Idrogenazione e ossidazione controllata di nanodiamanti: studio dell'interazione con l'acqua

Nanodiamonds (ND) are diamond nanocrystals with dimensions ranging from 4-5 nm to 300 nm, which are attracting increasing interest in the biomedical field due to their appealing properties. ND offer excellent biocompatibility, which is a fundamental feature when dealing with biological systems, are characterized by high surface to volume ratio and tunable surface structures, whose tailoring is paramount in determining their properties and, consequently, their potential utilities. Thermal treatments represent a powerful method to achieve the control of ND surface chemistry. Among them, hydrogenation is extremely important since hydrogenated ND has indeed recently emerged as a promising radiosensitizing agent, being capable to enhance injuries on cancer cells by boosting the production of Reactive Oxygen Species (ROS), thanks to its negative electron affinity. This property also triggers the transfer of electrons from the material to adsorbed water, resulting in the formation of a subsurface hole accumulation layer, which gives hydrogenated ND high electrical conductivity. Special consideration must also be given to oxidation treatments. Oxidized ND displays hydrophilic nature, and, due to the more homogeneous surface created by oxidation, it often constitutes the starting point for hydrogenation processes. Investigating the effects of hydrogenation and oxidation on ND properties constitutes a key step towards its final applications. The thesis was hence aimed at investigating ND water-influenced electrical properties, surface functional groups, structural modifications and behaviour in an aqueous solution by mean of current voltage characteristics measurements, DRIFT spectroscopy, Raman and photoluminescence spectroscopies, Dynamic Light Scattering and zeta potential analysis. Furthermore, a preliminar experiment, irradiating a water solution of ND with X-ray, was also performed to observe hydroxyl radicals production and thus assess the radiosensitizing effect of hydrogenated ND.