In situ encapsulation of antibody on TiO2 nanowire immunosensor via electro-polymerization of polypyrrole propylic acid

A conductance-based immunosensor was constructed based on an antibody/conducting polymer/TiO2 nanowire film. TiO2 nanowires (NWs) were made by the hydrothermal synthesis method and directly spin-coated on a gold microelectrode patterned surface. Conducting polymer polypyrrole propylic acid (PPa) and antibody composite films were electrochemically polymerized on patterned NWs using pyrrole propylic acid (Pa) and anti-rabbit IgG (1 Ab) mixture solutions. The surface properties in the designed immunosensor during the preparation processes of NWs, PPa (PPa/TiO2 NWs), anti-rabbit IgG (PPa-1 Ab/TiO2 NWs immunosensor), and the measurement of rabbit IgG (2 Ab/PPa-1 Ab/TiO2 NWs immunosensor) were recorded and expressed by the changes in current-voltage (I-V). The devices designed in this study can detect 2 Ab within a linear range of 11.2 μg/mL to 112 μg/mL, and the detection sensitivity and R-square are −0.64 A/(g/mL) and 0.896, respectively.