Label-Free Detection of Melittin Binding to a Membrane Using Electrochemical-Localized Surface Plasmon Resonance

Department of Applied Physics, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan, Schoolof Materials Science, Japan Advanced Institute of Science and Technology, 1-1, Asahidai, Nomi City, Ishikawa, 923-1292,Japan, and Department of Mechano-Micro Engineering,Interdisciplinary Graduate School of Science and Engineering,Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8502, Japan

Localized surface plasmon resonance (LSPR) and elec-trochemistry measurements connecting to core-shell structure nanoparticle are successfully exploited in asimultaneous detectable scheme. In this work, the surface plasmon band characterizations of this nanostructure type are initially examined by controlling the core size of the silica nanoparticle and shell thickness of the deposited gold. These results clearly show that when the shell thickness is increased, keeping the core size constant, the peak wavelength of the LSPR spectra is shifted to a shorter wavelength and the maximum of peak intensity is achieved at a particular shell thickness. On the basis of this structure, we present a membrane-based nanosensor for optically detecting the binding of peptide toxin melittin to hybrid bilayer membrane (HBM) and electrochemically assessing its membranedisturbing properties as a func-tion of concentrations. It will open up the way to detect functionally similar protein toxins and other membrane-targeting peptides with the intension of integrating this chip into a microfluid and expanding it into multiarray format.

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