A zwitterionic solution for smart ionic liquids to evade cytotoxicity.

By linking the cation and anion motifs of ionic liquids (ILs), zwitterionic liquids (ZILs) exhibit at least 146-2740 and 112-1550 folds less cytotoxicity in human gastric and colon cells than those of the structurally related ILs. Computer simulation shows that ZIL molecules hardly penetrate the cell membranes in contrast to ILs. These findings reveal a novel mechanism for ZILs to evade cytotoxicity, establishing a structure-based design principle for the next generation of sustainable ZILs.