Title:
Ultrahigh-sensitive oscillator biosensor for studying interaction between biomolecules

Hirotsugu Ogi
Graduate School of Engineering Science, Osaka University

Abstract:
Various tag proteins have been reported for affinity evaluation and purification to product recombinant proteins. However, conventional affinity tag systems use large-size tag proteins and have influence on the apparent affinity among biomolecules. Label-free methods are therefore important for studying inherent interactions of biomolecules. The quartz-crystal-microbalance (QCM) biosensor is a representative label-free biosensor. It detects the mass of adsorbed proteins on the receptor immobilized on a quartz oscillator through decrease of the oscillator resonance frequency. Its mass sensitivity was peaked because of indispensable heavy metallic electrodes on the oscillator surfaces. However, we recently succeeded in developing the wireless-electrodeless QCM (WE-QCM) biosensor using naked quartz oscillators and improved the mass sensitivity by a factor of 1000.
One important application is r eal-time monitoring of deposition reaction of A – beta peptides on various nuclei over long-time periods ( ～40 h). Various nuclei of the peptides were immobilized on the sensor chips , and isolated A -beta peptides were flowed at the neutral pH, focusing on interaction between the nuclei and monomers, excluding other interactions among seeds and other aggregates. The notable deposition behavior was observed in the accelerated deposition of A -beta 1-40 peptide on A -beta 1-42 nuclei grown at lower pH, which can be an important model for Alzheimer’s disease.

References:
H. Ogi, Y. Fukunishi, T. Yanagida, H. Yagi, Y. Goto, M. Fukushima, K. Uesugi, and M. Hirao, “Seed-dependent deposition behavior of A-beta peptides studied with wireless quartz-crystal-microbalance biosensor”, Anal. Chem. 83, 4982-4988 (2011).

H. Ogi, H. Nagai,Y. Fukunishi, T. Yanagida, M. Hirao, and M. Nishiyama “Multichannel Wireless-Electrodeless Quartz-Crystal Microbalance Immunosensor”, Anal. Chem. 82, 3957-3962 (2010).

H. Ogi, H. Nagai,Y. Fukunishi, M. Hirao, and M. Nishiyama “170-MHz Electrodeless Quartz Crystal Microbalance Biosensor: Capability and Limitation of Higher Frequency Measurement”, Anal. Chem. 81, 8068-8073 (2009).