Controlling the nanotoxicity of polyelectrolyte-functionalized titania nanoparticles
April 3-7, 2016
This study gives important insights of the various factors controlling the nanotoxicity of titania nanoparticles (TiO2NPs). We studied the nanotoxicity of TiO2NPs of various hydrodynamic diameters and crystallite sizes on C. Reinhardtii (microalgae) and S. cerevisiae (yeast) upon illumination with UV/visible light . The cell viability was assessed for a range of nanoparticle concentrations and incubation times. Bare TiO2NPs affect the microalgae viability at much lower particle concentrations than for yeast. We also found an increased nanotoxicity upon illumination with visible light which indicates that they may also interfere with the microalgae photosynthetic system leading to decreased chlorophyll content upon exposure to TiO2NPs. The results indicate that the larger the hydrodynamic diameter of the TiO2NPs the lower is their nanotoxicity, with anatase TiO2NPs generally being more cytotoxic than rutile TiO2NPs. We also prepared a range of polyelectrolyte-coated TiO2NPs using the layer by-layer method and studied their nanotoxicity on yeast and microalgae. The toxicity of the coated TiO2NPs alternates with their surface charge. TiO2NPs coated with cationic polyelectrolyte as an outer layer exhibit much higher nanotoxicity than the ones with an outer layer of anionic polyelectrolyte. TEM images of sectioned microalgae and yeast cells exposed to different polyelectrolyte-coated TiO2NPs confirmed the formation of a significant build-up of nanoparticles on the cell surface for bare- and cationic polyelectrolyte-coated TiO2NPs. The effect is coming from the increased adhesion of cationic nanoparticles to the cell walls. Significantly, coating the TiO2NPs with an anionic polyelectrolyte as an outer layer led to a reduced adhesion and much lower nanotoxicity due to electrostatic repulsion with the cell walls. This suggest a new way of making the TiO2NPs potentially safer for use in different formulations by pre-coating them with anionic polyelectrolytes.
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Vesselin N. Paunov, Gillian M. Greenway, and Mohammed Al-Awady, "Controlling the nanotoxicity of polyelectrolyte-functionalized titania nanoparticles" in "Design and Manufacture of Functional Microcapsules and Engineered Products", Chair: Simon Biggs, University of Queensland (Aus) Co-Chairs: Olivier Cayre, University of Leeds, UK Orlin D. Velev, North Carolina State University, USA Eds, ECI Symposium Series, (2016). http://dc.engconfintl.org/microcapsules/4