Application of Living Free Radical Polymerization for Nucleic Acid Delivery

Abstract

CONSPECTUS Nucleic acid-based therapeutics can potentially address otherwise untreatable genetic disorders and have significant potential for a wide range of diseases. Therapeutic gene delivery can restore protein function by replacing defunct genes to restore cellular health while RNA interference (RNAi) can mask mutated and harmful genes. Cationic polymers have been extensively studied for nucleic acid delivery applications due to their self-assembly with nucleic acids into virus-sized nanoparticles and high transfection efficiency in vitro, but toxicity and particle stability have limited their clinical applications. The advent of controlled radical polymerization has improved the quality, control and reproducibility of synthesized materials. Controlled radical polymerization yields well-defined, narrowly disperse materials of designable architectures and molecular weight, allowing study of the effects of polymer architecture and molecular weight on transfection efficiency and cytotoxicity for improved design of next-generation vectors. Robust methods such as atom transfer radical polymerization (ATRP), reverse addition-fragmentation chain transfer polymerization (RAFT), and ring-opening metastasis polymerization (ROMP) have been used to engineer materials that specifically enhance extracellular stability, cellular specificity, and decrease toxicity. This Account reviews findings from structure-function studies that have elucidated key design motifs necessary for the development of effective nucleic acid vectors. In addition, polymers that are biodegradable, form supramolecular structures, target specific cells, or facilitate endosomal release are also discussed. Finally, promising materials with in vivo applications ranging from pulmonary gene delivery to DNA vaccines are described.

Living Radical Polymerization by the RAFT Process – A Third Update

“…include those on the kinetics and mechanism of RAFT polymerization, [26,27] RAFT agent design and synthesis, [28] the use of RAFT to probe the kinetics of radical polymerization, [29] microwaveassisted RAFT polymerization, [30,31] RAFT polymerization in microemulsion, [32] end-group removal/transformation, [33][34][35][36] the use of RAFT in organic synthesis, [37] the combined use of RAFT polymerization and click chemistry, [38] the synthesis of star polymers and other complex architectures, [39][40][41][42] the synergistic use of RAFT polymerization and ATRP, [43,44] the synthesis of self assembling and/or stimuli-responsive polymers, [45][46][47] and the use of RAFT-synthesized polymers in green chemistry, [48] polymer nanocomposites, [49][50][51] drug delivery and bioapplications, [41,46,47,[52][53][54][55][56][57][58][59][60] and applications in cosmetics [61] and optoelectronics. [62] The process is also given substantial coverage in most recent reviews that, in part, relate to polymer synthesis, living or controlled polymerization or novel architectures.…”

“…[62] The process is also given substantial coverage in most recent reviews that, in part, relate to polymer synthesis, living or controlled polymerization or novel architectures. Some of those that include significant mention of RAFT polymerization include reviews on RDRP, [63] mechanism and reagent design, [11,64,65] click chemistry, [66][67][68][69][70][71][72] synthesis of telechelics, [73] the polymerization of carbazole-containing monomers, [74] N-vinyl-1,2,3-triazoles, [75] N-vinyl heterocycles, [76] fluoro-monomers, [77] and glycomonomers, [78][79][80] synthesis of metallopolymers, [81] conjugated block copolymers, [82] dye-functionalized polymers, [83] stimuliresponsive polymers, [84,85] complex architectures, [86,87] polyolefin blocks, [88] biopolymer-polymer conjugates and bioapplications, [59,[89][90][91][92][93] polysaccharide modification, [94,95] polymerization in heterogeneous media, [96,97] microwave-assisted polymerization, [65,98,99] industrial prospects for RDRP, [100,…”

Prospects for polymer therapeutics in Parkinson's disease and other neurodegenerative disorders

“…5 shows a library of acetyl containing acid cleavable polymers created by Fréchet and coworkers [65]. These forms of acid cleavable linkage, are also easy to incorporate into living polymerizations [66,67], the preparation method of choice for many gene vectors [68,69]. However, to date, the vast majority of degradable polymers for delivery to the brain use a reduction sensitive moiety (disulfide bond) instead.…”

Phosphonium polymers for gene delivery

“…6 Within this context, controlled radical polymerisation (CRP, also known as reversibledeactivation radical polymerisation, RDRP) techniques have been extensively investigated, as they enable control over the polymer composition, architecture as well as molecular weight and dispersity. 7,8 CRP techniques relevant for the synthesis of gene delivery vehicles 9 are copper-mediated living radical polymerisation, 10 especially atom transfer radical polymerisation (ATRP), 11,12 reversible addition fragmentation chain transfer (RAFT) 13,14 polymerisation, and nitroxide-mediated polymerisation (NMP). 15 One of the most common strategies to deliver oligo/polynucleotides in vitro and in vivo is to assemble them into polyplexes, where they are bound to suitable polymer carriers through non-covalent interactions between multiple copies of negatively charged nucleotide phosphate groups and polycationic polymers 16 ( Figure 1).…”