Surface properties of nucleolipids and photo-controlled release of hydrophobic guest molecules from their micellar aggregates†
Two series of nucleolipids have been designed and synthesized, one with a varying chain length (the dT-Cn series) and the other incorporating an aromatic photo-responsive moiety at the molecular hydrophobic and hydrophilic interface (the P-dT-Cn series). Surface tension measurements revealed the variations of critical micelle concentrations (CMCs) with the alkyl chain length and the incorporation of the photo-responsive segment. The P-dT-Cn series showed broadly lower CMCs and the minimum area per molecule (Amin) values because the π–π stacking between the additional aromatic rings favours more tight packing in the micelle formation. Both series showed similar surface tensions at the CMCs to conventional surfactants with equivalent molecular structures. Their micellar aggregates were used for encapsulation of hydrophobic Nile Red (NR). For the P-dT-Cn series, the encapsulated NR was released upon light irradiation and the controlled release was readily realized by controlling irradiation intensities or switching on and off irradiation. The integration of biocompatibility, complementary base recognition and photo-responsiveness makes the amphiphilic nucleolipids promising in biomedical and biotechnological applications.