**Abstract**

The antisense technology that emerged with the discovery of RNA interference nearly 20 years ago has gained a significant place in gene therapy. siRNA, one of two important components of RNA interference, efficiently downregulates gene expression in human cells, so it has the potential to eradicate disease. siRNA delivery systems, which can be applied both systemically and locally in different diseases, have gained significant importance. Naked small RNAs can be delivered directly to cells, but because of their instability, exposure to enzyme degradation, and difficulties in reaching/entering the target cell or tissue in blood stream, these initiatives are failing. For this reason, the method of delivery or encapsulation of siRNA is usually required. Various nanoparticles, nanocapsules, emulsions, micelle systems, metal ion nanoparticles, and nanoconjugates have been used for siRNA delivery. In these transport systems, lipidic and polymeric systems are very attractive due to their advantages such as being biodegradable and biocompatible, safety, being able to electrostatically bind to RNA, long-term stability, well-illuminated structure and features, simple and easy production, etc. Issues such as particle size, zeta potential, and stability of siRNA-loaded system should be taken into consideration in the development of siRNA delivery systems.

**Keywords:** lipidic nanoparticles, polymeric nanoparticles, nanocarrier, transfection, barriers, siRNA delivery
