Fabrication of Dual-Functional Micelles Based on Star-Shaped Copolymer for Bioimaging

Dual-modal fluorescent/magnetic resonance imaging attracts more and more attentions in biomedical applications. Herein, star-shaped poly(ε-caprolactone)-b-poly(N-vinylpyrrolidone) amphiphilic copolymer with a tetrakis-(4-amino)-terminated tetraphenylethylene core was synthesized. Then, dual-functional nano micelles were achieved via a facile self-assembly of the star copolymer and in situ encapsulation of iron oxide nanoparticles. The fluorescent characteristic of the tetraphenylethylene moiety and encapsulation of iron oxide endowed the resultant dual-functional micelles with bright fluorescence and superparamagnetic properties, which indicated that the PCL segments coated on magnetic nanoparticles is effective at separating the conjugated core from iron oxide nanoparticles to minimize fluorescence quenching. The obtained micelles were found to have a good colloidal and fluorescent stability in different environment. In vitro studies revealed that these dual-functional micelles could serve as an effective fluorescent probe to achieve imaging of MCF-7 cells without obvious cytotoxicity. Thus, this work provides a facile strategy to fabricate fluorescent-magnetic dual-functional micelles for dual-modal imaging applications.