The potential risk of health damage to humans caused by the exposure to nanometric-sized particles is, nowadays, a very current topic. In particular, titanium dioxide (TiO2) nanoparticles (NPs) are extensively studied since they are widely used in industry for several applications ranging from sunscreens, pigments and construction materials to solar cells. The biological effects depend mainly on their surface chemistry (phase composition, structural defects, impurities) and nanostructure (morphology, size). The biological activity of TiO2 is enhanced by UV light exposure due to TiO2 photoactivation generating radicals such as ?OH and O2?- and other reactive oxygen species (ROS), able to react with a wide range of organic molecules. NPs surface functionalization with silica (SiO2) is a "safety by design" approach expected to control and harmonize the biological activity due to hydrophilicity, biocompatibility, chemical and thermal stability of silica. The present work is addressed to the production and characterization of SiO2-coatings on TiO2 NPs, dispersed in aqueous solutions (commercial nanosols) with the aim to manage their potential risk. A colloidal approach, based on electrostatic attraction between opposite surface charges (heterocoagulation), was followed. Physicochemical properties such as zeta potential, particle-size distribution, morphology and hydrophilicity of the samples produced with different SiO2:TiO2 weight ratios were measured and compared with photocatalytic properties. Photocatalytic efficiency assessed by Rhodamine B (RhB) photodegradation, used as model reaction, was correlated to the ability to produce ROS in order to indirectly predict the toxicological effect on human health. The ?OH and superoxide radicals determination was performed by two trapping methods based on salicylic acid and tempone-H hydrochloride under irradiation, respectively. The research leading to this commentary has received funding through the project "SANOWORK" (FP7-NMP4-SL-2011-280716).
"Safety by design" approach to manage nanotitania surface photoreactivity
S Ortelli;M Blosi;C Delpivo;AL Costa
2014
Abstract
The potential risk of health damage to humans caused by the exposure to nanometric-sized particles is, nowadays, a very current topic. In particular, titanium dioxide (TiO2) nanoparticles (NPs) are extensively studied since they are widely used in industry for several applications ranging from sunscreens, pigments and construction materials to solar cells. The biological effects depend mainly on their surface chemistry (phase composition, structural defects, impurities) and nanostructure (morphology, size). The biological activity of TiO2 is enhanced by UV light exposure due to TiO2 photoactivation generating radicals such as ?OH and O2?- and other reactive oxygen species (ROS), able to react with a wide range of organic molecules. NPs surface functionalization with silica (SiO2) is a "safety by design" approach expected to control and harmonize the biological activity due to hydrophilicity, biocompatibility, chemical and thermal stability of silica. The present work is addressed to the production and characterization of SiO2-coatings on TiO2 NPs, dispersed in aqueous solutions (commercial nanosols) with the aim to manage their potential risk. A colloidal approach, based on electrostatic attraction between opposite surface charges (heterocoagulation), was followed. Physicochemical properties such as zeta potential, particle-size distribution, morphology and hydrophilicity of the samples produced with different SiO2:TiO2 weight ratios were measured and compared with photocatalytic properties. Photocatalytic efficiency assessed by Rhodamine B (RhB) photodegradation, used as model reaction, was correlated to the ability to produce ROS in order to indirectly predict the toxicological effect on human health. The ?OH and superoxide radicals determination was performed by two trapping methods based on salicylic acid and tempone-H hydrochloride under irradiation, respectively. The research leading to this commentary has received funding through the project "SANOWORK" (FP7-NMP4-SL-2011-280716).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
