Polydopamine nanospheres as high-affinity signal tag towards lateral flow immunoassay for sensitive furazolidone detection

•Polydopamine nanospheres (PDA NPs) were first used as signal substrate in the LFIA.•The PDA NPs based LFIA was well applied for furazolidone monitoring in food samples.•For a change, here the antibody and PDA NP were bound by covalent connection.•The stability of antibody-PDA NP probe was superior than that of formerly used probe. Currently, the low sensitivity and poor binding stability of detection probe prepared via electrostatic adsorption have become the dilemmas of colloidal gold-based lateral flow immunoassays (Au-LFIAs). In this connection, polydopamine nanospheres (PDA NPs) with an eminent covalent connectivity property were introduced as a promising substitute to improve the stability of probe and sensitivity of LFIA. Whereafter, the PDA NPs-based LFIA was applied for the monitoring of furazolidone (FZD) in food samples because of the potential carcinogenic/mutagenic effects to human of its metabolite (3-amino-2-oxazolidinone, AOZ). Compared with electrostatic adsorption, the binding stability of PDA NPs-based probes was superior. And, as expected, the PDA NPs-based LFIA biosensor exhibited higher sensitivity than that of the Au-LFIA with a detection limit of 3.5 ng mL−1 for AOZ by naked-eye readout. Based on the significant enhanced binding stability and sensitivity, the PDA NPs-based LFIA is of certain spreading value for detecting other analytes.