Magnetic Electrochemical Sensing Platform for Biomonitoring of Exposure to Organophosphorus Pesticides and Nerve Agents Based on Simultaneous Measurement of Total Enzyme Amount and Enzyme Activity

Journal Article · Sun May 15 00:00:00 EDT 2011 · Analytical Chemistry, 83(10):3770-3777

DOI:https://doi.org/10.1021/ac200217d· OSTI ID:1015892

Du, Dan; Wang, Jun; Wang, Limin; Lu, Donglai; Smith, Jordan N; Timchalk, Charles; Lin, Yuehe

We report a new approach for electrochemical quantification of enzymatic inhibition and phosphorylation for biomonitoring of exposure to organophosphorus (OP) pesticides and nerve agents based on a magnetic beads (MBs) immunosensing platform. The principle of this approach is based on the combination of MBs immuno-capture based enzyme activity assay and competitive immunoassay of total amount of enzyme for simultaneous detection of enzyme inhibition and phosphorylation in biological fluids. Butyrylcholinesterase (BChE) was chosen as a model enzyme. In competitive immunoassay, the target total BChE in a sample (mixture of OP-inhibited BChE and active BChE) competes with the BChE modified on the MBs to bind to the limited anti-BChE antibody labeled with quantum dots (QDs-anti-BChE), and followed by electrochemical stripping analysis of the bound QDs conjugate on the MBs. This assay shows a linear response over the total BChE concentration range of 0.1~20 nM. Simultaneously, real time BChE activity was measured on an electrochemical carbon nanotube-based sensor coupled with microflow injection system after immuno-capture by MBs-anti-BChE conjugate. Therefore, the formed phosphorylated adduct (OP-BChE) can be estimated by the difference values of the total amount BChE (including active and OP-inhibited) and active BChE from established calibration curves. This approach not only eliminates the difficulty in screening of low-dose OP exposure (less than 20% inhibition of BChE) because of individual variation of BChE values, but also avoids the drawback of the scarce availability of OP-BChE antibody. It is sensitive enough to detect 0.5 nM OP-BChE, which is less than 2% BChE inhibition. This method offers a new method for rapid, accurate, selective and inexpensive quantification of phosphorylated adducts and enzyme inhibition for biomonitoring of OP and nerve agent exposures.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1015892
• Report Number(s): PNNL-SA-78964; 24822; 400412000; TRN: US201112%%36
• Journal Information: Analytical Chemistry, 83(10):3770-3777, Vol. 83, Issue 10
• Country of Publication: United States
• Language: English

Related Subjects

77 NANOSCIENCE AND NANOTECHNOLOGY
ADDUCTS
AVAILABILITY
CALIBRATION
CARBON
DETECTION
ENZYME ACTIVITY
ENZYMES
IMMUNOASSAY
NERVES
PESTICIDES
PHOSPHORYLATION
QUANTUM DOTS
SENSORS
TARGETS
Biosensor
biomonitoring
organophosphorus and nerve agent exposure
enzyme activity
immunoassay
Environmental Molecular Sciences Laboratory