Abstract: In this study, a down-conversion fluorescence-aptamer immunochromatographic strip was constructed for the rapid and efficient detection of aflatoxin B1 (AFB1) in foods. The presence of AFB1 in the system will weaken the binding ability of down-conversion-aptamer fluorescent nanoparticles to the hapten AFB1 when down-conversion-aptamer fluorescent nanoparticles reach the T-line, thus leading to the attenuation of down-conversion fluorescence signal and consequently highly efficient detection of AFB1. In the range of 1–40 ng/mL, the concentration of AFB1 had a good linear relationship with the fluorescence signal, showing a correlation coefficient of 0.994, and the detection limit for AFB1 was 0.287 ng/mL. By taking advantage of the long-lived luminescence and the near infrared fluorescence characteristics of rare earth doped fluorescent nanoparticles, this method effectively reduced the interference of biological background fluorescence and improved the specificity of the detection system, making it a promising candidate for application in the rapid and sensitive detection of AFB1.

Key words: rare earth doped fluorescent nanoparticles; fluorescence immunochromatographic assay; aflatoxin B1; rapid detection