title: The effect of RAFT-derived cationic block copolymer structure on gene silencing efficiency.
abstract: In this work a series of ABA tri-block copolymers was prepared from oligo(ethylene glycol) methyl ether methacrylate (OEGMA(475)) and N,N-dimethylaminoethyl methacrylate (DMAEMA) to investigate the effect of polymer composition on cell viability, siRNA uptake, serum stability and gene silencing. Reversible Addition-Fragmentation Chain Transfer (RAFT) polymerization was used as the method of polymer synthesis as this technique allows the preparation of well-defined block copolymers with low polydispersity. Eight block copolymers were prepared by systematically varying the central cationic block (DMAEMA) length from 38 to 192 monomer units and the outer hydrophilic block (OEGMA(475)) from 7 to 69 units. The polymers were characterized using size exclusion chromatography and (1)H NMR. Chinese Hamster Ovary-GFP and Human Embryonic Kidney 293 cells were used to assay cell viability while the efficiency of block copolymers to complex with siRNA was evaluated by agarose gel electrophoresis. The ability of the polymer-siRNA complexes to enter into cells and to silence the targeted reporter gene enhanced green fluorescent protein (EGFP) was measured by using a CHO-GFP silencing assay. The length of the central cationic block appears to be the key structural parameter that has a significant effect on cell viability and gene silencing efficiency with block lengths of 110-120 monomer units being the optimum. The ABA block copolymer architecture is also critical with the outer hydrophilic blocks contributing to serum stability and overall efficiency of the polymer as a delivery system.
authors: CSIRO-Livestock Industries, Australian Animal Health Laboratory, Geelong, Vic 3220, Australia. tracey.hinton@csiro.au
authors: Tracey M
authors: TM
authors: Hinton
authors: Carlos
authors: C
authors: Guerrero-Sanchez
authors: Janease E
authors: JE
authors: Graham
authors: Tam
authors: T
authors: Le
authors: Benjamin W
authors: BW
authors: Muir
authors: Shuning
authors: S
authors: Shi
authors: Mark L V
authors: ML
authors: Tizard
authors: Pathiraja A
authors: PA
authors: Gunatillake
authors: Keith M
authors: KM
authors: McLean
authors: San H
authors: SH
authors: Thang
mesh_terms: D000818:Animals; D016466:CHO Cells; D002412:Cations / Q000737:chemistry*; D002470:Cell Survival; D002850:Chromatography, Gel; D006224:Cricetinae; D004587:Electrophoresis, Agar Gel; D020868:Gene Silencing; D018014:Gene Transfer Techniques; D057809:HEK293 Cells; D006801:Humans; D018625:Microscopy, Atomic Force; D008970:Molecular Weight; D053758:Nanoparticles / Q000648:ultrastructure; D011092:Polyethylene Glycols / Q000737:chemistry; D058105:Polymerization; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry*; D034741:RNA, Small Interfering / Q000378:metabolism; D044967:Serum / Q000378:metabolism
chemical_list: D002412:Cations; D011108:Polymers; D034741:RNA, Small Interfering; D011092:Polyethylene Glycols