The Preparation, Biodistribution, and Dosimetry of Encapsulated Radio-Scandium in a Dendrimer for Radio-nano-pharmaceutical Application.

This study aimed to investigate the synthesis, characterization, and biodistribution of scandium nanoparticles encapsulated within poly (amidoamine) (PAMAM) dendrimers, as well as to estimate the human absorbed dose. It also aimed to examine, in particular, the amine-terminated PAMAM dendrimers in generation 5. Irradiation of the compound in the nuclear reactor resulted in the formation of Sc-radioactive complex nanoparticles. The compound of the dendrimer-Sc3+ was confirmed by the UV-vis spectrometer. The size of the particles was less than 10 nm, and it was assessed using high-resolution transmission electron microscopy (HRTEM) and dynamic light scattering (DLS). The synthesized complex was irradiated by the 3 × 1011 n.cm-2s-1 flux of neutron for 2 h. Mice bearing a breast tumor were employed to assess the therapeutic dose that was delivered by the poly scandium-46-nanoparticles. As opposed to the untreated groups, a single injection of poly phosphate-buffered saline to intratumoral in other groups to deliver a dose of 100 µCi resulted in a statistically significant 39.24% reduction in tumor volume 14 days after injection. After applying the biokinetics data in mice, the human's absorbed dose from scandium-47 encapsulated PAMAM was extrapolated based on animal data. The absorbed doses in critical organs, including the liver, lung, spleen, kidney, and bone, were 0.879, 0.0472, 0.191, 0.107, and 0.155 mGy/MBq, respectively.

Dosimetry of 175Ytterbium-poly (amidoamine) Therapy for Humans' Organs.

PURPOSE: This investigation focuses on biodistribution of irradiated dendrimer encapsulated ytterbium-175 (175Yb) and to estimate the absorbed dose from intravenous injection of PAMAM encapsulated 175Yb to human organs. METHODS: A dendrimer compound containing an average of 55 Yb+3 ions per dendrimer was prepared and irradiated with neutrons for 2h at 3×1011 n.cm-2s-1 neutron flux. The resulting mixture was injected into a group of tumor bearing mice and the mice were excised, weighed and counted at certain times to study the biodistribution. The human organs absorbed dose was assessed by MIRD schema and MCNP simulation. RESULTS: The specific activity and radiochemical purity of the irradiated nano-composite were 7MBq/mg and >99% respectively. The rapid up take of dendrimer was in liver, lung, and, spleen. MIRD and MCNPX were applied for dose estimation. The human absorbed dose in liver, lung, spleen, kidney and bone that simulated by MCNP are 1.266, 0.8081, 0.8347, 0.03979 and 0.01706 mGy/MBq respectively and these values for MIRD schema are 1.351, 0.73, 1.03, 0.039, and 0.0097 mGy/MBq respectively. CONCLUSION: The results showed that 175Yb-PAMAM nano-radiopharmaceutical has potential of application for liver and lung tumors.

Development of Dendrimer Encapsulated Radio-Ytterbium and Biodistributionin Tumor Bearing Mice.

The aim of this study is preparation of dendrimer encapsulated ytterbium-175 radio-nanoparticles and investigation of the compound chemical characteristic before and after the neutron irradiation and also study the in vivo biodistribution for targeted radiopharmaceutical dose delivery to solid tumors. For preparation of dendrimer-metal nanocomposite, a dendrimer compound containing an average of 55 Yb+3 ions per dendrimer was prepared. The synthesized encapsulated ytterbium irradiated by neutron for 2 h at 3×1011 n.cm [Formula: see text] neutron flux. The resulting mixture was injected into 2 separate groups of tumor bearing mice. One group were injected intravenously and the other group were injected directly in tumor and were excised, weighed and counted at certain times to study the biodistribution and to compare the tumor treatment and the leakage of the radiopharmaceutical to non-target organs. The formation of dendrimer-Yb3+complex was confirmed by UV-vis spectrometer. High-resolution transmission electron microscopy (HRTEM) and Dynamic Light Scattering (DLS) results showed a particle size of less than 10 nm. The specific activity and radio-ytterbium purity of the irradiated nano-composite were as follows: 7 MBq/mg and >95%. The measured radiochemical purity by Instant Thin Layer Chromatography (ITLC) was more than 99%. In intravenous injection the complex showed rapid up take in liver, spleen, and lung, while accumulation in other organs was insignificant. In tumor direct injection the average size of the tumor mass in mice was reduced by 30%.