Nucline th

All animal experiments were approved by institutional ethical committee and research advisory committee of the Shiraz University of Medical Sciences (Shiraz, Iran) based on the ethical guidelines for the care and use of animals in medical research. Female Balb/c mice were obtained from the animal laboratory of Shiraz University of Medical Sciences. Each mice received 5.55 MBq (150 μl) dose of the labeled polyplexes via the tail vein intravenous injection. The static images were obtained with a single-headed gamma camera (Nucline TH, Mediso, Hungary) equipped with a low energy general purpose (LEGP) collimator. Gamma camera images were acquired at 30 to 240 min after injection. Finally, the mice were sacrificed at 0.5, 1, 2, and 4 hours post injection and various organs including kidney, brain, heart, spleen, liver and intestine were dissected. The collected organs were washed with normal saline and dried followed by weighting and their activity was measured by dose calibrator. The biodistribution of radiolabeled polyplexes in each organ was measured as a percentage of the injected dose per gram of tissue. The difference between the original syringe activity and the remaining activity after the injection was considered as the total activity injected per animal. Correction was made for background radiation and physical decay during counting^{28 (link),29 (link)}.