Voltammetric Immunoassay for the Detection of Protein Biomarkers

Abstract

A strategy for a fast (ca. 20 min), specific, electrochemical immunoassay for the cardiac biomarker creatine kinase (CK) and the human cytokine interleukin 10 (IL10) has been developed in this paper. The polyaniline modified gold surface formed from electrochemical reduction of diazonium salt supplies a solid substrate to link the activated carboxylic acid groups from the antibodies, which were labelled with ferrocene. The direct electrochemistry of ferrocene allows the analysis of protein markers with good sensitivity. The creatine kinase sensor demonstrates limit of detection of 0.5 pg mL À1 in a physiological Krebs-Henseleit solution. The anti-IL10 antibody retained fluorescence activity after further coupling to ferrocene and covalent immobilization on to a gold electrode, showing a linear detection range for IL-10 from 0.001 ng mL À1 to 50 ng mL À1 in PBS. We attribute the high sensitivity to the well-controlled modified surface which results in end-on antibodies that can specifically capture the antigen with ease.

Ultrasensitive IgG quantification using DNA nano-pyramids

“…Additionally, the cyclic voltammograms from the prepared immunosensor varied at different scan rates (Supplementary Figure S4), which corresponded to the oxidation of the antibody-tethered ferrocene into the ferricinium cation. 36 In addition, both the anodic and cathodic peak currents increased linearly with the square root of the scan rate within the range from 50 to 500 mV s À1 (inset of Supplementary Figure S4), which confirmed the diffusion-controlled nature of the redox species in this process. 36 Despite earlier work that suggests that individual FeC assembled at the top vertex of a DP would yield poor current signals, we speculated the charge transfer mechanism in our current system may be that the ferrocene moieties on the Ab1-Atg-(FeC-Ab2) complex are flexible enough to physically impinge on the electrode surface and maintain a sufficiently high current signal.…”

Double-chained cationic surfactant modification of SU-8/Pyrex® microchips for electrochemical sensing of carboxylic ferrocene after reverse electrophoresis

“…Electroactive labeling requires the employ of highly detectable molecules that could be attached to the analyte or to a molecule related to it. Ferrocene carboxylic acid (FCA) contains a group that can be used for biomolecule labeling [51,52] and the reversibility of the redox process of ferrocene derivatives is well known. Then, labeling with FCA enables the detection of originally nonelectroactive analytes (e.g., proteins) by electrochemical methods [53].…”

“…For evaluating the stability and precision of the film and therefore of the analytical signal of FCA, a 0.1 mM concentration of DDAB, which has already been shown to produce a reversal of the EOF [44,51] has been chosen.…”

Antibody-Electroactive Probe Conjugates Based Electrochemical Immunosensors

“…The immobilization of ferrocene-prefunctionalized antibodies on a gold electrode surface modified with polyaniline formed based on electrochemical reduction of diazonium salt has been developed [51] ( Figure 4B). The direct reduction/oxidation process of ferrocene with a potential at ca.…”