The invention discloses a pharmaceutical composition of pH-sensitive liposome nanoparticles for lodging in a target tissue cell in situ of an animal subject, the nanoparticles comprising a proton-releasing photosensitive compound that releases protons upon photolysis, wherein the compound is in vesicles of the liposomes. A light or UV light is provided to induce the photosensitive compound to release the protons, thus the released protons causing the pH-sensitive liposome to decompose.