biostudies-literatureUnknown10Li ZSingle-stranded siRNA (ss-siRNA) refers to the antisense strand of siRNA, which plays the role of gene silencing. Since single-stranded RNA is unstable, the present study employed a homemade neutral cytidinyl/cationic lipid delivery system and chemical modifications to improve its stability. The results showed that with the aid of mixed lipids, ss-siRNA could knock down 40% of target mRNA at 25 nM. With 2'-F/2'-OMe, phosphorothioate and 5'-terminal phosphorylation, the optimized ss-siRNA could knock down 80% of target mRNA at 25 nM. Further knocking down AGO2, the ss-siRNAs could not effectively silence target mRNAs. Analysis of the biodistribution <i>in vivo</i> showed that ss-siRNA was less durable than siRNA, but spread more quickly to tissues. This study provides a safe and efficient ss-siRNA delivery and modification strategy, which lays the foundation for future works.Frontiers in chemistry843181https://www.ebi.ac.uk/biostudies/studies/S-EPMC8957067biostudies-literatureOptimization in Chemical Modification of Single-Stranded siRNA Encapsulated by Neutral Cytidinyl/Cationic Lipids.PMC8957067Yang ZLi ZGuan ZWang XZhou XWang JfalseOptimization in Chemical Modification of Single-Stranded siRNA Encapsulated by Neutral Cytidinyl/Cationic Lipids.Single-stranded siRNA (ss-siRNA) refers to the antisense strand of siRNA, which plays the role of gene silencing. Since single-stranded RNA is unstable, the present study employed a homemade neutral cytidinyl/cationic lipid delivery system and chemical modifications to improve its stability. The results showed that with the aid of mixed lipids, ss-siRNA could knock down 40% of target mRNA at 25 nM. With 2'-F/2'-OMe, phosphorothioate and 5'-terminal phosphorylation, the optimized ss-siRNA could knock down 80% of target mRNA at 25 nM. Further knocking down AGO2, the ss-siRNAs could not effectively silence target mRNAs. Analysis of the biodistribution <i>in vivo</i> showed that ss-siRNA was less durable than siRNA, but spread more quickly to tissues. This study provides a safe and efficient ss-siRNA delivery and modification strategy, which lays the foundation for future works.2022-01-01T00:00:00Z20222024-10-15T21:37:17.712Z2024-10-15T21:37:17.712ZS-EPMC89570673534553910.3389/fchem.2022.843181