Penicillin Sensors Based on an Ion-Sensitive Field Effect Transistor Coated with Stearic Acid Langmuir-Blodgett Membrane

Abstract

The gate surface of an ion-sensitive field effect transistor (ISFET) was covered with a penicillinase-adsorbed Langmuir-Blodgett (LB) membrane in order to examine the potentiometric response to H+ ion and penicillin G. The LB membrane-modified ISFET exhibited pH response of -30--40mV/pH, whereas near-Nernstian response was obserbed for the ISFET without LB membrane. The ISFET penicillin sensor showed the potentiometric response to penicillin G at milimolar level in 5mM phosphate buffer. The penicillin sensor could be used to determine penicillin G for more than 12 days without any deterioration.