Construction
of AG/PyOx/CHIT bi-enzymatic sensor For the construction of the bioactive layer, the graphite electrodes were polished and washed thoroughly with distilled water and sonicated for 2 min [30]. 20 μl of CHIT or CHIT–CNT solutions (1.0%), 10 μl of AG solution (0.6 U) and 10 μl of PyOx solution (9.0 U) were placed on the graphite electrode and allowed to dry at+4 °C for 18 h. Then 20 μl of glutaraldehyde solution (1.0%; in potassium phosphate buffer, pH 7.5, 50 mM) spread evenly onto the CHIT modified graphite electrode and allowed to stand at +4 °C for 30 min [29]. Then, it was
washed with distilled water to remove excess of glutaraldehyde and unbound enzymes. Protein analysis was carried out in washing solu