Síntese e caracterização de nanopartículas metálicas utilizando extratos de Hymenaea courbaril

Abstract

Nanotechnology is a multidisciplinary field that encompasses several areas, such as biology, physics, chemistry and engineering for the creation, manipulation and application of materials at the nanometer scale. The synthesis of metallic nanoparticles (NPs) can be carried out by physical, chemical or biological methods, however, when it is carried out by physical or chemical methods, these can present disadvantages, due to the need for a chemical reducing agent, stabilizing agents or chemical agents that can limit your applications. Therefore, obtaining new simple and less toxic synthetic routes of NPs is necessary. The work highlights the biosynthesis of gold and silver NPs, in aqueous medium, using extracts of bark, leaf and seed of Jatobá (Hymenaea courbaril). Interest in the synthesis of NPs using natural products has been growing in recent decades, as natural products are also an important source of new antimicrobial compounds. The plant extracts were initially diluted in distilled, deionized water (H2O) and dimethylsulfoxide (DMSO). In a beaker containing water, under stirring and heating (80oC), the metallic precursors, tetrachloroauric acid (HAuCl4) were added for the synthesis of gold NPs and silver nitrate (AgNO3) for the synthesis of silver NPs. Then, extracts from the bark, seed and leaf of Jatobá were added separately in each beaker. After the addition of metallic precursors, a change in the color of the reaction medium was observed, indicating the formation of NPs. The characterizations of NPs were performed by UV-Visible absorption spectroscopy and by transmission electron microscopy (TEM). The methodology of biosynthesis of metallic NPs showed to be promising due to the speed and simplicity of the process. Through spectroscopic analysis, a maximum absorption was observed in the range between 530 and 540 nm for gold NPs. TEM images showed the formation of gold NPs with dimensions between 2 and 40 nm. The use of extracts was also promising in obtaining silver NPs. Through the UV-Visible absorption spectra, high absorption intensities were observed at 275 nm, characterizing the compounds present in the extracts. Samples containing Jatobá seed extracts were more advantageous in the formation of silver NPs due to the identification of absorption peaks at 430 nm. In this work, it was observed that extracts of bark, leaves and seeds of Jatobá can replace different toxic reducing agents used in the chemical synthesis of NPs. The use of plant extracts in the synthesis of metallic NPs is not yet fully understood, but they show promise for use in several synthesis methodologies and in future biotechnological applications.