Size Distribution of Gold Nanoparticles Synthesized by Artemisia annua L. Hairy Root Extracts

Abstract

"Green" synthesis is a novel and effective method of obtaining metal nanoparticles. Using plant extracts to synthesize nanoparticles is safe for the environment and does not require expensive and complex equipment. Based on their particular characteristics, such nanomaterials have potential applications in various fields of industry and medicine. Gold nanoparticles (AuNPs) are used in different areas where chemical inertia, nontoxicity, and good biocompatibility are required. That is why optimization of methods of AuNP obtaining besides theoretical has a practical interest. In this work, the features of gold nanoparticles obtained using extracts from the hairy roots of Artemisia annua L. during storage were investigated. AuNPs were obtained by adding ethanol (70%) extracts from the roots to a solution of HAuCl₄. Nanoparticles were studied using transmission electron microscopy (TEM) on the first and 14th days after initiation. TEM analysis revealed significant differences in the sizes of nanoparticles and changes during their storage. After two weeks post-initiation, AuNPs increased in size, and conglomerates formed, leading to nanoparticle precipitation. Such changes were noted for samples of AuNPs produced using extracts from transgenic roots and, to a lesser extent, those samples obtained when extracts from the roots of the control plants were added to the HAuCl₄ solution. This data indicates the necessity for additional research to explain the mechanisms of this effect and to test more hairy root lines to find extracts that will promote the formation of more stable AuNPs.