The sensitivity of acetylcholinesterase (AChE) biosensorsfor insecticide detection could be increased substantiallyby engineering AChE B of
Nippostrongylus brasiliensis.The introduction of 10 single and 4 double mutations intothe AChE peptide chain led to an increase in sensitivityto 10 of the 11 insecticides tested. The combination ofthree mutants with the wild-type enzyme in a multienzymebiosensor array enabled the detection of 11 out of the 14most important organophosphates and carbamates atconcentrations below 10
g/kg, the maximum residuelimit of infant food. The detection limit for pirimiphosmethyl could be reduced from 10
g/L to a value as lowas 1 ng/L (3.5 × 10
-12 mol/L). The newly createdbiosensors exhibited an extraordinary high storage stability. There was no loss of sensitivity of
N. brasiliensisAChE B, immobilized on screen-printed, disposable electrodes, even after 17-month storage at room temperature.