Simultaneous surface acoustic wave and surface plasmon resonance measurements: electrodeposition and biological interactions monitoring

TL;DR

This paper introduces a combined SAW and SPR instrument to measure protein layer properties, including water content, using two independent methods for enhanced biological interaction analysis.

Contribution

It demonstrates the integration of SAW and SPR techniques to simultaneously analyze physical and dielectric properties of protein layers, providing new insights into their water content.

Findings

Mass sensitivity calibration with copper electrodeposition

Monitoring of biological processes using combined methods

Determination of protein layer thickness and water content ratio

Abstract

We present results from an instrument combining surface acoustic wave (SAW) propagation and surface plasmon resonance (SPR) measurements. The objective is to use two independent methods, the former based on adsorbed mass change measurements and the latter on surface dielectric properties variations, to identify physical properties of protein layers, and more specifically their water content. We display mass sensitivity calibration curves using electrodeposition of copper leading to a sensitivity in liquid of 150$\pm15$ $cm^2/g$ for the Love mode device used here, and the application to monitoring biological processes. The extraction of protein layer thickness and protein to water content ratio is also presented for S-layer proteins under investigation. We obtain respectively 4.7$\pm$0.7 nm and 75$\pm$15%.