A novel label-free electrochemical immunosensor for detection of surfactant protein B in amniotic fluid

The deficiency of Surfactant Protein B (SPB) in Amniotic Fluid (AF) has been associated with severe respiratory pathologies in newborns such as respiratory distress syndrome (RDS). Early-stage diagnosis of these respiratory complications by monitoring the SPB in AF could be a significant clinical tool and the first step toward adopting efficient therapy. In this work, we report the development of a novel sensitive electrochemical immunosensor for the detection of SPB in human AF samples. The surface biofunctionalization steps were characterized by using Electrochemical Impedance Spectroscopy (EIS), cyclic voltammetry, and quartz crystal microbalance techniques. The performance of the immunosensor was investigated by EIS, showing a linear dynamic range between 2 ng/mL and 2000 ng/mL and a limit of detection of 0.1 ng/mL. The immunosensor was also selective and specific to other surfactant proteins presented in AF. To the best of our knowledge, this is the first developed electrochemical biosensor for SPB detection. More significant, the immunosensor developed is simpler than the traditional enzyme-linked immunosorbent assay, and present a higher sensitivity for SPB, indicating that it could be a promising alternative approach for SPB detection in the clinical diagnosis.