Characterization of the interactions between immobilized parathion and the corresponding recombinant scfv antibody using a piezoelectric biosensor

Abstract

A piezoelectric quartz crystal sensor with immobilized parathion was used for real‐time kinetic characterization of the interactions with recombinant anti‐parathion single chain Fv antibody IFRN AA01 (scFv). Parathion was linked to the sensor gold electrodes modified with a self‐assembled layer of aminothiophenol using either bovine serum albumin (BSA) or dextran as spacer molecules. The kinetic dissociation rate constant k_d was 8 × 10⁻⁴ s⁻¹ for both types of sensors, and the association rate constants k_a, were 590 and 260 mol⁻¹ 1 s⁻¹ for BSA and dextran‐linked parathion, respectively. The regeneration of BSA‐parathion coated crystals was not successful, however. Those crystals with bound scFv were used to study the formation of scFv dimers. Dextran‐parathion modified crystals were successfülly regenerated using proteinase K. The affinity of scFv to dextran‐parathion was 50 X lower when compared with the affinity of the anti‐parathion monoclonal antibody (IgG, IFRN 1701) the sequence of which served for production of scFv.

Keywords:

• Piezoelectric biosensor
• immunosensor
• recombinant antibody
• pesticide
• parathion
• kinetic constants