title: EQCM immunoassay for phosphorylated acetylcholinesterase as a biomarker for organophosphate exposures based on selective zirconia adsorption and enzyme-catalytic precipitation.
abstract: A zirconia (ZrO(2)) adsorption-based immunoassay by electrochemical quartz crystal microbalance (EQCM) has been initially developed, aiming at the detection of phosphorylated acetylcholinesterase (Phospho-AChE) as a potential biomarker for bio-monitoring exposures to organophosphate (OP) pesticides and chemical warfare agents. Hydroxyl-derivatized monolayer was preferably chosen to modify the crystal serving as the template for directing the electro-deposition of ZrO(2) film with uniform nanostructures. The resulting ZrO(2) film was utilized to selectively capture Phospho-AChE from the sample media. Horseradish peroxidase (HRP)-labeled anti-AChE antibodies were further employed to recognize the captured phosphorylated proteins. Enzyme-catalytic oxidation of the benzidine substrate resulted in the accumulation of insoluble product on the functionalized crystal. Ultrasensitive EQCM quantification by mass-amplified frequency responses as well as rapid qualification by visual color changes of product could be thus, achieved. Moreover, 4-chloro-1-naphthol (CN) was studied as an ideal chromogenic substrate for the enzyme-catalytic precipitation. Experimental results show that the developed EQCM technique can allow for the detection of Phospho-AChE in human plasma with a detection limit of 0.020 nM. Such an EQCM immunosensing format opens a new door towards the development of simple, sensitive, and field-applicable biosensor for biologically monitoring low-level OP exposures.
authors.affiliation: Pacific Norwest National Laboratory, Richland, WA 99352, United States.
authors.forename: Hua
authors.initials: H
authors.lastname: Wang
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.forename: Daiwon
authors.initials: D
authors.lastname: Choi
authors.forename: Zhiwen
authors.initials: Z
authors.lastname: Tang
authors.forename: Hong
authors.initials: H
authors.lastname: Wu
authors.forename: Yuehe
authors.initials: Y
authors.lastname: Lin
mesh_terms: D000110:Acetylcholinesterase / Q000737:chemistry*; D000327:Adsorption; D015415:Biomarkers / Q000032:analysis; D002384:Catalysis; D011232:Chemical Precipitation; D004781:Environmental Exposure / Q000032:analysis*; D004784:Environmental Monitoring / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007118:Immunoassay / Q000295:instrumentation*; D055617:Micro-Electrical-Mechanical Systems / Q000295:instrumentation*; D010755:Organophosphates / Q000032:analysis*; D010766:Phosphorylation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D015040:Zirconium / Q000737:chemistry*
chemical_list: D015415:Biomarkers; D010755:Organophosphates; D015040:Zirconium; D000110:Acetylcholinesterase; C028541:zirconium oxide