N, N-dimethylindoaniline mediated-amperometric detection of L-lactate

It was found that N,N-dimethylindoaniline works as an excellent electron-transfer mediator for lactate oxidase. The second-order rate constant (k(med)) with lactate oxidase in solution was much higher than that of other typical mediators, such as ferrocene and potassium hexacyanoferrate(II). An enzyme electrode using this compound as a mediator showed a larger response current and a higher sensitivity to lactate than a Pt-based H2O2 detecting lactate sensor. This sensor demonstrated a clear independence on the oxygen concentration in a buffer and a quite low interference current by ascorbic acid, etc. A H2O2 detecting sensor was strongly interfered by acetaminophen and uric acid, while a mediator based sensor was slightly influenced by uric acid. This sensor also showed good durability, which retained more than 90% of the initial activity until day 11.