In addition to the nanoparticles synthesized and characterized by the procedures described above, commercial GNPs (BBInternational) were also analyzed for comparison. Size and number density of these nanoparticles were obtained from the manufacturer’s datasheet. To facilitate a distinction between the two types of particles, results obtained from the commercial nanoparticles are symbolized with down triangles, whereas the results obtained from in-house synthesized nanoparticles are symbolized with up triangles in all figures.