Effect of graphitic carbon nitride on the in vitro tumor cell cytotoxicity

What is it about?

In this study, graphitic carbon nitride (g-C3N4) was synthesized using different nitrogen-rich precursors, namely melamine, urea, thiourea and dicyandiamide via thermal polycondensation routes, and characterized with several analytical tools such as SEM, EDS, XRD, DRS, BET, FTIR and Raman spectroscopy. The structural and physical characterization results revealed that the precursor type used significantly affects the microstructure and surface area of g-C3N4. The FTIR and Raman spectrums and XRD patterns of samples showed characteristic peaks of g-C3N4 corresponding successful formation of g-C3N4 structure using all precursors. SEM analysis confirmed the formation of the characteristic graphitic framework and corresponding nanosheet and nanoflake morphology. The samples synthesized with dicyandiamide, urea and thiourea exhibit a characteristic porous structure with a smooth and irregular topography. It was also found that the thiourea-derived g- C3N4 exhibited the highest BET surface area with a 2.8-fold increase compared to other samples. The cytotoxic profiles of g-C3N4 samples were evaluated on human skin fibroblast (HFF-1) and hepatocellular carcinoma (Huh-7) cell lines. Dose- and time-dependent in vitro assays revealed that lower and moderate concentrations (50–200 μg/mL) of all samples promoted HFF-1 cell proliferation over 72 h, while the highest concentration (400 μg/mL) induced growth arrest. Conversely, Huh-7 cells displayed limited proliferation at lower concentrations and marked growth inhibition at 400 μg/mL, suggesting a higher sensitivity to g-C3N4 exposure. Among the precursors, no significant differences were observed in the overall cytotoxic profiles, indicating the final g-C3N4 product drives the biological response more than the synthetic origin. These findings highlight the potential of g-C₃N₄ materials, particularly at intermediate concentrations, for selective anticancer applications or biomedical uses requiring biocompatibility, such as drug delivery or bio-imaging platforms. The results align with previous literature on g-C3N4’s low toxicity toward healthy cells and extend current knowledge by providing new evidence on its effects in hepatocellular carcinoma models.

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