Oriented construction of an electrochemiluminescence immunosensing interface based on a DNA ligand targeting the Fc segment of antibody for toxin detection.

In this study, the newly developed and prepared DNA ligand targeting the Fc segment of antibody (Fc-DNAL) was employed as a functional molecule to realize the oriented immobilization and ordered arrangement of antibodies on the surface of gold magnetic particles. The signal amplification effect of functionalized gold magnetic particles with Fc-DNAL on the screen-printed electrode with electrochemiluminescence (SPE-ECL) multi-phase sensing interface was assessed, offering concept for the development of novel immunosensors. Gold-magnetic nanoparticles were employed to immobilize thiol-modified Fc-DNAL through interaction, and the screened DNA ligands were used to directionally immobilize toxin monoclonal antibodies (McAb1) as functionalized magnetic capture probes, and Ru (bpy)32+-labeled toxin monoclonal antibodies (McAb2) served as specific signal detection probes. By utilizing SPE-ECL technology, trace detection of abrin was achieved, which approach effectively validated the performance of the screened Fc-DNAL for oriented antibody immobilization on complex ECL immunosensing interfaces involving gold-magnetic, ECL signal probes, and screen-printed electrodes. The developed method achieved a LOD of 4.70 pg/mL for abrin, with a linear range from 5 pg/mL to 1 × 104 pg/mL, and regression equation was Y = 2201.57 × lg (Cabrin) - 928.76 (N = 8, R2 = 0.999, p < 0.001). Compared with the traditional non-oriented antibody immobilization strategy on ECL immunosensing interfaces, the LOD was decreased by 10-fold. This method can resist interference from complex matrices in toxin detection and meets the analytical requirements for environmental samples.