Quantitative detection of aflatoxin B1 using quantum dots-based immunoassay in a recyclable gravity-driven microfluidic chip

To achieve rapid and sensitive detection of aflatoxin B1 (AFB1), we developed a polydimethylsiloxane gravitydriven cyclic microfluidic chip using the two-signal mode strategy. The structural design of the chip, together with the two-wavelength quantum dot ratio fluorescence, effectively eliminates the influence of environmental factors, improves the signal stability, and ensures that the final detection result positively correlates with the target concentration. Moreover, the theoretical analysis performed for the established physical model of the three-dimensional reaction interface inside the chip confirmed the improved reaction rate of immune adsorption in the microfluidic strategy. Overall, the method exhibited a wide analytic range (0.2-500 ng mL-1), low detection limit (0.06 ng mL-1), high specificity, good precision (coefficient of variation < 5%), excellent reusability (20 times, 89.1%) and satisfactory practical sample analysis capacity. Furthermore, the reusability and designability of this chip provide a reliable scheme for field detection of AFB1, analysis of other small molecules, and establishment of high-throughput detection systems under different conditions.