High performance of ethanol colorimetric biosensor using core-shell biocomposite.

The requirement for ethanol detection for product quality control, consumer safety, health risk management, and halal certification encourages the development of fast, accurate, reliable, and selective detection methods. Alcohol oxidase (AOx) immobilised on an Ag@SiO2 core-shell has been developed as a colorimetric biosensor for ethanol detection. The biocomposite features a silver core coated with amine-modified silica (Ag@SiO₂) and is cross-linked with AOx to serve as a colorimetric probe for ethanol detection. Ethanol detection is based on the redox reaction of Ag with hydrogen peroxide generated from the oxidation of ethanol to acetaldehyde by AOx biocatalysts. A linear correlation between the discolouration of the solution was observed following the addition of the AOx/Ag@SiO2 biosensor into the solution at a variation of ethanol concentration. The high specificity of AOx, along with the improved properties of the core-shell composite, results in a biosensor with excellent analytical performance. The biosensor has a linear range of 40-2000 mM, a detection limit of 11.42 μM, and RSDs for repeatability and reproducibility were 2.90 and 3.37%, respectively, under optimum circumstances. Additionally, the biosensor shows outstanding stability and selectivity. Satisfactory recovery values of 97.22-101.67% in both local and industrial beer samples show the biosensor's high performance. The core-shell biocomposite architecture provides more than just physical protection but also allows for controlled mass transfer, selective diffusion of reactive substances, stabilisation of the plasmonic and redox behaviour, and high robustness in complex matrices, hence making it suitable for the simple, reliable, and selective determination of ethanol.