(24e) GHz-Dielectric Relaxation Stimulates the Hydration State of Lipid Bilayer Membrane

Tauchi, A., Osaka University
Okamoto, Y., Osaka University
Suga, K., Osaka University
Umakoshi, H., Osaka University


Liposomes is a self-assembly of phospholipids
and is known as model biological membranes. Recent studies have shown that
liposomes selectively adsorb only L-form amino acids. However, its mechanism
has not been clarified, and it is a problem that adsorption / desorption
control canft be performed. Molecular adsorption onto liposomes is greatly
affected by membrane properties, and liposomes can flexibly change the membrane
structure with external factors, such as temperature. Therefore, we focused on
alternating electric field (AC EF) in this study. It has been reported that by
applying AC EF to liposomes, it is possible to change the shape of the membrane
and the molecular orientation of lipid molecules, hydrated water molecules.
Among them, in this research, we focused on the change of the hydration
environment of the membrane surface by high frequency AC EF. The hydration
environment of liposomes acts as a barrier for molecular adsorption and also
greatly influences hydrogen bonding between liposomes and target molecules.
Hydrogen bonding between liposomes and amino acids is an important factor for
chiral selective adsorption of amino acids, and the change of the hydration
environment is important for controlling the molecular recognition ability of

In this
study, the influence of AC EF on the adsorption behavior of D-mandelic acid (D-MA) onto positively charged liposome DPTAP
was evaluated as a model system. Application of AC EF to DPTAP caused
dehydration of water molecules from the membrane surface and enhanced
adsorption by strengthening hydrogen bonding between liposome and D-MA. This
phenomenon does not occur in other adsorbents, thus applying AC EF to liposome
is an effective method to control the molecular recognition ability.


1. Takada K.; Umakoshi
H. et al., 2012, Proc. IEEE Sens, 6411071.

2. Tauchi
A. et al., 2017, Langmuir, 33, 3831-3838.

3. Tauchi
A. et al., 2018, to be submitted.