The development of ZnO nanoparticle-embedded graphitic-carbon nitride towards triple-negative breast cancer therapy

The present study deals with the effects of curcumin-loaded ZnO nanoparticles (NPs) embedded in graphitic-carbon nitride (g-C₃N₄) sheets for breast cancer cells. The synthesis of these sheets was carried out by a simple co-precipitation method. The physicochemical and thermal properties of the composite sheets were studied using various characterization techniques. The powder X-ray diffraction and high-resolution transmission electron microscopy analyses confirmed the hexagonal wurtzite phase of the ZnO nanoparticles, which were randomly distributed on the g-C₃N₄ nanosheets, generating a finely bonded interface between the two components. The X-ray photoelectron spectroscopy analysis confirmed the successful formation of the g-C₃N₄@ZnO composite, while the thermal studies revealed the thermal stability of the composite. In addition, the drug release and kinetics studies proved that the release of curcumin was more significant under acidic conditions (pH 5) compared with neutral pH (7.4). Further, the biological assays verified the antibacterial activity (against two different cultures of E. coli and S. aureus) and anticancer activity (against MDA-MB-231 cancer cells) of the g-C₃N₄@ZnO/C nanocomposite. Finally, the lactate dehydrogenase activity assay presented the cytotoxic assessment of the nanocomposite based on its cytoplasmic activity and the extent of enzymes released from the damaged cells.