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Issue 6, 2008
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A lab-on-a-chip for detection of nerve agent sarin in blood

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Abstract

Sarin (C4H10FO2P,O-isopropyl methylphosphonofluoridate) is a colourless, odourless and highly toxic phosphonate that acts as a cholinesterase inhibitor and disrupts neuromuscular transmission. Sarin and related phosphonates are chemical warfare agents, and there is a possibility of their application in a military or terrorist attack. This paper reports a lab-on-a-chip device for detecting a trace amount of sarin in a small volume of blood. The device should allow early detection of sarin exposure during medical triage to differentiate between those requiring medical treatment from mass psychogenic illness cases. The device is based on continuous-flow microfluidics with sequential stages for lysis of whole blood, regeneration of free nerve agent from its complex with blood cholinesterase, protein precipitation, filtration, enzyme-assisted reaction and optical detection. Whole blood was first mixed with a nerve gas regeneration agent, followed by a protein precipitation step. Subsequently, the lysed product was filtered on the chip in two steps to remove particulates and fluoride ions. The filtered blood sample was then tested for trace levels of regenerated sarin using immobilised cholinesterase on the chip. Activity of immobilised cholinesterase was monitored by the enzyme-assisted reaction of a substrate and reaction of the end-product with a chromophore. Resultant changes in chromophore-induced absorbance were recorded on the chip using a Z-shaped optical window. Loss of enzyme activity obtained prior and after passage of the treated blood sample, as shown by a decrease in recorded absorbance values, indicates the presence of either free or regenerated sarin in the blood sample. The device was fabricated in PMMA (polymethylmethacrylate) using CO2-laser micromachining. This paper reports the testing results of the different stages, as well as the whole device with all stages in the required assay sequence. The results demonstrate the potential use of a field-deployable hand-held device for point-of-care triage of suspected nerve agent casualties.

Graphical abstract: A lab-on-a-chip for detection of nerve agent sarin in blood

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Publication details

The article was received on 10 Jan 2008, accepted on 13 Mar 2008 and first published on 16 Apr 2008


Article type: Paper
DOI: 10.1039/B800438B
Citation: Lab Chip, 2008,8, 885-891
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    A lab-on-a-chip for detection of nerve agent sarin in blood

    H. Y. Tan, W. K. Loke, Y. T. Tan and N. Nguyen, Lab Chip, 2008, 8, 885
    DOI: 10.1039/B800438B

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