Silica modification of titania nanoparticles enhances photocatalytic production of reactive oxygen species without increasing toxicity potential in vitro
posted on 2019-01-03, 16:05authored bySimona Ortelli, Anna L. Costa, Pietro Matteucci, Mark R. Miller, Magda Blosi, Davide Gardini, Syed A.M. Tofail, Lang Tran, Domenica Tonelli, Craig A. Poland
Titania (TiO2) nanoparticles were surfacemodified using silica and citrate to implement a ‘safe-by-design’
approach for managing potential toxicity of titania nanoparticles by controlling surface redox reactivity.
DLS and zeta-potential analyses confirmed the surface modification, and electron microscopy and
surface area measurements demonstrated nanoscale dimensions of the particles. Electron
paramagnetic resonance (EPR) was used to determine the exogenous generation of reactive oxygen
species (ROS). All the produced spray dried nanotitania lowered levels of ROS when compared to the
corresponding dispersed nanotitania, suggesting that the spray drying process is an appropriate design
strategy for the control of nano TiO2 ROS reactivity. The modification of nanotitania with silica and
with citrate resulted in increased levels of ROS generation in exogenous measurements, including
photoexcitation for 60 minutes. The dichlorodihydrofluorescein (DCFH) assay of dose-dependent
production of oxidative stress, generated by pristine and modified nanotitania in macrophages and
alveolar epithelial cells, found no significant change in toxicity originating from the generation of
reactive oxygen species. Our findings show that there is no direct correlation between the
photocatalytic activity of nanotitania and its oxidative stress-mediated potential toxicity, and it is
possible to improve the former, for example adding silica as a modifying agent, without altering the
cell redox equilibrium.
Funding
Study on Aerodynamic Characteristics Control of Slender Body Using Active Flow Control Technique