Overexpression of the epidermal growth factor receptor (EGFR) has been observed in many solid tumors, and it has been shown to affect cell proliferation, apoptosis, angiogenesis and metastatic expansion [1, 2]. The receptor activates upon binding of the EGF peptide to the extracellular domain, leading to dimerization or activation of pre-existing dimers . New classes of therapeutic agents aim to block the receptor dimerization, with possible consequences in cell proliferation and apoptosis .
In this research, plasmonic nanoparticles (NPs) were used to investigate and block the spatial receptor organization that controls the EGFR signalling activity in HeLa cells. NPs of different shapes (spheres, rods) and dimensions were functionalized with EGF for subsequent EGFR binding by direct thiolation of the protein . Verification of the particle functionalization was determined with spectroscopy and transmission electron microscopy techniques. These revealed a preferential protein binding site on the tips of the rods. Verification of the receptor binding was performed by imaging the scattered light from the NP-treated cells. Cell proliferation was determined via a colorimetric assay (MTS), showing an inhibition of cell proliferation with the use of the rod-shape particles. To the best of our knowledge, this effect has never been reported before and it appears to be linked to the mechanical blocking of the dimerization configuration. The use of NPs as EGFR blocking agents holds great potential for future studies on measuring the EGFR dimerization length using standard biophysical and plasmonic techniques [4, 5].