pH-Sensitive N,N-Dimethylalkane-1-amine N-Oxides in DNA Delivery: From Structure to Transfection Efficiency

Abstract

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 (L α c ) or epitaxially connected L α c and a condensed inverted hexagonal (H II c ) phase (L α c & H II c ), were found to be very similar. The change in pH from acidic to neutral induces phase transition L α c & H II c → Q II + L α , with cubic phase Q II of the Pn3m space group. Q II detected in lipoplexes of most efficient composition CnNO/DOPE (n = 16 and 18) facilitates DNA release and promotes its internalization in the cell.

Polymyxin B-Enriched Exogenous Lung Surfactant: Thermodynamics and Structure

“…Interestingly, PxB molecules mediated “close mutual contact” of EPS bilayers even if they constitute ULV that are diluted enough to avoid any interaction between particles (1 wt % of the lipid). This finding correlates well with the concept that PxB mimics the properties of SP-B protein and the formation of stable vesicle–vesicle contacts allowing the exchange of phospholipids. , A similar “condensing” effect was recently reported for the interaction of cationic nanoparticles and polymers with PSUR, , cationic liposomes with polyelectrolytes of opposite charges, such as DNA, − or in the context of antimicrobial mechanisms of cationic peptides that interact with bacterial model membranes . However, it is worth stressing two points: (1) our experiments show that binding of PxB molecules onto EPS bilayers results in charge inversion of the membrane, as shown by the zeta potential and proved by SANS measurements.…”

Calcium mediated DNA binding in non-lamellar structures formed by DOPG/glycerol monooleate

“…In addition to the promising utilization of cubic phases for encapsulation and delivery of short fragmented nucleic acids as mentioned above, also cubic and hexagonal structures with DNA strands containing thousands of base pairs have been reported recently (Dittrich et al 2018;Tassler et al 2019). The presence or formation of intracellular nonlamellar, namely cubic phases, on the DNA delivery path was revealed as an enhancing factor of transfection efficiency (Koynova et al 2006;Tenchov et al 2008;Safinya et al 2014;Liskayová et al 2019). The fusogenicity of lipoplexes plays a crucial role in transfection rate.…”

Stimulus-responsive liposomes for biomedical applications

“…These smart drug carriers were stable at pH 7.4, whereas they showed size increase and 80% release of their cargo within 5 hours at pH 4.5 due to the cleavage of the cyclic acetal. Liskayová et al [137] investigated the relationship between the structure of N,Ndimethylalkane-1-amine N-oxides 62 (CnNO, n=1-18, Fig. 14) and in vitro TE of pH-sensitive DNA-CnNO/DOPE lipoplexes (cationic, non-viral lipid-DNA complexes) by delivering plasmid DNA (pEGFP-N1) into human bone OS epithelial cells (U2OS).…”