Paper-based electroanalytical strip for user-friendly blood glutathione detection

Paper-based devices are always more gaining a relevant position in the field of sensors. The continuous demandfor affordable, simple, sustainable, and portable devices, is making paper as the ideal basis towards the reali-zation of analytical tools for the easy self-testing. In this work, we demonstrate, for the first time, the devel-opment of a disposable paper-based printed electroanalytical strip for reliable, rapid, and high-throughput de-tection of glutathione in blood. The detection is based on the thiol-disulfide exchange reaction, which produces adetectable compound easily oxidizable at a Prussian Blue/carbon black nanocomposite involving a favorablelow-interference overpotential. This nanocomposite is mixed within a carbon-based conductive ink and suc-cessively screen-printed onto a wax-patterned filter paper. The employment of paper provides a reagent-freedevice, as a consequence of the reagents pre-loading within the testing area. After the experimental conditionshave been optimized, glutathione has been detected up to 10 mM, with a detection limit of 60 μM, and a sen-sitivity of (0.102 ± 0.005) μA/mM. This sensor showed satisfactory repeatability (relative standard deviationequal to 10%, for detection of glutathione 1 mM), especially by considering the hand-made manufacturingprocess. The “real-world” applicability of this strip has been evaluated by quantifying blood glutathione atphysiological levels and by recovery studies achieving satisfactory value.