CD44 and breast cancer: Glycoprotein CD44 is overexpressed on most breast cancercells and is the primary cell surface receptor for hyaluronan (HA).To facilitate breast cancer diagnosis, we report an indocyanine green(ICG) and HA conjugated iron oxide nanoparticle (NP-ICG-HA), whichenabled active targeting to breast cancer by HA-CD44 interaction anddetected metastasis with magnetic particle imaging (MPI) and near-infraredfluorescence imaging (NIR-FI).