Today, Magnetic Resonance Imaging (MRI) is a powerful clinically used imaging method which provides three-dimensional images with excellent resolution. However, conventional molecular MRI techniques that rely on the observation of water protons still suffer from reduced sensitivity and often lack selectivity. The use of hyperpolarized xenon can improve both the selectivity and sensitivity of the MRI method. As xenon has no specificity for any biological receptor, it needs to be vectorized. For this purpose, authors have proposed to encapsulate xenon inside molecular cages functionalized to recognize specific biological targets. The best candidates so far as biosensors are cryptophanes.The aim of this work is to design and synthesize new cryptophanes that are better suited for 129Xe MRI applications and relevant biosensors for future in vivo applications. In a first part, new cages were developed in order to study the encapsulation properties of xenon inside different cryptophanes. Then, biosensors were synthesized by functionnalization of known water-soluble cryptophanes for different applications of biological interest. We have therefore assessed the possibility of detecting metal ions specifically in a very sensitive way thanks to 129Xe MRI. New bimodal sensors were also designed and tested.
