Gold nanoparticles were synthesized using the citrate reduction method [53 (link)]. First, 300 μL of 1% chloroauric acid (HAuCl4·3H2O) (Sigma-Aldrich, Oakville, ON, Canada) was added to 30 mL of double–distilled water and heated on a hot plate while stirring. Once it reached the boiling point, 1 mL of 1% sodium citrate tribasic dehydrate (HOC(COONa)(CH2COONa)2·2H2O) (Sigma-Aldrich) was added. After the color of the solution changed from dark blue to bright red, the solution was left to boil for another 5 min while being stirred. Finally, the GNP solution was brought to room temperature while being stirred.
The GNPs were characterized by Transmission Electron Microscopy (TEM) (H7000; Hitachi Corp., Tokyo, Japan), UV-spectroscopy (Lambda 40; PerkinElmer, Waltham, MA, USA), Hyper Spectral Imaging (HSI), and by Dynamic Light Scattering (DLS) using a 90 Plus Particle Sizer Analyzer (Brookhaven Instruments Corp., New York, NY, USA) to determine the size of the NPs.
The GNPs were characterized by Transmission Electron Microscopy (TEM) (H7000; Hitachi Corp., Tokyo, Japan), UV-spectroscopy (Lambda 40; PerkinElmer, Waltham, MA, USA), Hyper Spectral Imaging (HSI), and by Dynamic Light Scattering (DLS) using a 90 Plus Particle Sizer Analyzer (Brookhaven Instruments Corp., New York, NY, USA) to determine the size of the NPs.