An ultrasensitive visual detection platform for forchlorfenuron: from simulation-assisted hapten and antibody...

Forchlorfenuron (FCF), a widely utilized cytokinin-type plant growth regulator, poses a considerable threat to human health and ecological stability when overapplied. This issue has consequently driven an escalating demand for real-time, on-site monitoring technologies capable of detecting FCF residues in agricultural products and environmental matrices. Herein, computational quantum chemical analyses were conducted to elucidate the 3D structures of FCF and four designed haptens, thereby enabling the systematic evaluation of potential epitope masking sites. On the basis of these analyses, two structurally reliable haptens were screened out, which further facilitated the successful development of a highly matrix-tolerant and specific anti-FCF monoclonal antibody (mAb). Based on mAb, the AuNP-labeled double-T immunochromatographic assay was firstly developed to detect FCF in orange, grape, and soil samples. The limits of detection (LOD) were 2.640 µg kg^-1, 1.069 µg kg^-1, and 3.628 µg kg^-1, respectively, with linear ranges of 3.55-296.25 µg kg^-1, 1.44-231.37 µg kg^-1, and 5.28-438.03 µg kg^-1, respectively. Method validation confirmed that the obtained results were in good agreement with those derived from LC-MS/MS, thus verifying that the established double-T immunochromatographic assay is well suited for the rapid, quantitative, and on-site monitoring of FCF residues in food and environmental samples.