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Electrochemical Immunoassay with Microscopic Immunomagnetic Bead Domains and Scanning Electrochemical Microscopy
Author(s) -
Wijayawardhana C. Ajith,
Wittstock Gunther,
Halsall H. Brian,
Heineman William R.
Publication year - 2000
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/1521-4109(200005)12:9<640::aid-elan640>3.0.co;2-7
Subject(s) - scanning electrochemical microscopy , immunoassay , analyte , alkaline phosphatase , chemistry , electrochemistry , primary and secondary antibodies , chromatography , enzyme , electrode , antibody , biochemistry , biology , immunology
The formation of mound‐like microscopic domains of biochemically active paramagnetic beads reported earlier is extended towards a miniaturized sandwich enzyme immunoassay for the model analyte mouse‐IgG. After mouse‐IgG is captured by the primary anti‐mouse‐IgG antibody (Ab) coated magnetic beads of 2.8 µm in diameter, a second anti‐mouse‐IgG Ab conjugated to an enzyme‐label is bound to the analyte. The enzyme label alkaline phosphatase (ALP) is used to catalyze the hydrolysis of 4‐aminophenyl phosphate (PAPP) to 4‐aminophenol (PAP). The enzymatic activity, which depends on the concentration of captured mouse‐IgG, is recorded by scanning electrochemical microscopy (SECM) where a 10 µm Pt electrode scanned over the bead domains detects PAP by oxidation. The anodic current correlates with the concentration of mouse‐IgG.