Electrostatic Polyion Micelles with Fluorescence and MRI Dual Functions

We report in this work the formation of fluorescence and MRI bimodal imaging nanoparticles achieved by electrostatic self-assembly. The nanoparticles are micelles formed with Gd3+ ion, a bisligand that contains aggregation induced emission (AIE) group, and a block copolymer. The coordination between the Gd3+ ion and the bisligand produces a negatively charged coordination complex, which interacted with the positive-neutral block copolymer to form polyion micelles. The micelles exhibit considerable fluorescence owing to the rotation restriction of the AIE group; meanwhile, the longitudinal relaxation of water was significantly slowed down which provide T1 contrast for magnetic resonance imaging. In vitro fluorescence imaging and in vivo MRI measurements verified this micelle indeed exhibit dual imaging ability. We expect that this orthogonal imaging may provide more accurate diagnosis in practical applications and will pave the way for the development of an advanced technique for diagnosis.