Surface Polarity-Dependent Cellular Uptake and Apoptotic Response of Liposomal Carbon Quantum Dots in MCF-7 Cells

Carbon quantum dots have emerged as promising nanomaterials for cancer theranostics owing to their tunable fluorescence properties, biocompatibility, and potential therapeutic activity. In this study, the anticancer effects of hydrophobic CQDs (Hb-CQD) and 3-APTMS functionalized hydrophilic CQDs (Hp-CQD) derived from a single precursor curcumin and their liposomal formulations (L-Hb-CQD and L-Hp-CQD) were investigated in MCF-7 breast cancer cells. Cellular uptake and cell-associated fluorescence were evaluated by fluorescence microscopy, while cytotoxicity and apoptosis induction were assessed using MTT and Annexin V-FITC/propidium iodide assays, respectively. All CQD formulations exhibited concentration-dependent cytotoxicity toward MCF-7 cells. L-Hp-CQD showed the greatest antiproliferative activity with the lowest IC50 value (119.7 μg mL–1), followed by Hb-CQD (124.5 μg mL–1), L-Hb-CQD (125.4 μg mL–1), and Hp-CQD (156.2 μg mL–1). Fluorescence imaging revealed that liposomal encapsulation significantly enhances cell-associated fluorescence, particularly in the case of L-Hp-CQD. Flow cytometric analysis demonstrated a pronounced shift from viable to apoptotic cell populations following treatment. Hb-CQD induced the highest total apoptotic population (73.43%), followed by Hp-CQD (72.01%), L-Hp-CQD (68.20%), and L-Hb-CQD (51.47%). Importantly, necrotic cell populations remained low across all treatment groups, indicating that cell death occurred predominantly through apoptosis rather than nonspecific cytotoxic damage. These findings demonstrate that CQD surface polarity and liposomal delivery significantly influence cellular uptake and anticancer efficacy. The ability of these fluorescent nanomaterials to combine efficient cellular imaging with apoptosis-mediated cancer cell killing highlights their potential as multifunctional platforms for future cancer theranostic applications.