Properties of surface functionalized iron oxide nanoparticles (ferrofluid) conjugated antibody for lateral flow immunoassay application

► The effects of acid functionalization and biocompatible polymer on iron oxide nanoparticles (IONPs) ferrofluid were studied. ► The IONPs functionalized using citric acid (IONPs-CA) is the most stable ferrofluid with zeta potential value of −49 mV. ► IONPs-CA can be directly conjugated with antibody without biocompatible polymer coating. ► IONPs-CA had optimum detection efficiency of 15 min assay time. ► IONPs-CA showed the highest colour intensity in labelling lateral flow immunoassay.