Figure 2.

Characterization of GNPs. (A) Schematic diagram showing the presence of both PEG and RGD peptide molecules on GNP_PEG-RGD complex used for the study. (B) TEM images of GNPs with a core size of ~17.73 nm (±0.17 nm). Scale bar is 50 nm. (C) DF and HSI images of as-made GNP. Scale bar is 40 µm. For (D–G), the GNP_PEG are GNPs that are functionalized with a polyethylene glycol (PEG) molecule as a stabilizing agent, and the GNP_PEG-RGD are GNP that are functionalized with PEG and with RGD peptides to improve GNPs uptake. (D–F) UV–Visible absorption spectra, hydrodynamic diameter, and ζ-potential measurements of pure GNPs, GNP_PEG, and GNP_PEG-RGD, respectively. (G) Summary of peak absorption wavelength, hydrodynamic diameter, and mean ζ-potential for pure GNPs, GNP_PEG, and GNP_PEG-RGD. (Note: the error is represented by the standard deviation over three different measurements).