Affibody‐Functionalized Gold–Silica Nanoparticles for Raman Molecular Imaging of the Epidermal Growth Factor Receptor

Abstract The affibody functionalization of fluorescent surface‐enhanced Raman scattering gold–silica nanoparticles as multimodal contrast agents for molecular imaging specific to epidermal growth factor receptor (EGFR) is reported. This nanoparticle bioconjugate reports EGFR‐positive A431 tumors with a signal nearly 35‐fold higher than EGFR‐negative MDA‐435S tumors. The low‐level EGFR expression in adjacent healthy tissue is 7‐fold lower than in the positive tumors. Validation via competitive inhibition reduces the signal by a factor of six, and independent measurement of EGFR via flow cytometry correlates at R 2 = 0.92.