What is it used for?Small RNA extraction is the first step prior to proceeding for microRNA RT-PCR. Before performing small RNA isolation from total RNA (extracted in previous section), two more steps are required: 1. DNase treatment and 2. Agarose gel electrophoresis, which are respectively crucial for eliminating of DNA contamination and to check the extracted RNA quality.

Nucleic acids play different roles besides storing information and proteins coding. For example, singlestranded nucleic acids can fold into complicated structures with capability of molecular detection, catalyzing bioreactions and therapy. The development of RNA-based therapies has been rapidly progressed in the recent years. RNA aptamers are biomolecules with a size of 10 to 50 nm that can be useful for targeted therapy and systemic release of therapeutics into the desired tissues. Aptamers can be linked to other RNA drugs and form a biohybrid RNA nanostructure. The chemical nature of the aptamers makes them attractive therapeutic agents compared to other small molecules and antibodies. In this review, we discuss different approaches related to drug targeting and release by RNA aptamers, since the importance of the aptamer-based nanomedicine is now well demonstrated and this field become a promising platform in the treatment of diseases.

Background: RNA interference (RNAi) is a phenomenon uses double-stranded RNA (dsRNA) to specifically inhibit gene expression. The non-specific silencing caused by interferon response to dsRNA in mammalian cells limits the potential of utilizing RNAi to study gene function. Duplexes of 21-nucleotide short interfering dsRNA (siRNA) inhibit gene expression by RNAi. In some organisms, siRNA can also function as a primer converting mRNA into dsRNA that are further cleaved to produce more siRNA. This activity involves the enzyme RNA-dependent RNA polymerase (RdRP). There are no known RdRP involved in RNAi in mammals. By using an RdRP from Caenorhabditis elegance named ego-1, investigators intend to enhance RNAi effect in mammalian cells. The aims of this project were: 1) to investigate the efficiency of siRNA to enhanced green fluorescent protein (eGFP) gene silencing and 2) to enhance the RNAi effect. Methods: We used a vector-based siRNA to target eGFP. Also we used a vector expressing ego-1 to test for a possible amplification effect of RNAi. The expression of eGFP in the cells was detected by using fluorescent microscopy, flowcytometry and Western-blotting. Results: Transfection of the plasmid into P19 cells significantly decreased eGFP fluorescence. In addition, eGFP protein was reduced. Preliminary data suggested that the presence of ego-1 enhanced the RNAi effect. Conclusion: The results indicated that use of hairpin siRNA expression vectors for RNAi is a promising method to inhibition of gene expression in mammalian cells. Also, introducing RdRP enzyme to mammalian cells might amplify the RNAi effect in the cells. Iran.