Silica nanogelling of environment-responsive PEGylated polyplexes for enhanced stability and intracellular delivery of siRNA.
In this study, poly(ethylene glycol) (PEG)-block-polycation/siRNA complexes (PEGylated polyplexes) were wrapped with a hydrated silica, termed "silica nanogelling", in order to enhance their stability and functionality. Silica nanogelling was achieved by polycondensation of soluble silicates onto the surface of PEGylated polyplexes comprising a disulfide cross-linked core. Formation of silica nanogel layer on the PEGylated cross-linked polyplexes was confirmed by particle size increase, surface charge reduction, and elemental analysis of transmission electron micrographs. Silica nanogelling substantially improved polyplex stability against counter polyanion-induced dissociation under non-reductive condition, without compromising the reductive environment-responsive siRNA release triggered by disulfide cleavage. Silica nanogelling significantly enhanced the sequence-specific gene silencing activity of the polyplexes in HeLa cells without associated cytotoxicity, probably due lower endosomal entrapment (or lysosomal degradation) of delivered siRNA. The lower endosomal entrapment of the silica nanogel system could be explained by an accelerated endosomal escape triggered by deprotonated silanol groups in the silica (the proton sponge hypothesis) and/or a modulated intracellular trafficking, possibly via macropinocytosis, as evidenced by the cellular uptake inhibition assay. Henceforth, silica nanogelling of PEGylated siRNA polyplexes is a promising strategy for preparation of stable and functional siRNA delivery vehicles.
Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan.
Noha
N
Gouda
Kanjiro
K
Miyata
R James
RJ
Christie
Tomoya
T
Suma
Akihiro
A
Kishimura
Shigeto
S
Fukushima
Takahiro
T
Nomoto
Xueying
X
Liu
Nobuhiro
N
Nishiyama
Kazunori
K
Kataoka
D003432:Cross-Linking Reagents / Q000737:chemistry; D004220:Disulfides / Q000737:chemistry; D006367:HeLa Cells; D006801:Humans; D000080385:Nanogels; D011073:Polyamines / Q000737:chemistry*; D000071228:Polyelectrolytes; D011092:Polyethylene Glycols / Q000737:chemistry*; D011094:Polyethyleneimine / Q000737:chemistry*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000008:administration & dosage* / Q000235:genetics; D012822:Silicon Dioxide / Q000737:chemistry*
D003432:Cross-Linking Reagents; D004220:Disulfides; D000080385:Nanogels; D011073:Polyamines; D000071228:Polyelectrolytes; D011092:Polyethylene Glycols; D011094:Polyethyleneimine; D034741:RNA, Small Interfering; D012822:Silicon Dioxide; C413692:polyethylene glycol polyethyleneimine nanogel