RNA interference (RNAi) is a key biological process in central dogma. RNAi is an gene silencing process suppressing the translation by the RISC(RNA Induced Silencing Complex) which lead to cleavage or translation repression of the target mRNA molecules. This process is triggered by double stranded RNA (dsRNA). Long dsRNAs from intrinsic or external source are cut by dicer enzyme into short (~21 nucleotides) duplexed nucleotides. These small fragments, referred to as small interfering RNAs (siRNA), constitute the RNA-induced silencing complex (RISC) and leads to the cleavage of the target mRNA. siRNA can be synthesized chemically and introduced to cytoplasm, which share the same mechanism of RISC.