Development of radiolabeled dextran coated iron oxide nanoparticles with 111-In and its biodistribution studies

The main aim of this study is to radiolabel dextran coated iron oxide nanoparticles (NPs) (with 80 nm hydrodynamic size) with the Indium-111 and evaluation their biodistribution after intravenous injection normal mice.

The chelator Diethylenetriamine Pentaacetic Acid (DTPA) dianhydride was conjugated to SPION using a small modification of the well-known cyclic anhydride method at a ratio of 1:5 (NPs:DTPA) molar ratio. The reaction was purified with magnetic assorting columns (MACs) using high gradient magnetic field following incubation. Then the radiochemical purity of the radiolabeled NPs were determined using RTLC method. The magnetic properties of nanoparticles were measured by a 1.5 tesla clinical human MRI.

The NPs showed high super paramagnetic properties whereas their r2/r1 was 17.6. The RTLC showed that the purity of compound was above 99% after purification and the compound has shown a good in-vitro stability until 6 hours in the presence of human serum. The biodistribution of 111In-DTPA-NPs in mice demonstrated high uptake in the reticuloendothelial system (RES) and the blood clearance was so fast.

Due to magnificent uptakes of this radiotracer in the liver and spleen, its stability and their fast clearance from other tissues, especially in blood, it is suggested that this radiotracer would be suitable for RES theranostics purposes.