Research Project 2


(Arslan, Hwang, Han, Ray, Yu, Li, Leszczynski, Hill)

Understanding of environmental fate of graphene oxide based nanoscale architectures: Here we aim to understand how the toxicity of graphene nanomaterials vary with size and chemical composition upon exposure to various environmental conditions, such as, light, humidity, oxygen (air), and humic substances. The main change will be oxidation and subsequent leach into the environmental matrix. The surface oxidation will be determined by dissolution into acidic solutions without damaging the core. 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 graphene mamomaterials 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), graphene oxide and 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 59-62 to predict physical and chemical properties of nanomaterials (Nature Nanotechnology, 2011, 6, 175-178). In this project, our aim is to understand the reactivity 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.