Results at Molecular Level

Superlattice SL Domains in Lipid Bilayers

We propose that lipids of different chemical structures, e.g., headgroup sizes, level of hydrations, charge, hydrophobic lengths and shapes, can form nanoscopic superlattice SL domains, on the x-y plane of the lipid bilayers. We have provided probe -dependent and non-invasive spectroscopic evidence of the headgroup and sterol SL domains in binary lipid mixtures. The intriguing regulation mechanisms of lipid SL domains in cells at the molecular level are currently investigated.

Nanosecond-resolved Fluorescence spectroscopic investigation of Cholesterol SL domains

Using a chain-labeled fluorescent lipid (DPH-PC), in which one acyl chain of a PC is replaced by a DPH fluorophore or probe, time-resolved fluorescence decay lifetimes (t1 and t2), orientational order (S) and rotational correlation time (tr) of the probe in bilayers of PC/Cholesterol binary mixtures were measured. Our measurements revealed the partitioning of DPH-PC probe in the packing defect regions of the bilayers near the predicted critical compositions of cholesterol SL.

Fourier Transform Infrared (FTIR) Spectroscopic Investigation of cholesterol SL Domains

Using a non-invasive FTIR technique, we reported an increase order of the C-H (chain), hydration or packing of both the C=O (water/bilayer interfacial region) and O=P=O (phosphate headgroup) of the PC molecules in PC/Cholesterol bilayers at the predicted critical compositions of cholesterol SL.