Reliable colorimetric aptasensor exploiting 72-Mers ssDNA and gold nanoprobes for highly sensitive detection of aflatoxin M1 in milk

Abstract

The development of a label-free colorimetric aptasensor has been accomplished for rapid quantification of aflatoxin M1 (AFM1) based on localized surface plasmon resonance (LSPR) and aggregation of gold nanoparticles (AuNPs). The sensor utilizes competitive interactions of the aptamer to the AFM1 or the AuNPs under a specific condition exploiting sodium chloride to aggregate AuNPs. In principle, the aptamer interacts with AFM1 selectively, resulting in a change of its structure; consequently, the aptamer cannot prevent AuNPs aggregation induced by sodium chloride. A new color tone of the solution caused by the LSPR peak shift of aggregated AuNPs can be measured by a colorimetric method. The detection limit of the sensor was 0.002 ng mL−1, providing exceptionally analytical sensitivity that conforms to the maximal residue limits of AFM1. Moreover, the current method has been successfully utilized to determine AFM1 in milk. Recoveries obtained were higher than 80 %, with RSD lower than 10 %, denominating that the colorimetric aptasensor devotes practicability for real samples.