyanine dye (DY-676) to a specific antibody fragment directed against CEA (arcitumomab) and a nonspecific IgG Fab fragment, a bio-optical high-affinity fluorescent probe (anti-CEA–DY-676) and a low-affinity fluorescent probe (FabIgG–DY-676) were designed. The dye-to-protein ratios were determined, and both probes were tested for NIRF imaging in vitro on CEA-expressing LS-174T human colonic adenocarcinoma cells and CEA-nonexpressing A-375 human melanoma cells by using a bio-optical NIR small-animal imager. In vivo data of xenografted LS-174T and A-375 tumors in mice (n = 10) were recorded and statistically analyzed (Student t test). Results: The dye-to-protein ratios were determined as 3.0–3.5 for both probes. In vitro experiments revealed the specific binding of the anti-CEA–DY-676 probe on CEA-expressing cells as compared with CEA-nonexpressing cells; the FabIgG–DY-676 probe showed a markedly lower binding affinity to cells. In vivo LS-174T tumors xenografted in all mice could be significantly distinguished from A-375 tumors with application of the anti-CEA–DY-676 but not with that of the FabIgG–DY-676 at different times (2–24 hours, P < .005) after intravenous injection of the probes. Semiquantitative analysis revealed maximal fluorescence signals of anti-CEA–DY-676 to CEA-expressing tumors about 8 hours after injection. Conclusion: Findings of this study indicate the potential use of the high-affinity probe anti-CEA–DY-676 for specific NIRF imaging in in vivo tumor diagnosis. KW - Fluorescence spectroscopy KW - NIR fluorescent dye KW - NIRF imaging KW - Antibogy fragment arcitumomab KW - Carcinoembryonic antigen PY - 2008 DO - https://doi.org/10.1148/radiol.2472070123 SN - 0033-8419 SN - 1527-1315 VL - 247 IS - 3 SP - 779 EP - 787 PB - Radiological Society of North America CY - Oak Brook, Ill. AN - OPUS4-17629 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lezhnina, M.M. A1 - Kätker, H. A1 - Kaiser, Martin A1 - Stegemann, L. A1 - Voss, E. A1 - Resch-Genger, Ute A1 - Strassert, C. A1 - Kynast, U. T1 - Chemical behavior and spectroscopic properties of rare earth borates in glazes JF - Journal of Luminescence N2 - Efficient Near UV excited materials (350<λ<400 nm) responding with green line emission are sparse in comparison to higher energy UV excited emitters (λ<350 nm), while corresponding red line emitters are more abundant, albeit typically also restricted to excitation wavelengths below 400 nm. This situation is disadvantageous for several important actual and potential applications. Among these, excitation with high power UV-LEDs and laser diodes are of particular interest. Here we present results on green emitting YBO3:Ce, Tb, which can be excited with 370–380 nm radiation at quantum efficiencies of up to 60% and decay times in excess of 2 ms. Moreover, as powderous phosphors typically require stable matrices to be hosted in, we investigated low melting, lead- and fluoride-free glasses for their capability to accommodate the phosphor and yet retain its optical properties. In these, we even observed an increase of the quantum efficiencies of up to 70% at decay times approaching 3 ms. Finally, we characterized the thermal quenching behavior, which showed a clear advantage of the phosphors in glassy matrices. KW - Rare earth phosphors KW - Energy transfer KW - Luminescent glasses and glazes PY - 2016 DO - https://doi.org/10.1016/j.jlumin.2015.05.005 SN - 0022-2313 SN - 1872-7883 VL - 170 SP - 387 EP - 394 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-35131 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Busch, C. A1 - Schröter, T. A1 - Grabolle, Markus A1 - Wenzel, M. A1 - Kempe, H. A1 - Kaiser, W.A. A1 - Resch-Genger, Ute A1 - Hilger, I. T1 - An in vivo spectral multiplexing approach for the cooperative imaging of different disease-related biomarkers with near-infrared fluorescent Förster resonance energy transfer probes JF - Journal of nuclear medicine N2 - In recent years, much progress has been made in analyzing the molecular origin of many diseases in vivo. For most applications, attention has been devoted to the detection of single molecules only. In this study, we present a proof of concept for the straightforward monitoring of interactions between different molecules via Förster resonance energy transfer (FRET) in an in vivo spectral multiplexing approach using conventional small organic dyes covalently attached to antibodies. Methods: We coupled the fluorophores DY-682 (donor; absorption [abs]/emission [em], 674/712 nm), DY-505 (control donor; abs/em, 498/529 nm), and DY-782 (acceptor; abs/em, 752/795 nm) to the model antibody IgG. The occurrence of FRET between these fluorophores was assessed in vitro for conjugate mixtures adsorbed onto membranes, after accumulation into the phagocytic compartment of macrophages (J774 cells), and in vivo in a mouse edema model using a whole-body animal imaging system with multispectral analysis features. Results: When the free acceptor DY-782 was combined with the DY-682 donor, FRET occurred as a consequence of small dye-to-dye distances, unlike the case for mixtures of the dyes DY-782 and DY-505. Our proof of concept was also transferred to living cells after internalization of the DY-682-IgG–DY-782-IgG pair into macrophages and finally to animals, where intermolecular FRET was observed after systemic probe application in vivo in edema-bearing mice. Conclusion: Our simple cooperative-imaging approach enables the noninvasive detection of the presence of two or principally even more neighboring disease-related biomarkers. This finding is of high relevance for the in vivo identification of complex biologic processes requiring strong spatial interrelations of target molecules in key pathologic activation processes such as inflammation, cancer, and neurodegenerative diseases. KW - FRET KW - IgG antibodies KW - In vivo molecular imaging KW - Near-infrared (NIR) fluorophores KW - Multiplexing KW - Cooperative signaling PY - 2012 DO - https://doi.org/10.2967/jnumed.111.094391 SN - 0161-5505 SN - 0097-9058 SN - 0022-3123 SN - 1535-5667 VL - 53 IS - 4 SP - 638 EP - 646 PB - SNM CY - Reston, Va. AN - OPUS4-26069 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -