Abstract
1118
Objectives Nanoparticle carrier encapsulating drug is new drug delivery systems (DDS) to specific organ/tissue. We labeled nanoparticles with radionuclide, injected intravenously in mice, and analyzed whole body kinetics by means of γ-camera.
Methods We used a hydrophobic poly(γ-glutamic acid) (γPGA) nanoparticles as nanoparticle carrier. Hydrophobic γPGA nanoparticles were labeled with I-125 by iodogen method. Paricle size was measured by zetasizer. The labeled compound solution (0.1ml) was injected subcutaneously in mice (200 µg/animal, 1.1 - 2.2 MBq/animal). I-125 NaI solution (0.1 ml) was injected subcutaneously as the control compound. Whole body kinetics of I-125 γPGA and NaI was imaged by γ-camera. Radioactivity of autopsied samples was measured by γ-counter over time (1 hour, 1 day, 3 days, 7 days and 11 days).
Results The labeling efficacy of I-125 labeled hydrophobic γPGA nanoparticles was 10 - 18 %. Particle size in diameter was approximately 200 nm. At 1 hour after injection of I-125 labeled hydrophobic γPGA nanoparticles, more than 60% of the radioactivity was detected on the injection site. Then, it slowly disappeared from the injection site (At 1, 3 and 11 days after injection, approximately 30 %, 10% and 3 %, respectively). In addition, over 70 % of radioactivity was excreted from the body at 11 days postinjection without accumulation over time in stomach, thyroid and other organs. In contrast, I-125 NaI on the injection site was less than 1% at 1 day after injection. It was imaged high radioactivity from stomach at 1 hour postinjection and retained still in thyroid at 7 days postinjection by γ-camera.
Conclusions Although the labeling efficacy of γPGA needed further improvement, we visualized a kinetics of γPGA nanoparicle after subcutaneous injection by means of I-125 labeled nanoparticles and γ-camera in mice.