Palladium responsive liposomes for triggered release of aqueous contents

Palladium (Pd) is a promising metal catalyst for novel bioorthogonal chemistry and prodrug activation. This report describes the first example of palladium responsive liposomes. The key molecule is a new caged phos-pholipid called Alloc-PE that forms stable liposomes (large unilamellar vesicles,-220 nm diameter). Liposome treatment with PdCl2 removes the chemical cage, liberates membrane destabilizing dioleoylphosphoethanol-amine (DOPE), and triggers liposome leakage of encapsulated aqueous contents. The results indicate a path towards liposomal drug delivery technologies that exploit transition metal triggered leakage.