Inclusion of a single-tail amino acid-based amphiphile in a lipoplex formulation: Effects on transfection efficiency and physicochemical properties

Abstract

Effects of the addition of a cationic amino acid-based synthetic amphiphile, arginine N-lauroyl amide dihydrochloride (ALA), to a lipid-based transfection formulation have been investigated. It is shown that the inclusion of ALA results in a substantial enhancement of the transfection capability of lipoplexes prepared with liposomes of 1-palmitoyl-2-oleoyl-sn-glycero-3-ethylphosphocholine and cholesterol, which themselves mediate highly efficient transfection. A possible explanation for the increased biological activity is that ALA adsorbed to the surface of the DNA-lipid complexes is involved in triggering internalization. However, in order to identify possible additional factors underlying the enhanced transfection efficiency, the physical properties of formulations with and without ALA were characterized using cryo-transmission electron microscopy, dynamic light scattering, and an ethidium bromide intercalation assay. ALA seems to have limited influence on the initial internal structure of the complexes and the protection of DNA, but its presence is found to decrease the average effective size of the dispersed particles; this change in size may be important in improving the biological activity. Furthermore, ALA can act to influence the transfection efficiency of the formulation by promoting the release of DNA following internalization in the transfected cells.

Keywords::

• Gene therapy
• colloid science
• mechanism

Acknowledgments

The authors would like to thank Gunnel Karlsson of Lund University, who performed the cryo-TEM experiments.

Declaration of interest: This work was financially supported by the Hans Werthén foundation, the sixth EU framework program as being part of a EU-STREP project with NEST program (NEONUCLEI, Contract 12967), the Linnaeus Center of Excellence on Organizing Molecular Matter through the Swedish Research Council, and Fundação para a Ciência e a Tecnologia (Portuguese Science Council) (Contracts SFRH/BPD/48522/2008, SFRH/BPD/43838/2008, and PPCDT/QUI/58689/2004). The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.