TEM and UV-vis images. (A) Gold nanoparticles by Tris. (B) Nanoparticles by glucose form a variety of structures. (C) Gold nanoparticles by sodium citrate are spherical monodispersed. (D) The UV-vis spectra: the absorbance intensity of AuNPs by citrate methods, glucose method, and Tris method are peaked at 519, 547, and 524 nm, respectively.