TITLE:
Screening of Total Organophosphate Pesticides in Agricultural Products with a Cellular Biosensor
AUTHORS:
Kelly Lokka, Panagiotis Skandamis, Spiridon Kintzios
KEYWORDS:
Bioelectric Recognition Assay (BERA); Matrix Effects; N2a Cells; Organophosphates; Tobacco Pro-toplasts
JOURNAL NAME:
CellBio,
Vol.2 No.3,
September
18,
2013
ABSTRACT: Organophosphates belong to the most important pesticides
used in agricultural practice worldwide. Although their analytical
determinations are quite feasible with various conventional methods, there is a lack of efficient screening methods, which will facilitate the rapid, high-throughput detection of organophosphates
in different food commodities. This study
presents the construction of a rapid and sensitive cellular biosensor test
based on the measurement of changes of the cell membrane potential of immobilized
cells, according to the working principle of the Bioelectric Recognition Assay
(BERA). Two different cell types were used, derived either by animal
(neuroblastoma) or plant cells (tobacco protoplasts). The sensor was applied
for the detection of a mixture of two organophosphate pesticides, diazinon and
chlorpyrifos in two different substrates (tomato, orange). The pesticides in
the samples inhibited the activity of cell membrane-bound acetylcholinesterase
(AChE), thus causing a measurable membrane depolarization in the presence of
achetylcholine (Ach). Based on the observed patterns of response, we
demonstrate that the sensor can be used for the qualitative and, in some
concentrations, quantitative detection of organophosphates in different
substrates with satisfactory reproducibility and sensitivity, with a limit of
detection at least equal to the official Limit of Detection (LOQ). The assay is rapid
with a total duration of 3 min at a competitive cost. The sensitivity of the
biosensor can be further increased either by incorporating more AChE-bearing cells per test reaction unit
or by using cells engineered with more potent
AChE isoforms. Standardization of cultured cell parameters, such as age of the
cells and subculture
history prior to cell immobilization, combined with use
of planar electrodes, can further increase the reproducibility of the
novel test.