In situ neutron reflectivity studies of the adsorption of DNA by charged diblock copolymer monolayers at the air–water interface

Yang, Ping-Feng; Lin, Tsang–Lang; Liu, I-Ting; Hu, Yuan; James, M. R.

doi:10.1039/c2sm25297j

Cited by 13 publications

(34 citation statements)

References 73 publications

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“…For example, in the presence of divalent cations, DNA condensation to a cationic lipid monolayer or to a cationic diblock copolymer monolayer at the air-water interface was observed in reectivity studies. [50][51][52][53][54] Furthermore, the degree of DNA condensation is governed by the concentration of divalent ions. 54,55 As a result, calcium ions could agglutinate the DNA array encapsulated between lipid bilayers at higher calcium ion concentrations as that happens in the cationic-DNA system.…”

Section: Resultsmentioning

confidence: 99%

“…[50][51][52][53][54] Furthermore, the degree of DNA condensation is governed by the concentration of divalent ions. 54,55 As a result, calcium ions could agglutinate the DNA array encapsulated between lipid bilayers at higher calcium ion concentrations as that happens in the cationic-DNA system. 56 Other than the studies on the AB-DNA complex aggregation structure by SAXS, TEM was also employed to visualize the realspace images of the ion-mediated AB-DNA complex formation.…”

Section: Resultsmentioning

confidence: 99%

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Formation of divalent ion mediated anionic disc bicelle–DNA complexes

Yang

Lin

et al. 2014

Soft Matter

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Disc-shaped bicelles are formed by mixing long-chain lipids with short-chain lipids at suitable molar ratios and they have a relatively uniform size, typically around a few tens of nanometers in diameter. Different from the typically formulated cationic or anionic liposome–DNA complexes, which are used as nonviral vectors for improving the transfection efficiency of gene therapy, a novel way of packing the DNA can be developed by using the much smaller disc-like bicelles. We demonstrate that anionic lipid bicelle-ion–DNA (AB–DNA) complexes can be formed with the help of divalent ions. Multi-stacked AB–DNA complexes can be formed with diameters of around 50–100 nm and lengths of around 50–150 nm as revealed by TEM. Using the anionic lipid–DNA complexes has the advantage of lower cytotoxicity than using cationic lipids. The interaction of DNA with anionic bicelles was investigated by SAXS. It was found that the anionic bicelle could not form stable complexes with DNA at low calcium ion concentrations, such as 1 mM. The AB–DNA complexes can be formed in the investigated range of 10 mM to 100 mM calcium ion concentrations. However, for an equal anionic lipid charge and DNA charge system, an ion-membrane phase (multilamellar vesicles) would gradually appear as the calcium ion concentration is increased above a critical concentration. It indicates that DNA could be packed closer at above the critical divalent ion concentration. If more DNA is added to such a two-phase coexistence system (originally with the total anionic lipid charge equal to that of DNA), the ion-membrane phase could be transformed into the AB–DNA complexes. As a result, more DNA can be packed in the form of AB–DNA complexes at above the critical calcium ion concentration.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Formation of divalent ion mediated anionic disc bicelle–DNA complexes

Yang

Lin

et al. 2014

Soft Matter

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“…This information allows us to propose a mechanism of interaction. A future direction of the work could be to apply a technique such as neutron reflectometry to gain supporting insight into the interfacial structure including the volume fraction and thickness of the layers [ 18 , 52 ], although clearly this remains outside the scope of the present work. Given the use of DNA/polymer systems in research on gene delivery [ 53 ] and electronic devices [ 54 ], the new insight into the mechanism of formation of their nanostructures at interfaces provided by the present work can have a variety of future implications.…”

Section: Discussionmentioning

confidence: 99%

DNA Interaction with a Polyelectrolyte Monolayer at Solution—Air Interface

et al. 2021

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The formation of ordered 2D nanostructures of double stranded DNA molecules at various interfaces attracts more and more focus in medical and engineering research, but the underlying intermolecular interactions still require elucidation. Recently, it has been revealed that mixtures of DNA with a series of hydrophobic cationic polyelectrolytes including poly(N,N-diallyl-N-hexyl-N-methylammonium) chloride (PDAHMAC) form a network of ribbonlike or threadlike aggregates at the solution—air interface. In the present work, we adopt a novel approach to confine the same polyelectrolyte at the solution—air interface by spreading it on a subphase with elevated ionic strength. A suite of techniques–rheology, microscopy, ellipsometry, and spectroscopy–are applied to gain insight into main steps of the adsorption layer formation, which results in non-monotonic kinetic dependencies of various surface properties. A long induction period of the kinetic dependencies after DNA is exposed to the surface film results only if the initial surface pressure corresponds to a quasiplateau region of the compression isotherm of a PDAHMAC monolayer. Despite the different aggregation mechanisms, the micromorphology of the mixed PDAHMAC/DNA does not depend noticeably on the initial surface pressure. The results provide new perspective on nanostructure formation involving nucleic acids building blocks.

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“…16 Most of the authors who have worked on this topic previously considered the interactions of nucleic acids with polyelectrolytes in the bulk phase. To the best of our knowledge, only the groups of James 17 and Matsumuto 18 have studied the aggregation of DNA with oppositely charged macromolecules in spread layers at the liquidgas interface. On the other hand, it is well known that the layers of amphiphilic molecules at fluid interfaces can be considered as physical models of biological membranes, 19,20 and therefore information on DNA/polyelectrolyte interactions in the surface layer of their solutions can lead to stepwise advances in the understanding of the structure and mechanism of aggregate formation of these substances in real biological systems.…”

Section: Introductionmentioning

confidence: 99%

Network Formation of DNA/Polyelectrolyte Fibrous Aggregates Adsorbed at the Water–Air Interface

et al. 2019

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It is discovered that complexes of DNA and hydrophobically modified polyelectrolytes form a rigid network of threadlike or fibrous aggregates at the liquidgas interface whose morphology can dramatically affect the mechanical properties. While mixed solutions of DNA and poly(N,N-diallyl-N,N-dimethylammonium chloride) (PDADMAC) exhibit no notable surface activity, the complexes formed from DNA with poly(N,N-diallyl-N-butyl-N-methylammonium chloride) are surface active, in contrast to either of the separate components. Further, complexes of DNA and poly(N,N-diallyl-N-hexyl-N-methylammonium chloride) (PDAHMAC) with its longer hydrophobic side chains exhibit pronounced surface activity with values of the surface pressures up to 16 mN/m and dynamic surface elasticity up to 58mN/m. If the PDAHMAC nitrogen to DNA phosphate molar ratio, N/P, is between 0.6 and 3, abrupt compression of the adsorption layer leads unexpectedly to a noticeable decrease of the surface elasticity. Application of imaging techniques reveals that this effect is a consequence of the destruction of a rigid network of threadlike DNA/polyelectrolyte aggregates at the interface. The toroidal aggregates, which are typical for the bulk phase of DNA/PDADMAC solutions in this range of N/P ratios, are not observed in the surface layer. The observed link between the mechanical properties and interfacial morphology of surface active complexes formed from DNA with hydrophobically modified polyelectrolytes indicates that tuning the polyelectrolyte hydrophobicity in these systems may be a means to develop their use in applications ranging from nonviral gene delivery vehicles to conductive nanowires.

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In situ neutron reflectivity studies of the adsorption of DNA by charged diblock copolymer monolayers at the air–water interface

Cited by 13 publications

References 73 publications

Formation of divalent ion mediated anionic disc bicelle–DNA complexes

Formation of divalent ion mediated anionic disc bicelle–DNA complexes

DNA Interaction with a Polyelectrolyte Monolayer at Solution—Air Interface

Network Formation of DNA/Polyelectrolyte Fibrous Aggregates Adsorbed at the Water–Air Interface

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