Electrochemical biosensors: recommended definitions and classification

Two Divisions of the International Union of Pure and Applied Chemistry (IUP AC). namely Physical Chemistry (Commission 1.7 on Biophysical Chemistry for merly Steering Committee on Biophysical Chemistry) and Analytical Chemistry (Commission V.5 on Electroanalytical Chemistry) have prepared recommendati ons on the definition, classification and nomenclature related to electroch emical biosensors: these recommendations could, in the future, be extended to other types of biosensors. An electrochemical biosensor is a self-contai ned integrated device, which is capable of providing specific quantitative or semi-quantitative analytical information using a biological recognition element (biochemical receptor) which is retained in direct spatial contact with an electrochemical transduction element. Because of their ability to b e repeatedly calibrated, we recommend that a biosensor should be clearly di stinguished from a bioanalytical system, which requires additional processi ng steps. such as reagent addition. A device that is both disposable after one measurement, i.e. single use, and unable to monitor the analyte concent ration continuously or after rapid and reproducible regeneration. should be designated a single use biosensor. Biosensors may be classified according to the biological specificity-conferring mechanism or, alternatively, to th e mode of physico-chemical signal transduction. The biological recognition element may be based on a chemical reaction catalysed by, or on an equilibr ium reaction with macromolecules that have been isolated, engineered or pre sent in their original biological environment. In the latter cases, equilib rium is generally reached and there is no further, if any, net consumption of analyte(s) by the immobilized biocomplexing agent incorporated into the sensor. Biosensors may be further classified according to the analytes or r eactions that they monitor: direct monitoring of analyte concentration or o f reactions producing or consuming such analytes; alternatively, an indirec t monitoring of inhibitor or activator of the biological recognition elemen t (biochemical receptor) may be achieved. A rapid proliferation of biosenso rs and their diversity has led to a lack of rigour in defining their perfor mance criteria. Although each biosensor can only truly be evaluated for a p articular application, it is still useful to examine how standard protocols for performance criteria may be defined in accordance with standard IUPAC protocols or definitions. These criteria are recommended for authors. refer ees and educators and include calibration characteristics (sensitivity, ope rational and linear concentration range, detection and quantitative determi nation limits), selectivity, steady-state and transient response times, sam ple throughput, reproducibility. stability and lifetime. (C) 2001 Elsevier Science B.V. All rights reserved.