Biosensors are defined as analytical devices that composed of a biological recognition element, named as bioreceptor, coupled to a chemical or physical transducer. Free radicals are highly reactive molecules generated during cellular metabolism. However, their overproduction results in oxidative stress, a deleterious process that can damage cell structures, including lipids and membranes, proteins and DNA. Antioxidants respond to this problem, scavenging free radicals.