Lanthanide-Loaded Nanoscaffolds for Multimodal Imaging and Therapy

Multimodal imaging techniques are emerging in medical diagnosis. The synergistic combination of imaging techniques, such as MRI and PET/SPECT, is highly useful to strengthen each of the individual imaging modalities while reducing any of their disadvantages. In recent years, the progress of technical integration of imaging scanners has led to a clear motivation to design multimodal agents by chemists that can be used simultaneously and hence profit optimally of the new hybrid imaging scanners. Nanoscaffolds combining discrete functions (e.g. magnetic, radioactive, optical or therapeutic) are particularly interesting in this regard. There has been an increasing endeavour to design and synthesize multifunctional nanocomposites for practical applications in dual imaging modalities such as MRI-optical, MRI-PET, PET-optical, PET-CT, MRI-SPECT. Chapter 1 of this thesis summarizes the state-of-the-art in the development of multimodal probes for medical imaging and therapy, in which the roles of metal ions are highlighted. Chapters 2-5 focus on the exploration of porous nanomaterials, e.g. zeolite LTL in particular, which is suitable for the above-mentioned purposes due to their ability to accommodate large amounts of lanthanide ions through ion-exchange of alkali cations that counterbalance the AlO4- of the crystalline framework. The surface chemistry and biocompatibility study are also included. Chapter 6 describes a facile methodology to synthesize the lanthanide-nanoparticles with controllable size and application of the synthesized materials as MRI contrast agents. Chapter 7 shows that these versatile materials are also applicable in a very different field: they are very efficient in the storage and release of oxygen.
In conclusion, the findings of the thesis mainly provide insights into the merits and understanding of zeolite-based MR imaging probes.