Annual Report 2006

I nsect Biomaterial and Technology Department
Development of biosensors and
related materials focusing on the
immolization of chemical
recognition molecules
We have been reported that liposome
containing insect sensory organ extracts and
the membrane potential sensitive dye is a new
type biosensor. We immobilized the liposome on
a photodiode and measured membrane
potential changes triggered by salt stimulation
(Fig. 1 Left). The photodiode output was in
proportional to the concentration of salt
solution. We also constructed the other type of
biosensor that uses a planar lipid bilayer
membrane which is used for immobilization of
receptor proteins from insect sensory organs.
This biosensor is fabricated by combining
receptors with a field effect transistor (FET).
Our FET device could detect the membrane
potential changes stimulated by salt solution
(Fig. 1 Under). Lactose immobilized silk fibroin
was indicated a better substrate for fibroblast
culture than no-treated silk fibroin by the
results of mice fibroblast cultivation study. We
established the lipofection method which
transfect plasmid DNA transiently into
silkgland cells of silkworm larva, and we
optimized the experimental conditions.
Development of measurement
and recording methods for
obtaining bio-physical information
on insects
Multichannel microelectrodes are being
developed in order to record action biopotentials
of insects. Silicon was conventionally used as
the electrode material and microelectrodes
were fabricated by anisotropic etching and
reactive ion etching. Because electrode
microprobe shape and size were very difficult
to control, we proposed a novel pin-shaped
multichannel microelectrode that used epoxybased
UV sensitive photoresist as the electrode
material. Analysis of the electrical properties of
this type electrode showed that it has
properties excellent enough to record insect
biopotentials. We could record muscle action
potentials from a flapping silk moth using our
epoxy-based multichannel microelectrodes (Fig.
2).
Fig. 1
Recorded membrane potential changes
(Left: Photodiode system; Under: FET system)