Poster Presentation 2014 International Biophysics Congress

Effect of oligonucleotide on bilayer structure of cationic DODAB vesicles (#472)

Julio H.K. Rozenfeld 1 , Evandro L. Duarte 1 , M. Teresa Lamy 1
  1. Instituto de Física, Universidade de São Paulo, São Paulo, Brazil

Dioctadecyldimethylammonium bromide (DODAB) is a versatile cationic lipid that has been applied in drug delivery and vaccine design. In this work, the effect of a small (10 bases) single-stranded oligonucleotide (ODN) on the structure of DODAB vesicles was investigated by means of dynamic light scattering (DLS), small angle X-ray scattering (SAXS), electron spin resonance (ESR) and differential scanning calorimetry (DSC).

Stable anionic assemblies were formed in presence of excess ODN negative charge. ODN adsorption induced bilayer fusion and formation of multilamellar structures, as observed from the appearance of Bragg peaks in SAXS spectra. It also increased the phase transition temperature by almost 10°C but decreased transition cooperativity. Below the phase transition, ESR spectra show a more rigid phase in presence of oligonucleotide. At the fluid phase, a simultaneous decrease in bilayer surface packing and increase in bilayer core rigidity is observed in presence of oligonucleotide. These data may be useful in preparing new DODAB formulations.

Acknowledgements: Supported by Fapesp (2011/13079-9) and CNPq.