Etude de différentes méthodes de biofonctionnalisation pour la ...

III. Etudes du film Lan gmuir-Blodgett enzymatique
All of the measurements were carried out in individual mode. A saturated calomel electrode was
used as reference electrode. The drain current and tension were fixed at loo pA and 0.5 V
respectively.
The steady state was obtained within 30s.
In our work, we determined the inhibition degree of enzyme by comparing the activity of ENFETs
before and after the inhibition.
Vg
SCE
ODA
enzyme
Isolate (Si02 +Sj
Metal
Electrolyte
LB enzymatic
me m b ra n e
I(ÛTIIÌTÍIAÏ
OTS
Canal "
Source
Substrate Silicium
////7///
VD
Figure 1. Schematic illustration of the BuChE-FET coated with an
enzymatic LB fl/rn.
3. Results and discussion
3. 1. Surface pressure-area (r -A) isotherm characteristics of the Lan gmuir mono/ayers
-A isotherms for the stearylamine monolayer and mixed BuChE/stearylamine monolayer are
shown in Fig 2. Since the enzyme BuChE is generally negatively charged and amine is positively
charged at the subphase pH =5.5.[20][21], BuChE molecules are adsorbed and permeated into the
stearylamine monolayer through this electrostatic force. After 3 hours of equilibration, the surface
pressure kept constant and equal to 26 mN m1, then the monolayer compression was carried out.
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