A NEW ANION-SENSITIVE BIOSENSOR USING AN ION-SENSITIVE FIELD-EFFECT TRANSISTOR AND A LIGHT-DRIVEN CHLORIDE PUMP, HALORHODOPSIN

A new biosensor sensitive to chloride anion using a light-driven chlor ide pump protein, halorhodopsin (hR), and an ion-sensitive field effec t transistor (ISFET) has been developed. Membrane vesicles of halophil ic bacteria containing hR were immobilized in the matrix of polyvinylb utyral resin on the surface of the ISFET. The gate voltage of this dev ice changed in the min time scale under yellow light illumination. The response for chloride anion increased according to the increase of ch loride anion concentration in the bulk aqueous phase. In the dark, the gate potential did not change even in the presence of chloride anion. These chloride-dependent gate potential changes of the hR-ISFET indic ate that the chloride pumping by hR is active on the ISFET and that IS FET detects the light-dependent chloride transport by hR.