Biosensors research/development

Enzyme sensors are based primarily on the immobilization of an enzyme onto an electrode, either a metallic electrode used in amperometry (e.g., detection of the enzyme-catalyzed oxidation of glucose) or an ISE employed in potentiometry (e.g., detection of the enzyme-catalyzed liberation of hydronium or ammonium ions). The first potentiometric enzyme electrode, which appeared in 1969 due to Guilbault and Montalvo [140], was a probe for urea with immobilized urease on a glass electrode. Hill and co-workers [141] described in 1986 the second-generation biosensor using ferrocene as a mediator. This device was later marketed as the glucose pen . The development of enzyme-based sensors for the detection of glucose in blood represents a major area of biosensor research. 

M.I.P. and S.A. thank the PhD students and E Zacco for her valuable work on biosensor research and development involving composite materials. M.-P Marco is also acknowledged for her collaboration. M.I.P. also acknowledges the support of Universidad National del Litoral (Argentina). 

Before dealing with the central topic, I would like to raise some further issues pertinent to it, and indeed to the development of thick-film sensors in general. Thick-film sensors are an important part of biosensor research because some blood glucose sensors for use in the home are made this way—if these are successful surely others can be Further, thick-film technology is not expensive and allows research laboratories to produce quickly, reasonably uniform devices in sufficient numbers for well replicated experiments. At the same time, some insight can be gained into the nature and demands of an industrial production process. 

The biosensor research areas including modern biospeciflc analytical techniques are developing very rapidly and it is fair to say that analytical chemistry plays a very important role in these developments. New challenges lie ahead with new discoveries and tools opening up novel dimensions in both fundamental research and in possible applications. However, as in many other areas in analytical chemistry for major breakthroughs, we rely on developments in other areas that have contributed and will contribute to new research directions as well as successful improvements in already existing areas. 

Because of the volume of the literature regarding amperometric biosensors as well as space limitations it is not possible to cite any substantial contribution to the field. We selected - to the best of our knowledge - representative work that can be of use not only for beginners but also for advanced researchers in the field as a basis for discussion. Examples of success stories accomplished in biosensor research are given as case studies in Section 1.4. General milestones and achievements relevant to biosensor research and development are listed in Table 1.2. The final conclusions are given in Section 1.5. 

Milestones and Achievements Relevant to Biosensor Research and Development... 

Biosensors have been studied extensively during the last fifty years. Hence, a number of milestones mark the progress made in biosensor research. Table 1.2 summarizes the main scientific milestones that are relevant to biosensor discovery and further development of this technology. 

Table 1.2 Milestones and achievements relevant to biosensor research and development.

In this chapter, the role of electrochemical and magnetic biosensors towards development of portable, compact and inexpensive biochip devices has been demonstrated. Direct measurement of electrochemical signals, such as ferrocene molecule, is a preferred approach to simplify the process towards miniaturized biochip devices. Furthermore, the use of magnetic probes promises to increase the sensitivity. Future research may be in the direction of developing new probes, e.g. nanomaterials for differing bio-applications. 

Electrochemical sensors have been used as the basis or as an integral part of many chemical and biosensor developments. The introduction of microelectrode assembly added a new dimension to electrochemical sensors, and, consequently, to chemical and biosensor research. In recent years, the advancement of microelectronic fabrication technology has provided new impetus to the development of micro or miniature electrochemical sensors. 

One of the fields of chemical application of alkaloids is the development of biosensDrs. Alkaloids and their regulatory function of enzymes, metabolism, and CNS are suitable molecules for the sensory investigation and biosensor research and development area. Moreover, a molecular modification of alkaloids is a large area in the chemical application of alkaloids. Synthetic alkaloids and transformation of natural or semi-natural and S5mthetic molecules are also chemical applications. A good example is natural alkaloid piperidine, which presently is also S5mthetically produced by different methods of sjmthesis. ... 

Miniaturization is intensively studied in present biosensor research [218] aiming at the development of total microelectro-chemical systems for local detection, multisensor arrays, implantable or portable devices. Not only the relevance of the items but also the electrochemical properties of microelectrodes that often make them superior to macroelectrodes allows miniaturization to become a necessity [219] see also Chapter 2.5 in this volume. 

Whilst in the biosensor research laboratory these benefits can be exploited to the full, problems arise in developing sensors incorporating microorganisms that can be produced commercially. Central to this is the need to develop methods of handling microorganisms during fabrication and bulk production of biosensors. In particular, further development is required for ... 

Turner APF (1989) Current trends in biosensor research and development. Sensors Actuat 17 (3 ) 433 50... 

Table 2.1 Approximate state of biosensor research [(x) fundamental research, (xx) research and development of prototypes, (xxx) research and commercial devices. ...

Japan dominates the present worldwide effort in biosensor research and development (R D The Japanese market in biosensor products is currently estimated at 1.5 million yen. About a hundred different firms from a variety of fields consider biosensors to be an important research direction (for example, Toyo Jozo, Fuji Electric, Toyobo, and Denki) or form collaborations for better development (for example, Daikin of Sumitomo and NEC). In Germany, 15 million D.marks were placed for financing biosensor research and development between 1988 and 1991. Other European countries (Great Britain, France, Italy and Spain) also participate actively in research in this field. 

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