Design,Synthesis And Applications Of Bioresponsive Dual-Functional MRI Molecular Probes

Molecular Imaging,with its ability to monitor the molecular changes of physiological activities in vivo and conduct qualitative or quantitative studies by means of apparatus,has become an indispensable part of disease diagnosis and treatment.Aided by molecular imaging,doctors can overcome the difficulties in early cancer diagnosis and formulate more appropriate therapeutic plans.With its advantages such as high tissue penetration,imaging in any direction with multi-parameter and multi-sequence and free of ionization radiation,magnetic resonance imaging(MRI)can detect lesions at an early stage,thus it has been used for the diagnosis and prognosis of various diseases.As the relaxation time of early diseased tissues shows little difference from those of normal ones with MRI,MRI contrast agents are used to enhance the contrast for better detection and treatment of diseases.In addition,19F has become a prmising magnetic nucleus of MRI due to no background signal interference and its magnetogyric ratio similar to that of 1H,which has caught extensive attention in the research community.Therefore,in this paper,the author has developed two 1H and 19F dual-mode molecular MRI contrast agents and demonstrated their advantages through in vitro experiments.Chapter One:the author summarizes the research progress of MRI technology and T1molecular contrast agents and briefs the topic selection and content of this paper.Chapter Two:the author synthesizes a dual-mode MRI contrast agent responsive to calcium ions.In vitro and cellular experiments demonstrate that the molecular contrast agent can achieve significant signal recovery in the presence of calcium ions for 1H and 19F dual-mode MRI.The same effect is also observed in blood.Chapter Three:the author synthesizes a dual-mode MRI contrast agent responsive to esterase.The presence of esterase triggers the dissociation of the contrast agent which recovers the 19F signal,and the 1H signal is enhanced as well due to the additional coordination number of water molecules.With this probe,the dual-mode MRI responsive to esterase is achieved.In conclusion,we synthesized two 1H and 19F dual-mode MRI probes responsive to different stimuli.Both of them showed significant signal recovery effects upon the presence of stimuli,which helps to pave the way for the future realization of in vivo dual-mode MRI for the detection of specific physiological functions.