Fig. 2

The characterization of the synthesized naked and conjugated GNPs. a UV–Vis absorption spectra of GNPs before and after modifications. b DLS curves of GNPs and GNP–VGB3 related to hydrodynamic diameters. c The zeta potentials of GNPs and GNP–VGB3. d FT-IR spectra of GNP and VGB3 and their conjugations in the 400–4000 cm⁻¹ region. e AFM of GNP and GNP–VGB3. (1, 2) AFM analysis depicted the mean diameter of GNPs in 3D and 2D images, respectively (scale bar: 500 nm), and (3, 4) In the same way, the obtained images from GNP–VGB3 were dedicated within a scan area of 0.5 μm × 0.5 μm. f TEM images to verify the size, shape and the size distributions of GNPs and GNP–VGB3, respectively (scale bar: 50 nm) and g EDS analysis of GNPs-VGB3 and its mapping to identify each element in the sample (Au: red; C: green, and O: Violet)