Rofo 2013; 185 - WI_PO30
DOI: 10.1055/s-0033-1346627

NIR-Emissive Nanosensors for oxygen sensing in tumors

J Napp 1, T Behnke 2, L Fischer 3, Ch Würth 3, M Wottawa 4, DE Katschinski 4, F Alves 5, U Resch-Genger 2, M Schäferling 3
  • 1Universitätsmedizin Göttingen, Diagnostische Radiologie, Göttingen
  • 2BAM Federal Institute for Materials Research and Testing, Berlin
  • 3University of Regensburg, Institute of Analytical Chemistry, Chemo- and Biosensors, Regensburg
  • 4University Medical Center Göttingen, Department of Cardiovascular Physiology, Göttingen
  • 5University Medical Center Göttingen, Department of Hematology and Oncology, Göttingen

Ziele: Hypoxia is one of the major attributes of solid tumors, caused by a combination of an increased oxygen consumption and usually insufficient oxygen supply. Therefore, there is a high demand for sensitive and cost effective tools for the determination of tumor oxygenation in vivo and in real time. Here, we present the development and the first in vitro and in vivo application of NIR-emissive polystyrene nanobeads with high potential for measurements of the tumor oxygen levels in vivo. Methode: 100 nm polystyrene nanoparticles were dopes with an oxygen-sensitive phosphorescent Pd(II) porphyrin and an innert reference dye, both excitable at 635 nm. With this probe (Ox-NP), the oxygen partial pressure can be obtained by calculating the ratio of oxygen-sensitive (lambdaem = 800 nm) and the reference (lambdaem = 675 nm) dye emission. MH-S macrophages were used for NIRF microscopy. The applicability of the Ox-NPs for in vivo imaging was evaluated in nude mice bearing subcutaneous human tumor xenografts with the Optix MX2. Ergebnis: The phosphorescence of oxygen-sensitive dye is completely quenched in oxygen-saturated solution, while the reference signal is not affected. A linear relation between the oxygen concentration and the ratiometric response of Ox-NP was measured, with a –4-fold increase in signal intensity for oxygen-free conditions. The intensity ratio was strongly increased in macrophages incubated with Ox-NP under hypoxic conditions (1% and 5% O2) in comparison to cells incubated in 20% O2. The accumulation of the hypoxia marker HIF-1a, analyzed by Western blot confirmed the hypoxic status of the cells. First results in tumor-bearing mice showed passive accumulation of the probe in tumor and an increase in the ratiometric response between high and low oxygen conditions in tumor tissue. Schlussfolgerung: We developed a novel NIR fluorescent ratiometric system consisting of dye-loaded polystyrene nanoparticles that can be applied for in vitro and in vivo oxygen sensing.

Korrespondierender Autor: Napp J

Universitätsmedizin Göttingen, Diagnostische Radiologie, Robert-Koch Str. 40, 37075 Göttingen

E-Mail: jnowako1@gwdg.de

NIRF Imaging - oxygen sensing - tumor imaging - sensor probes - nanoparticles