3Apparatus and methods are described for use with a subject suffering from cancer. A nanoparticle (22) includes an inner core (30) that comprises a phase change material that is configured to absorb latent heat of fusion by undergoing a phase change. An outer layer (32) disposed around the inner core includes a plurality of nano spheres (34) of at least one metal and a plurality of molecules (38) of a substance that binds preferentially with cancerous cells relative to non cancerous cells. The nanoparticle has a volume of at least 65 000 nm and is elongatable into an ellipsoid such that when the nanoparticle is maximally elongated each of the semi axes defined by the ellipsoid is greater than 5 nm and at least two of the semi axes of the ellipsoid are less than 30 nm. Other applications are also described.
