Amperometric sensing — Bioelectroanalysis

Abstract

It seems quite timely that Analytical and Bioanalytical Chemistry (ABC) is devoting a special issue to sensing. Less obvious is that the issue is limited to electrochemical sensing, even less so to amperometric sensing, bioelectrosensing included. Actually, electroanalysis is not the most widely applied analytical technique. Optical methods definitely overwhelm the electrochemical ones in popularity; once mass spectrometry, chromatography, and the relevant hyphenated techniques, are taken into account together with the optical ones, only a restricted room is seemingly left to electrochemical methods of analysis. However, especially in the field of biosensors, this general description does not alway hold and electroanalytical techniques are presently dominating successful commercial applications of biosensors. A big change in electroanalysis has occurred in the last 30 years, caused by the invention of modified electrodes. The modification of electrode surfaces has also led to improved anchoring of highly specific biological recognition elements, allowing unprecedented performance in electrocatalytic biosensing. Electrode systems have attained increasing complexity and a large variety of electrode modifiers have been proposed, such as synthetic and natural macromolecules, different types of nanoparticles and conducting polymers or clays. Among the novel materials developed in the last 20 years, only a limited number have been tested and used in an electrochemical context, and an even much lower number have been considered for electroanalysis. This encourages analytical chemists to closely follow developments in the field of material chemistry, basic studies in electrochemistry and electrochemical applications to potentially transfer this knowledge to effective electroanalytical systems. Concomitantly with the development of novel electrode materials, optimization of the overall system structure has become more complex, requiring its characterization using a large number of spectroscopic, microscopic and electrochemical techniques. Consequently, interdisciplinarity has become a must for the effective development of novel modified electrodes for electroanalysis. Only combinations of analytical techniques provide sufficient insight into the in-depth functioning of modified electrodes for electroanalysis and the interplay between the different components ultimately composing the complex electrode architecture. Complete knowledge, in the widest sense, is necessary to achieve the best performance of an envisaged sensor as a whole. A lot of time has passed since the years in which ‘bare’ electrodes were used in molecular electrochemistry studies, which were subsequently transferred to electroanalysis. More or less complex electrode mechanisms were studied only by electrochemical techniques that allowed the electrode mechanism to be fully elucidated from a qualitative and even quantitative point of view. Such a ‘simple’, though rigorous approach is not possible with more complex modified electrode systems any more, owing to the enormous variety of possible structures, depending on a number of possible compositions and the conditions under which the system has been realized. A danger lies in the tendency to separate the field into two ‘different kinds’ of scientists doing electroanalysis: those strictly following an ‘it works!’ approach describing often useful effects which cannot be given an in-depth account, owing to the too great complexity of the system, Published in the topical collections Amperometric Sensing with guest editors Renato Seeber, Fabio Terzi, and Chiara Zanardi and Bioelectroanalysis with guest editors Nicolas Plumere, Magdalena Gebala, and Wolfgang Schuhmann. R. Seeber (*) : F. Terzi :C. Zanardi Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, Via G. Campi, 183, 41100 Modena, Italy e-mail: renato.seeber@unimore.it