In-situ monitoring of H2O2 degradation by live cells using voltammetric detection in a lab-on-valve system

Abstract

This paper describes a method for monitoring the degradation of hydrogen peroxide by cells immobilized on a beaded support. The detection is based on the voltammetric reduction of hydrogen peroxide on a mercury film working electrode, whilst combining the concept of sequential injection (SI) with the lab-on-valve (LOV) manifold allows the measurements to be carried out in real time and automatically, in well-defined conditions. The method is shown to be capable of simultaneously monitoring hydrogen peroxide in the 10–1000 µM range and oxygen in the 160–616 µM range. A correction algorithm has been used to ensure reliable H₂O₂ results in the presence of varying oxygen levels. The method has been successfully applied to monitoring the degradation of H₂O₂ by wild-type cells and by catalase-overexpressing mouse embryonic fibroblasts. Since the technique allows the monitoring of the initial response rate, it provides data not accessible by current methods that are end-point-based measurements.