Fig. 1.
Synthesis and characterization of HGNPs. A) Synthesis of GNPs and HGNPs. B) Transmission electron microscopy (TEM) image of GNPs (scale bar: 20 nm) and photograph of the GNP solution. C) The hydrodynamic diameter of GNPs analyzed by dynamic light scattering (DLS). D) TEM image of HGNPs (stained with 2% phosphotungstic acid, pH = 6.0, scale bar: 20 nm) and photograph of the HGNP solution. E) The hydrodynamic diameter of HGNPs obtained by DLS analysis.