Targeting EGFR-overexpressed A431 cells with EGF-labeled silica-coated magnetic nanoparticles

Human epidermal growth-factor receptor (EGFR) has emerged as an attractive target for cancer therapy. In this study, amino- or carboxyl-functionalized silica-coated maghemite nanoparticles were conjugated with epidermal growth-factor (EGF) using five different binding modes: carbodiimide chemistry, two types of homo-bifunctional cross-linking reagents, and electrostatic interactions between the nanoparticles and the EGF. The nanoparticles and their aqueous suspensions were characterized by transmission electron microscopy, zeta-potential measurements and dynamic light scattering. The binding efficiency of the EGF to the nanoparticles was measured by flow cytometry using a specific anti-EGF antibody. The ability of EGF bioconjugates to target the EGF receptors was tested using EGFR over-expressing A431 cells in comparison to EGFR negative HeLa cells. Our results showed that the bioconjugates where the EGF was bonded by carbodiimide chemistry are the most effective for the specific targeting of EGFR-expressing cells in vitro.