Small size nanoparticles-Co₃O₄ based lateral flow immunoassay biosensor for highly sensitive and rapid detection of...

Lateral flow immunoassay (LFIA) biosensor is a paper-based tool and widely utilized in various fields. Here, we developed a novel LFIA biosensor by introducing Co₃O₄ nanoparticles (NPs) as signal labels for highly sensitive detection of 3-amino-2-oxazolidinone (AOZ), a metabolite of furazolidone. The characteristic brown color of Co₃O₄ NPs enabled AOZ to be visually detected by the LFIA. Significantly, the size of Co₃O₄ NPs is relatively small compared with most of other signal labels, which could remarkably reduce steric hindrance, increase immunoreaction probability and shorten the analysis time. Under optimal conditions, the novel Co₃O₄ NPs-LFIA could possess high sensitivity for the detection of AOZ with a detection limit of 0.4 ng mL^-1 by naked eyes, which was at least 3-fold improved than that of the conventional gold nanoparticles (GNPs) based LFIA. Moreover, the detection could be achieved within 6 min and without cross-reactions with other analogue small molecules. Taking merits of convenience, rapid and sensitivity, the proposed Co₃O₄ NPs-LFIA may be readily adapted for the detection of other small molecules.