posted on 2019-10-03, 15:36authored byGilda Liskayová, Lukáš Hubčík, Alexander Búcsi, Tomáš Fazekaš, Juan Carlos Martínez, Ferdinand Devínsky, Martin Pisárčik, Mária Hanulová, Sandra Ritz, Daniela Uhríková
pH-sensitive
liposomes composed of homologues of series of N,N-dimethylalkane-1-amine N-oxides (CnNO, n = 8–18,
where n is the number of carbon atoms in the alkyl
substituent) and neutral phospholipid dioleoylphosphatidylethanolamine
(DOPE) were prepared at two molar ratios (CnNO/DOPE
= 0.4:1 and 1:1) and tested for their in vitro transfection
activity. Several techniques (SAXS/WAXS, UV–vis, zeta potential
measurements, confocal microscopy) were applied to characterize the
system in an effort to unravel the relationship among the transfection
efficiency, structure, and composition of the lipoplexes. The transfection
efficiency of CnNO/DOPE for plasmid DNA in U2OS cells
follows a quasi-parabolic dependence on CnNO’s
alkyl substituent length with a maximum at n = 16.
The transfection efficiency of CnNO/DOPE (n = 12–18) lipoplexes was found to be higher than
that of commercially available Lipofectamine 2000. C16NO/DOPE also
positively transfected HEK 293T and HeLa cells. Small-angle X-ray
scattering (SAXS) shows large structural diversity depending on the
complex’s composition and pH. Transfection efficiencies mediated
by two structures, either a condensed lamellar (Lαc) or epitaxially connected Lαc and a condensed inverted hexagonal (HIIc) phase (Lαc & HIIc), were found to be very similar. The change in pH from acidic
to neutral induces phase transition Lαc & HIIc → QII + Lα, with cubic phase QII of the Pn3m space group. QII detected in lipoplexes
of most efficient composition CnNO/DOPE (n = 16 and 18) facilitates DNA release and promotes its
internalization in the cell.