Magnetic electrochemical immunoassays with quantum dot labels for detection of phosphorylated acetylcholinesterase in plasma.
Wang H; Wang J; Timchalk C; Lin Y
Anal Chem 2008 Nov; 80(22):8477-8484
A new magnetic electrochemical immunoassay has been developed as a tool for biomonitoring exposures to organophosphate (OP) compounds, e.g., insecticides and chemical nerve agents, by directly detecting organophosphorylated acetylcholinesterase (OP-AChE). This immunoassay uniquely incorporates highly efficient magnetic separation with ultrasensitive square wave voltammetry (SWV) analysis with quantum dots (QDs) as labels. A pair of antibodies was used to achieve the specific recognition of OP-AChE that was prepared with paraoxon as an OP model agent. Antiphosphoserine polyclonal antibodies were anchored on amorphous magnetic particles preferably chosen to capture OP-AChE from the sample matrixes by binding their phosphoserine moieties that were exposed through unfolding the protein adducts. This was validated by electrochemical examinations and enzyme-linked immunosorbent assays. Furthermore, antihuman AChE monoclonal antibodies were labeled with cadmium-source QDs to selectively recognize the captured OP-AChE, as characterized by transmission electron microscopy. The subsequent electrochemical SWV analysis of the cadmium component released by acid from the coupled QDs was conducted on disposable screen-printed electrodes. Experimental results indicated that the SWV-based immunoassays could yield a linear response over a broad concentration range of 0.3-300 ng/mL OP-AChE in human plasma with a detection limit of 0.15 ng/mL. Such a novel electrochemical immunoassay holds great promise as a simple, selective, sensitive, and field-deployable tool for the effective biomonitoring and diagnosis of potential exposures to nerve agents and pesticides.
Agricultural-chemicals; Air-sampling; Analytical-chemistry; Biological-effects; Biochemical-analysis; Biological-effects; Biological-factors; Biological-monitoring; Electrochemical-analysis; Electrochemical-properties; Electrochemical-reactions; Environmental-contamination; Environmental-exposure; Environmental-factors; Environmental-hazards; Environmental-technology; Immunochemistry; Immune-reaction; Immunotoxins; Insecticide-poisoning; Insecticides; Particulate-sampling-methods; Pesticides; Pesticides-and-agricultural-chemicals; Particle-aerodynamics; Particle-counters; Quantitative-analysis
Yuehe Lin, Pacific Northwest National Laboratory, Richland, Washington 99352
Agriculture, Forestry and Fishing
Battelle Pacific Northwest Laboratories