Single-Step Aerosol-Assisted Plasma Deposition of Biocomposite Glucose Oxidase/Poly(ethylene oxide) Films for Biosensing Applications

Aerosol-assisted plasma deposition (AAPD) is a promising technique for the immobilization of delicate biomolecules, such as enzymes, on a variety of substrates. Here, we demonstrate for the first time the single-step deposition of glucose oxidase (GOx) in a poly(ethylene oxide) (PEO) matrix by AAPD with an atmospheric pressure plasma jet. The resulting biocomposite GOx/PEO films retain enzymatic activity, show excellent sensitivity, and allow glucose sensing in cell culture medium with 10% fetal bovine serum (FBS). We show that water evaporation during aerosol transport governs film morphology: enzymes precipitate in droplets reaching the substrate with a small volume fraction of water (ϕH₂O), leading to a solid-like behavior when impacting on the substrate and formation of (hemi)spherical particles in/on the GOx/PEO films. In contrast, droplets retaining a high ϕH₂O can spread upon impaction, leading to the formation of disk-like features in the GOx/PEO films and increased sensitivity of the films for glucose. The optimized films show a sensitivity for glucose of 4 μA cm⁻² mM⁻¹ in cell culture medium with 10% FBS and a linear range between 0.5 and 8 mM, which is comparable with typical values reported in the literature for a first-generation glucose biosensor. Furthermore, the films preserve 87% of their sensitivity after 4 weeks of dry storage. These findings demonstrate the potential of AAPD as a scalable, environmentally friendly method for the immobilization of biomolecules in a biocompatible matrix with tunable morphology and properties. The insights presented here can serve as a basis for further film optimization and for extending the process to other biomolecules.