Syntheses and aggregation properties of new squalene receptors bearing open chain ligands

ABSTRACT

New squalene receptors bearing open-chain polyether ligands (SQ-diEG, SQ-triEG, SQ-tetraEG) were synthesised. The stoichiometries and association constants (K_a) for the interactions between these squalene receptors and representative alkaline earth metal ions (Mg²⁺, Ca²⁺, and Ba²⁺) were determined in solution. Fluorescence spectral studies revealed that the squalene receptors self-associate with critical vesicle concentrations at 25 °C of 2.2 × 10⁻⁵ M for SQ-diEG, 2.3 × 10⁻⁵ M for SQ-triEG, and 2.5 × 10⁻⁵ M for SQ-tetraEG. The self-assembly behaviour was probed using laser diffraction particle size-based analyses and scanning electron microscopy. A decrease in the SQ-tetraEG vesicle size was readily induced by the addition of alkaline earth metal ions, confirmed by cryogenic transmission electron microscopy.

Graphical abstract

KEYWORDS:

• Squalene
• receptor
• aggregate
• alkaline earth metal ion
• critical vesicle concentration

Acknowledgments

The authors greatly thank Prof. N. Adachi, Prof. M. Kawasaki, and Prof. T. Senda for cryo-TEM observations in High Energy Accelerator Research Organization (KEK), Tsukuba.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

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