Dual-color MoS₂@QD nanosheets mediated dual-mode lateral flow immunoassay for flexible and ultrasensitive detection of multiple drug residues

The sensitive on-site monitoring of multiple agricultural drugs in complex real media is critical to human health but remains a challenge. In this paper, we reported the design of film-like dual-mode nanolabel (MTQD), using molybdenum disulfide (MoS₂) nanosheet-loaded numerous quantum dots (QDs) to generated co-enhanced colorimetric-fluorescence signals, and demonstrated its powerful capabilities in competitive lateral flow immunoassay (LFA) for flexible, ultrasensitive, and multiplex detection of four kinds of common agricultural drugs. Three layers of red and green QDs were continuously coated onto the surface of MoS₂ to suppress the inner filter effect of two-dimensional nanomaterials effectively and greatly improve the specificity of the LFA system for multitarget analysis. The dual-mode LFA combined with a low-cost dual-fluorescence reading instrument can flexibly and simultaneously monitor two pesticides (clothianidin, carbendazim) and two veterinary drugs (kanamycin, chloramphenicol) in complex food and experimental samples with low detection limits of 0.1 ng/mL level in the observation of colorimetric signals and showed at least a 46-fold improvement in sensitivity in the sensing of fluorescence signals. This colorimetric dual-fluorescence platform greatly broadens the application range of existing LFA techniques without increasing testing time, thus showing great application prospects for the point-of-care testing of small-molecule pollutants in different situations.