A wearable origami-like paper-based electrochemical biosensor for sulfur mustard detection

The synthesis and employment of volatile toxic compounds as chemical weapons with a large-scale destructive power has introduced a new insidious threat over the last century. In this framework, the development of wearable sensing tools represents a critical point within the security field, in order to provide early alarm systems. Herein, a novel wearable electrochemical biosensor was developed for the rapid and on-site detection of mustard agents. Since a chemical attack is typically carried out by spraying these volatile agents into air, the sensor was designed in order to be able to measure mustard agents directly in the aerosol phase, further than in the liquid phase. The electrodes were screen-printed onto a filter paper support, which allowed to harness the porosity of paper to pre-load all the needed reagents into the cellulose network, and hence to realise an origami-like and reagent-free device. Mustard agent detection was carried out by monitoring their inhibitory effects toward the choline oxidase enzyme, through the amperometric measurement of the enzymatic by-product hydrogen peroxide. A carbon black/Prussian blue nanocomposite was used as a bulk-modifier of the conductive graphite ink constituting the working electrode, allowing for the electrocatalysis of the hydrogen peroxide reduction. After having verified the detecting capability toward a mustard agent simulant, the applicability of the resulting origami-like biosensor was demonstrated for the rapid and real-time detection of real sulfur mustard, obtaining limits of detection equal to 1 mM and 0.019 g·min/m³ for liquid and aerosol phase, respectively.