Tuning nanoparticle uptake: live-cell imaging reveals two distinct endocytosis mechanisms mediated by natural and artificial EGFR targeting ligand.

Therapeutic nanoparticles can be directed to cancer cells by incorporating selective targeting ligands. Here, we investigate the epidermal growth factor receptor (EGFR)-mediated endocytosis of gene carriers (polyplexes) either targeted with natural EGF or GE11, a short synthetic EGFR-binding peptide. Highly sensitive live-cell fluorescence microcopy with single particle resolution unraveled the existence of two different uptake mechanisms; EGF triggers accelerated nanoparticle endocytosis due to its dual active role in receptor binding and signaling activation. For GE11, an alternative EGFR signaling independent, actin-driven pathway is presented.