Abstract
N,N'-Dimethylated imidazo[1,5-a]pyridinium salt having good water solubility and exhibiting fluorescence emission was found to work as not only a bioimaging agent but also a therapeutic agent under UVA-LED irradiation conditions. Because the continuous UVA-LED irradiation to HeLa cells stained by the synthesized salt resulted in the cell death due to the mitochondrial damage, the salt has a potential application as photodynamic therapy agent against tumor cells.