Investigating the Role of Sucrose Esters in Stabilizing Biosensor Electrodes using GISAXS

Introduction

Enzyme-based biosensors are powerful tools that enable the sensitive and selective monitoring of key metabolites such as lactate. Among these, sweat-sensing devices which employ lactate oxidase (LOx) have gained particular interest due to their potential application in sports medicine, health monitoring, and the growing field of wearable electronics. These devices provide real-time, non-invasive analysis of metabolic activity.

A critical challenge, however, is the strong dependence of LOx activity on the surrounding pH. In acidic environments such as human sweat, with a typical pH around 4-5, the enzyme rapidly loses activity. In consequence, this restricts the performance, stability and lifetime of these sensors, thereby limiting its practical applicability. 

In this study, the structure of biosensor surfaces, incorporating sucrose esters as a stabilizing additive for LOx-based sensors was investigated using grazing-incidence small-angle X-ray scattering (GISAXS). The aim was to determine how nanostructural changes at the sensor surface contribute to protecting the enzyme’s function and thereby improve the biosensor’s overall performance.

In GISAXS, a sample’s surface is probed with a collimated X-ray beam at a very shallow incidence angle (~0.2°), which provides structural information from the surface and surface-near domains (1, 2). In contrast to electron microscopy, the GISAXS method is non-destructive and yields important averaged data over a relatively large sample area, making it particularly suited for analyzing sensors and obtaining representative information.

References

1. Schnablegger H., Singh Y., The SAXS Guide –
   Getting acquainted with the principles. 5th Ed. (2023), Anton Paar GmbH: Graz, Austria.
2. Müller-Buschbaum P., A Basic Introduction to Grazing Incidence Small-Angle X-Ray Scattering. In: Gomez, M., Nogales, A., Garcia-Gutierrez, M., Ezquerra, T. (eds) Applications of Synchrotron Light to Scattering and Diffraction in Materials and Life Sciences. Lecture Notes in Physics, vol 776. (2009) Springer, Berlin, Heidelberg.