Be Our Guest: 129Xe Detection in Macrocycles and Oriented Environments

Nuclear Magnetic Resonance (NMR) is an extrememly powerful technique for determin- ing chemical structure, which can look in opaque samples. Using 129Xe as our detected nucleus we can synthesize molecualar cages that interact with their chemical environment or molecular target, which is observed through the chemical shift of the xenon in the molecular cage. The use of spin exchange optical pumping (SEOP) the pool of xenon can be hy- perpolarized to give signal enhancement that makes it on par with proton NMR techniques. Further using chemical exchnge saturation transfer (CEST) we can use the exchange of xenon in and out of the molecualr cage to detect concentrations in the nanomolar range. In chapter 3 we will look at a cryptophane-A based sensor and how the chemical shift changes when the cage is chelated to different metal ions. In chapter 4 we looked at using a relaxation based detection method for cryptophane sensors showing a decrease in relaxation time when bound to the protein Avidin. In chapter 5 we look at cucurbituril based xenon detection with a base activated sensor using a rotaxane backbone. In chapter 6 we further develop the rotaxane to include a peptide sequence recognizable by the enzyme MMP2. In chapter 7 we explore a new device that allows for xenon to dissolve directly into ordered media without disturbing the local structure, and in chapter 8 we show preliminary results and discuss the future of xenon based sensors