Biomedical Engineering Reference
In-Depth Information
3.3.2
In-Vivo Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . .
21
3.3.3
Bedside Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . .
23
3.3.4
Multianalyte Determination . . . . . . . . . . . . . . . . . . . . . .
23
3.3.5
Hybrid Sensors; Enzyme Substrate Recycling . . . . . . . . . . . .
23
3.4
Other Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.4.1
Enzyme-Activity Measurement . . . . . . . . . . . . . . . . . . . .
24
3.4.2
Food . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
24
3.4.3
Environmental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
25
3.4.4
Fluoride Sensing . . . . . . . . . . . . . . . . . . . . . . . . . . . .
26
3.4.5
Cellular Metabolism . . . . . . . . . . . . . . . . . . . . . . . . . .
26
3.5
Miscellaneous Applications . . . . . . . . . . . . . . . . . . . . . .
27
4
Future Developments . . . . . . . . . . . . . . . . . . . . . . . . . . 28
4.1
Telemedicine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
28
4.2
Home Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.3
Other Developments . . . . . . . . . . . . . . . . . . . . . . . . . .
29
5
Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
1
Introduction
1.1
Fundamentals of Calorimetric Devices
Life is made up of lifeless molecules, but when the molecules react with each
other there is an exchange of several forms of energy. One well-known form of
energy is heat. The merits of measuring heat (calorimetry) were identified
several decades ago. Almost all effects, either physical, chemical or biological
involve exchange of heat. Specifically, biological reactions involving enzyme
catalysis are associated with rather large enthalpy changes. Based on the nature
of the catalytic reaction, either a single enzyme or a combination of enzymes
can be employed for generating a detectable thermal signal.
In earlier investigations a wider application of calorimetry, especially in
routine analysis, was limited due to the need for sophisticated instrumentation,
the relatively slow response and the high costs [1]. Several simple calorimetric
devices based on immobilized enzymes were introduced in the early 1970s that
combined the general detection principle of calorimetry with enzyme catalysis
[2]. The advantages of these instruments were reusability of the biocatalyst, the
possibility of continuous flow operation, inertness to optical and electrochemi-
cal interference, and simple operating procedures. Several of these concepts,
developed in the following years, culminated in the development of the enzyme
thermistor (ET) designed in our laboratory. The technique drew immediate
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