Research Project 2

IMPACT OF ENGINEERED NANOMATERIALS ON THE ENVIRONMENT

(Arslan, Leszczynska, Hwang, Ray, Yu, Leszczynski, Hill)

Nanomaterials are rapidly becoming a part of our daily life in the forms of cosmetics, food packaging materials, bandages, socks, protective clothing, and laundry detergents. Critical questions to be explored in this REU proposal are: A) What are the fates of nanoparticles in air, water, and soil? B) What is the biodegradation potential of nanoparticles and what are the possible mechanisms? JSU has been at the forefront of environmental nanotoxicity research due to the establishment of the Interdisciplinary Nanotoxicity Center (ICN) in 2008, funded by the NSF and the Center for Environmental Health (CEH) in 1998, funded by the NIH. In this REU site proposal, we will focus on the following projects suitable for REU students.

Understanding Environmental Fate of Silver and Carbon Nanomaterials: How the toxicity of silver nanoparticles and carbon nanomaterials vary with the size and shape of the particle upon exposure to various environmental conditions, such as, light, humidity, oxygen (air), and humic substances will be explored. The main change will be oxidation of surface silver atoms and subsequent leach into the environmental metrix. The surface silver oxide will be determined by dissolution into acidic solutions without damaging the core of the nanosilver particle. Cell viability tests and Comet assay to understand cellular DNA damage after treating human epidermal cell line, HaCaT keratinocytes with nanomaterials will be determined. REU students will be involved in synthesis and characterization of silver nanoparticles and testing of their environmental toxicity and environmental fate.

Rapid Screening of Light-Induced Toxicity: The objectives of this project are to determine: a) how efficient light-induced excitation energy in nanomaterials is to transform molecular oxygen into ROS, and b) effects of material features such as particle size, dose, aggregation, surface functionalization/modification/charge on photosensitization ability. The target nanomaterials are titania (TiO2), C60 fullerenes, single-walled and multi-walled carbon nanotubes. Photochemical techniques include time-resolved laser and steady-state photolysis. REU students will learn characterization of these nanomaterials with TEM and will carry out time-resolved and steady-state photolysis experiments to detect ROS formation.

Quantitative Structure-Activity Relationships (QSARs). QSAR study can be used to elucidate toxicity mechanisms on the basis of chemical structure. During the last two years, a QSAR technique model was developed to predict physical and chemical properties of nanomaterials (Nature Nanotechnology, 2011, 6, 175-178). In this project, the aim is to understand the reactivity properties of C60 and other carbon nanomaterials with respect to toxicity. Various quantum-chemical methods will be used initially before the parameters for the QSAR studies will be defined based on these quantum mechanical calculations. REU students will learn computational programs and existing QSAR models to study the relationship between toxicity and structure.