Electrochemical investigations of the interaction of C-reactive protein (CRP) with a CRP antibody chemically immobilized on a gold surface

• Published in: Analytica chimica acta 2009-06, Vol.643 (1), p.45-53
• Main Authors: Hennessey, Hooman, Afara, Nadia, Omanovic, Sasha, Padjen, Ante L.
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Antibodies, Immobilized - chemistry; Antibody–antigen interactions; C-reactive protein; C-Reactive Protein - chemistry; Chemistry; Chronoamperometry; Cyclic voltammetry; Differential pulse voltammetry; Electrochemical impedance spectroscopy; Electrochemical methods; Electrochemistry; Electrodes; Exact sciences and technology; Gold - chemistry; Kinetics; Sensitivity and Specificity; Surface Properties
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2009.04.009

A possibility of using a range of dc and ac electrochemical techniques to probe associative interactions of C-reactive protein (CRP) with CRP antibody (aCRP) immobilized on a gold electrode surface was investigated. It was demonstrated that the investigated electrochemical techniques can be used efficiently to probe these interactions over a wide CRP concentration range, from 1.15 × 10 −5 to 1.15 mg L −1. The measured sensitivity of the techniques is in the following decreasing order: differential pulse voltammetry, charge-transfer resistance obtained from electrochemical impedance spectroscopy (EIS), cyclic voltammetry, chronoamperometry, and double-layer capacitance deduced from EIS measurements which gave the poorest sensitivity. Measurements of kinetic parameters demonstrated that the associative interactions of CRP with the immobilized aCRP reached quasi-equilibrium after 20–30 min. The kinetics of these interactions was modeled successfully using a two-step kinetic model. In this model, the first step represents reversible CRP–aCRP associative–dissociative interactions, while the second step represents the irreversible transformation of the bound CRP into a thermodynamically stable configuration. It was demonstrated that the thermodynamically stable configuration of CRP starts prevailing after 7 min of interaction of CRP with the immobilized aCRP.