Structure and morphology of vesicular dispersions based on novel phosphatidyl glucose and phosphatidyl choline with different acyl chains

Hypothesis: Phospholipids are widely used in food and pharmacological formulations. However, these typically suffer from limitations such as low colloidal stability. Promising stability has been observed for vesicles based on phosphatidylglucose (P-Glu), but fundamental knowledge on this lipid is missing and those observations were made using P-Glu containing mixed acyl groups. The acyl groups are expected to influence the properties of phosphatidylglucose to a large extent. Experiments: Using an enzyme-based method, P-Glu containing either palmitic (DPP-Glu), stearic (DSP-Glu) or oleic (DOP-Glu) acid were synthesized. The morphology of the lipid dispersions was studied using small angle x-ray scattering and cryogenic transmission electron microscopy and the data was modelled to extract bilayer structural parameters. Phosphatidylcholine lipids containing the same fatty acids were studied for comparison. Findings: All phosphatidylcholine lipids formed mainly multilamellar vesicles. DOP-Glu formed unilamellar vesicles (ULVs), while disc like objects were observed in the case of DPP-Glu and DSP-Glu formed predominantly bilayer stacks. In the 1:1 mixture of the DOPC and DOP-Glu, ULVs were formed. The bilayer thickness increased as follows: DOP-Glu < DPP-Glu < DSP-Glu and in the PC series the same trend was seen for the lamellar spacing. DSP-Glu had similar lamellar spacing as DSPC.