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Name (Title):
Keitaro Yoshimoto (Lecturer) and Yukio Nagasaki (Prof.)
Affiliation:
Center for Tsukuba Advanced Research Alliance (TARA), Tsukuba Research
Center for Interdisciplinary Materials Science (TIMS)University of Tsukuba,
and Satellite Laboratory, International Center for Materials Nanoarchitechtonics
(MANA), National Institute of Materials Science. (NIMS)
Address: 1-1-1 Ten-nodai, Tsukuba, Ibaraki 305-8573, Japan.
Email: yoshimoto@ims.tsukuba.ac.jp
Home Page: http://www.ims.tsukuba.ac.jp/~nagasaki_lab/yoshimotoprofile.htm
Presentation Title:
Bioreactivity of PEGylated gold surfaces constructed by mixed homo-/hetero-telechelic PEGs
Abstract:
Improved method for functionalizing surfaces with bioactive molecules, retaining the excellent non-fouling
character, would accelerate the development of immunoassays, diagnostics, and tissue engineering applications. We
present herein new strategies for constructing bioactive molecules-terminated surfaces with excellent nonfouling
character by homo-/hetero-telechelic poly(ethylene glycol)s (PEGs).
Sulfanyl-terminated PEGylated gold surfaces was constructed by the combined use of a longer-homo-telechelic
PEG, α,ω-disulfanyl PEG (SH-PEG-SH(5k)), and shorter-semi-telechelic PEG, α-methoxy-ω-sulfanyl PEG (MeO-
PEG-SH(2k)) [1]. This consecutive treatment prevents a loop formation of SH-PEG-SH(5k) on the gold surface. On
the constructed MeO-PEG-SH (2k)/SH-PEG-SH (5k) mixed tethered-chain surface, the selective immobilization of
Fab’ fragment and maleimide group-containing protein were demonstrated as shown in Figure 1 and evaluated by
surface plasmon resonance (SPR) spectroscopy. The protein-installed SH-PEG-SH (5k)/MeO-PEG-SH (2k)modified
surface recognized the target molecules selectively and showed a fairly low non-specific protein adsorption
as strong as that of the conventional MeO-PEG-SH (5k)/MeO-PEG-SH (2k) mixed surface, which showed a superior
non-fouling characteristic in our previous work [2]. We also established a technique for constructing PEGylated gold
nanoparticle (GNP), which possessed small compounds on their surfaces with high level functionalities, using
hetero-telechelic PEG, α-sulfanyl-ω-amino-PEG (SH-PEG-NH2). SPR analysis revealed that the PEGylated GNP
with 4 % of antigen functionalities showed small binding affinity on antibody Fab’ immobilized sensor surface and
dissociation behavior from the surface was observed by the competitive reaction of free antigen. In contrast, the
constructed PEGylated GNPs with 30-100 % of antigen functionalities on its surface had a high binding affinity
accompanying with nondissociative property on antibody Fab’ immobilized sensor surface [3]. These results
indicated that the surface functionalization techniques using homo/hetero-telechelic PEGs provided a bioreactive
surfaces with excellent binding properties and nonfouling character.
100
Poster Session PB-6
Fig.1 Schematic illustration of protein immobilization on SH-terminated Mixed-PEG(2k/5k) modified
gold surface (left). Xray-photospectroscopy S2p spectra (right, A) of SH-terminated Mixed-PEG(2k/5k)
surface and the conventional MeO-PEG-SH (2k)/MeO-PEG-SH (5k) mixed tethered-chain gold surface
(right, B).
References:
[1] Yoshimoto K., Hirase T., Nemoto S., Hatta T., Nagasaki Y., Langmuir, 24 (2008) 9623.
[2] Uchida K., Hoshino Y., Tamura A., Yoshimoto K., Kojima S., Yamashita K., Yamanaka I., Otsuka H., Kataoka
K., Nagasaki Y., Biointerphases, 2 (2007) 126.
[3] Yoshimoto K., Hoshino Y., Ishii T., Nagasaki Y., Chemical Communications, (2008) 5369.