Rapid monitoring of CFP-10 during culture of Mycobacterium tuberculosis by using a magnetophoretic immunoassay

Here, we introduce a rapid and robust sensing kit using sandwich-type magnetophoretic immunoassay (MPI) for the colorimetric detection of a secreted tuberculosis (TB)-associated antigen, CFP-10, in cultures of Mycobacterium tuberculosis (Mtb). Detection using this assay relies on the antigen-specific formation of complexes between Au nanoparticles (NPs) and magnetic microparticles (MMPs), such that magnetophoresis in the presence of CFP-10 decreases the plasmon absorbance of the assay solution due to the removal of Au NPs. The MPI offers rapid (results are obtained in 10 min), quantitative, and qualitative monitoring of CFP-10 expression in a detection range from 10 to 10,000 pg/mL with a detection limit of 10 pg/mL. Assay validation was performed by monitoring CFP-10 secreted during the Mtb culture. The data revealed a linear relationship between the concentration of CFP-10 in culture supernatants and the duration of Mtb culture. Thus, it shows high potential that the rapid and robust MPI sensing kit can be used for early TB diagnosis through immunoassay detection of TB-specific antigens in Mtb culture with further clinical investigation.