Herein, we developed facial greener approach for the synthesis of water-soluble heteroatom-doped Carbon quantum dots (CQDs). Doping heteroatom into CQDs, not only creates surface functional groups but also changes the electronic distribution. One-pot microwave-assisted synthesis was used for the synthesis of heteroatom-doped CQDs: prepared by doping the heteroatom into CQDs (Mn@CQDs). The higher quantum yields (QY) and optical properties of Mn@CQDs suggest that, a potential for the use fluorescent imaging agents. The blue emitting Mn@CQDs were conjugated with hyaluronic acid (HA) forming HA-Mn@CQDs, which enabled higher biocompatibility, less toxicity, and targeting capability. The targeting ability was confirmed towards CD44 overexpressed B16F1 cells and CD44 negative HeLa cells. Subsequently, our results showed that this synthesized multifunctional Mn@CQDs have excellent magnetic, fluorescent and structural properties enabled us to use for dual modal in vitro fluorescence and MR imaging. A chemotherapeutic application was done using doxorubicin (DOX) as a model drug for conjugation with HA-Mn@CQDs termed as HA-Mn@CQDs/DOX which enabled targeted drug delivery system. The as-prepared nanocomposite displayed apparent toxicity to B16F1 cells (CD44 positive). The in vitro and in vivo cytotoxicity results showed that heteroatom-doped carbon quantum potential uses for diagnostic and therapeutic applications.

KEYWORDS. Heteroatom-doped, hyaluronic acid, fluorescent imaging, MR imaging, targeted drug delivery