Nanobody-based dual-mode sensing platform for highly sensitive detection of aflatoxin B1

Lateral Flow Immunochromatography (LFIA) has been widely used to rapidly detect mycotoxins like aflatoxin B1 (AFB1) due to its simplicity and effectiveness. However, conventional LFIA methods rely heavily on antigens, leading to high production costs and health risks. To address these issues, we developed a nanobody-alkaline phosphatase fusion protein (AP2-5), which can be used as an alternative to antigens in AFB1 analysis. Moreover, AP (alkaline phosphatase) can spontaneously dimerise in solution to make a bivalent nanobody with increasing affinity. Through a two-step strategy involving Cu substitution of oxygen vacancies and tannic acid encapsulation, we successfully synthesized a novel bimodal signaling tracer Cu-MoOx NPs (CMO), which demonstrated outstanding water dispersibility, exceptional colorimetric intensity, high photothermal conversion efficiency (η = 45.58 %), and significantly enhanced antibody coupling efficiency (79.10 %-94.68 %). Leveraging the innovative CMO platform, we developed a colorimetric (CM)/photothermal (PT) dual-mode LFIA (CM-LFIA/PT-LFIA) for the rapid and sensitive detection of AFB1 in food products. The system exhibited a limit of detection (LOD) of 0.0191 ng mL^-1 and achieved excellent recoveries ranging from 85.07 % to 117.03 % in corn, oatmeal, and soybean samples. This study represents a novel approach in the development of eco-friendly and cost-effective mycotoxin detection methods, offering new potential for advancing food quality control and public health.