Sucrose Monolaurate as a Stabilizer for Lactate Oxidase Electrodes at Low pH: A Structural Analysis Based on Grazing Incidence Small-Angle X-ray Scattering

Sugars and sugar surfactants can increase the storage stability of enzyme electrodes. In this study, the feasibility of using sugar surfactants as stabilizers for enzyme electrode operation under acidic conditions was investigated along with their stabilizing mechanism. Lactate oxidase (LOx)-sucrose monolaurate-modified electrodes maintained ∼80% of their activity at pH 5.0, compared with ∼50% activity retention without a stabilizer. To elucidate the stabilizing mechanism, the structure of sucrose monolaurate with and without LOx on common electrode materials was analyzed using grazing incidence small-angle X-ray scattering (GI-SAXS). The results revealed that LOx was embedded in hexagonal arrangements and lamellar structures comprising sucrose monolaurate. Encapsulation protected the microenvironment of the enzyme against pH changes, without hindering its access to the substrate and mediator. This study confirms the high potential utility of GI-SAXS as a powerful tool for elucidating the structure-derived mechanisms of enzyme-electrode modifications.