Electrochemical Sensing of Ovalbumin Based on the Interaction between Lysozyme Origin/Tyrosine‐rich Peptides Modified on Magnetic Beads and Oligothreonine/Ovalbumin‐origin Peptide

We developed a highly sensitive electrochemical system for the sensing of ovalbumin (OVA). Lysozyme origin/tyrosine‐rich peptides (RNRCKGTDVQAWY 4 C) were immobilized on magnetic beads, and the competitive reaction between OVA and oligothreonine/OVA origin peptide probe (T 8 VLLPDEVSG) could then be measured. In a previous study, the detection of OVA at the 10 −13  M level was achieved using RNRCKGTDVQAWY 4 C‐modified beads via a cross‐linker. To improve the sensitivity to OVA, this system uses T 8 VLLPDEVSG peptide probe to measure the interaction to RNRCKGTDVQAWY 4 C immobilized on magnetic beads. The peak of Y 4 C actually was an electron‐transfer peptide, which represented the oxidation of a phenolic hydroxyl group. First, we confirmed that the oxidation response of Y 4 C was increased based on an improvement in the electron transfer accessibility by oligothreonine. Next, T 8 VLLPDEVSG peptide probe was used for the electrochemical sensing of OVA in solutions that contained consistent amounts of RNRCKGTDVQAWY 4 C on magnetic beads. As a result, the peak current decreased as the concentration of OVA increased. The sensitivity to OVA was improved compared with the use of only RNRCKGTDVQAWY 4 C on magnetic beads. The OVA detection level was 10 −14  M, which approximates the results from antibody‐antigen reactions. Consequently, the proposed system is a powerful new concept in protein sensing.