Highly sensitive magnetic relaxation sensing method for aflatoxin B1 detection based on Au NP-assisted triple self-assembly cascade signal amplification

Highly sensitive detection of aflatoxin B 1 (AFB 1 ) is of great significance because of its high toxicity and carcinogenesis. We propose a magnetic relaxation sensing method based on gold nanoparticles (Au NPs)-assisted triple self-assembly cascade signal amplification for highly sensitive detection of AFB 1 . Both AFB 1 antibody and initiator DNA (iDNA) are labeled on Au NPs to form Ab-Au-iDNA probe. iDNA is enriched by Au NPs to achieve first signal amplification. Different amounts of Ab-Au-iDNA were bound with AFB 1 antigen by indirect competitive immunoassay, and then hybridization chain reaction event was initiated by iDNA to produce long hybridization chain reaction products to enrich more horseradish peroxidase-streptavidin for the second signal amplification. Dopamine could be rapidly converted to polydopamine by HRP catalysis, which is used as the third signal amplification. The Fe 3+ solution, providing paramagnetic ions with a strong magnetic signal, could be adsorbed by the polydopamine due to the formation of coordination bonds of phenolic hydroxyl groups with Fe 3+ . This effective interaction between polydopamine and Fe 3+ significantly changes the transverse relaxation time signal of Fe 3+ supernatant solution, which can be used as a magnetic probe for highly sensitive detection of AFB 1 . The sensor exhibited high specificity and sensitivity with a detection limit of 0.453 pg/mL owing to the Au NP-assisted triple self-assembly cascade signal amplification strategy. It has been successfully employed for AFB 1 detection in animal feed samples with consistent results of enzyme linked immune sorbent assay and high-performance liquid chromatography. • A magnetic resonance sensing (MRS) was proposed with signal amplification for Aflatoxin B 1 detection. • The sensitivity is significantly improved by Au NPs-assisted triple cascade signal amplification. • The stability of signal readout is effectively improved by the coordination bond between polydopamine and Fe 3+ .