Reaction mixtures based on the CTAB–Dodecyl Epoxide–water microemulsion for the synthesis of novel Nucleo-Lipids

Nucleotide-functionalized amphiphiles can be generated in an aqueous microemulsion based on the cationic surfactant CetylTrimethylAmmonium Bromide (CTAB). The lipophilic precursor, Dodecyl Epoxide (DE), was able to hydrophobically modify several types of nucleotides (NMPs) giving rise to the production of novel anionic Nucleo-Lipids (NL), through a ring-opening reaction occurring at level of the CTAB micellar interface. The coexistence of both cationic (CTAB) and NL monomers triggered the spontaneous formation of aqueous suspensions of onion-like aggregates, as confirmed by optical microscopy and spectroturbidimetry. The solubilization process of DE into CTAB micellar phase in the presence of NMPs was first characterised through conductometry. DLS data showed a gradual micellar swelling resulting in a higher oil uptake upon addition of NMPs in the starting liquid L(1) phase. An important result achieved in this study was obtained through the inspection of long-aged suspensions incubated with each of four different types of NMPs, including their binary equimolar combinations. Samples made with the complementary pairs AU and CG showed up very stable vesicular systems, unlike the other random base paired mixtures, where we found a coexistence of liquid crystalline domains in equilibrium with either transparent liquid phases or dense isotropic gel phases. The potential role of the molecular recognition on the self-assembly properties of NL monomers has been discussed.