Ascorbate oxidase enabling glucometer readout for portable detection of hydrogen peroxide

A rapid, portable, and cost-effective method using personal glucose meter (PGM) for quantitative analysis of hydrogen peroxide (H₂O₂) was established based on ascorbate oxidase (AAO)-catalyzed reaction for the first time. Ascorbic acid (AA) can rapidly reduce ferricyanide (K₃[Fe(CN)₆]) to ferrocyanide (K₄[Fe(CN)₆]) in the glucose test strip and transfer electron to the electrode to generating a PGM detectable signal. Thus, the concentration of AA can be directly determined by the PGM as simple as measuring the blood glucose. On the other hand, AAO can catalyze the reduction of H₂O₂ and produce an enzyme-peroxide complex, which decreases the yields of dehydroascorbic acid formed by the oxidation of AA, resulting in the increase in PGM detectable signal of residual ascorbic acid (re-AA). Therefore, the concentration of H₂O₂ is proportional to the concentration of re-AA. After optimization of the experimental conditions, the developed method can be used to detect H₂O₂ at linear range of 2.5-5 × 10³ μM with the quantification limit of 2.5 μM. In addition, the satisfactory spiked recoveries (95.3-108.9 %) of real samples (i.e., tap water, contact lens solution, medical hydrogen peroxide, and normal human serum) confirm its feasibility for practical applications. In short, this study provides a feasible PGM-based method for H₂O₂ detection with simple operations.