چكيده به لاتين
Nanoparticles, especially gold nanoparticles, have attracted a lot of attention in recent years. With decreasing the size of a particle, its surface-to-volume ratio increases, and many of its properties change significantly. Gold nanoparticles are used widely in the biological and medical fields. They can generate high heat to kill cancer cells in hyperthermia and carry different types of drugs in chemotherapy. In this project, the impression of ligands type and carbon chain length of them, and temperature on the solubility, optical and electronic properties of the smallest gold nanoparticle with the general formula of Au18S14, was investigated in water solvent. Quantum mechanical calculations and molecular dynamics simulations were employed to obtain the data. In the first part of the work, ligands including 1,1-Mercaptoethyl alcohol, Beta-Mercaptoethanol, Cysteamine, and Thioglycolic acid add to the sulfur atoms in the central gold structure with the general formula of Au18S14. Calculations of the electronic and dynamic properties showed 1,1-mercaptoethyl alcohol-containing particle has the best electronic properties in terms of light absorption and safety for use in cancer treatment methods such as hyperthermia. Also, dipole moment, chemical hardness, radial distribution function, mean square displacement, and solvent free energy data showed that the nanoparticle with 1,1-mercaptoethyl alcohol ligands is more soluble than other nanoparticles. In the second part of the work, 2-Dimethylaminoethane thiol, 4-Mercaptobenzoic acid, and 3-Mercaptopropionic acid ligands were applied to the gold nanoparticle. Studies of the properties of these structures in three temperatures: 290, 300, and 310 K, showed that increasing the temperature leads to more solubility. Among these structures, nanoparticles containing 4-mercaptobenzoic acid ligands have the highest solubility at all three temperatures. Also, by changing the carbon chain length in the particle with 3-mercaptopropionic acid ligands, molecules with 4-mercaptobutyric acid and 5-mercaptopentanoic acid ligands, which have four- and five-carbon chains, respectively, were obtained. So, examining the length of the ligand showed that increasing the length of the carbon chain to a certain extent can improve the stability and solubility of the nanoparticle.