Mass spectrometry and biosensing research
by Wilkins, Charles L.
At the outset of the WTEC study on biosensing research and development, it was recognized that mass spectrometry is playing an increasingly important role in the field of biosensing research. As noted during the WTEC December 2002 Workshop on Biosensing Research and Development in the United States (wtec.org/biosensing/proceedings/), historically a certain degree of ambiguity has existed with respect to the terms "biosensing" and "biosensor. " For example, as Turner notes (1996), the term biosensor ". has been used to describe a thermometer, a mass spectrometer, daphnia in pond water, electrophysiology equipment, chemical labels for imaging, and ion-selective electrodes. " However, he concludes that, as defined in an earlier work, ". a biosensor [is] defined as a compact analytical device incorporating a biological or biologicallyderived sensing element either integrated within or intimately associated with a physicochemical transducer. The usual aim of a biosensor is to produce either discrete or continuous digital electronic signals which are proportional to a single analyte or a related group of analytes" (Turner, Karube, and Wilson 1987). Within this context, a mass spectrometer clearly qualifies as a biosensor. On the other hand, when one considers the desirable characteristics of a biosensor (specificity, sensitivity, stability, wide applicability, low cost, and portability), there are a number of respects where generally available mass spectrometry technology falls short, most notably in the areas of low cost and portability. For biosensor applications, present laboratory-based mass spectrometry provides superior performance. There are also a number of options available for so-called "field-portable" applications. Finally, and perhaps of most interest, there is considerable research directed toward the long-range goal of achieving truly portable (or perhaps personal) mass spectrometers. The WTEC panel's charge with respect to reviewing relevant recent advances in mass spectrometry are focused on the degree to which they broaden the potential for biosensor applications of the field. In addition to addressing this issue, this chapter identifies some of the factors that currently limit biosensor applications of mass spectrometry and considers the prospects for addressing these limitations. Finally, as charged by the panel's sponsors, the chapter summarizes and compares the current status of mass spectrometry research and development in Europe, Japan, and the United States.