An in vivo study of silica coating magnetic nanoparticles (MNPs) biodistribution by using radionuclide imaging

239 Objectives Magnetic nanoparticles (MNPs) have found various applications in biomedicine, hyperthermia, and magnetic resonance imaging (MRI). The purpose of this study is to visualize and semi-quantify 99Tcm labeled Fe3O4 magnetic nanoparticles biodistribution by radionuclide scintigraphy. Methods Fe3O4 MNPs core were coated around with a thin layer silica shell. Amines are functionalized on the silica surface. The silica coating MNPs were further modified and synthetized to MNPs@SiO2-NH-DTPA-99Tcm composite. Twelve male New Zealand rabbits were averagely assigned to three groups (A and B as control group, C as MNPs group) for three different radiopharmaceuticals: 99TcmO4-, 99Tcm-DTPA, and 99Tcm-MNPs. 37MBq radionuclide agents were introduced into experimental animals via ear vein. Two hours after injection, planar static images were acquired by SPECT. Semi-quantitative analysis was calculated by region of interesting (ROI) technique. Semi-quantitative indicators included counts/mm2 and lesion-background radioactive counts ratio (L/B ratio) in different organs. Results Fe3O4 MNPs@SiO2-NH-DTPA-99Tcm is about 20 nm in diameter. Radiation activities were observed in thyroid gland, stomach and bladder on 99TcmO4- scintigraphy (group A). Kidney and bladder showed radionuclide accumulations on 99Tcm-DTPA imaging (group B). 99Tcm-MNPs uptakes were observed in kidney, liver, lung, and bladder in group C. The counts/mm2 of different organs on 99Tcm-MNPs imaging are: kidney (133), liver (58), lung (92). The L/B ratios of different organs on 99Tcm-MNPs images are: kidney (4.7), liver (2.0), and lung (3.2). Conclusions Most of the MNPs were eliminated from body by urinary system, a part of MNPs were stopped in kidney, liver, and lung. 99Tcm labeled silica coating MNPs scintigraphy may be an effective tracer for detecting MNPs biomedicine drug delivery in vivo