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Name (Title):
Chiho Kataoka (NIMS fellow)
Affiliation:
Biomaterials Center and International Center for Materials
Nanoarchitectonics (MANA), NIMS
Address:
1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
Email: KATAOKA.Chiho@nims.go.jp
Home Page:
Presentation Title:
Detection of Supported Lipid Bilayers Using Their Electric Charge
Abstract:
The electric charge of lipids plays crucial roles
in biochemical processes. Charged lipids can
sometimes be incorporated into supported lipid
bilayers (SLBs) by vesicle fusion. Since SLBs are
useful in vitro mimics for biological membranes,
their properties and formation mechanisms have
been widely studied by monitoring various signals
including fluorescence, mass, viscoelasticity,
refractive index, topography, and impedance. In
this study, SLBs were detected through their
charge using field-effect devices. The field-effect
sensing technique has been employed for various
analytes including polymers and DNA. Similarly,
field-effect devices might potentially serve as
biosensors for analyzing molecular recognition
events involving lipid membranes. However, little
is known about the field effect of SLB systems.
In this work, charged bilayers adsorbed on Si3N4/SiO2/Si supports were monitored in terms of
the flat-band voltage (VFB). The flat-band voltage was obtained before and after lipid adsorption.
We then calculated the shift (∆VFB) by subtracting the value obtained before adsorption from that
obtained after adsorption. When SLBs were composed of cationic DOTAP and zwitterionic
DOPC, the flat-band shift increased with the increase of the DOTAP ratio (Figure 1) [1]. This is
consistent with the expectation that the positive charge of DOTAP affects the flat-band voltage.
In the presentation, we show that the flat-band voltage shift is affected by the lipid composition,
the salt concentration, the lipid surface coverage, and the buffer composition.
Reference:
[1] C. Kataoka-Hamai, H. Inoue, and Y. Miyahara, Langmuir 24 (2008) 9916.
�V FB (mV)
5
0
-5
-10
-15
Poster Session PB-1
0 20 40 60 80 100
DOTAP (mol %)
Fig. 1. Planar DOTAP/DOPC bilayers. Buffer: 20
mM KCl, 10 mM potassium phosphate, pH 8.0.
95