4.2 Chemical Sensors Using Biological Cells, Molecules, and Methods

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Figure 4.6: An odorant-binding protein peptide from Drosophila is deposited onto a quartz crystal mi-

crobalance to create a sensor for rotting meat smells (adapted from [20]). (a) Set-up of the biosensor;

(b) signal of the sensor with alcohol present.

in baseline, this calculation makes different sensors comparable and reproducible as

well. Each of the different GPCR sensors reacts differently to different chemicals, each

in a concentration-dependent manner. Therefore, this sensor could in the future be com-

bined with combinatorial identification capabilities, chemicals could thereby be identi-

fied out of mixtures.

That is already being attempted in the following example: The recognition element

in that sensor is the sweet receptor binding domain, stabilized by a membrane that is

immobilized on a gold electrode [22]. The transducer is a carbon nanotube field effect

transistor. Binding of different sugars to the receptor domain changes the transistor cur-

rent output, which can be analyzed. This sensor was independently verified by fluores-

cence quenching as well. This sensor was able to measure “sweet” in solution mixtures