Dual-amplified Colorimetric Immunoassay Based on PtNPs-PV for Detection of Ractopamine at Ultra-trace Level in Meat Samples
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Abstract:
A colorimetric immunoassay for the detection of ractopamine (RAC) residues in pork is presented in this study. This method combined the high selectivity of antigen-antibody specific binding and the signal-amplification effect from the complex of colloidal platinum nanoparticles (PtNPs) and the PowerVision (PV) agent. It could detect RAC residues at ultra-trace levels specifically and sensitively. The secondary antibodies and a large amount of horseradish peroxidase (HRP) contained in the PV agent can specifically bind with antibodies and catalyze the substrate 3,3'-diaminobenzidine (DAB) to generate colored precipitates. PtNPs can also catalyze DAB to produce colored precipitates and complexes, thereby, achieving a double amplification effect. The amount of RAC residues in the sample can be calculated by measuring the changes in the absorbance of DAB precipitation. Under the optimized assay conditions, this method exhibited a high detection sensitivity and a good correlation in the range of 0.05~20 ng/mL with R2 = 0.992 And the detection limit was 0.025 ng/mL. This approach showed many advantages,including high sensitivity, selectivity, and accuracy as well as rapid detection,which can meet the requirement of onsite surveillance of RAC residues in pork.
