In terms of biomarkers, magnetic nanoparticles can be used to label cells or biological molecules for detection and analysis. For cell separation, magnetic nanoparticles can bind to cell-specific antibodies and achieve targeted separation and analysis of cells. In targeted cell therapy, magnetic nanoparticles can be combined with drugs and used for targeted therapy of cells. As for drug delivery, magnetic nanoparticles can act as carriers to transport drugs to the desired treatment site.