AIEgen-Conjugated Magnetic Nanoparticles as Magnetic–Fluorescent Bioimaging Probes

Colloidal nanoparticles with a magnetic–fluorescent property and varied surface chemistry have enormous biomedical application potential. However, the synthesis of a high quality of such a nanoparticle with <100 nm hydrodynamic size is challenging, and current approaches produce large size particles with significant loss of the fluorescence property because of an aggregation-induced quenching issue. AIEgen molecules with the aggregation-induced emission property offer a new opportunity in the development of such a nanoparticle. Here we report an AIEgen-based magnetic–fluorescent nanoparticle with varied surface chemistry and average hydrodynamic size between 25 and 50 nm. The approach involves covalent linking of soluble AIEgen to a polymer coated colloidal magnetic nanoparticle surface that can “switch on” the AIEgen fluorescence. The resultant colloidal nanoparticle has cationic/anionic/zwitterionic surface charge with primary amine termination. The developed nanoparticle has been used as a fluorescent cell imaging probe and for magnetic separation of labeled cells. The presented approach can be extended for development of AIEgen-based nanoparticles and nanobioconjugates with various functionalities.