Nanoparticle stabilizer as a determining factor of the drug/gold surface interaction: SERS and AFM-SEIRA studies

Abstract

Metal nanoparticles, with their unique physicochemical and biological properties, have become increasingly studied for application in the medical field. However, the observed cytotoxicity of these structures is still a concerning issue. One of the factors determining the toxic effect of nanoparticles is the stabilizer that is present on the nanoparticle surface to prevent aggregation. In this study, the effect of the stabilizer on the drug/metal interaction is considered. For this purpose, surface-enhanced Raman spectroscopy (SERS) was applied for the characterization of erlotinib (drug included in non-small-cell lung cancer therapy) adsorption on two types of gold nanoparticles (AuNPs) obtained from a chemical reduction method using trisodium citrate (CT) and sodium borohydride (SB). Additionally, atomic force microscopy in combination with infrared spectroscopy (AFM-IR) was used with two polarization modulations to more locally determine the drug adsorption geometry, namely, at a nanoscale spatial resolution. The obtained results indicate that the aliphatic functional groups of erlotinib, NH, CH2, and OCH3, demonstrate a stronger interaction with AuSBNPs in comparison with AuCTNPs. These data imply that the effect of the stabilizing layer should be taken into account in the design of drug/metal nanoparticle conjugates.