Journal Article

TiO2 Nanoparticles Are Phototoxic to Marine Phytoplankton

Miller, Robert J., Pease, Scott, Lenihan, Hunter S., Bennett, Samuel, Keller, Arturo A.

2012

Overview

Nanoparticulate titanium dioxide (TiO(2)) is highly photoactive, and its function as a photocatalyst drives much of the application demand for TiO(2). Because TiO(2) generates reactive oxygen species (ROS) when exposed to ultraviolet radiation (UVR), nanoparticulate TiO(2) has been used in antibacterial coatings and wastewater disinfection, and has been investigated as an anti-cancer agent. Oxidative stress mediated by photoactive TiO(2) is the likely mechanism of its toxicity, and experiments demonstrating cytotoxicity of TiO(2) have used exposure to strong artificial sources of ultraviolet radiation (UVR). In vivo tests of TiO(2) toxicity with aquatic organisms have typically shown low toxicity, and results across studies have been variable. No work has demonstrated that photoactivity causes environmental toxicity of TiO(2) under natural levels of UVR. Here we show that relatively low levels of ultraviolet light, consistent with those found in nature, can induce toxicity of TiO(2) nanoparticles to marine phytoplankton, the most important primary producers on Earth. No effect of TiO(2) on phytoplankton was found in treatments where UV light was blocked. Under low intensity UVR, ROS in seawater increased with increasing nano-TiO(2) concentration. These increases may lead to increased overall oxidative stress in seawater contaminated by TiO(2), and cause decreased resiliency of marine ecosystems. Phototoxicity must be considered when evaluating environmental impacts of nanomaterials, many of which are photoactive.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Antibacterial materials / Anticancer properties / Aquatic organisms / Biocompatibility / Biology / Biomedical materials / Cancer / Catalysis / Chlorophyta / Cytotoxicity / Disinfection / Dunaliella tertiolecta / Ecosystem biology / Environmental impact / Environmental science / Experiments / Free radicals / Growth rate / In vivo methods and tests / Isochrysis galbana / Light levels / Luminous intensity / Marine ecosystems / Materials Science / Metal oxides / Microorganisms / Nanomaterials / Nanoparticles / Nanoparticles - chemistry / Nanotechnology / Oxidative stress / Oxidative Stress - drug effects / Oxidative Stress - radiation effects / Oxygen / Photobiology / Photocatalysis / Photochemistry / Phototoxicity / Phytoplankton / Phytoplankton - drug effects / Phytoplankton - metabolism / Phytoplankton - radiation effects / Plankton / Population growth / Reactive oxygen species / Reactive Oxygen Species - metabolism / Seawater / Spectrum analysis / Surgical implants / Titanium - toxicity / Titanium dioxide / Toxicity / U.V. radiation / Ultraviolet radiation / Ultraviolet Rays / Wastewater