This thesis focuses on the evolution of the physicochemical properties of two carbide nanoparticles, SiC and TiC, in contact with biocompatible dispersants. The rationale is based on the fact that several of the toxicological evaluation required manipulations and / or interactions cause changes in the nanoparticles physicochemical surface. These changes call into question the relevance of existing tests and, to some extent, may raise unfounded concerns about their potential toxicity to humans and the environment. The nanoparticles were dispersed in aqueous dispersants following various dispersion protocols; later, these dispersions were mixed with culture medium or biological medium in the particular conditions of in vitro assays. This thesis shows that toxicological evaluation results can be influenced by the various necessary manipulations and / or interactions. The evaluation first defined the nanoparticles fingerprints in their pristine state, before contact with the biological medium. Next, the objective was to elucidate the evolution of key physicochemical parameters at different stages of contact with biocompatible fluids. Their physicochemical parameters were monitored during cell line incubation for toxicity assessment and using human reconstituted gastric fluid. Finally, for a better overview of the specific nanoparticle– culture medium interaction, a SiC nanoparticles evaluation with three different cell line tests was performed. The evaluation was focused on two main parameters: particle size distribution and surface composition. It was found that the nanoparticles physicochemical properties evolve from initial conditions to an altered state, highlighting the contact with the biocompatible medium. On the one hand, modifications were produced in the nanoparticles in a type-, time- and dispersion medium-dependent way and on the other hand, these modifications were found to alter the test results. To summarize, it is highlighted that a case by case scenario is mandatory for nanoparticle evaluation because they behave differently in each medium, due to interaction and modifications produced on their surface.
Study of the physicochemical properties of SiC and TiC nanoparticles and their evolution in biocompatible dispersants
Mejia Mendoza, J. H. (Author). 29 Nov 2012
Student thesis: Doc types › Doctor of Sciences