Multi-branched gold nanoflower-enhanced aptamer-based lateral flow assay for the detection of aflatoxin M1 in milk

The conventional aptamer-based lateral flow assay (Apt-LFA) often encounters limitations in sensitivity and detection range, primarily due to the use of gold nanoparticles (AuNPs) with insufficient brightness as labels and the strong affinity between the aptamer and complementary DNA (cDNA). To address this issue, we developed a multi-branched gold nanoflower (MAuNFs)-enhanced Apt-LFA, facilitating high-sensitive and on-site detection of aflatoxin M1 (AFM1). The MAuNFs functioned as signal amplification probes, possessed a three-dimensional branched structure, a broad absorption spectrum, and a high molar extinction coefficient, which collectively confer superior colorimetric properties and efficient molecular coupling. And AFM1-specific aptamer A21 was modified onto the MAuNFs surface, while cDNA was immobilized on the test line to establish a competitive detection system. To optimize the aptamer-cDNA affinity, the length of cDNA was systematically varied, with cDNA11 yielding the highest signal difference. The developed Apt-LFA achieved a limit of detection of 0.13 ng/mL for AFM1, with a linear range of 0.5-500 ng/mL. This study provides a novel approach for the utilization of advanced nanomaterial-aptamer conjugate systems in the sensitive detection of mycotoxins.