ABSTRACT
New squalene receptors bearing open-chain polyether ligands (SQ-diEG, SQ-triEG, SQ-tetraEG) were synthesised. The stoichiometries and association constants (Ka) 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
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
Supplemental data for this article can be accessed here.