Fig. 2
Characterization of gold nanoparticles (GNPs) that were used as the model NP system for this study. a Schematic diagram of a GNP functionalized with a peptide containing integrin-binding domain, RGD (referred to as RGD peptide) and polyethylene glycol (PEG). This GNP complex is referred to as GNPPEG-RGD. b Transmission electron microscopy (TEM) image of GNPs with measured core diameter of ~ 15 nm. c, d Darkfield image and spectral profile of GNPs, respectively. e, f UV–visible absorption spectra and \(\zeta\)-potential measurements of as-made GNPs and GNPPEG–RGD. (g) Summary of characterization data for as-made GNPs, GNPPEG, and GNPPEG-RGD. The measurements were done using three different samples (n = 3) and error represents standard deviation