TY - JOUR A1 - Fokong, S. A1 - Theek, B. A1 - Wu, Z. A1 - Koczera, P. A1 - Appold, L. A1 - Jorge, S. A1 - Resch-Genger, Ute A1 - van Zandvoort, M. A1 - Storm, G. A1 - Kiessling, F. A1 - Lammers, T. T1 - Image-guided, targeted and triggered drug delivery to tumors using polymer-based microbubbles N2 - Microbubbles (MB) are routinely used contrast agents for functional and molecular ultrasound (US) imaging. In addition, they have been attracting more and more attention for drug delivery purposes, enabling e.g. US-mediated drug delivery across biological barriers and US-induced triggered drug release from the MB shell. The vast majority of efforts in this regard have thus far focused on phospholipid-based soft-shell MB, which are suboptimal for stably incorporating large amounts of drug molecules because of their relatively thin shell. Using poly(butyl cyanoacrylate) (PBCA)-based hard-shell MB, we show here that both hydrophilic (Rhodamine-B) and hydrophobic (Coumarin-6) model drugs can be efficiently and stably entrapped within the ~ 50 nm shell of PBCA MB. In addition, we demonstrate that model drug loading does not negatively affect the acoustic properties of the MB, and that functionalizing the surface of fluorophore-loaded MB with anti-VEGFR2 antibodies enables image-guided and targeted model drug delivery to tumor blood vessels. Finally, we show both in vitro and in vivo that disintegrating VEGFR2-targeted MB with high-mechanical index US pulses leads to high levels of model drug release. Consequently, these findings indicate that polymer-based MB are highly suitable systems for image-guided, targeted and triggered drug delivery to tumors and tumor blood vessels. KW - Ultrasound KW - Microbubbles KW - Fluorescent reporter KW - Drug delivery KW - Tumor targeting KW - Theranostics PY - 2012 U6 - https://doi.org/10.1016/j.jconrel.2012.05.007 SN - 0168-3659 SN - 1873-4995 VL - 163 IS - 1 SP - 75 EP - 81 PB - Elsevier CY - Amsterdam AN - OPUS4-27591 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hodenius, M. A1 - Würth, Christian A1 - Jayapaul, J. A1 - Wong, J. E. A1 - Lammers, T. A1 - Gätjens, J. A1 - Arns, S. A1 - Mertens, N. A1 - Slabu, I. A1 - Ivanova, G. A1 - Bornemann, J. A1 - De Cuyper, M. A1 - Resch-Genger, Ute A1 - Kiessling, F. T1 - Fluorescent magnetoliposomes as a platform technology for functional and molecular MR and optical imaging N2 - Here, we present a detailed characterisation of rhodamine B-containing magnetoliposomes (FLU-ML), emphasising the dependence of their fluorescence properties on the presence of iron oxide cores, and the molar fraction of the fluorophore. The magnetoliposome types used exist as colloidally stable, negatively charged clusters with an average hydrodynamic diameter of 95 nm. The molar rhodamine B fractions were 0.67 % and 1.97 %. Rhodamine B normalised fluorescence, quantum yields and fluorescence lifetimes were substantially reduced by inner filter effects as the magnetoliposome concentration is increased, by increasing molar rhodamine B fraction, and by quenching originating from the iron oxide cores. MR relaxometry at 3 T revealed extremely high r2 relaxivities (440 to 554 s-1mM-1) and moderately high r1 values (2.06 to 3.59 s-1mM-1). Upon incubating human prostate carcinoma (PC-3) cells with FLU-ML, a dose-dependent particle internalisation was found by MR relaxometry. In addition, the internalised FLU-ML were clearly visible by fluorescence microscopy. At the FLU-ML concentrations used (up to 3 × 103 M Fe) cell viability was not substantially impaired. These results provide valuable insights on the fluorescence properties of bimodal magnetoliposomes and open promising perspectives for the use of these materials as a platform technology for advanced functional and molecular MR and optical imaging applications. KW - Fluorescent magnetoliposomes KW - Steady state and time resolved fluorometry KW - Quantum yield KW - Fluorescence lifetimes KW - MR relaxivities KW - PC-3 cells KW - Cell viability PY - 2012 U6 - https://doi.org/10.1002/cmmi.467 SN - 1555-4309 SN - 1555-4317 VL - 7 IS - 1 SP - 59 EP - 67 PB - Wiley CY - Chichester AN - OPUS4-25577 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stengel, Dominik A1 - Kießling, F. A1 - Mehdianpour, Milad A1 - Özbey, U.-Y. A1 - Pohl, H. T1 - Windlasten auf Freileitungen - Windmessungen an einer 380-kV-Freileitung N2 - Windeinwirkungen auf Freileitungen wurden in der Vergangenheit meist an exponierten Standorten bestimmt. In einem Langzeitversuch wurden seit 2012 an einer mit moderner Messtechnik ausgerüsteten 380-kV-Leitung der 50 Hertz Transmission GmbH, die im nicht besonders exponierten Gelände verläuft und somit den Leitungen im Netz entspricht, die Windgeschwindigkeiten entlang der Leiter und deren Auswirkungen auf die Stützpunkte gemessen. Die Messungen und die begleitenden Auswertungen bestätigen die heute verwendeten normativen Vorgaben für die Windwirkung auf die Leiter von Freileitungen, soweit dies in der relativ kurzen Zeit von fünf Jahren möglich ist. KW - Wind KW - Freileitungen PY - 2017 VL - 2017 IS - 9 SP - 68 EP - 72 PB - EW Medien und Kongresse GmbH CY - Frankfurt am Main AN - OPUS4-42119 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -