Investigating the specific uptake of EGF-conjugated nanoparticles in lung cancer cells using fluorescence imaging

Targeted nanoparticles have the potential to deliver a large drug payload specifically to cancer cells. Targeting requires that a ligand on the nanoparticle surface interact with a specific membrane receptor on target cells. However, the contribution of the targeting ligand to nanoparticle delivery is often influenced by non-specific nanoparticle uptake or secondary targeting mechanisms. In this study, we investigate the epidermal growth factor (EGF) receptor-targeting specificity of a nanoparticle by dual-color fluorescent labeling. The targeted nanoparticle was a fluorescently labeled, EGF-conjugated HDL-like peptide–phospholipid scaffold (HPPS) and the cell lines expressed EGF receptor linked with green fluorescent protein (EGFR-GFP). Using LDLA7 cells partially expressing EGFR-GFP, fluorescence imaging demonstrated the co-internalization of EGFR-GFP and EGF-HPPS, thus validating its targeting specificity. Furthermore, specific EGFR-mediated uptake of the EGF-HPPS nanoparticle was confirmed using human non-small cell lung cancer A549 cells. Subsequent confocal microscopy and flow cytometry studies delineated how secondary targeting mechanisms affected the EGFR targeting. Together, this study confirms the EGFR targeting of EGF-HPPS in lung cancer cells and provides insight on the potential influence of unintended targets on the desired ligand–receptor interaction.