Characterization of a Ternary System Based on Hybrid Nanoparticles

Hybrid nanoparticles (NPs) are emerging as an important family of multifunctional nanoscale materials. Due to its unique properties cyclodextrins (CDs) present the possibility to be employed in nanostructured devices for multiple applications. Therefore the study of hybrids NPs containing CDs, metal nanoparticles and an organic molecular guest is promising for applications in separation science, sensing, optics, catalysis and medical therapy. To investigate the hybrid nanoparticles properties in light of technological and medical science interfaces we chose tramadol hydrochloride as the model molecular guest. Using 2D 1H NMR and FTIR spectroscopies and ESI-MS we studied the topology and host-guest stoichiometry of inclusion compound between 2-hydroxypropyl-α-cyclodextrin and tramadol. These techniques confirmed that the inclusion compounds present 1:1 stoichiometry with the tramadol aromatic moiety inserted in the CD cavity and the amine part interacting with the CD superficial OHs. Performing capillary electrophoresis experiments, the stability constants of inclusion compounds were obtained and showed that the increase of temperature during the synthesis of these NPs can decrease their stabilities. Precipitated palladium nanoparticles were determined to have 80-200 nm of size distribution and the incorporation of tramadol was evidenced by additional 1H NMR experiments.