The Preliminary Study Of High-resolution NMR Spectroscopy For Biological Applications

Nuclear magnetic resonance(NMR)spectroscopy play an important role for structure elucidation and composition analysis of complex chemical samples and biological samples by providing related information of chemical shifts,J coupling constants,multiplet patterns and relative peak areas.Therefore,NMR spectroscopy has found wide applications in many fields,such as chemistry,materials science,and life science.High spectral resolution is generally pursued by all NMR researchers,and numerous NMR approaches,such as pure shift method and intermolecular multiple-quantum coherence(iMQC)method,have been proposed for enhancing spectral resolution and achieving high-resolved NMR spectra,Pure shift methods can collapse J coupling effects and convert all signals into singlets for each distinct chemical shift size,alleviating spectral congestion and enhancing spectral resolution.Since the discovery of iMQCs,iMQCs have drawn lots of interests in NMR community.Due to its special signal properties,iMQCs have been widely applied to many application fields,especially to high-resolution NMR spectra in inhomogeneous fields.In this thesis,we focus on the applications of high-resolution NMR spectroscopy on biological tissues.The main work of this thesis is summarized as follows:1.A brief review of the development history of NMR were introduced,then the concept of pure shift methods was discussed and several pure shift experiments was introduced.Then we briefly summarized the classical methods of localized spectroscopy and applications of iMQCs to biological samples.2.Based on the combination of PSYCHE and spatially localized techniques,we proposed a NMR method,namely PSYCHE-1 DPRESS,to obtain single-voxel localization 1H magnetic resonance spectroscopy(MRS).This new method can be used to obtain high-resolved pure shift spectra from a whole biological sample with a large voxel size in a MRI scanner system.Experiments on in vitro intact pig brain tissue and in vivo rat brain were performed to demonstrate the feasibility of the PSYCHE-1DPRESS sequence on biological applications.This method presents an alternative to the conventional PRESS method for MRS measurements on biological samples,and it may provide a promising tool for in vivo MRS application.3.In this chapter,an NMR approach based on the combination of iDQCs,spin echo schemes and 3D acquisition was proposed for high resolved 2D J-resolved measurements directly from inhomogeneous fields without any sample pretreatment or additional NMR hardware requirement.The noteworthy enhancement in spectral resolution and quality is illustrated in our experiments on aqueous solution and brain phantom.This method is applicable on common liquid-state NMR spectrometers because no additional hardware device is required,constituting a convenient and promising manner for practical applications to biological tissues.