Improved electrochemical performance of metal doped Zirconia nanoparticles for detection of Ochratoxin-A

Here, aluminum (Al) doped Zirconia nanoparticles (ZrO2 NPs) were proposed as a novel material for the fabrication of an efficient electrochemical immunosensor. X-ray diffraction (XRD) analysis and high resolution-transmission electron microscopy (HR-TEM) images visualized phase stabilization and generation of oxygen deficiency in the ZrO2 lattice due to doping of Al ions (Al3+). On the increase in Al3+ concentration, a sequential decrease in crystallite size of ZrO2 NPs describes the Zener pinning effect. Further increase in Al3+concentration (beyond 11 mol%) terminated crystallinity of ZrO2 NPs. The generated oxygen deficiency due to Al3+ doping increased the surface charge and hydrophilicity of ZrO2 NPs as observed by zeta potential and contact angle measurements, respectively. Moreover, oxygen deficiency was the main reason for the remarkable enhancement in the electrochemical behavior of Al3+ doped ZrO2 NPs, and maximum was observed for 7 mol% Al3+ doped ZrO2 NPs. Thus, 7 mol% Al3+ doped ZrO2 NPs based Al3+-ZrO2/ITO electrodes were fabricated via electrophoretic deposition and further functionalized with antibodies specific to Ochratoxin A (anti-OTA) and bovine serum albumin (BSA). Fabricated BSA/anti-OTA/Al3+-ZrO2/ITO immunoelectrode showed improved sensitivity of 34.07 μA (log ng mL−1)−1 and LOD of 0.14 ng mL−1 in the detection range of 1-10 ng mL−1 as compared to BSA/anti-OTA/ZrO2/ITO immunoelectrode for the detection of OTA. Moreover, recovery of OTA from the spiked sample was observed in the range of 93.3-99.2% with maximum relative standard deviation (RSD) of 4.86.