Amperometric Biosensors for Lactate, Alcohols, and Glycerol Assays in Clinical Diagnostics

Biosensors are bioanalytical devices which transform a biorecognition response into a measurable physical signal. Although biosensors are a novel achievement of bioanalytical chemistry, they are not only a subject of intensive research, but also a real commercial product (Kissinger, 2005). The estimated world analytical market is about $20 billion per year of which 30 % is in the healthcare field. The biosensors market is expected to grow from $6.72 billion in 2009 to $14.42 billion in 2016 (http://www.marketresearch.com, Analytical Review of World Biosensors Market). Although up to now IUPAC has not accepted an official definition of the term biosensor, its electrochemical representative is defined as “a self-contained integrated device, which is capable of providing specifc 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’’ (Thevenot et al., 2001). Generally, the biosensor is a hybrid device containing two functional parts: a bioelement (an immobilized biologically active material) and a physical transducer. As bioelements pieces of tissue, microbial cells, organelles, natural biomembranes or liposomes, receptors, enzymes, antibodies and antigens, abzymes, nucleic acids and other biomolecules and even biomimetics which imitate structural and functional features of the natural analogue can be used. The bioelement is a recognition unit providing selective binding or biochemical/metabolic conversion of the analyte that result in changes in physical or physico-chemical characteristics of the transducer (Scheller et al., 1991; Schmidt & Karube, 1998; Gonchar et al., 2002; Nakamura & Karube, 2003; Sharma et al., 2003; Investigations on Sensor Systems and Technologies, 2006). The bioelement in such constructions is usually prepared in immobilized form and often covered with an outer membrane (or placed between two membranes in a sandwich manner), which either prevents the penetration of