In vivo SPECT imaging of tumors by 198,199Au-labeled graphene oxide nanostructures

Graphene oxide (GO) sheets functionalized by aminopropylsilyl groups (8.0 wt.%) were labeled by Au-198,Au-199 nanoparticle radioisotopes (obtained through reduction of HAuCl4 in sodium citrate solution followed by thermal neutron irradiation) for fast in vivo targeting and SPECT imaging (high purity germanium-spectrometry) of tumors. Using instant thin layer chromatography method, the physicochemical properties of the amino-functionalized GO sheets labeled by Au-198,Au-199 NPs (Au-198,Au-199@AF-GO) were found to be highly stable enough in organic phases, e.g. a human serum, to be reliably used in bioapplications. In vivo biodistribution of the Au-198,Au-199@AF-GO composite was investigated in rats bearing fibrosarcoma tumor after various post-injection periods of time. The Au-198,Au-199@AF-GO nanostructure exhibited a rapid as well as high tumor uptake (with uptake ratio of tumor to muscle of 167 after 4 h intravenous injection) that resulted in an efficient tumor targeting/imaging. Meantime, the low lipophilicity of the Au-198,Au-199@AF-GO caused to its fast excretion (-24 h) throughout the body by the kidneys (as also confirmed by the urinary tract). Because of the short half-life of Au-198,Au-199 radioisotopes, the Au-198,Au-199@AF-GO with an excellent tumor targeting/imaging and fast washing out from the body can be suggested as one of the most effective and promising nanomaterials in nanotechnology-based cancer diagnosis and therapy. (C) 2014 Elsevier B.V. All rights reserved.