A personal glucose meter-utilized strategy for portable and label-free detection of hydrogen peroxide

Rapid and precise detection of hydrogen peroxide (H₂O₂) holds great significance since it is linked to numerous physiological and inorganic catalytic processes. We herein developed a label-free and washing-free strategy to detect H₂O₂ by employing a hand-held personal glucose meter (PGM) as a signal readout device. By focusing on the fact that the reduced redox mediator ([Fe(CN)₆]^4-) itself is responsible for the final PGM signal, we developed a new PGM-based strategy to detect H₂O₂ by utilizing the target H₂O₂-mediated oxidation of [Fe(CN)₆]^4- to [Fe(CN)₆]^3- in the presence of horseradish peroxidase (HRP) and monitoring the reduced PGM signal in response to the target amount. Based on this straightforward and facile design principle, H₂O₂ was successfully determined down to 3.63 μM with high specificity against various non-target molecules. We further demonstrated that this strategy could be expanded to identify another model target choline by detecting H₂O₂ produced through its oxidation promoted by choline oxidase. Moreover, we verified its practical applicability by reliably determining extracellular H₂O₂ released from the breast cancer cell line, MDA-MB-231. This work could evolve into versatile PGM-based platform technology to identify various non-glucose target molecules by employing their corresponding oxidase enzymes, greatly advancing the portable biosensing technologies.