Table 1.

The most common stimuli-responsive liposomes.

Stimuli liposomes	Stimuli	Principle	Advantages	Reference
Light-sensitive liposomes	UV, near infrared or visible light irradiation,	Modification of fatty acyl chains of the phospholipids with light-sensitive functional groups and the resulting phospholipids have yielded photoactivable liposomes	Controlling time, exposure, wavelength, and intensity	[131, 132]
Thermosensitive (temperature-sensitive) liposomes	Radiofrequency or microwave ablation	Lipids with a transition temperature of 40–45 °C, such as DPPC, have been employed to make these liposomes	Drug release at high-temperature sites	[133, 134, 135, 136]
Redox-sensitive liposomes	Reactive oxygen species (ROS) peroxides, hydroxyl radicals, singlet oxygen	Depends on the redox potential difference between the intracellular reducing space and oxidizing extracellular space that occur during biological activities.	ROS leads to high concentration levels of glutathione (GSH) in tumor cells cleaving the liposomal formulations	[137, 138]
Enzyme-responsive liposomes	Protease, amidase, and esterase enzymes	Based on amides or esters hydrolysis by protease or esterase enzymes release loaded drugs.	Decreases the adverse side effects of toxic drugs and enable encapsulation of prodrugs	[139, 140, 141]
pH-sensitive liposomes	pH change	Cholesteryl hemisuccinate (CHEMS) and 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), were used to prepare pH-sensitive liposomes	Liposomes with pH-dependent release features	[142, 143, 144]