Development of a novel electrochemical immuno-biosensor for circulating biomarkers of the inner ear

Current approaches for diagnosis of hearing or vestibular disorders are mostly based on physical examinations that cannot provide information about the exact location of cellular damage inside the inner ear. Therefore, there is a need for new diagnostic methods capable of identifying the sites of damage through the detection of inner ear blood-circulating biomarkers. Here, we developed the first biosensor platform for rapid detection of otolin-1 and prestin, blood-circulating proteins specifically expressed in the vestibule and cochlea, respectively. The platform was designed on a DNA-based immunoassay that employed conjugated antibodies for target protein recognition, which when bound, altered the DNA-DNA hybridization on the surface, resulting in generation of a concentration-dependent signal. The signal was recorded when the redox moiety brought to the surface by the target enabled a selective electrochemical output directly in whole blood. Signal amplification was acquired by employing high-curvature nanostructured electrodes for sensitive sample analysis at picomolar concentrations with a three-fold quantitative range. The combination of nanostructuring and optimum density of the probes on the surface provided low-picomolar detection limits while utilizing small 10 μL sample volume with a 10-min response time. The proposed immuno-biosensor is highly selective and quantitative and can easily be adapted for rapid detection of any blood-circulating protein using their specific antibodies as recognition elements.