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Contrast Media & Molecular Imaging
Volume 2017 (2017), Article ID 4693417, 8 pages
https://doi.org/10.1155/2017/4693417
Research Article

Radiolabeling and Quantitative In Vivo SPECT/CT Imaging Study of Liposomes Using the Novel Iminothiolane-99mTc-Tricarbonyl Complex

1Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest 1117, Hungary
2Department of Biophysics and Radiation Biology, Semmelweis University, Budapest 1094, Hungary
3Institute of Nuclear Techniques, Budapest University of Technology and Economics, Budapest 1111, Hungary
4CROmed Translational Research Centers, Budapest 1047, Hungary

Correspondence should be addressed to Zoltán Varga; uh.atm.ktt@natloz.agrav

Received 17 March 2017; Accepted 4 May 2017; Published 31 May 2017

Academic Editor: Ralf Schirrmacher

Copyright © 2017 Zoltán Varga et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The in vivo biodistribution of liposomal formulations greatly influences the pharmacokinetics of these novel drugs; therefore the radioisotope labeling of liposomes and the use of nuclear imaging methods for in vivo studies are of great interest. In the present work, a new procedure for the surface labeling of liposomes is presented using the novel Tc-tricarbonyl complex. Liposomes mimicking the composition of two FDA approved liposomal drugs were used. In the first step of the labeling, thiol-groups were formed on the surface of the liposomes using Traut’s reagent, which were subsequently used to bind Tc-tricarbonyl complex to the liposomal surface. The labeling efficiency determined by size exclusion chromatography was 95%, and the stability of the labeled liposomes in bovine serum was found to be 94% over 2 hours. The obtained specific activity was 50 MBq per 1 μmol lipid which falls among the highest values reported for Tc labeling of liposomes. Quantitative in vivo SPECT/CT biodistribution studies revealed distinct differences between the labeled liposomes and the free Tc-tricarbonyl, which indicates the in vivo stability of the labeling. As the studied liposomes were non-PEGylated, fast clearance from the blood vessels and high uptake in the liver and spleen were observed.