A photoactive amphipathic compound (SP6), inducing cytotoxicity due to cell membrane destruction by visible light irradiation, was developed for the control of cytotoxicity. Such cytotoxicity, called cell lysis, could be expected to activate the autoimmune cycle, resulting in efficiently attack cancer cells. The spiropyran compound, SP6, was stable in the hydrophilic merocyanine form (MC-form) and isomerized to the hydrophobic spiro form (SP-form) by visible light irradiation. Cell lysis by SP6 was activated by visible light irradiation at concentrations between the critical aggregation concentration of the isomers. Thus, photochemical switching of cell lysis from the OFF to ON state was achieved. The results provide an important step in developing novel next generation photo-chemotherapy drugs.
