title: Electrochemical enzyme immunoassays on microchip platforms.
abstract: A microfluidic device for conducting electrochemical enzyme immunoassays is described. The new "lab-on-a-chip" protocol integrates precolumn reactions of alkaline phosphatase-labeled antibody (anti-mouse IgG) with the antigen (mouse IgG), followed by electrophoretic separation of the free antibody and antibody-antigen complex. The separation is followed by a postcolumn reaction of the enzyme tracer with the 4-aminophenyl phosphate substrate and a downstream amperometric detection of the liberated 4-aminophenol product Factors influencing the reaction, separation, and detection processes were optimized, and the analytical performance was characterized. An applied field strength of 256 V/cm results in free antibody and antibody-antigen complex migration times of 125 and 340 s, respectively. A remarkably low detection limit of 2.5 x 10(-16) g/mL (1.7 x 10(-18) M) is obtained for the mouse IgG model analyte. Such combination of a complete integrated immunoassay, an attractive analytical performance, and the distinct miniaturization/portability advantages of electrochemical microsystems offers considerable promise for designing self-contained and disposable chips for decentralized clinical diagnostics or on-site environmental testing.
authors.affiliation: Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces 88003, USA.
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: A
authors.initials: A
authors.lastname: Ibáñez
authors.forename: M P
authors.initials: MP
authors.lastname: Chatrathi
authors.forename: A
authors.initials: A
authors.lastname: Escarpa
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D004563:Electrochemistry / Q000379:methods*; D007124:Immunoenzyme Techniques / Q000379:methods*; D051379:Mice; D013379:Substrate Specificity
chemical_list: D000469:Alkaline Phosphatase