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Biomonitoring of organophosphorus agent exposure by reactivation of cholinesterase enzyme based on carbon nanotube-enhanced flow-injection amperometric detection.

Authors
Du-D; Wang-J; Smith-JN; Timchalk-C; Lin-Y
Source
Anal Chem 2009 Nov; 81(22):9314-9320
NIOSHTIC No.
20036506
Abstract
A portable, rapid, and sensitive assessment of subclinical organophosphorus (OP) agent exposure based on reactivation of cholinesterase (ChE) from OP-inhibited ChE using rat saliva (in vitro) was developed using an electrochemical sensor coupled with a microflow-injection system. The sensor was based on a carbon nanotube (CNT)-modified screen printed carbon electrode (SPE), which was integrated into a flow cell. Because of the extent of interindividual ChE activity variability, ChE biomonitoring often requires an initial baseline determination (noninhibited) of enzyme activity which is then directly compared with activity after OP exposure. This manuscript describes an alternative strategy where reactivation of the phosphorylated enzyme was exploited to enable measurement of both inhibited and baseline ChE activity (after reactivation by an oxime, i.e., pralidoxime iodide) in the same sample. The use of CNT makes the electrochemical detection of the products from enzymatic reactions more feasible with extremely high sensitivity (5% ChE inhibition) and selectivity. Paraoxon was selected as a model OP compound for in vitro inhibition studies. Some experimental parameters, e.g., inhibition and reactivation time, have been optimized such that 92-95% of ChE reactivation can be achieved over a broad range of ChE inhibition (5-94%) with paraoxon. The extent of enzyme inhibition using this electrochemical sensor correlates well with conventional enzyme activity measurements. On the basis of the double determinations of enzyme activity, this flow-injection device has been successfully used to detect paraoxon inhibition efficiency in saliva samples (95% of ChE activity is due to butyrylcholinesterase), which demonstrated its promise as a sensitive monitor of OP exposure in biological fluids. Since it excludes inter- or intraindividual variation in the normal levels of ChE, this new CNT-based electrochemical sensor thus provides a sensitive and quantitative tool for point-of-care assessment and noninvasive biomonitoring of the exposure to OP pesticides and chemical nerve agents.
Keywords
Agricultural-chemicals; Air-sampling; Analytical-chemistry; Biochemical-analysis; Biochemical-tests; Biochemistry; Biodynamics; Biological-effects; Biological-factors; Biological-monitoring; Biological-transport; Biostatistics; Exposure-assessment; Exposure-levels; Exposure-methods; Immunochemistry; Insecticides; Laboratory-animals; Laboratory-testing; Metabolic-study; Organo-phosphorus-compounds; Pesticides; Pesticides-and-agricultural-chemicals; Pharmacodynamics; Quantitative-analysis; Risk-analysis; Risk-factors; Toxic-effects; Toxins; Immunotoxins; insecticide-poisoning; Insecticides; Pesticides
Contact
Yuehe Lin, Key Laboratory of Pesticide and Chemical Biology of Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, PR China
CODEN
ANCHAM
Publication Date
20091115
Document Type
Journal Article
Email Address
yuehe.lin@pnl.gov
Funding Type
Grant
Fiscal Year
2010
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-R01-OH-008173
Issue of Publication
22
ISSN
0003-2700
Priority Area
Agriculture, Forestry and Fishing
Source Name
Analytical Chemistry
State
WA
Performing Organization
Battelle Pacific Northwest Laboratories
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