An electrochemical peptide-based Ara h 2 antibody sensor fabricated on a nickel(II)-nitriloacetic acid self-assembled monolayer using a His-tagged peptide

We report, for the first time, the use of a Ni(II)-nitriloacetic acid (NTA) self-assembled monolayer (SAM) in the fabrication of an electrochemical peptide-based (E-PB) sensor for detection of anti-Ara h 2 antibodies. We compared the performance of the sensor fabricated on a Ni(II)-NTA SAM using a His-tagged peptide with the sensor fabricated using the conventional approach via direct immobilization of a thiolated peptide. While both sensors responded only to the correct antibody in the presence of random antibodies, we observed differences between the sensors. Specifically, the detection limit of the His-tagged sensor was 1 pM, significantly lower than the 200 pM detection limit of the conventional thiolated sensor. More importantly, unlike our previously developed E-PB sensors, both sensors are regenerable and reusable. The thiolated sensor can be readily regenerated using guanidine hydrochloride; whereas the His-tagged sensor can be regenerated by direct displacement of the His-tagged probes using Ni(II) ions. Overall, our results show that both approaches are well-suited for E-PB sensor fabrication; more importantly, specific sensor properties such as detection limit and dynamic range can be tuned by simply using a different probe immobilization method.