Evidence of an inverted hexagonal phase in self-assembled phospholipid-DNA-metal complexes

Francescangeli, O.; Pisani, Michela; Stanić, Vesna; Bruni, P.; Weiß, Thomas

doi:10.1209/epl/i2004-10091-y

Cited by 53 publications

(61 citation statements)

References 18 publications

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“…In previous papers, we have found a close correspondence between the phase structure of the pure lipid and that of the related complex, both for lamellar (DOPC and DLPC) 20-22 and hexagonal (DOPE) 26 phases. In the present DPPC-based complexes, such correspondence appears to be still strong yet not fully achieved.…”

Section: Resultssupporting

confidence: 67%

Structure and Phase Behavior of Self-Assembled DPPC−DNA−Metal Cation Complexes

et al. 2006

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Multilamellar liposomes of dipalmitoylphosphatidylcholine (DPPC) in solution with DNA and bivalent metal cations (Ca2+, Mn2+, Mg2+) self-assemble into a ternary DPPC-DNA-Me2+ complex. The supramolecular structure of the complex consists of an ordered multilamellar assembly where hydrated DNA helices are sandwiched between the lipid bilayers and the metal cations bind the phosphate groups of DNA to the lipid polar heads. In the range of explored incubation times, the complex coexists with the uncomplexed DPPC over the whole temperature range investigated (20-55 degrees C). Accordingly, two distinct coexisting lamellar phases are observed, one corresponding to the ternary complex and the other to the uncomplexed lipid. The structure and thermotropic phase behavior of both of these have been investigated by means of synchrotron X-ray diffraction, and the relevant structural data are deduced from experimental electron density profiles. While the uncomplexed lipid exhibits the same phase behavior as pure DPPC, that is, L beta'-P beta'-L alpha, the thermotropic behavior of the bound lipid in the complex is partially altered. This is manifested as an increase in the main transition temperature and the disappearance of the ripple phase leading to the single -phase transition. The role of the different metal cations in promoting and stabilizing the DNA condensation into the ternary complex is also discussed.

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Section: Resultssupporting

confidence: 67%

Structure and Phase Behavior of Self-Assembled DPPC−DNA−Metal Cation Complexes

et al. 2006

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“…In fact, it is known that the equilibrium phase of pure DOPE in excess water is the inverted hexagonal, H II , whose structure elements are infinitely-long rigid rods, all identical and cristallographically equivalent, regularly packed in a 2D hexagonal lattice. As recently demonstrated [12], DOPE and divalent metal cations (Fe 2þ , Co 2þ , Mn 2þ , Mg 2þ ) in water solution can condense DNA into a novel invertedhexagonal phase, H c II , in which DNA strands fill the water gap inside the cylinders of pure DOPE. The structure, derived from synchrotron XRD, consists of cylindrical DNA strands coated by neutral lipid monolayers and arranged on the 2D hexagonal lattice.…”

Section: Resultsmentioning

confidence: 72%

Self-Assembled Liposome-DNA-Metal Complexes Related to DNA Delivery

Pisani

Bruni

Conti

et al. 2005

Molecular Crystals and Liquid Crystals

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We have carried out a systematic structural study of novel liquid-crystal phases of self-assembled neutral lipid-DNA-metal cation complexes in water solution. Small-angle X-ray scattering experiments have given new insight into the structures of these ternary complexes. We have shown that different divalent metal cations are equally active in promoting the DNA condensation into the ternary complex when different lipid and DNA species are used. In addition, strong indication has been found that the phase of the complexes reflects the structure and symmetry of the parent lipid phase. These achievements provide an important structure-composition correlation that may drive the best design of these materials for future applications as non-viral DNA carriers in gene therapy.

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“…The lower intensity of the (11) and (20) lipoplex diffraction peaks relative to the H II pattern of the pure lipid is known to result from the higher electron density of DNA relative to water. 48 It is thus an indication of the presence of DNA in the core of the hexagonal phase cylinders. 31 DiC18:1-C6PC represents the sole example to date of a cationic PC that forms a cubic phase by itself and forms H II phase lipoplexes when the lipid/DNA weight ratio is 4:1 ( Figure 9B).…”

Section: ■ Introductionmentioning

confidence: 99%

Nonlamellar Phases in Cationic Phospholipids, Relevance to Drug and Gene Delivery

Koynova

Tenchov

MacDonald

2015

ACS Biomater. Sci. Eng.

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Lipid aggregates have been used as drug carriers for several decades. Recently, nonlamellar liquid crystalline lipid systems have attracted attention as possible drug-delivery vehicles because of their unique nanostructure and physicochemical properties. Here we summarize data on the nonlamellar phase-forming propensity of the cationic phosphatidylcholines (cationic PCs). The class of cationic PCs has been specifically designed and explored for the purpose of nonviral gene delivery. These lipids were found to comprise an attractive cationic lipid class because they are biodegradable, have low toxicities, and in a number of cases, display high transfection activity. Lipids of this class form a variety of polymorphic and mesomorphic phases−lamellar and nonlamellar, depending on the structure of their hydrocarbon chains and especially on the third hydrocarbon chain used to alkylate the PC phosphate group and convert the zwitterionic PC headgroup into a cation. Here we characterize the phase behavior and transfection activity of eight cationic PCs that have been identified as forming nonlamellar phases−inverted hexagonal and cubic. We then demonstrate that those cationic PCs that also form nonlamellar lipoplexes are notably less efficient gene nanocarriers in comparison with the cationic PCs forming lamellar phase lipoplexes.

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Evidence of an inverted hexagonal phase in self-assembled phospholipid-DNA-metal complexes

Cited by 53 publications

References 18 publications

Structure and Phase Behavior of Self-Assembled DPPC−DNA−Metal Cation Complexes

Structure and Phase Behavior of Self-Assembled DPPC−DNA−Metal Cation Complexes

Self-Assembled Liposome-DNA-Metal Complexes Related to DNA Delivery

Nonlamellar Phases in Cationic Phospholipids, Relevance to Drug and Gene Delivery

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