Chemical-staining based lateral flow immunoassay: A nanomaterials-free and ultra-simple tool for a small molecule detection

[Display omitted] •A chemical-staining (crystal violet) based lateral flow immunoassay (LFIA) is first proposed for small molecule detection.•The developed LFIA significantly simplify the assay behavior and conquer the intrinsic limitations of nanomaterials labels.•The LFIA were successfully applied in several food samples for furazolidone detection. The nanomaterials based lateral flow immunoassays (LFIAs) have been widely used for on-site detection of small molecules contaminants. Nevertheless, their practical applications are often constrained by the complicated materials synthesis and surface modification process of nanomaterials. Herein, inspired by chemical-staining, a crystal violet (CV) staining based LFIAs was innovatively developed for the first time to analyze small molecules contaminant with significantly simplified behaviour and surpassing repeatability. This nanomaterials-free technique overcomes the intrinsic limitations of nanomaterials, owing to the superior protein dye property of CV. To demonstrate the feasibility of the unique strategy, furazolidone (FZD) was used as a model analyte, results showed detection limits of as low as 7 and 1.53 ng mL−1 by visual observation and quantitative analysis, respectively. Finally, to validate its applicability in actual conditions, the platform is well applied in three kinds of food samples (shrimp, fish and pork). Furthermore, as the detection principle is based on the molecular recognition between antigen and antibody, our method may find general applications by staining other antibodies against other target analytes.