Phase Behavior of Ascorbyl Palmitate Coagels Loaded with Oligonucleotides as a New Carrier for Vaccine Adjuvants

BENEDINI LUCIANO; ULLO GAMBOA GABRIELA; ALLEMANDI DANIEL; SCHULZ PABLO

JOURNAL OF SURFACTANTS AND DETERGENTS

SPRINGER HEIDELBERG

Lugar: HEIDELBERG; Año: 2016 vol. 19 p. 747 - 767

1097-3958

In this work, the phase behavior variations ofan ascorbyl palmitate (Asc16) system in aqueous solutionwere analyzed when immunologically active hydrophiliccompounds (CpG and OVA) were introduced. This studywas carried out through optical polarizing microscopy(OPM) and differential scanning calorimetry (DSC) atdifferent temperatures and over a broad range of concentrations.The combination of both techniques allowed thedetermination of a complete phase diagram which wascompared with those built for Asc16-water system and itwas demonstrated that fixed concentrations of hydrophiliccompounds (300 and 24 lg/g for CpG-ODN and OVArespectively) generate two lamellar liquid crystals, a cubicliquid crystal phase, and also other aggregates. However,no changes were observed in the phase diagram in terms offormation of new mesophases. The aqueous phase behaviorwas also studied as a function of surfactant and temperature.DSC and Fourier transform infrared spectroscopy(FT-IR) measurements show differences in the free waterand mainly in the secondary hydration layer, which confirmthat the studied compounds are situated in the aqueousdomain. The construction and analysis of Asc16 phasediagrams with a fixed concentration of CpG-ODN/OVAallows the comprehension of Asc16 phase behavior andcould be easily adapted to other concentrations. Moreover,these findings could be extrapolated to other hydrophilicsubstances in aqueous solution introduced in liquid crystalphases since they follow a similar behavior as thosereported in the literature.