Gallotannin-Capped Gold Nanoparticles: Green Synthesis and Enhanced Morphology of AFM Images.

Gold nanoparticles (AuNPs) were synthesized by a green method using a plant secondary metabolite, gallotannin. Gallotannin was used as a reducing and capping agent to convert gold ions into AuNPs for the generation of gallotannin-capped AuNPs (GT-AuNPs). This synthetic route is ecofriendly and eliminates the use of toxic chemical reducing agents. The characteristic surface plasmon resonance of the GT-AuNPs was observed at 536 nm in the UV-visible spectra. The face-centered cubic structure of GT-AuNPs was verified by X-ray diffraction analysis. The majority of the GT-AuNPs had a spherical shape with an average diameter of 15.93 ± 8.60 nm. Fourier transform infrared spectra suggested that the hydroxyl functional groups of gallotannin were involved in the synthesis of GT-AuNPs. The size and shape of nanoparticles can have a crucial impact on their biological, mechanical, and structural properties. Herein, we developed a modified anisotropic diffusion equation to selectively remove nanoscale experimental noise while preserving nanoscale intrinsic geometry information. To demonstrate the performance of the developed method, the ridge and valley lines were plotted by utilizing the principle curvatures. Compared to the original anisotropic diffusion and raw atomic force microscopy (AFM) experimental data, the developed modified anisotropic diffusion shows excellent performance in nanoscale noise removal while preserving the intrinsic aeometry of the nanoparticles.