Síntese e caracterização de nanopartículas magneto-plasmônicas de Au-Fe(óxido) e sua aplicação como substrato SERS

Abstract

The synthesis of hybrid nanomaterials combining optical and magnetic properties has attracted great interest due to their potential applications in nanobiophotonics and molecular sensing. In this dissertation, Au-Fe(oxide) magneto-plasmonic hybrid nanoparticles were synthesized using the laser ablation in liquid solution (LASiS) technique, a physical synthesis method considered clean and efficient, which does not require chemical reducing agents or surfactants, allowing the production of high-purity nanoparticles. The samples were characterized by UVVis spectroscopy, Dynamic Light Scattering (DLS), Scanning Electron Microscopy (SEM) coupled with Energy-Dispersive X-ray Spectroscopy (EDS), Transmission Electron Microscopy (TEM), and Raman spectroscopy, enabling the evaluation of their morphology, composition, and optical response. TEM analyses indicated that either core-shell or coresatellite structures could be formed, although further studies are needed for detailed structural confirmation. As proof of concept, the synthesized nanoparticles were used as substrates in Surface-Enhanced Raman Spectroscopy (SERS) for the detection of biological molecules in aqueous solutions. Cysteine, cysteamine, urea, thiourea, glycine, and mercaptopropionic acid were investigated, compounds containing functional groups of interest for potential binding to the hybrid nanoparticles. The analysis of the obtained spectra revealed characteristic vibrational signatures for each molecule, demonstrating the efficiency of Au-Fe(oxide) nanoparticles in enhancing the Raman signal and their potential for biomedical applications, including protein biomarker detection, targeted drug delivery, and the development of magneto-plasmonic biosensors.