Biosensor piezoelectric

Types of biosensors can be named either by the biological components, physical transducing devices, or the measured analytes. Researchers were originally using biological components to define types of biosensors (Table 2). Types of transducers had also been included in the name to identify the physical transducing device, i.e., enzyme electrodes, acoustic-immunosensors, optical biosensors, piezoelectric-immunosensors, and biochips. 

Fig. 3. Detail of enzyme-modified quartz radio crystal used in a piezoelectric biocatalytic biosensor.

M. Minunni, P. Skladal, and M. Mascini, A piezoelectric quartz crystal biosensor for atrazine. Life. Chem. Repts 11, 391-398 (1994). 

J. Horacek and P. Skladal, Improved direct piezoelectric biosensors operating in liquid solution for the competitive label-free immunoassay of 2,4-dichlorophenoxyacetic acid. Anal. Chim. Acta 347, 43-50 (1997). 

H. Muramatsu, E. Tamiya, and I. Karube, Piezoelectric crystal biosensor system for detection of Escherichia coli. Anal. Lett. 22, 2155-2166 (1989). 

R.L. Bunde, EJ. Jarvi, and J.J. Rosentreter, Piezoelectric quartz crystal biosensors. Talanta 46, 1223-1236 (1998). 

Using the same PAbs an optical biosensor system has been developed for 2,4,6-TCP [224]. The principle is the detection of laser-induced fluorescence (LIF) in single microdroplets by a homogeneous quenching fluorescence immunoassay (QFIA). The competitive immunoassay occurs in microdroplets (d=58.4 mm) produced by a piezoelectric generator system. A continuous Ar ion laser (488 nm) excites the fluorescent tracer and its fluorescence is detected by a spectrometer attached to a cooled, charge-coupled device (CCD) camera... 

S. Tombelli, M. Mascini, and A. P. F. Turner, "Improved Procedures for Immobilisation of Oligonucleotides on Gold-coated Piezoelectric Quartz Crystals," Biosensors Bioelectronics 17, 929-936 (2002). 

J.H.T. LUONG and G.G. GUILBAULT, "Analytical applications of piezoelectric crystal biosensors", in "Biosensors Principles and Applications", M. Dekker, Inc., New York, 1991. 

The history of electrochemical sensors began in the thirties of the twentieth century, when the pH-sensitive glass electrode was deployed, but no noteworthy development was carried out till the middle of that century. In 1956, Clark invented his oxygen-sensor based on a Ft electrode in 1959, the first piezoelectric mass-deposition sensor (a quartz crystal microbal-ance) was produced. In the sixties, the first biosensors (Clark and Lyons, 1962) and the first metal oxide semiconductor-based gas sensors (Taguchi, 1962) started to appear. 

Wu, T.Z. (1999) A piezoelectric biosensor as an olfactory receptor for odour detection electronic nose. Biosens. Bioelectron. 14 9-18. 

Ko, H.J., Park, T.H. (2005) Piezoelectric olfactory biosensor ligand specificity and dose-dependence of an olfactory receptor expressed in a heterologous cell system. Biosens. Bioelectron. 20 1327-1332. 

As well as these major application fields, biosensors and analytical techniques should also benefit from the technology. Some examples have already been described. The detection of formaldehyde by a formaldehyde dehydrogenase coated onto a piezoelectric crystal has been performed at the ppm level. Detection of pesticides and organophosphorus compounds at the ppb level has been rendered... 

The simple cases where one enzyme is employed afford a limited scope of potential targets. Usually two or more enzyme reactions are coupled, as exemplified by the development of a piezoelectrically-transduced biocatalytic biosensor that couples two enzyme reactions to detect glucose [492-62-6], C6H120 > (3) (13). In this biosensor a quartz radio crystal is functionalized with the enzyme glucose-6-phosphate dehydrogenase. As shown in Figure 3, a thin film of Prussian blue [14038 43-8], C18N18Fe7, is then coated onto the crystal. 

Heat is the most common product of biological reaction. Heat measurement can avoid the color and turbidity interferences that are the concerns in photometry. Measurements by a calorimeter are cumbersome, but thermistors are simple to use. However, selectivity and drift need to be overcome in biosensor development. Changes in the density and surface properties of the molecules during biological reactions can be detected by the surface acoustic wave propagation or piezoelectric crystal distortion. Both techniques operate over a wide temperature range. Piezoelectric technique provides fast response and stable output. However, mass loading in liquid is a limitation of this method. 

J.M. Abad, F. Pariente, L. Hernandez, H.D. Abruna and E. Lorenzo, Determination of organophosphorus and carbamate pesticides using a piezoelectric biosensor, Anal. Chem., 70 (1998) 2848-2855. 

Photoswitchable antigen/antibody (substrate/ receptor) complexes 1. Reversible immunosensors 2. Patterning of surfaces with biomaterials using antigen/antibody-biomaterial conjugates (Design of biosensor arrays, biochips) 1. Immobilization of systems on electronic transducers (electrodes, piezoelectric crystals, FET) or the assembly of biomaterials on inert supports by non-covalent interactions (eg. glass, polymers)... 

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