Effects of molecular structures on the olfactory responses of phospholipid membranes to four alcohols.

In order to understand the relationship between phospholipid molecular structures and their olfactory responses to odorants, we designed and synthesized four phosphatidylcholine analogues with different long hydrocarbon (CH) chains and selected three natural phospholipids with different head-groups. By using interdigital electrodes (IEs) as olfactory sensors (OSs), we measured the responses of the IEs coated with these seven different lipid membranes to four alcohol vapors in a gas flow system. The IEs voltage changes were recorded and the voltage-relative saturate vapor pressure (V-P/P degree) curves were also plotted. It was found that with a methyl (-CH3) placed at the C-8 position in the 18-carbon chain, the olfactory responses could be improved about ten times and with conjugated double bonds (C-C) in the long chains, the sensitivity could be increased by 3-4 orders of magnitude. As to head-groups, choline is preferred over ethanolamine and serine in phospholipid structures in terms of high olfactory sensitivity. These results are expected to be useful in further designing and manufacturing lipid-mimicking OSs.