BAmP-TK-12 is a ROS-responsive ionizable lipid designed for tumor-cell mRNA delivery. It features a bis(aminopropyl)piperazine-derived ionizable headgroup and four C12 tails connected through cleavable thioketal linkers. In the reported study, BAmP-TK-12 achieved RFP expression in up to 95% of HeLa cells, comparable to Lipofectamine 3000, with lower cytotoxicity under the tested conditions. ROS-triggered linker cleavage supported intracellular mRNA release in high-ROS tumor cells. When formulated with DUF5 mRNA, the LNP suppressed tumor growth in HCT-116 and A549 xenograft models, supporting its use as a promising preclinical research lipid for stimulus-responsive mRNA delivery.