Paclitaxel-Loaded Biotinylated Fe 2+ -Doped Carbon Dot: Combination Therapy in Cancer Treatment.

The present research work delineates the design and preparation of covalently tailored biotinylated Fe 2+ -doped carbon dots ( FCD b ). The FCD b was successfully used as a pro-drug activator, diagnostic probe, and target-specific delivery vehicle for anticancer drug paclitaxel in pro-drug-free drug combination therapy of cancer treatment. Fe 2+ -doped carbon dot was synthesized via the hydrothermal method ( FCD ). The surface of FCD was covalently modified with cancer cell targeting ligand biotin ( FCD b ). Microscopic and spectroscopic methods were used to characterize aqueous soluble FCD and FCD b . Both FCD and FCD b emit blue fluorescence under UV light irradiation. FCD and FCD b can effectively sense H 2 O 2 by fluorescence quenching as well as activate H 2 O 2 (pro-drug), which oxidatively damage the DNA through the generation of reactive oxygen species (ROS: superoxide (O 2 •- ), hydroxyl radical ( • OH), etc). Both FCD and FCD b were utilized as selective cellular markers for cancer cell B16F10 owing to their high H 2 O 2 content, which was more distinct in the case of FCD b due to the overexpression of biotin receptor in cancer cell. Anticancer drug paclitaxel (PTX)-loaded FCD b ( FCD b - PTX) was employed for the selective killing of B16F10 cancer cells. This pro-drug-free drug formulation ( FCD b - PTX) exhibited ∼2.7- to 3.5-fold higher killing of B16F10 cells mostly via early as well as late apoptotic path in comparison to noncancer NIH3T3 cells through the synergistic action of ROS (generated from H 2 O 2 in the presence of FCD b ) and anticancer effect of PTX. Hence, this newly developed FCD b - PTX can act as a potential theranostic agent in the domain of combination therapy of cancer treatment.