A Novel method for the preparation of fluorescent C 60 poly(amino acid) composites and their biological imaging.

Recently, fullerene (C60 ) and its derivatives have been widely explored for many applications owing to their enriched physical and chemical properties. Specifically, the synthesis and biomedical applications of fluorescent C60 have been extensively investigated previously. However, the preparation of polymer-functionalized fluorescent C60 has not been reported thus far. In this study, water-dispersible fluorescent C60 polymer composites were successfully synthesized through the combination of the thiol-ene click reaction and subsequent ring-opening polymerization. First, 2-aminoethanethiol was introduced on the surface of C60 by the thiol-ene click reaction. The surface of amino group-functionalized C60 (C60 -NH2 ) was further modified with poly(amino acid)s via ring-open polymerization of GluEG N-carboxyanhydrides (NCAs). The morphology, functional groups, optical properties and biocompatibility were examined by a number of characterization equipment and assays in detail. We demonstrated that the resultant fluorescent C60 poly(amino acid) (C60 -GluEG) composites have a small size (about 5 nm), high water dispersibility, intense fluorescence and high photostability. Cell viability results implied that the C60 -GluEG composites possess low cytotoxicity. Moreover, these C60 -GluEG composites can easily penetrate into live cells, indicating their great potential for biological imaging applications.