The present invention relates to a pH sensitive particle, a method of preparation thereof, and a use thereof. More particularly, the invention provides a pH sensitive metal nanoparticle and its use for medical treatment utilizing cell necrosis during photothermal therapy. The pH sensitive metal nanoparticle based on this invention consists of a pH sensitive ligand compound whose charge changes depending on the pH of the metal nanoparticle. The particle can be collected in cells, such as cancer cells which present an abnormal pH environment. The pH sensitive metal nanoparticle based on this invention can induce cell death through a photothermal procedure after aggregation. Therefore, the invention enables medical treatment using cell necrosis for e.g. cancer treatment.
