Table 1.

Main differences between unmodified AS-ODN and siRNA

ODN	siRNA
Single-stranded	Double-stranded
Short length	Short length
Negatively charged	Negatively charged
Hydrophilic	Hydrophilic
Poorly stable	Stable
Low intracellular penetration	Low intracellular penetration
Target is cytoplasm or nucleus	Target is cytoplasm
Cleavage or blockage of mRNA	Cleavage of mRNA
Short-term activity	Long-term activity

AS-ODN, antisense oligonucleotides; mRNA, messenger RNA; siRNA, small interfering RNA.