Abstract
IMPORTANCE OF THE FIELD: Nucleic acids such as plasmid DNA, antisense oligonucleotide, and RNA interference (RNAi) molecules, have a great potential to be used as therapeutics for the treatment of various genetic and acquired diseases. To design a successful nucleic acid delivery system, the pharmacological effect of nucleic acids, the physiological condition of the subjects or sites, and the physicochemical properties of nucleic acid and carriers have to be thoroughly examined. AREAS COVERED IN THIS REVIEW: The commonly used lipids, polymers and corresponding delivery systems are reviewed in terms of their characteristics, applications, advantages and limitations. WHAT THE READER WILL GAIN: This article aims to provide an overview of biological barriers and strategies to overcome these barriers by properly designing effective synthetic carriers for nucleic acid delivery. TAKE HOME MESSAGE: A thorough understanding of biological barriers and the structure-activity relationship of lipid and polymeric carriers is the key for effective nucleic acid therapy.