Study of superparamagnetic nanoparticles as labels in the quantitative lateral flow immunoassay

The superparamagnetic nanoparticles (MNPs) with a series of sizes and magnetite contents are designed and prepared as labels used in lateral flow immunoassay (LFIA) to test if the size and magnetite content of MNPs can affect the performance of LFIA. The result showed that detection time was mainly determined by the size of MNPs, while the signal intensity was closely correlated to the magnetite content of the MNPs. In addition, the magnetic signals intensity remained stable over a long time period. Smaller MNPs with higher magnetite content are first choices as labels to construct a rapid and high-sensitive quantitative LFIA.