Synthesis and Characterization of Passivated Silver Nanoparticles. Sophia Lee Matracia, Kimberly Muljono & Carcy Chan
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Metal nanoparticles are crystals composed of thousands of atoms. These nanoparticles are bits of matter that lay between the single atom and bulk metal. Initially synthesized to probe quantum confinement effects, a wide variety of nanoparticles now serve as fluorescent markers in biological systems and building blocks for functional, macroscopic materials. In this study, passivated Ag nanoparticles are synthesized and their sizes and crystallinity are characterized. The passivation layer serves to ease size-selection methods in organic solvents and produce narrow size distributions. The silver nanoparticles were prepared in the presence of sodium borohydride, dodecanethiol, org! anic solvents such as toluene or chloroform, and a phase transfer reagent, which transfers the particles from the aqueous solution to the organic solution. Following synthesis and size-selection, the silver nanoparticles were characterized via UV/Visible spectrometry, AFM (Atomic Force Microscope), and TEM (Transmission Electron Microscope). The results show that the toluene synthesis had a high yield, while the chloroform synthesis yielded a low quantity. In addition, the average diameter of silver nanoparticles synthesized in toluene was smaller than the one prepared in the presence of chloroform. Finally, ideas for the purposeful conjugation of discrete numbers of these nanoparticles will be presented.