TABLE 1.

Characteristics of three kinds of most common PCMs.

Types	Advantages	Disadvantages
Liposomes	Hydrophilic and oleophilic, rapid and lots of drug release in the heated area	Lack of triggers, low stability, low efficiency
Micelles	Easy prepare, small and uniform particle size, high drug load	Susceptible to decomposition and results in drug early release
Hydrogels	Good 3D mesh structure, no need for crosslinking agents, organic solvents, easy prepare	Large liquidity and cannot be the precise location