Dual Signal Amplification Strategy for Detection of Ricin Toxin through Bio-Barcode Assay Combined with Hybridization Chain Reaction

A novel highly sensitive and specific method for detection of ricin toxin (RT) based on bio-barcode combined with hybridization chain reaction (HCR) amplification was developed. Functional gold nanoparticles (GNPs) were coated with anti-ricin polyclonal antibodies (pAb) and barcode DNA. The "mAb-RT-pAb/AuNPs/barcode DNA" sandwich structure was formed by co-identification with the anti-ricin monoclonal antibody (mAb) , and HCR was further carried out by using barcode DNA as an initiation chain probe for triggering the chain-triggered biotin label, which resulted in a long double-stranded DNA with repeating units. Immediately, streptavidin labeled horseradish peroxidase (SA-HRP) was combined with biotin on long strand DNA. Finally, the chemiluminescence values were detected through adding substrates of luminol and hydrogen peroxide. The results showed that the linear range of RT was 0. 61 ng/mL -5000 ng/mL , and the limit of detection (LOD) was 0. 52 ng/mL(S/N= 3) . This method showed a wide detection range and a low detection limit. The recoveries of spiked samples in milk and water samples ranged from 83. 4% to 112. 4% , and the relative standard deviations (RSDs) ranged from 2. 2% to 5. 4% . This method exhibited great application prospects in food drinking water safety control and prevention of bioterrorism attacks.