RNA interference (RNAi), also known as gene silencing, is a biological process in which a short RNA strand binds to messenger RNA (mRNA) preventing mRNA’s sequence from being translated to protein. The enzyme Dicer starts the RNAi process by cleaving double stranded RNA or hairpin RNA. The resulting products- small interference RNA (siRNA) and microRNA (miRNA) respectively- are 19-22 nucleotide long double stranded RNA fragments. The protein Argonaute takes up these fragments, releases one strand (called the passenger) of each fragment and uses the other strand (called the guide) to base-pair to mRNA. Argonaut then cleaves the target RNA silencing the gene it encodes. Just eight years after RNAi mechanism was first uncovered, its discoverers won the Nobel Prize and commercial efforts to develop therapeutics and insect control in agriculture were well underway. However, the key to RNAi successful applications is proving to be the development of systemic delivery systems.