Aggregation Behavior and Thermodynamics of Binding between Poly(ethylene oxide)-block-Poly(2-(diethylamino)ethyl methacrylate) and Plasmid DNA

Abstract

The aggregation behavior and the thermodynamics of binding between poly(ethylene oxide)-block-poly(2-(diethylamino)ethyl methacrylate) (PEO-b-PDEAEMA) block copolymers and plasmid DNA were examined. Binding between the polymer and DNA were confirmed by gel electrophoresis. The high affinity between the polymer and DNA was demonstrated through the ethidium bromide (EtBr) displacement assay, and the binding was found to be related to the stoichiometric balance between the amine group of the polymer and the DNA nucleotide molar ratio (N/P molar ratio). The light scattering and TEM results showed that, at low polymer concentration, the hydrodynamic radii (R(h)) of the polymer/DNA complexes was around 90 nm; however, at sufficiently high polymer concentration, the complexes condensed to around 35 nm induced by a structural rearrangement of the amphiphilic nature of the block copolymer. The isothermal titration calorimetric results showed that the binding between the polymer and DNA is driven by a large favorable enthalpy.

Polycationic graft copolymers of poly(N-vinylpyrrolidone) as non-viral vectors for gene transfection

“…6c). A similar spherical morphology has recently been reported using amine methacrylate-based systems and PEG copolymers [22,36]. The reasons for the small size and uniform complexes formed using PVP grafted copolymer could be explained by a micelle-like structure.…”

“…Oriented micellisation of the copolymer would be expected to lead the close association of polycationic segment with negatively charged DNA. This may allow the hydrophilic PVP grafts to be oriented outwards from the DNA containing core, producing a hydrophilic steric barrier to stabilize the complexes and prevent aggregation with other species [20,22,30]. These results confirm improved aggregation behavior of complexes with polymer modified by the inclusion of PVP grafts.…”

“…Although cationic polymers with high charge density exhibit enhanced DNA condensation, this property also contributes to their higher cytotoxicity [19]. Among amine methacrylatebased polymers, PDMAEMA has previously been reported to be one of the efficient cationic condensing agents for DNA delivery [20], but the high positive charge and the production of large insoluble aggregates of polymer-DNA complexes remain problematic [21,22].…”

Impact of molecular weight and degree of conjugation on the thermodynamics of DNA complexation and stability of polyethylenimine-graft-poly(ethylene glycol) copolymers

“…Recently, isothermal titration calorimetry (ITC) has been used to determine the thermodynamics of the DNA or siRNA interactions of PEI, poly-L-lysine, poly(2-(dimethylamino) ethyl methacrylate), poly(2-(diethylamino)ethyl methacrylate), poly (glycoamidoamine) and chitosan [43][44][45][46][47][48][49][50][51][52][53][54]. The difficulty with application of ITC is that not only binding heat is detected.…”

Thermodynamic Studies of DNA-Cationic Components Interactions Using Titration Calorimetry

“…The binding constant K decreased by increasing NaCl concentration, moreover it became more dependant with the decrease in degree of polymerization of PLL (Figure 4) [29]. Tan et al [30] studied the thermodynamics of binding between poly(ethylene oxide)-block-poly(2(diethylamino) ethyl methacrylate) block copolymers and plasmid DNA. They found that as the polymer solution was titrated into the DNA solution, a pronounced exothermic heat was observed showing that the interaction between the block copolymer and DNA was highly favorable enthalpically.…”