Biosensors for pesticides - Electrochemical Sensors, Biosensors and Their Biomedical Applications - page 38

b

a

1.50 m

1.50 m

c d

137 nm

200 nm

FIGURE 2.6 SEM images of cross-linked chitosan (a) and CMC (b) membranes and TEM images of
CMC (c) and single CNT (d) (adapted from [11]).

MWNTs favored the detection of insecticide from 1.5 to 80 nM with a detection limit
of 1 nM at an inhibition of 10% (Fig. 2.7). Bucur et al. [58] employed two kinds of
AChE, wild type Drosophila melanogaster and a mutant E69W, for the pesticide detec-
tion using fl ow injection analysis. Mutant AChE showed lower detection limit (1

10 7 M) than the wild type (1 10 6 M) for omethoate. An amperometric FIA bio-

sensor was reported by immobilizing OPH on aminopropyl control pore glass beads
[27]. The amperometric response of the biosensor was linear up to 120 and 140 M

for paraoxon and methyl-parathion, respectively, with a detection limit of 20 nM (for
both the pesticides). Neufeld et al. [59] reported a sensitive, rapid, small, and inexpen-
sive amperometric microfl ow injection electrochemical biosensor for the identifi cation
and quantifi cation of dimethyl 2,2

µ

-dichlorovinyl phosphate (DDVP) on the spot. The
electrochemical cell was made up of a screen-printed electrode covered with an enzy-
matic membrane and combined with a fl ow cell and computer-controlled potentiostat.
Potassium hexacyanoferrate (III) was used as mediator to generate very sharp, rapid,
and reproducible electric signals. Other reports on pesticide biosensors could be found
in review [17].