Hydrophilic/hydrophobic features of TiO2 nanoparticles as a function of crystal phase, surface area and coating, in relation to their potential toxicity in peripheral nervous system

• Published in: Journal of colloid and interface science 2012-03, Vol.369 (1), p.28-39
• Main Authors: Bolis, V., Busco, C., Ciarletta, M., Distasi, C., Erriquez, J., Fenoglio, I., Livraghi, S., Morel, S.
• Format: Article
• Language: English
• Subjects: Anatase; Animals; Apoptosis; Catalysis; Cell Survival - drug effects; Cells, Cultured; Chemistry; Chick Embryo; Coating; Colloidal state and disperse state; Crystallization; Crystals; Dispersions; Dorsal root ganglion cells; Exact sciences and technology; Ganglia, Spinal - cytology; Ganglia, Spinal - drug effects; General and physical chemistry; Hydrodynamic diameter; Hydrophilicity; Hydrophobic and Hydrophilic Interactions; Microcalorimetry; Models, Molecular; Nanoparticles; Nanoparticles - chemistry; Nanoparticles - toxicity; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Rutile; Surface chemistry; Surface physical chemistry; Surface Properties; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; TiO2 dispersions; TiO2 polymorphs; Titanium - chemistry; Titanium - toxicity; Titanium dioxide; Viability cells assays; Water adsorption; Zeta potential
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2011.11.058

[Display omitted] ► TiO2-NP hydrated surface hydrophilicity depends on crystal phase and surface coating. ► TiO2-NP surface charge is negative and similar for all polymorphs. ► TiO2-NP neurotoxicity depends on crystal phase (anatase–rutile>anatase≫rutile). ► Inorganic/organic surface coating does not protect against the TiO2-induced apoptosis. ► Optimized dispersion protocol allowed to perform viability DRG cells assays. The hydrophilic/hydrophobic properties of a variety of commercial TiO2 nanoparticles (NP), to be employed as inorganic filters in sunscreen lotions, were investigated both as such (dry powders) and dispersed in aqueous media. Water uptake and the related interaction energy have been determined by means of adsorption microcalorimetry of H2O vapor, whereas dispersion features in aqueous solutions were investigated by dynamic light scattering and electrokinetic measurements (zeta potential). The optimized dispersions in cell culture medium were employed to assess the possible in vitro neuro-toxicological effect on dorsal root ganglion (DRG) cells upon exposure to TiO2-NP, as a function of crystal phase, surface area and coating. All investigated materials, with the only exception of the uncoated rutile, were found to induce apoptosis on DRG cells; the inorganic/organic surface coating was found not to protect against the TiO2-induced apoptosis. The risk profile for DRG cells, which varies for the uncoated samples in the same sequence as the photo-catalytic activity of the different polymorphs: anatase–rutile>anatase≫rutile, was found not to be correlated with the surface hydrophilicity of the uncoated/coated specimens. Aggregates/agglomerates hydrodynamic diameter was comprised in the ∼200–400nm range, compatible with the internalization within DRG cells.