Multifunctional Nanostructured Materials Applied in Controlled Radiopharmaceuticals Release

The metaiodobenzylguanidine (MIBG) radiopharmaceutical, an analogue of norepinephrine, has been used to diagnose certain diseases in the cardiovascular system when radiolabeled with I. This radiopharmaceutical can also be used to treat tumors, such as neuroblastomas and pheochromocytomas, when radiolabeled with I. Its clinical use is often accompanied by a slow intravenous administration, where a significant dose of radiation can directly affect workers in nuclear medicine services. To overcome this problem, the incorporation and controlled release of radiopharmaceuticals from the matrix of mesoporous systems based on silica, such as SBA-15 and hybrid [SBA-15/P(N-iPAAm)], can lead to a significant reduction in radiation doses received by workers. In the present study, silica matrices SBA-15 and hybrid [SBA-15/P(N-iPAAm)] containing the radiopharmaceutical MIBG were prepared and physicochemically characterized through FTIR, SEM, and small angle X-ray diffraction techniques. The release profiles of MIBG from SBA-15 and [SBA-15/P(N-iPAAm)] were studied in a simulated body fluid (SBF) to evaluate their potential application as vehicles for controlled releases. Furthermore, in vitro studies were performed to assess the cytotoxicity of matrices as compared to human lung fibroblast cells (MRC-5). The results revealed that the amount of MIBG incorporated within the studied matrices was indeed quite different, showing that only the hybrid [SBA-15/P(N-iPAAm)] system allowed for a more adequate release profile of MIGB. Taking all results into consideration, it can be concluded that the hybrid matrix [SBA-15/P(N-iPAAm)] can be considered a potential alternative material for the controlled release delivery of radiopharmaceuticals.