| Summary: | 碩士 === 東海大學 === 化學系 === 98 === In this research, we use the amino acid tyrosine as a reducing agent under alkaline conditions to yield stable nanoparticles in water. The reducing capability of tyrosine is due to ionization of the phenolic group of tyrosine at high pH, which by electron transfer to gold and silver ions, then synthesis of Au core-Ag shell nanoparticles. The results show that phenolic group transforms to ketone group type.
In the experiment, we control the reactant concentrations, pH values of solution, reaction temperature, and quantity of the reducing agent. The reactant concentrations increasing can make shell thickness growth. Change the pH values of solution to control tyrosine reducing ability and nanoparticle’s mean size. If the synthesis process through heating, it can accelerate the reduction and make it more complete. In another way, the quantity of the reducing agent has a great effect on the acidic solution, and particle’s mean size is between 20-32 nm. Finally, we use UV-Visible spectroscopy, Transmission electron microscopy (TEM), Fourier transform Infrared spectroscopy (FT-IR), X-ray photoemission spectroscopy (XPS) and Small-Angle X-ray Scattering (SAXS) to analyse and characterize the physical and chemical properties of nanaoparticles. The Tyrosine-reduced silver nanoparticle’s mean size is about 22.84 nm; Tyrosine-reduced gold nanoparticle’s mean size is between 11-32 nm; Au Core-Ag Shell nanoparticle’s mean size is between 10-18 nm.
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