Presently, the light sources used in photodynamic therapy are high intensity lasers or light emitting diodes, making it unsuitable for large-volume tumors and those located deep inside the body. To overcome this limitation, we propose an in situ light source to excite the photosensitizer to generate toxic singlet oxygen and kill tumor cells directly. In this research, luminol served as the in situ light source in 5-aminolevulinic acid-mediated photodynamic treatment of Caco-2 cell cultures. 72 h after luminol excitation the viability of the treated cells significantly decreased compared to the control cells in assays including cell viability, cytotoxicity, flow cytometry and fluorescence confocal microscopy. According to the results, we suggested luminol could be used as an in situ light source for 5-aminolevulinic acid-mediated photodynamic therapy. This method would have great potential to extend the application of photodynamic therapy to tumors located deep inside the body.
