الفهرس 
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Abstract
Selenium is one of the most important dietary supplements that should be contained in the human diet. It is incorporated into the synthesis of many antioxidant proteins that called scavengers of reactive oxygen species such as glutathione peroxidase. Selenium nanoparticles are the most superior form of selenium element, as they exceed other selenium species in many biological features such as toxicity and biocompatibility. Selenium nanoparticles (SeNPs) have become one of the most prospective and promising tools in the course of cancer diagnosis and therapy. Here we describe the synthesis of two novel radioactive platforms for solid tumor imaging using selenium nanoparticles. SeNPs were synthetized by chemical reduction methods and ascorbic acid (vitamin C) and glutathione as capping agents to prepare the compounds ASC/SeNPs and GSH/SeNPs respectively using sodium selenite as a precursor. SeNPs were then radiolabeled with the radioactive isotope technetium-99m (99mTc), the most common and famous radioactive isotope used for imaging purposes. A characteristic profile for the two synthesized SeNPs compounds was performed including size analysis, zeta potential, antioxidant activity, in-vitro stability, radiochemical yield and in-vivo biodistribution in normal and solid tumor bearing mice. Size analysis of ASC/SeNPs showed amorphous cores of a mean diameter 16±7 nm with a hydrodynamic size of 23±5.0 nm and -31 mV at pH 7 zeta potential. Moreover, GSH/SeNPs showed spherical cores of a mean diameter 21±5 nm with a hydrodynamic size of 43±8 nm and -28 mV zeta potential. The two synthesized compounds also showed a superior antioxidant activity of radical scavenging capacity percentages (RSC %) of 45.7±5.0% and 42.5±4.4% according to DPPH assay for ASC/SeNPs and GSH/SeNPs respectively. In addition, satisfying radiochemical yield up to 97±1.5 was achieved. In vivo studies were applied on male Swiss albino mice that demonstrated a good biodistribution pattern of both compounds in normal mice with a moderate accumulation in liver at 30 and 60 minutes post injection and their clearance was via kidneys. Excellent target/non-target ratios were obtained in solid tumor bearing mice throughout the experimental time points. The as-synthetized selenium nanoparticles demonstrated surprising and satisfying features which make them promising enough for solid tumor imaging. Finally, this study has concluded that both of the obtained SeNPs based compounds are potentially suggested for imaging of solid tumors.
Key words:
Selenium nanoparticles, Vitamin C, Glutathione, Molecular imaging, Technetium-99m, radiopharmaceuticals, Tumor imaging.