In vitro physiological performance factors of a catalase-based biosensor for real-time electrochemical detection of brain hydrogen peroxide in freely-moving animals

Abstract

Physiological performance factors of a catalase-based paired microelectrochemical biosensor, developed for real-time neurochemical monitoring of hydrogen peroxide (H₂O₂), were determined in the in vitro environment. The excellent ascorbic acid (AA) rejection characteristics and high sensitivity of the paired H₂O₂ sensor were assessed and verified. The highly suitable response time of the H₂O₂ sensor was demonstrated and the limit of detection of this sensor was calculated as ca. 0.075 μM. The H₂O₂ sensor was selective over the electroactive substance Mercaptosuccinate which is used in vivo to disrupt the enzymatic degradation of brain H₂O₂. The H₂O₂ sensing element of this paired design was impervious to an acidic/basic shift in environmental pH (6.5/8.0) relative to physiological levels (7.4). The influence of a temperature transition (ca. 23 °C to 37 °C) and a physiological temperature fluctuation expected to be found in vivo (1–4 °C), on the response of the paired H₂O₂ sensor was deemed negligible and consistent with other amperometric methods. The enzymatic component of the paired H₂O₂ sensor was found to be stable over a 14 day period of continuous ex vivo brain tissue exposure.