Worldwide R&D

Designing a Bio/Nano-Interface
Yukio Nagasaki, Professor, Nagasaki Laboratory, Department of Materials Science andTechnology, Faculty of Industrial Science and Technology, Tokyo University of ScienceE-mail: nagasaki@rs.noda.tus.ac.jp
Our laboratory strives to design biomaterials that function
within a living organism. The laboratory currently has twentyfive members, including Dr. Yukio Nagasaki, assistant
Yoshinori Katsuyama, postdoctoral fellow Hajime Oishi, three
doctoral students, ten masters students, and nineundergraduate seniors.

we could almost completely suppress nonspecific adsorption
by immobilizing PEG chains with different molecular weights(Fig. 1). Highly sensitive biosensors and other devices can becreated on this material surface by immobilizing specificfunctional groups (antibodies, enzymes, sugars, etc.) on thetermini of the PEG chain.

Scheme 1

The basic goal of our laboratory is to manufacture"biomaterials," which are materials that function within a livingorganism. It is particularly important to design a contact
interface between blood or tissue and the material in theorganism. Hence, the design of "bio/nano-interfaces" hasbecome our most important task. In designing this interface,
we have also focused our studies on polyethylene glycol(PEG), commonly found in living organisms. A heterobifunctional PEG having functional groups introduced indifferent quantities on its termini can be employed as a usefulmaterial for designing various surfaces (see Fig. 1).
By immobilizing a hetero-bifunctional PEG synthesized inthis way on the surface of various materials, it is possible todesign an interface on which such biological components asproteins, lipids, and cells are not adsorbed. We discovered that

Ligand introducing
site

Further, we discovered that by similarly pegylating thesurface of micro- or nano-size particles, it is possible not only
to control nonspecific adsorption on the surface, but also to
improve dispersion stability drastically.
This revolutionary technique facilitates the use of suchparticles, which were previously very difficult to disperse inbiological fluids with high ion concentration, such as sodium
and potassium. These pegylated nanoparticles make it possible
to employ various nanoparticles of gold, semiconductors, silica,and fullerene to be used in a bioenvironment.
We are now working day and night with the students todevelop practical bio/nanomaterials such as these.
On October 1, 2004, our laboratory will be transferred tothe Tsukuba Research Center for Interdisciplinary Materials
Science (TIMS).

PEG

Nonspecific adsorption control

SH

PEG

HS
Thiol

Increase in brush density
Fig. 1 Developing a highly functional bio/nanointerface

Nanoparticles

Ligands
Fig. 2 Regulating pegylated nanoparticles tofunction in a living organism

MICROMACHINE No. 49
MICROMACHINE is published quarterly by Micromachine Center (MMC) to promote the international exchange ofinformation related to micromachines, R&D and other technical topics, and is circulated free of change. Please send
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