Polymeric Gene Carriers Bearing Pendant β-Cyclodextrin: The Relevance of Glycoside Permethylation on the “In Vitro” Cell Response

Abstract

The incorporation of cyclodextrins (CDs) to nonviral cationic polymer vectors is very attractive due to recent studies that report a clear improvement of their cytocompatibility and transfection efficiency. However, a systematic study on the influence of the CD derivatization is still lacking. In this work, the relevance of β‐CD permethylation has been addressed by preparing and evaluating two series of copolymers of the cationic N‐ethyl pyrrolidine methacrylamide (EPA) and styrenic units bearing pendant hydroxylated and permethylated β‐CDs (HCDSt and MeCDSt, respectively). For both cell lines, CDs permethylation shows a strong influence on plasmid DNA complexation, “in vitro” cytocompatibility and transfection efficiency of the resulting copolymers over two murine cell lines. While the incorporation of the hydroxylated CD moiety increased the cytotoxicity of the copolymers in comparison with their homopolycationic counterpart, the permethylated copolymers have shown full cytocompatibility as well as superior transfection efficiency than the controls. This behavior has been related to the different chemical nature of both units and tentatively to a different distribution of units along the polymeric chains. Cellular internalization analysis with fluorescent copo­lymers supports this behavior.

Hydroxyl versus permethylated glycopolymers as gene carriers

“…Contrarily, the permethylated systems tended to form smaller particles with increasing content of the permethylated neutral unit. This behavior is in agreement with the reported differences obtained in our previous work, with hydroxylated and permethylated CD-derivatives, where the hydroxylated moieties form bigger particles, probably due to hydrogen bonding between the hydroxyl groups of the glucose units and the amino N or O or the carboxyl and phosphate groups of DNA, respectively [32].…”

Evaluation of Poly(N-Ethyl Pyrrolidine Methacrylamide) (EPA) and Derivatives as Polymeric Vehicles for miRNA Delivery to Neural Cells

“…Poly(N-ethyl pyrrolidine methacrylamide) (EPA) is a cationic, linear, non-toxic, and non-crosslinked polymer that was synthesized and characterized for the first time by Velasco and colleagues in 2007 [ 15 ]. The synthesis and characterization of other polymer systems, except terpolymers, ECDP, composed of EPA-HCD-APEG, have been previously described [ 17 , 19 , 22 ]. EG is a copolymer of EPA with the monomer, GLSt, which is derived from glucose, with 0.9/0.1 (EG10) and 0.95/0.05 (EG5) molar fractions, whereas EM is a copolymer of EPA and MGLSt, a permethylated glucose monomer, with 0.9/0.1 (EM10) and 0.95/0.05 (EM5) molar fractions [ 19 ].…”

“…HPMA is a precursor with a biocompatible nature, whose copolymerization of HPMA with cationic precursors enhances the performance as gene carriers of cationic component homopolymers and allows the modulation of the charge density of polymeric entities and their interaction with the surrounding media in a flexible and tailored way [ 18 ]. ECD is a copolymer of EPA and a cyclodextrin (HCD)-derivative monomer designed to improve the cellular uptake of polyplexes, and good interactions with the cellular membrane have been described before, and their transfection capability improves when fibroblasts cell lines are used [ 22 ]. Due to their unique structure with multiple hydroxyl groups, amphiphilic cyclodextrin-based polymers provide low toxicity, good bioavailability, and biodegradability, as well as the ability to form well-defined aggregated nanostructures [ 29 ].…”

“…The synthesis and characterization of respective synthetic monomers, homopolymer poly-EPA (EPA) [ 17 ], and copolymers, EPA-GLCSt (EG) and EPA-MGLCSt (EM) [ 19 ], EPA-HCD (ECD) [ 22 ], and EPA-HPMA (EHPMA) [ 16 ], have been previously described. On the other hand, EPA-HCD-APEG (ECDP-) terpolymers were prepared via free radical polymerization procedures where the monomers and the initiator (AIBN, 2,2′-azobisisobutyronitrile, Fluka) were dissolved in N , N ’dimethyl formamide (DMF) at concentrations of 1.0 and 1.5 × 10 −2 M, respectively, using 0.85/0.1/0.05 (ECDP5), 0.8/0.1/0.1 (ECDP10), and 0.7/0.1/0.2 (ECDP20) molar fractions of EPA/HCD/APEG, respectively.…”

Efficient and Low Cytotoxicity Gene Carriers Based on Amine-Functionalized Polyvinylpyrrolidone

“…Some studies have reported higher effectiveness through polymer modification, which consisted of the introduction of secondary and tertiary amines to enhance its buffering capacity [28], thus improving its properties when releasing the genetic material into the cytoplasm. Furthermore, more complex entities such as cyclodextrins have been anchored to different polymers to increase the complexing capacity of the genetic material [29][30][31].…”