Development of a quantum dot nanobead-based fluorescent strip immunosensor for on-site detection of aflatoxin B1 in lotus seeds

Abstract

Owing to the serious threat of aflatoxin B₁ (AFB₁) to public health, development of a reliable method for accurate determination of it is extremely necessary and urgent. In this study, a simple, rapid and highly-sensitive quantum dot nanobeads (QBs) based lateral flow fluorescent strip immunosensor was developed for on-site detection of AFB₁ in edible and medicinal lotus seeds. Carboxylated QBs were used as the fluorescent markers to prepare the fluorescent probe through coupling QBs with anti-AFB1 antibodies. Bovine serum albumin (BSA)-AFB₁ antigens and goat anti-mouse IgG antibodies were coated on the nitrocellulose (NC) membrane to prepare the test (T) and control (C) lines, respectively. Qualitative analysis of AFB₁ was realized by naked eye, and the quantitative determination was achieved with a portable strip reader. Results showed that the newly-developed test strip sensor could achieve rapid detection of AFB₁ within 15 min, allowing a limit of detection (LOD) of 1 ng/mL (2 μg/kg) and a linear range of 1-19 ng/mL (2-38 μg/kg). Recovery rates from the fortified lotus seeds with low, medium and high spiking concentrations (2.5, 5 and 10 μg/kg) ranged from 94.0% to 116.0% with relative standard deviations less than 10%. All the results were confirmed by a standard LC-MS/MS method. The QBs-based fluorescent strip immunosensor with high sensitivity, easy operation, and low cost provided a preferred solution for rapid, on-site screening and highly-sensitive quantitation of AFB₁ in a large number of lotus seed samples.

Keywords: Aflatoxin B(1); Fluorescent strip immunosensor; Highly-sensitive on-site detection; Lotus seed; Quantum dot nanobeads.