1H NMR Determination of Incorporated Porphyrin Location in Lipid Membranes of Liposomes

Abstract

Abstract Lipid-membrane-incorporated symmetrical and unsymmetrical porphyrins were prepared with relatively high concentrations via exchange from cyclodextrins to liposomes. We determined the location of these porphyrins in the lipid membranes from chemical shift changes of the lipid signals in the 1H NMR spectra. Symmetrical tetraphenyl porphyrin accumulates in the hydrophobic core of the lipid membranes. In contrast, several unsymmetrical porphyrins with more polar group(s), such as pyridine and pyridinium moieties, are located close to the liposome surface.