Highly sensitive detection of a small molecule by a paired labels recognition system based lateral flow assay

Leina Dou, Bingxin Zhao, Tong Bu, Wentao Zhang, Qiong Huang, Lingzhi Yan, Lunjie Huang, Yanru Wang, Jianlong Wang, Daohong Zhang

Small molecules are difficult to detect by conventional gold lateral flow assay (GLFA) sensitively because the test system must satisfy the conflict requirements between enough signal intensity and limited antibody (Ab) amount. In this work, a paired labels recognition (PLR)-based biosensor was designed by utilizing the specific binding of Ab and secondary antibody (anti-Ab) to enhance signal intensity and reduce antibody amount applied in small molecule detection. The PLR amplification system is fabricated by self-assembling the common detection probe, Au-labeled Ab (Au-Ab), and the signal booster, Au-labeled anti-Ab (Au-anti-Ab). Benefiting from this, a powerful network structure can be generated to accumulate numerous gold nanoparticles (GNPs) and thus significantly strengthen the signal intensity of detection. Therefore, a lower Ab amount will be applied to offer adequate signal strength, and further, the limit of detection will be obviously downregulated due to the more effective competition reaction. Using furazolidone (FZD) as a model analyte, we achieve a detection limit of as low as 1 ng mL-1, which was at least fivefold improved over that of the traditional GLFA. Furthermore, the practicality of this strategy was certificated in five different food samples. Graphical abstract A paired labels recognition (PLR) amplification system is fabricated by self-assembling the common detection probe, Au-labeled Ab (Au-Ab), and the signal booster, Au-labeled anti-Ab (Au-anti-Ab). In this novel strategy, owing to the recognition of both Ab and anti-Ab labeled on gold nanoparticles (GNPs), a powerful network structure can be generated to accumulate numerous GNPs and thus significantly strengthen the signal intensity of detection.