The effect of backbone structure on polycation comb-type copolymer/DNA interactions and the molecular assembly of DNA

Sato, Yu; Kobayashi, Yuki; Kamiya, Tomoya; Watanabe, Haruo; Akaike, Toshihiro; Yoshikawa, Kenichi; Maruyama, Atsushi

doi:10.1016/j.biomaterials.2004.03.018

Cited by 57 publications

(51 citation statements)

References 45 publications

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“…The partial globule structure was previously observed with poly(oxyethylene) derivatives having amino groups. 8 In agreement with a previous report, 3 highest graft content, 40K91D, gave DNA images similar to DNA alone. The conclusion that DNA condensation was not induced by 40K91D was supported by the images at 561 nm:…”

supporting

confidence: 81%

“…3 We have shown that PLL-g-Dex increases stability of DNA hybrids, 2 accelerates DNA hybridization, 4 and activates DNA strand-exchange reactions.…”

mentioning

confidence: 99%

“…2 The copolymer with a high degree of grafting forms totally soluble DNA complexes without inducing collapse. 3 We have shown that PLL-g-Dex increases stability of DNA hybrids, 2 accelerates DNA hybridization, 4 and activates DNA strand-exchange reactions. 5 However, interaction of the copolymer with DNA is not thoroughly understood and the influence of the copolymer grafting degree on conformation of DNA has not been assessed.…”

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confidence: 99%

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Cationic Comb-type Copolymers Do Not Cause Collapse but Shrinkage of DNA Molecules

et al. 2011

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A flow-stretching assay was employed to elucidate polycation/DNA interactions at the single-molecule level. Bacteriophage -DNA (48.5 kbp) was attached at one end to a PEGmodified glass surface and stretched by buffer flow. The stretched DNA had an approximate length of 12¯m. Upon injection of polylysine homopolymer, the DNA folded into a globule structure within a few seconds. Injection of a polylysine graft copolymer having hydrophilic dextran side chains also induced collapse of the stretched DNA. In comparison to these polymers, a copolymer with higher graft content did not cause DNA collapse but rather caused 25% shrinkage of the extended DNA. These results were compared with those observed with unstretched DNA.Long DNA molecules can undergo discrete coil to globule transitions. Polycations like polylysine are effective inducers of the transition.1 Upon complex formation with polycations, the DNA molecules collapse into compact globule conformations. The complexes subsequently aggregate and precipitate from the solution. We have been interested in soluble complex formation observed with cationic graft copolymers containing poly(Llysine) and dextran, PLL-g-Dex ( Figure 1); PLL-g-Dex has a polycation backbone and hydrophilic side chains.2 The copolymer with a high degree of grafting forms totally soluble DNA complexes without inducing collapse. 3 We have shown that PLL-g-Dex increases stability of DNA hybrids, 2 accelerates DNA hybridization, 4 and activates DNA strand-exchange reactions.5 However, interaction of the copolymer with DNA is not thoroughly understood and the influence of the copolymer grafting degree on conformation of DNA has not been assessed. Here, we employed a DNA flow-stretching assay to further evaluate DNA/polycation interactions. The DNA flow-stretching assay has high spatiotemporal resolution and has been used to study DNA/protein interactions. 6 The results of the flowstretching assay were compared to that from assays with DNA and polycations in solution.PLL-g-Dex copolymers (M n of PLL: 4.0 © 10 4 , M n of Dex: 8.4 © 10 3 , Dex grafts: 38, 61, and 91 wt %) were prepared as previously reported.2 The nomenclature used for the copolymers reflects the degree of grafting: Polymers with grafts of 38, 61, and 91 wt % are referred to as 40K38D, 40K61D, and 40K91D, respectively. First, we observed the effect of these copolymers on conformation of bacteriophage -DNA (48.5 kbp) in aqueous buffer solution using a method described by Yoshikawa et al. 7 We observed images of cationic polymers in the same mixtures by employing a second fluorescent label. As shown in Figure 2, 11 DNA was visualized with SYBR Gold staining (488 nm excitation) and polymers were imaged (561 excitation) by TRITC labeling. The -DNA alone shows amorphous fluorescence images with 35¯m long axes on average. The DNA images wobbled due to Brownian motion, indicating an extended coil conformation of the DNA. When polylysine homopolymer (40K) was added to the DNA solution, bright DNA clots were observed, indicating that the 40K ...

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supporting

confidence: 81%

“…3 We have shown that PLL-g-Dex increases stability of DNA hybrids, 2 accelerates DNA hybridization, 4 and activates DNA strand-exchange reactions.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

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Cationic Comb-type Copolymers Do Not Cause Collapse but Shrinkage of DNA Molecules

et al. 2011

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“…It is known (Lepecq & Paoletti, 1967) that EtBr can exhibit great increase in fluorescence intensity to itself by DNA intercalation, which makes it a suitable fluorescence probe for vector-gene interaction study (Sato et al, 2005). The introduction of polycation reduces this fluorescence by competing and excluding EtBr from DNA complex, indicating its DNA binding strength (Geall & Blagbrough, 2000).…”

Section: Complex Formation Between Dextran Conjugates With Pamam Dendmentioning

confidence: 99%

Water soluble cationic dextran derivatives containing poly(amidoamine) dendrons for efficient gene delivery

Mai

Zhang

Liang

et al. 2015

Carbohydrate Polymers

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“…Our choice of dextran for the carbohydrate chains was motivated by several factors. First, there are already reports on the synthesis and applications for drug/gene delivery of poly (L-lysine)-g-dextran (PLL-g-dex) in the literature [25][26][27][28][29][30][31]. Second, since the dextran is neutral, it does not present problems due to electrostatic interactions when grafted onto a polycationic backbone (PLL).…”

Section: Introductionmentioning

confidence: 99%

End-grafted Sugar Chains as Aqueous Lubricant Additives: Synthesis and Macrotribological Tests of Poly(l-lysine)-graft-Dextran (PLL-g-dex) Copolymers

2008

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Comb-like graft copolymers with carbohydrate side chains have been developed as aqueous lubricant additives for oxide-based tribosystems, in an attempt to mimic biological lubrication systems, whose surfaces are known to be covered with sugar-rich layers. As adopted in the previous studies of the graft copolymer poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG), which showed both excellent lubricating and antifouling properties, a similar approach was chosen to graft dextran chains onto the same backbone, thus generating PLL-g-dex. PLL-g-dex copolymers readily adsorb from aqueous solution onto negatively charged oxide surfaces. Tribological characterization at the macroscopic scale, either under pure sliding conditions or a mixed sliding/rolling contact regime, shows that PLL-g-dex is very effective for the lubrication of oxide-based tribosystems. The relative lubricating capabilities of PLL-g-dex copolymers compared with PLL-g-PEG copolymers were observed to be highly dependent on the molecular structure of the copolymers (in particular, sidechain density along the backbone) and the measurement conditions (in particular, time between tribocontacts); the PLL-g-dex copolymers with a low degree of grafted side chains (B20% grafting of available protonated primary amine groups along the backbone) showed better lubricating performance than their PLL-g-PEG counterparts at high tribocontact frequency (Cca. 0.32 Hz).

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The effect of backbone structure on polycation comb-type copolymer/DNA interactions and the molecular assembly of DNA

Cited by 57 publications

References 45 publications

Cationic Comb-type Copolymers Do Not Cause Collapse but Shrinkage of DNA Molecules

Cationic Comb-type Copolymers Do Not Cause Collapse but Shrinkage of DNA Molecules

Water soluble cationic dextran derivatives containing poly(amidoamine) dendrons for efficient gene delivery

End-grafted Sugar Chains as Aqueous Lubricant Additives: Synthesis and Macrotribological Tests of Poly(l-lysine)-graft-Dextran (PLL-g-dex) Copolymers

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