Development of Novel Diffusion NMR Methods : Preclinical Applications in Colloidal Model Systems

Sammanfattning: NMR is a powerful non-invasive technique utilizing radiofrequency and gradient pulses to manipulate the spinsof atomic nuclei. In particular, diffusion NMR uses strong magnetic field gradients to label the positions of spins allowing for the measurement of translational motion of molecules in liquids. The average displacement of water molecules can give information on the pore microstructure in various materials including biological cells and tissues.The interpretation of conventional diffusion NMR signal can be ambiguous, as it contains effects from microstructure, size and orientation. In this work, the underlying microscopic structures are exposed with novel diffusion NMR methods. q-MAS is a pulse sequence for isotropic diffusion encoding, which in combination with conventional diffusion NMR can be used to quantify the microscopic anisotropy. The shape of the microscopic diffusion tensor can be revealed by varying the anisotropy of the diffusion encoding. The methods are demonstrated in lyotropic liquid crystals and yeast cell suspensions.Diffusion NMR can be used to measure exchange between intra- and extracellular compartments. This can give information on the water transport across biological cell membranes. A method for measuring exchange in yeast cells with different intra- and extracelllular T2 values is presented.