Scintillating Metal Organic Frameworks for Low-Energy Radioisotope Detection: Material Development and Applications

Abstract

Metal-organic frameworks (MOFs), formed by the self-assembly of organic molecules andmetal components, represent a unique class of multifunctional materials. Their exceptional properties—such as modularity, high porosity, tunable emissions, and customizable crystalline structure and physical size—distinguish MOFs from other materials and have led to diverse applications across multidisciplinary fields. Notably, scintillating MOFs offer a novel approach to ionizing radiation detection. The well-ordered structure of MOFs enables precise atomic-level control over the arrangement of constituent molecules, enhancing scintillating properties. This precise control paves the way for developing next-generation scintillators with improved performance. This dissertation presents three innovative designs of scintillating MOFs for the direct detection of challenging low-energy beta-emitting radioisotopes in aqueous solutions, with applications also extending to biologically relevant fields. First, we synthesized scintillating MOFs by covalently coordinating scintillating molecules into MOF structures, demonstrating effective detection of tritium in its stable molecular form within aqueous solutions. Second, we developed fluorophore-doped MOFs for detecting low-energy beta-emitting radioisotopes. Here, the incorporated fluorophore molecules endow the MOFs with scintillating properties, presenting a straightforward method for producing scintillating MOFs with flexible design and optical tunability based on dopant fluorophores. Additionally, we introduce a MOF-based scintillation proximity assay (SPA). Initially, we fabricated the MOFs by coating them with polyethylenimine (PEI) for chemical derivatization, then conjugated them with 4-carboxyphenylboronic acid (4- CPBA) to enable selective binding to glucose via molecular recognition. Our results show that 4- CPBA-functionalized MOFs exhibit enhanced scintillation responses to radiolabeled glucose 20 through specific adsorption, demonstrating the potential of MOFs to enable molecular interaction detection—laying the groundwork for SPA applications. In summary, this dissertation highlights the effectiveness of MOFs as scintillating materials for analyzing low-energy beta-emitting radioisotopes and their potential utility and adaptability in advancing SPA methodologies.