Synthesis, Characterization, and Evaluation of Ferrocene−Theophylline Conjugates for Use in Electrochemical Enzyme Immunoassay

A series of 8-(ferrocenylalkyl)theophylline conjugates were synthesized for evaluation in a homogeneous, competitive electrochemical immunoassay for theophylline with amperometric detection of the ferrocene label at +320 mV. The electrical signal was amplified via redox cycling with the glucose oxid...

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Veröffentlicht in:Bioconjugate chemistry 2004-01, Vol.15 (1), p.137-144
Hauptverfasser: Forrow, Nigel J, Foulds, Nicola C, Frew, Jane E, Law, John T
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Sprache:eng
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Zusammenfassung:A series of 8-(ferrocenylalkyl)theophylline conjugates were synthesized for evaluation in a homogeneous, competitive electrochemical immunoassay for theophylline with amperometric detection of the ferrocene label at +320 mV. The electrical signal was amplified via redox cycling with the glucose oxidase/glucose system. The resulting catalytic current was strongly inhibited upon binding of the conjugates to anti-theophylline antibodies such that a large excess of theophylline was required to achieve complete reversal leading to an assay with poor sensitivity in the clinical range. A study of the nonspecific interaction of the antibodies with various ferrocene derivatives indicated that this was reduced when a charged functional group was present on the metallocene ring. Consequently, a conjugate was synthesized with a quaternary ammonium group which when incorporated into the assay resulted in improved sensitivity.
ISSN:1043-1802
1520-4812
DOI:10.1021/bc034131b