Smartphone-based reading system integrated with phycocyanin-enhanced latex nanospheres immunoassay for on-site determination of aflatoxin B1 in foodstuffs.

Traditional methods for aflatoxin B1 (AFB1) detection are complex, time-consuming, labor-intensive, and high cost. Moreover, they require sophisticated large-scale instrumentation, which limits their on-site rapid detection. Herein, phycocyanin fluorescent nanospheres based on fluorescence immunochromatographic assay were developed for quantitative detection of AFB1 at parts-per-billion (ppb) levels in foodstuffs. Phycocyanin and anti-AFB1 monoclonal antibodies were coupled on the surface of latex nanospheres to amplify the fluorescence signal and improve the sensitivity. The fluorescence intensity was measured by a self-developed smartphone-based reading system. Under the optimal conditions, this approach achieved quantitative point-of-care detection of AFB1 within 25 min. The calibration curve for AFB1 was linear in the range of 0.2-48 ppb, and the limit of detection was 0.16 ppb. The practical applicability of the proposed approach was demonstrated by the determination of AFB1 in naturally contaminated samples, and the results were consistent with HPLC detection.