A Biotin-streptavidin-enhanced Carbon Nanotube Amplification Strategy for an Ultrasensitive Immunodetection of...

The extensive use of polybrominated diphenyl ethers (PBDEs) has resulted in its increasingly widespread presence. Especially the lower halogenated PBDEs accumulate to a greater degree than the higher halogenated PBDEs in house dust, sewage sludge, pets, or even humans. In the present work, we developed an ultrasensitive biotin-streptavidin-enhanced carbon nanotube amplification strategy for the immunodetection of PBDEs, in which single-walled carbon nanotubes were used to immobilize numerous streptavidin. Meanwhile, we used biotin conjugated horseradish peroxidase (B-HRP) and biotin conjugated Goat anti-rabbit (B-IgG) to link the HRP and IgG to CNTs by using a biotin-streptavidin system. The sensitivity of the streptavidin-biotin-IgG-CNTs-HRP bioconjugate was compared with a commercial HRP-labelled IgG by using indirect competitive ELISA. The limit of this proposed ELISA detection (IC₁₀) was 0.0059 ng/mL, showing a 20-time lower detection limit over the commercial one (IC₁₀ = 0.1193 ng/mL). Finally, we applied the assay to the detection of PBDEs in dust samples. The results were consistent with those using GC-ECD, which confirmed that the proposed amplification strategy was accurate and receptive. This proposed biotin-streptavidin-enhanced carbon nanotube amplification strategy would be useful for ultrasensitive immunodetection in environmental studies.