Table 2. Advantages and disadvantages of non-viral vector delivery systems.

	Advantages	Disadvantages
Naked siRNA	Effective in certain organs. Lower toxicity and inflammatory responses. Simple formulation.	Lack of stability.
Chemically modified siRNA	Easily formulated. Medium efficiency. Lower immune response.	Impaired bioactivity. High Cost. Toxicity. Inflammatory response.
Liposome modified siRNA	Stable, variable, flexible and multifunctional. Easy to formulate. Biodegradable. No immune response and non-toxic in neutral liposome. More effective in cationic liposomes.	Low specificity. Low efficiency in neutral lipids. Inflammatory results with cationic lipids.
Nanoparticles	High stability. Decreased non-specific bio-distribution. Induces non-specific endocytosis.	Cell toxicity