Combined photodynamic-chemotherapy investigation of cancer cells using carbon quantum dot-based drug carrier system

The combined chemotherapy and photodynamic therapy have significant advantages for cancer treatments, which have higher therapeutic effects compared with other medicines. Herein, we focused on the synthesis of carbon quantum dot (CQD) based nanocarrier system. CQD and 5-aminolevulinic acid (5-ALA) were conjugated with mono-(5-BOC-protected-glutamine-6-deoxy) β-cyclodextrin (CQD-Glu-β-CD) moiety, and finally, the anticancer chemotherapy doxorubicin (DOX) drug was loaded in the 5-ALA-CQD-Glu-β-CD system. The stepwise physicochemical changes for the preparation of the DOX loaded 5-ALA-CQD-Glu-β-CD system were investigated by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM), and Raman fluorescence spectroscopy. The encapsulation efficiency of DOX in 5-ALA-CQD-Glu-β-CD was observed at ∼83.0%, and the loading capacity of DOX is ∼20.37%. The in vitro releasing of DOX and 5-ALA was observed through the UV–vis spectroscopy by the λ(max) value of 487 nm and 253 nm, respectively. By the investigation against the breast MCF-7 cancer cells, the high cytotoxicity and morphological changes of cancer cells were observed by the treating of DOX/5-ALA-CQD-Glu-β-CD. The generation of reactive oxygen species (ROS) upon 635 nm (25 mW cm(−2)) for 15 min laser irradiation-induced improved the therapeutic effects. In vitro cellular uptake studies recommend the synthesized DOX/5-ALA-CQD-Glu-β-CD nanocarrier could significantly enhance the cell apoptosis and assist in the MCF-7 cell damages. The result suggests a multifunctional therapeutic system for chemo/photodynamic synergistic effects on cancer therapy.