A Universal Oxygen Scavenger for Oxidase-based Biosensors

Enzyme-based electrochemical biosensors are extensively deployed for point-of-use applications due to their low cost, simplicity, and high selectivity. However, oxygen from ambient air often causes interferences, leading to inaccurate results. Here, we developed a universal enzymatic O2 scavenger composed of alcohol oxidase, catalase, and paraformaldehyde, designed to convert O2 into water within the sensor strip. The O2 scavenging was evaluated for implementation in oxidase-based biosensors. Alcohol oxidase is advantageous as a catalyst for O2 scavenging because it exclusively donates electrons to O₂, thereby preventing interferences with other sensor components. Additionally, paraformaldehyde acts as a solid precursor to formaldehyde, which can be oxidized by alcohol oxidase. This bypasses the need for any volatile compound in the sensor, thus allowing for long-term storage. The O2 scavenger was validated for glucose sensing across a glucose concentration range relevant to diabetes management. In the presence of the O2 scavenger, the sensing accuracy in ambient air was 99% of that achieved under inert gas conditions. In contrast, sensors without the scavenger exhibited readings that were less than 50% of those under inert gas conditions. Implementation in biosensors for lactate and creatinine show that the alcohol oxidase-based O2 scavenger is generally compatible with oxidase-based electrochemical biosensors for point-of-care applications.