Analytical Sciences

Enzyme-based Field-Effect Transistor for Adenosine Triphosphate (ATP) Sensing

Satoshi MIGITA,* Kazunari OZASA,** Tomoya TANAKA,* and Tetsuya HARUYAMA*

*Department of Biological Functions and Engineering, Kyushu Institute of Technology, Kitakyushu Science and Research Park, Fukuoka 808-0196, Japan
**RIKEN (The Institute of Physical and Chemical Research), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan

Adenosine triphosphate (ATP) not only functions as an energy-carrier substance and an informative molecule, but also acts as a marker substance in studies of both bio-traces and cellular/tissular viability. Due to the importance of the ATP function for living organisms, in situ assays of ATP are in demand in various fields, e.g., hygiene. In the present study, we developed an ATP sensor that combines the selective catalytic activity of enzyme and the properties of an ion selective field effect transistor (ISFET). In this system, the ATP hydrolyrase, “apyrase (EC 3.6.1.5.)” is encased in a gel and mounted on a Ta₂O₅ ISFET gate surface. When the enzyme layer selectively catalyzes the dephosphorylation of ATP, protons are accumulated at the gate because the enzymatic reaction produces H⁺ as a byproduct. Based on the interfacial enzymatic reaction, the response from the ISFET is completely dependent upon the ATP concentration in the bulk solution. This device is readily applicable to practical in situ ATP measurement, e.g. hygienic usage.

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