title: Reductively responsive siRNA-conjugated hydrogel nanoparticles for gene silencing.
abstract: A critical need still remains for effective delivery of RNA interference (RNAi) therapeutics to target tissues and cells. Self-assembled lipid- and polymer-based systems have been most extensively explored for transfection with small interfering RNA (siRNA) in liver and cancer therapies. Safety and compatibility of materials implemented in delivery systems must be ensured to maximize therapeutic indices. Hydrogel nanoparticles of defined dimensions and compositions, prepared via a particle molding process that is a unique off-shoot of soft lithography known as particle replication in nonwetting templates (PRINT), were explored in these studies as delivery vectors. Initially, siRNA was encapsulated in particles through electrostatic association and physical entrapment. Dose-dependent gene silencing was elicited by PEGylated hydrogels at low siRNA doses without cytotoxicity. To prevent disassociation of cargo from particles after systemic administration or during postfabrication processing for surface functionalization, a polymerizable siRNA pro-drug conjugate with a degradable, disulfide linkage was prepared. Triggered release of siRNA from the pro-drug hydrogels was observed under a reducing environment while cargo retention and integrity were maintained under physiological conditions. Gene silencing efficiency and cytocompatibility were optimized by screening the amine content of the particles. When appropriate control siRNA cargos were loaded into hydrogels, gene knockdown was only encountered for hydrogels containing releasable, target-specific siRNAs, accompanied by minimal cell death. Further investigation into shape, size, and surface decoration of siRNA-conjugated hydrogels should enable efficacious targeted in vivo RNAi therapies.
authors.affiliation: Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
authors.forename: Stuart S
authors.initials: SS
authors.lastname: Dunn
authors.forename: Shaomin
authors.initials: S
authors.lastname: Tian
authors.forename: Steven
authors.initials: S
authors.lastname: Blake
authors.forename: Jin
authors.initials: J
authors.lastname: Wang
authors.forename: Ashley L
authors.initials: AL
authors.lastname: Galloway
authors.forename: Andrew
authors.initials: A
authors.lastname: Murphy
authors.forename: Patrick D
authors.initials: PD
authors.lastname: Pohlhaus
authors.forename: Jason P
authors.initials: JP
authors.lastname: Rolland
authors.forename: Mary E
authors.initials: ME
authors.lastname: Napier
authors.forename: Joseph M
authors.initials: JM
authors.lastname: DeSimone
mesh_terms: D002470:Cell Survival; D003692:Delayed-Action Preparations / Q000737:chemistry*; D020868:Gene Silencing; D006367:HeLa Cells; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry*; D008156:Luciferases / Q000235:genetics; D053758:Nanoparticles / Q000737:chemistry*; D010084:Oxidation-Reduction; D011092:Polyethylene Glycols / Q000737:chemistry*; D034741:RNA, Small Interfering / Q000008:administration & dosage* / Q000235:genetics; D014162:Transfection
chemical_list: D003692:Delayed-Action Preparations; D034741:RNA, Small Interfering; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D011092:Polyethylene Glycols; D008156:Luciferases