The pH role about synthesis, distribution and potential applications of gold nanoparticles

The synthesis of metallic nanoaprticles (NPs) is currently performed through the development of methodologies using microorganisms, plant extracts, and even organic waste, seeking to mitigate the impact on the environment. However, for both synthesis and biosynthesis it is necessary to consider physical and chemical factors such as temperature, stirring and pH, that allow controlling size and shape in an accurate way, as size and shape play an important role in the optical, electronic and thermal properties and determine many features of the structure and activity of molecules and biomolecules. In this work, we carry out chemical synthesis and biosynthesis of AuNPs at acidic (3-6), neutral (7) and basic (9) pH; the process is fast, simple and eco-friendly. We obtained AuNPs from 5-100 nm and determined that the pH of the solution is a key factor in the distribution and shape of the nanoparticles. Uniform AuNPs were obtained at neutral pH, or values of pH near neutrality. In addition, they have potential applications in various fields, due to their optical, magnetic, catalytic and electrical properties.