BSA enzymatic membrane: a mixture of 5 mg BSA, 5
mg BuChE, 10 ml of glycerol in 90 ml of phosphate buffer
Ž . 1 mM, pH 8.0 was prepared. Then glycerol was used as a
plasticizer to avoid the formation of cracks in the enzymatic
membrane during storage and also to result in a
better homogeneity of the membrane and better adhesion
to the surface of the transducer. 0.5 ml of this mixture was
deposited on the sensitive area of a FET. Then the sensor
chips were placed in a saturated glutaraldehyde vapor for
30 min.
PVArSbQ enzymatic membrane: a mixture of 45 mg
PVArSbQ, 5 mg BuChE in 50 mg phosphate buffer 1Ž
mM, pH 8.0 was prepared. 0.5 . ml of this mixture was
deposited on the sensitive area of a FET. Then, the sensor
chips were exposed under UV light for 25 min.
The REFET was the reference ISFET working in the
differential measurement mode. The membrane of the
REFET used with BSA-ENFET was a mixture of 10 mg of
BSA, 10 ml of glycerol in 90 ml of phosphate buffer 1Ž
mM, pH 8.0 . 0.5 . ml of this mixture was deposited on the
insulator surface of the REFET. Then the sensor chips
were placed in a saturated glutaraldehyde vapor for 30
min. The REFET used for the PVArSbQ-ENFET was
prepared by depositing 0.5 ml of a mixture of 50 mg of
PVArSbQ and 50 mg of phosphate buffer 1 mM, pH 8.0 Ž .
on the insulator surface of the REFET and then exposed
under UV light for 25 min.