Bifunctional tracer-mediated sandwich ELISA: A novel and promising approach for highly selective and ultrasensitive detection of selenium

Our current work involves developing a sandwich enzyme-linked immunosorbent assay (ELISA) that utilizes biotinylated long-chain o-phenylenediamine dihydrochloride (Bio-lc-OPD·2 HCl) as a bifunctional ligand for highly selective and ultra-sensitive quantitative analysis of selenium (Se) in food samples. The approach has successfully achieved a remarkable limit of detection (LOD) at the femtomolar level, while also exhibiting a substantial enhancement in sensitivity, up to 32.7-fold higher than that of the traditional indirect competitive ELISA (ic-ELISA). We demonstrated the reliability and accuracy of our approach by assessing overall recoveries, ranging from 75.4% to 104.1% across four different Se species. To validate our proposed method, we conducted the Se detection in Se-rich food samples. The results exhibited high consistency with atomic absorption spectrometry (AAS) analysis, reaffirming the robustness of our sandwich ELISA. This purposed detection strategy emerges as a compelling alternative, offering simplicity, accuracy, and high sensitivity for Se detection.