A sensitive immunosorbent bio-barcode assay based on real-time immuno-PCR for detecting 3,4,3',4'-tetrachlorobiphenyl.

A functionalized gold-nanoparticle bio-barcode assay, based on real-time immuno-PCR (IPCR), was designed for the determination of 3,4,3',4'-tetrachlorobiphenyl (PCB77). 15 nm gold nanoparticles were synthesized, and modified with thiol-capped DNA and goat anti-rabbit IgG. The nanoparticle probes were used to replace antibody-DNA conjugate in the IPCR, and were fixed on the PCR tube wall via the immune reaction. Real-time PCR was performed to quantify the DNA signal directly. Under optimized conditions, the new method was used to detect PCB77 with a linearity range from 5 pg L(-1) to 10 ng L(-1), and the limit of detection (LOD) was 1.72 pg L(-1). Real samples of Larimichthys polyactis, collected from the East China Sea, were analyzed. Recovery was from 82 % to 112 %, and the coefficient of variation (CV) was acceptable. The results were compared with GC-ECD, revealing that the method would be acceptable for providing rapid, semi-quantitative, and reliable test results for making environmental decisions.