A smartphone-readable barcode assay for the detection and quantitation of pesticide residues

In this paper, we present a smartphone-readable barcode assay for the qualitative detection of methyl parathion residues, a toxic organophosphorus pesticide that is popularly used in agriculture worldwide. The detection principle is based on the irreversible inhibition of the enzymatic activity of a...

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Bibliographic Details
Published in:Analyst (London) 2015-08, Vol.140 (16), p.5518-5525
Main Authors: Guo, Juan, Wong, Jessica X H, Cui, Caie, Li, Xiaochun, Yu, Hua-Zhong
Format: Article
Language:English
Subjects:
Acetylcholinesterase - chemistry
Acetylcholinesterase - metabolism
Assaying
Bar codes
Biosensing Techniques - methods
Channels
Colorimetry
Colorimetry - methods
Enzymes, Immobilized - chemistry
Enzymes, Immobilized - metabolism
Malus - chemistry
Methyl parathion
Methyl Parathion - analysis
Pesticide Residues - analysis
Pesticides
Reservoirs
Residues
Smartphone - utilization
Spectrophotometry - methods
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Summary:In this paper, we present a smartphone-readable barcode assay for the qualitative detection of methyl parathion residues, a toxic organophosphorus pesticide that is popularly used in agriculture worldwide. The detection principle is based on the irreversible inhibition of the enzymatic activity of acetylcholinesterase (AchE) by methyl parathion; AchE catalytically hydrolyzes acetylthiocholine iodine to thiocholine that in turn dissociates dithiobis-nitrobenzoate to produce a yellow product (deprotonated thio-nitrobenzoate). The yellow intensity of the product was confirmed to be inversely dependent on the concentration of the pesticide. We have designed a barcode-formatted assay chip by using a PDMS (polydimethylsiloxane) channel plate (as the reaction reservoir), situated under a printed partial barcode, to complete the whole barcode such that it can be directly read by a barcode scanning app installed on a smartphone. The app is able to qualitatively present the result of the pesticide test; the absence or a low concentration of methyl parathion results in the barcode reading as "-", identifying the test as negative for pesticides. Upon obtaining a positive result (the app reads a "+" character), the captured image can be further analyzed to quantitate the methyl parathion concentration in the sample. Besides the portability and simplicity, this mobile-app based colorimetric barcode assay compares favorably with the standard spectrophotometric method.
ISSN:0003-2654
1364-5528
DOI:10.1039/c5an00874c