Cerium oxide-monoclonal antibody bioconjugate for electrochemical immunosensing of HER2 as a breast cancer biomarker

Abstract Metal oxide-based sensors have the advantage of rapid response and of high sensitivity in detecting specific active biological species and are relatively inexpensive. This report of the present study concerns the development of a cerium oxide – monoclonal antibody bioconjugate for its application as a sensitive immunosensor to detect a breast cancer biomarker. A cerium oxide-anti HER2 bioconjugate has been constructed by adding anti HER2 onto cerium oxide that had been previously reacted with APTMS and PEG-NHS-Maleimide. The FTIR spectra of the reaction product showed that the cerium oxide-anti HER2 bioconjugate was successfully synthesized. The resulted bioconjugate was then immobilized on a screen-printed carbon‑gold nanoparticles electrode surface by using the amine coupling bonding systems. The interaction of the synthesized cerium oxide-anti-HER2 bioconjugate with HER2 was found to inhibit an electron transfer and a decrease in the voltammetric Fe(CN)63-/4- peak current, which was proportional to the concentration of HER2. The optimal response of the current signal was generated at an anti-HER2 concentration of 5.0 μg/mL. The two linear ranges of HER2 concentration were found to be from 0.001 to 0.5 ng/mL and from 0.5 to 20.0 ng/mL. By using the first calibration curve, the limit of detection was found to be 34.9 pg/mL. The developed label-free immunosensor has been used to determine HER2 in a human serum sample with satisfactory results, as shown by a consistent result with the addition of standard. Thus, the resulted immunosensor in this study is promising and would have a potential application in clinical bio-analysis.