Design of experiments to optimize gallic acid carbon-based nanoparticle synthesis for enhanced photodynamic therapy in cancer cells

Carbon-based nanoparticles (CNPs) have attracted significant attention as photosensitizers for photodynamic therapy (PDT) due to their biocompatibility, facile synthesis, and ability to generate reactive oxygen species (ROS). In this study, green-synthesized gallic acid CNPs (GACNPs) were optimized and characterized for their physicochemical properties and biomedical potential. GACNPs exhibited no cytotoxicity to normal cells at concentrations up to 250 µg/mL, demonstrating excellent biocompatibility. Under LED light irradiation (350-700 nm, 0.124 W/cm², 10 min), GACNPs efficiently generated ROS, as assessed by photodynamic activity and intracellular ROS detection, confirming their photosensitizing function. The anticancer efficacy of GACNPs was evaluated in HeLa and MDA-MB-231 cell lines, revealing IC₅₀ values of 2.92 ± 0.14 µg/mL (exposure) versus 3.74 ± 0.22 µg/mL (non-exposure) for HeLa and 2.62 ± 0.24 µg/mL (exposure) versus 4.14 ± 0.19 µg/mL (non-exposure) for MDA-MB-231 cells, indicating significantly enhanced cytotoxicity upon light exposure. Furthermore, both cell lines showed that GACNPs significantly enhanced the anticancer effect upon exposure compared to the GA solution. Apoptosis assays showed 64% cell death after exposure, compared to 47% without exposure, in HeLa cells, and 93% cell death after exposure, compared to 74% in MDA-MB-231 cells. These findings demonstrate that GACNPs are promising nano-photosensitizers for PDT-based cancer therapy, combining low cytotoxicity with high ROS-mediated anticancer efficacy.