Environmentally Sustainable, Noble-Metal-free Enzyme Sensors Capable of Functioning in the Presence of Ascorbic Acid

We propose Prussian blue (PB) dispersed in graphene-coated porous silica spheres (G/PSS), referred to as PB/G/PSS, as an innovative and environmentally sustainable working electrode for a small enzyme sensor targeting H 2 O 2 detection. For devices that use conventional platinum electrodes, overlapping oxygen reduction and ascorbic acid oxidation reactions interfere with the H 2 O 2 measurements. As a result, ascorbic acid must be physically removed beforehand, and H 2 O 2 is typically measured by its oxidation current at +0.6 V vs. Ag/AgCl. In contrast, the PB/G/PSS electrode offers a distinct potential window (−0.1 to −0.05 V), free from these side reactions, enabling precise H 2 O 2 detection via reduction current, even in the presence of dissolved oxygen and ascorbic acid. Applying the PB/G/PSS construct in a device, we showed reliable glucose detection through enzyme-mediated reactions in a compact device. We further refined the design for glucose-sensing applications in biological solutions, targeting future applications in blood-based detection. Additionally, leveraging the dual functionality of PB/G/PSS as both a working and reference electrode, we successfully demonstrated a fully functional enzyme sensor with noble-free electrodes that leverage a streamlined and integrated architecture. This work highlights the versatility and potential of PB/G/PSS electrodes in advancing next-generation biosensor technologies.