Semiconductor enzyme sensors

Particularly attractive for numerous bioanalytical applications are colloidal metal (e.g., gold) and semiconductor quantum dot nanoparticles. The conductivity and catalytic properties of such systems have been employed for developing electrochemical gas sensors, electrochemical sensors based on molecular- or polymer-functionalized nanoparticle sensing interfaces, and for the construction of different biosensors including enzyme-based electrodes, immunosensors, and DNA sensors. Advances in the application of molecular and biomolecular functionalized metal, semiconductor, and magnetic particles for electroanalytical and bio-electroanalytical applications have been reviewed by Katz et al. [142]. 

Thermistor basedflow-through calorimetric sensors. Enzyme thermistors make the most widely developed type of heat measurement-based sensors. The thermistors are normally used as temperature transducers in these devices. Thermistors are resistors with a very high negative temperature coefficient of resistance. They are ceramic semiconductors made by sintering mixtures of metal (manganese, nickel, cobalt, copper, iron) oxides. Like the two previous groups, thermistor sensors do not comply strictly with the definition of "sensor" as they do not consist of transducers surrounded by an immobilized enzyme rather, they use a thermistor at the end of a small... 

Miyahara, Y. Matsu, F. Moriizumi, T. Matsuoka, H. Karube, I. Suzuki, S. Micro enzyme sensors using semiconductor and enzyme-immobilization techniques. Anal. Chem. Symp. Ser. 1983, 17, 501-506. 

Miyahara et al. (1985) developed an integrated enzyme FET based on a silicon-on-sapphire (SOS) sensor for simultaneous determination of glucose and urea. Three ISFETs and two metal insulator semiconductor FETs (MISFETs) were integrated on a surface area of 2.5 mm x 2.5 mm (Fig. 54). One of the ISFETs served as reference sensor in order to compensate the signals caused by pH changes of the solution the two others were covered by GOD and urease, respectively. The MISFETs can be used as pH electrodes. For enzyme immobilization the chip was covered with a laminated photosensitive layer of 75 pm thickness and,... 

Materials research has been influencing the direction and diversity of sensor research. Novel semiconductor and superconductor materials have led to new and more efficient transducers. Advances in biotechnology have also resulted in a broader range of enzymes and monoclonal antibodies for use in biosensors. Examples for utilizing tissue and microbes in biosensors include the use of tomatoes, eggplant, grapes, horseradish, parsley, and Antarctic krill in electrochemical biosensors. The logic is that the active component (usually an enzyme) is protected by... 

En me sensors involving semiconductors are called enzyme field-effect transistors, ENFET, and, as their name implies, exploit the association of an en me with a field-effect transistor (Fl. The transistor has a metal oxide semiconductor field-effect transistor (MOSFET) structure, which is constructed from, for example, a p-type silicon substrate (Figure 4.30). This central channel is defined by placing two n-type semiconducting zones, called the source and the drain, on opposite sides of the substrate. A metallic gate is isolated from the channel by a thin insulating film (Si02), which also covers the upper face of the substrate. 

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