Determination of Abrin by a Magnetic Affinity Immunoassay (MAIA) Based on the Signal Amplification of the Aptamer and Staphylococcal Protein A (SPA) Functionalized Gold Magnetic Microparticles (GMPs)

Abstract

A new magnetic affinity immunoassay (MAIA) was developed for the determination of abrin based on signal amplification of staphylococcal protein A (SPA) functionalized gold magnetic microparticles (GMPs) and the aptamer. This assay consisted of a sandwich format in which SPA-coated GMPs coupled anti-abrin monoclonal antibodies (mcAb) were used as the magnetic capture probe and the enzyme-labeled abrin aptamer was used as the signal probe. Abrin was successfully determined by the proposed strategy. This method exhibited a linear response to abrin from 0.031 to 31.25 μg/L with a detection limit of 0.031 μg/L. The staphylococcal protein A, gold magnetic microparticles, and aptamer increased the sensitivity by 4 times, 2 times and 2 times, respectively The integrated amplification produced by these parameters increased the sensitivity by 16-fold compared to the traditional double-antibody sandwich enzyme linked immunosorbent assay (ELISA). This method possesses a low detection limit, acceptable reproducibility, and high specificity, which demonstrates that the MAIA shows promise in trace toxin determination.

Keywords:

• magnetic affinity immunoassay (MAIA)
• staphylococcal protein A (SPA)
• gold magnetic microparticle (GMPs)
• aptamer
• abrin

Additional information

Funding

This work was supported by the Foundation of State Key Laboratory of NBC Protection for Civilians (SKLNBC2020-03).