Characterization of as-fabricated Au-decorated GO nanocomposites. Three as-fabricated nanocomposites including GO, GO-Au, and GO-Au (×2) were subjected to analyze: (A) UV-Vis absorption spectra, where the peak at 520 nm is the absorption wavelength of AuNPs; (B) FTIR spectra; (C) AFM image of GO; (D) average contact angle (θ). The contact angle from different materials without water is θ = 0°. Finally, (E) trapping potential for DPPH radical scavenging activity of three as-fabricated nanocomposites was also validated. The data were expressed as means ± SD of three independent experiments. ** p < 0.01. To validate the GO effectively stabilized on the glass substrates, first, GO was well-dispersed in either (F) DI-water or DI-water/methanol (MeOH) mixture solution (1:1, v/v) and then spin-coated onto glass substrates (cover slides). Next, these samples were placed on culture plates and soaked in different solutions including DMEM culture medium, PBS, and without solution (empty). Small pieces of GO film were suspended (indicated as yellow arrows), whereas well-coated and stabilized GO film was found.