KCS

Electrochemical immunosensors based on antibody provide a rapid and convenient approach for sensitive and specific disgnosis. Despite many advantages, it is still a challenge to find new approaches that could improve the simplicity, specificity, and sensitivity for clinical uses. To enhance performance of antibody based immunosensors, it is particularly important to develop label-free detection methods. Several strategies to achieve label-free immunoassays have been demonstrated by using fluorescence, electrochemistry, quartz crystal microbalance (QCM), and surface plasmon resonance (SPR) spectroscopy. Herein we reported on a novel approach to design a label-free immunosensors via use of electrochemically active nanoprobes such as ferrocene (Fc)-modified silica nanoparticles. The fragmented antibody (i.e., Fab’; regular molecular weight of 50 kDa) immobilized on a gold electrode leads to changes in the interfacial electron transfer properties. The surface coverage with target proteins specifically bound to Fab’ prohibits the access of electroactive probes to the electrode surface. To amplify such blocking effects associated with target protein-Fab’ complex formation, Fc-modified silica nanoparticles are utilized as a scaffold to design macromolecular electroactive probes. Various conjugation techniques and addressed fabrication methods for Fab’ oriented immobilization on a gold surface will be evaluated. Furthermore, we investigate the feasibility of applying the novel concept to develop the label-free, Fab’-based immunosensor to detect the biomarkers in allergic rhinitis such as Clara cell protein 16, tryptase, eosinophil cationic protein, and albumin. Finally, four biomarkers in artificial nasal discharge are simultaneously determined with multi-array sensor system equipped in a microfluidic device.