In the case of the creatinine sensor, one or all of the enzymes in the cascade for creatinine sensing (sarcosine oxidase, creatininase and creatinase) are strongly inhibited by paraformaldehyde (Figure ). To address this, we substituted paraformaldehyde with ethanol as the reducing agent for AOx. The ethanol based O2-scavenging systems suppressed oxygen reduction currents while adding the creatinine generated the expected catalytic wave for analyte oxidation catalyzed by the three-enzyme cascade (Figure ). This validates the absence of cross-reactions between the ethanol based AOx scavenger and the enzymes for creatinine detection (sarcosine oxidase, creatinase and creatininase), making it suitable for O2 removal in creatinine sensing.