Magnetic electrochemical immunoassays with quantum dot labels for detection of phosphorylated acetylcholinesterase in plasma.
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.
Pacific Norwest National Laboratory, Richland, Washington 99352, USA.
Hua
H
Wang
Jun
J
Wang
Charles
C
Timchalk
Yuehe
Y
Lin
D000110:Acetylcholinesterase / Q000097:blood* / Q000276:immunology / Q000378:metabolism; D000327:Adsorption; D000818:Animals; D000915:Antibody Affinity; D015415:Biomarkers / Q000097:blood / Q000378:metabolism; D002417:Cattle; D004563:Electrochemistry; D004781:Environmental Exposure; D004784:Environmental Monitoring; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D008280:Magnetics; D009943:Organophosphorus Compounds / Q000378:metabolism; D010750:Phosphoproteins / Q000097:blood*; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D011092:Polyethylene Glycols / Q000737:chemistry; D045663:Quantum Dots; D012680:Sensitivity and Specificity; D012710:Serum Albumin, Bovine / Q000737:chemistry; D013194:Staining and Labeling; D013499:Surface Properties; D013997:Time Factors
D015415:Biomarkers; D009943:Organophosphorus Compounds; D010750:Phosphoproteins; D010768:Phosphoserine; D012710:Serum Albumin, Bovine; D011092:Polyethylene Glycols; D000110:Acetylcholinesterase