چكيده لاتين :
Thermodynamic features related to preparation and use of self-assemblies formed between
multilamellar and unilamellar zwitterionic liposomes and polynucleotides with various conformation
and sizes are presented. The divalent metal cation or surfactant-induced adsorption, aggregation and
adhesion between single- and double-stranded polyribonucleotides and phosphatidylcholine vesicles was
followed by differential adiabatic scanning microcalorimetry. Nucleic acid condensation and compaction
mediated by Mg2+ and N-alkyl-N,N,N-trimetylammoniunl ions (CnTMA, n=12), regarding to interfacial
interaction with unilamellar vesicles. Microcalorimetric measurements ofsynthetic phospholipid vesicles
and poly(ribo)nucleotides and their ternary complexes with inorganic cations were used to build the
thermodynamic model of their structural transitions. The increased thermal stability of the phospholipid
bilayers is achieved by affecting their melting transition temperature by nucleic acid induced electrostatic
charge screening. Measurements give evidence for the stabilization of polynucleotide helices upon
their association with liposomes in the presence of divalent metal cations. Such an induced aggregation
of vesicles either leads to heterogeneous multilamellar DNA-lipid arrangements, or to DNA-induced
bilayer destabilization and lipid fusion. In contrast, stable monodispersed complexes are formed after
compaction of DNA with surfactant, followed by the addition of vesicles. Surfactants bind to DNA in
a cooperative manner and increased number of nucleic acid-bound Cl2TMA leads to a rise in the size
of the resulting DNA-surfactant complexes, due to their aggregation. The formation of these bundles
is governed by both elctrostatic and hydrophobic interactions of surfactant chains, the reaction being
mediated by condensed counterions, steric hindrance or by intrinsic chain flexibility. in here, further
employment of these polyelectrolyte nanostructures as an improved formulation in therapeutic gene
delivery trials, as well as in DNA chromatography is discussed..
