MANA International Symposium 2025

Semiconductor Materials - 10

Title

Real-Time In Situ ATR-SEIRA Monitoring of Lysozyme Adsorption Dynamics and Secondary Structure on Gold Near-percolated Nanogap Optimized Structure

Author's photo

Authors

Hiroyuki Yamada 1*, Chih-Chung Wang 2, Thien Duc NGO 1,
Andrea Seehuber 1, Dominik Enders 1 and Tadaaki NAGAO 1

Affiliations

1 Photonics Nano-Engineering Group, MANA, NIMS
2 Department of Engineering Science and Ocean Engineering, National Taiwan University

URL

https://www.nims.go.jp/group/nsp/members.html

Email

YAMADA.Hiroyuki2@nims.go.jp

Abstract

Understanding protein adsorption at solid-liquid interfaces is essential for advancing biosensing, biomaterials, and biocatalysis. In this study, we present a polarization-resolved attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRA) platform utilizing gold near-percolated optimized structure. Using hen egg white lysozyme as a model, in situ ATR-SEIRA spectra with s-polarized light revealed three distinct adsorption stages—gap-edge adsorption, gap-interior adsorption, and rinse stabilization—each characterized by dynamic changes in the amide I/II intensity ratio. Post-rinse spectral deconvolution of the s-polarized amide I band revealed secondary structure changes: a 4.8% decrease in α-helix, a 9.7% reduction in random coil, and increases of 2.3% in β-sheet and 12.2% in β-turn content. These results highlight that the nanogap-enhanced SEIRA platform provides a highly sensitive and structurally informative tool to investigate protein adsorption and conformational dynamics under physiologically relevant conditions.

Fig. 1. ATR-SEIRA spectra of lysozyme accompanied by schematic illustrations of the corresponding adsorption states on the gold nanostructured surface.