STUDY OF SYNTHESIS AND COORDINATION OF COLLOIDAL SILVER NANOPARTICLES WITH CAPPING CITRATEAND 3-MERCAPTOPROPIONIC

• Main Author: Taruna Hidayah, Yoda
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/80820
• Institution: Institut Teknologi Bandung

The development of the synthesis and application of metal nanoparticles is currently growing rapidly. Metal nanoparticles such as gold (AuNP) and silver (AgNP) are often used in various nanotechnology applications due to their unique optical properties, namely localized surface plasmon resonance (LSPR). This property occurs when there is an interaction between electromagnetic waves and metal nanoparticles. These interactions generate coherent local plasmon oscillations with frequencies that depend on the size and shape of the nanoparticles. In the process of making metal nanoparticles, capping is needed to prevent aggregation. In biosensor applications, organic materials such as thiol and citrate derivatives are often used due to their high affinity for gold and silver. At this time, much research has been carried out on AuNP, but not so on AgNP. This research aims to study the synthesis of silver nanoparticles using a modified chemical reduction method with citrate capping and 3-mercaptopropionic acid (3-MPA) and to characterize the experimental results obtained, as well as to carry out computational simulations to study the chemical coordination that occurs from the observed vibration frequencies. . Characterization of AgNPs was carried out using ultraviolet-visible spectroscopy (UV-Vis), fourier transform infrared (FTIR), and transmission electron microscopy (TEM). Computational simulations were carried out using the density functional theory (DFT) method with the Orca version 5.0.4 package which was used to see the optimization of geometry and vibration frequency. The results of UV-Vis characterization of AgNPs with a concentration of 1 wt% showed stable results with plasmonic peaks at wavelengths of 422 nm and 424 nm at week 4. Purification of AgNP is carried out to obtain pure AgNP by centrifugation process at high speed. The results of UV-Vis characterization after the centrifugation process on Ag-Citrate showed a second peak indicating aggregation of the nanoparticles, whereas on Ag-MPA, variations in speed of 6000 rpm showed that the second peak did not appear. FTIR characterization shows the types of coordination observed between Ag and capped citrate or 3-MPA molecules, especially for COO- coordination on citrate which is different between free COO- compared to COO- on Ag. Meanwhile, S-H and COOH from 3-MPA show different vibration peaks. To explain in more detail about this situation, a simulation of the coordination of Ag with citrate or 3-MPA was also carried out. From the simulation results it can be shown that the Ag atom has an ionic bond which is characterized by the Ag atom being bound to both oxygens in COO-. In this study, the spectrum peak in the COOH bond group of the 3-MPA structure from the experiment explains the occurrence of plasmon effects so that there are differences in the spectrum peak in the simulation results.