Synthesis And Application Of Lanthanide Complex-based Dual-moda-l Probes For Time-resolved Luminescene And MRI Bioimaging

Bioimaging that makes biologicl molecular visible is one of the most important tool for life science,medicine and clinical diagnosis.In this field development of bioprobes for the dual or multiple modality bioimaging have exciting potential and attracted a lot of research interests.Here the novel multimodal TRLI（Time Resolved Luminescence Imaging）-MRI（magnetic resonance imaging）probes based on lanthanide complexes were developed for molecular imaging in biological system.The multimodal TRLI-MRI imaging integrate the adavantage of both techniques,the high spatial resolution and deep tissue penertration of MRI and the high sensitivity and selectivity of TRLI.It provides a new powerful tool for bioimaging.Using PTTA-Tb³⁺ covalently bound silica-based luminescet nanoparticles as precursor,a new kind of multifunctional nanoparticles with long-lived luminescence,magnetic resonance and cancer cell targetable properties,Tb-Gd-FA@SiO₂,has been prepared by conjugating MRI contrast agent DO₃ANH_2-Gd^<sup>3+ and folic acid（FA）onto the surface of the nanoparticles.The nanoparticles not only can emit distinctly long-lived green luminescence from the Tb³⁺ complex,but also possess well T1 weighted MRI property(the T1 relaxivity（r1）of proton in the aqueous solution of nanoparticles is 33.8 s^-1/mmol L^-1 at 20 MHz).These unique properties enabled the nanoparticles to be used for both time-resolved luminescence imaging of living cancer cells and MRI of living animals.On the basis of previous research,we try to bind MRI contrast agent DO₃ANH_2-Gd^<sup>3+ to luminescent b-diketone-Eu³⁺ complex by bridging group,and prepare a new TRLI-MRI dual-mode small molecular probe which can avoid the toxicity that associated with long-term liver retention,and have the potential for more rapid diffusion through tissues.The probe has been synthesized,and the further characterization and biological application of the probe are in processing.