Principais técnicas empregadas para a caracterização de nanopartículas de ouro

Abstract

Nanoparticle characterization techniques play a fundamental role in understanding the properties and applications of these nanoscale structures. In particular, for the characterization of gold nanoparticles, molecular absorption spectroscopy in the ultraviolet and visible region (UV-Vis), Raman spectroscopy, dynamic light scattering (DLS) and transmission electron microscopy ( HE HAS). These techniques allow us to obtain valuable information about the structure, composition, size, shape and optical properties of nanoparticles. Using UV-Vis spectroscopy, the characteristic absorption pattern of particles can be monitored through plasmonic resonance; from Raman spectroscopy obtain information about the chemical composition through vibrational analysis; using the DLS technique, determine the size and frequency distribution of the diameters found of suspended particles, in addition to the zeta potential using the same instrument; and by TEM, visualization of the material through nanoscale images. In this scenario, we sought to present an overview, as well as the potential of such techniques for the characterization of gold nanoparticles (NPs) of different shapes, sizes and nature of surface functionalization. In this study, NPs were obtained in spherical and round shapes, with an average diameter of 13 nm and dimensions of 45x15 nm, in addition to a zeta potential of -55.7 mV and 79.4 mV respectively. The respective colloidal solutions obtained were quite stable, which was proven by the values obtained for the respective zeta potentials, whose surface charge signs depended on the nature of their surface. The modification of the NPs surface occurred through the addition of molecules containing functional groups with great affinity to the gold surface, such as thiol (-SH), using mercaptoacetic acid and cysteamine for spheres and rods respectively, where the interactions in different molar concentrations of gold and connector, in which the 1/1 concentration showed greater preservation of particle size and stability. Furthermore, characterization techniques have proven to be essential in the investigation and evaluation of studies with nanoparticles, and it is essential to continue studies that enable the surface modification of gold nanoparticles of different shapes and sizes, for potential applications, such as in biosensors, photonics and self-assembly, for example.