Biosensors Applications on Assessment of Reactive Oxygen Species and Antioxidants

Abstract

The importance of the subject dealing with oxidative stress and antioxidants protection against oxidative stress was increasing in the last three decades, a proof of this assertion being the huge number of publications appeared since 2000 (meaning 150582 publications) devoted, for example, to antioxidant. Addressing such a topic like Reactive Oxygen Species (ROS) and/or antioxidants (Aox) assessment it has to be clearly described the mean of both these terms and, concomitantly, the close inter-dependence between their actions and, respectively, effects. To support the assertion we would like to mention the fact that two of the four recommended steps in protocol for antioxidant assessment (Becker et al., 2004) are that regarding the evaluation of compound activity as inhibitor of lipid peroxidation in biological model systems and the study of the compound efficiency against relevant oxidative markers, these providing the evidence of strict correlation between ROS toxicity and antioxidant efficacy. As consequence, in this point it could be found the main reason in the attempt to develop flexible (versatile) bio-analytical tools applicable both in ROS toxicity assessment and antioxidant analysis, such are the sensors/biosensors. Reactive oxygen species (ROS) toxicity assessment was a subject of highly interest in all types of publications about the oxidative stress because in the last decades was proven an increasing occurrence of pathologies associated to ROS presence (Dalle-Donne et al. 2006, Butterfield et al. 2001). The ROS “attack” arises on specific receptors from a cellular component which is the oxidizable substrate, producing as result an oxidized molecular product. Generally, this is the key-event in several diseases evolution like Alzheimer's (Jaeger et al, 2008) cardiovascular diseases (Knopp et al. 2008) and others age-related diseases (Wang et al., 2008). In order to status a common basis of the used terms the beginning of this chapter is devoted to a short description of each of them, with examples, further followed by the biosensors development and application on assessment of ROS, respectively antioxidants. Up to date all reported biosensors employed various approaches, from direct analysis of compounds with characteristics antioxidants, to measuring the antioxidant enzymes activity and detection of free radicals. Most reported biosensors use immobilized enzymes in