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Inhibition of Adsorbed Alkaline Phosphatase Activity by an Anti‐Enzyme Antibody. An Approach to Carbon Paste Immunoelectrodes
Author(s) -
FernándezSánchez César,
CostaGarcía Agustín
Publication year - 1999
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/(sici)1521-4109(199912)11:18<1350::aid-elan1350>3.0.co;2-k
Subject(s) - chemistry , detection limit , alkaline phosphatase , adsorption , carbon paste electrode , electrode , electrochemistry , conjugate , voltammetry , hydrolysis , chromatography , indigo , nuclear chemistry , cyclic voltammetry , inorganic chemistry , enzyme , biochemistry , organic chemistry , mathematical analysis , art , visual arts , mathematics
The accumulation of alkaline phosphatase labeled immunoglobulin G (IgG‐AP) on the surface of an electrochemically pretreated carbon paste electrode and further enzyme inhibition with an anti‐AP antibody is presented in this work. The pretreatment is based on an anodization at a controlled potential of +1.5 V in 0.1 M NaOH solution. The obtained protein layer was detected by the electrodic oxidation of indigo, product of the 3‐indoxyl phosphate hydrolysis with AP. This molecule readily adsorbs on the electrode surface and displays a reversible electrodic process at –0.4 V (vs. Ag/AgCl) in 0.1 M Tris buffer pH 7.2. Thus, alternating current voltammetry was a very adequate electrochemical technique for its detection. Calibrations of the IgG‐AP conjugate adsorbed are presented, yielding a lower detection limit of 4×10 –13 M for the labeled IgG. Likewise, the determination of the anti‐AP antibody was performed. A decrease of the electrode response was observed when it reacted with the enzyme label. Thus, a detection limit of 2×10 –10 M for this antibody was achieved.