Silica modification of titania nanoparticles enhances photocatalytic production of reactive oxygen species without increasing toxicity potential in vitro

Simona Ortelli, Anna L. Costa*, Pietro Matteucci, Mark R. Miller, Magda Blosi, Davide Gardini, Syed A.M. Tofail, Lang Tran, Domenica Tonelli, Craig A. Poland

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Titania (TiO2) nanoparticles were surface modified 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.

Original languageEnglish
Pages (from-to)40369-40377
Number of pages9
JournalRSC Advances
Volume8
Issue number70
Early online date4 Dec 2018
DOIs
Publication statusE-pub ahead of print - 4 Dec 2018

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