AVS 51st International Symposium
    Biomaterial Interfaces Monday Sessions
       Session BI-MoP

Paper BI-MoP1
Immobilization of Avidin on COOH-modified SiO@sub 2@/Si(100) Surface and Characterization by AFM and BML-IRRAS

Monday, November 15, 2004, 5:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: N. Misawa, The Graduate University for Advanced Studies, Japan
Authors: N. Misawa, The Graduate University for Advanced Studies, Japan
S. Yamamura, The Graduate University for Advanced Studies, Japan
T. Urisu, Institute for Molecular Science, Japan
Correspondent: Click to Email
Nowadays bio-mimetic sensing techniques, using immobilization of intact biomolecules on solid surfaces, attract significant attentions. For solid substrates, silicon is a suitable material since precise micro-fabrication has been established. New biosensors can be combined with electronics devices on the same chip. Characterizations by IR spectroscopy and AFM observation are useful tools to investigate biomolecules immobilized on silicon surface. It is known that BML-IRRAS (Infrared Reflection Absorption Spectroscopy using Buried Metal Layer substrate [1]) is a high-resolution surface vibration spectroscopy on the semiconductor or insulator materials, which has sub-monolayer sensitivity for the wide frequency range including fingerprint regions. In this study we have immobilized avidin, which has high versatility for conjugation of biomolecules with solid surface, on the SiO@sub 2@/Si(100) surface modified with carboxyl group, and characterized the surfaces by AFM and BML-IRRAS for the first time. The -COOH modification was produced by the deposition of 2-(carbomethoxy) ethyltrichlorosilane and sequential hydrolysis by HCl. Immobilization of avidin was performed after condensation reaction by N-hydroxysucciniimide and EDC, which enhanced the reactivity of carboxyl group with amino group of avidin. AFM images showed that the roughness of the -COOH modified surface was less than 0.5 nm, and protrusions with about 15 nm diameter and 2 nm height appeared after the avidin immobilization. The BML-IRRAS measurements showed clear peaks at 1650 cm@super -1@ and 1550 cm@super -1@, which were assigned to Amide I and Amide II bands of avidin. These bands also consisted of several fine structures which might be assigned to secondary structures such as @alpha@-helix and @beta@-sheet etc. The detailed shape analysis of these bands could give the information with orientations of these immobilized proteins. [1] S.Yamamura. et al. Jpn. J. Appl. Phys. 42 3942 (2003).