Amperometric biosensors introduction

Biosensors for the determination of blood glucose have enjoyed widespread commercial success since the introduction of the pen-sized 30 s blood glucose meter [10]. However, researchers have continued to devise novel approaches in the development of amperometric biosensors based on screen-printing technology Table 23.1 summarises some examples of these approaches together with their performance characteristics. 

The number of publications, however, does not address the level of quality of the presented research. What, in fact, represents the outcome of all these publications. What represents the resulting scientific advancement This may not be so easy to answer as it as first seems. Thus, we will first give a general introduction to amperometric biosensors in the rest of this section, before we address the quality issue of biosensor research in Sections 1.2 and 1.3 and before we present some of the success stories of biosensor research (Section 1.4) in order to address the questions mentioned at the beginning of this paragraph. 

This enzyme-based biosensor uses glucose oxidase (GO) as a chemical recognition element, and an amperometric graphite foil electrode as the transducer. It differs from the first reported glucose biosensor discussed in the introduction to this chapter in that a mediator, 1,1 -dimethylferricinium, replaces molecular oxygen as the oxidant that regenerates active enzyme. The enzymatic reaction is given in Eq. 7.15, and the electrochemical reaction that provides the measured current is shown in Eq. 7.16. 

Abstract Brief historic introduction precedes presentation of main types of transducers used in sensors including electrochemical, optical, mass sensitive, and thermal devices. Review of chemical sensors includes various types of gas sensitive devices, potentiometric and amperometric sensors, and quartz microbalance applications. Mechanisms of biorecognition employed in biosensors are reviewed with the method of immobilization used. Some examples of biomimetic sensors are also presented. 

Increased selectivity and prevention of passivation of the BDD surface may be also achieved by its modification. An enzyme-based amperometric sensor was proposed for detection of phenolic compounds by Notsu et al. BDD was anod-ically polarized for the introduction of hydroxyl groups onto its surface, then treated with (3-aminopropyl)triethoxysilane (APTES), and finally coated with a tyrosinase film cross-linked with glutaraldehyde. Tyrosinase catalyzes oxidadmi of phenol and various phenol derivatives to o-benzoquinone derivatives via catechol derivatives and thus the quinones generated are ready to be reduced electrochemically at an appropriate potential and obtained reduction currents serve as good analytical signals for the determination of the phenol derivatives. Bisphenol A and 17-/ -estradiol were detected at —0.3 V vs. Ag/AgCl with the detection limit of 1 pmol in FIA. However, the biosensor retained its activity only for a few days due to weak bonding of APTES to BDD surface. 

---