Fabrication of micromagnetic beads with molecular recognition/electron-transfer peptides for the sensing of ovalbumin

•Ovalbumin recognition/electron-transfer peptides were immobilized on magnetic beads.•The accumulation of the protein through the peptides on the beads caused the change of electrode response.•The magnetic beads could be reused for sensing of ovalbumin.

Electrochemical sensing of ovalbumin (OVA) was performed using magnetic beads with OVA recognition (RNRCKGTDVQAW)/electron-transfer (YYYYC) peptides. The focus of this study was to construct a highly sensitive and regenerative tool for OVA detection based on the interaction between a protein and peptide-1(RNRCKGTDVQAWYYYYC). The peptide-1 was introduced to the bead through four types of cross-linking reagents. Magnetic beads of different sizes with N-(6-maleimidocaproyloxy)sulfosuccinimide (Sulfo-EMCS) were also prepared. An oxidation peak due to tyrosine residues at 0.65 V depended on the distance of the electron-transfer peptide from the bead surface and on the surface area of the magnetic beads that contacted the electrode surface. The response of the electro-transfer peptide moiety was decreased because the protein was accumulated via the recognition peptide on the beads. When using Sulfo-EMCS and beads that were 6.0-6.9 μm in diameter, the calibration curve of OVA was linear and ranged from 8.0 × 10−13 to 2.0 × 10−11 M. To regenerate the magnetic beads, the measurements were achieved after removal of the OVA using a denaturing reagent. When OVA was added to fetal bovine serum containing a complex matrix, OVA was recovered at a rate of 98-100%. Consequently, these magnetic beads could be a powerful tool for the sensing of OVA in real samples.

Graphical abstractDownload high-res image (326KB)Download full-size image