Environmental implications of using nanomaterials
Nanomaterials are extensively used in a wide range of industrial applications owing to their exceptional physical, mechanical, and electrical properties compared to their corresponding bulk materials. However, these unique properties, which make nanomaterials so attractive, also pose potential risks for human health and the environment. Specifically, a growing environmental concern is the contamination of water sources with nanomaterials released through a plethora of discharge routes.
One of the main challenges associated with emerging nanomaterials is monitoring and characterizing their toxicity in water. Current approaches assessing toxicity use discrete sampling methods followed by laboratory analyses with living cells, an expensive and time-consuming process providing no real-time data. In light of inherent complexities and dynamics in cell membranes, artificial membranes are suggested as model systems to gain fundamental insights into nonspecific interactions of cells and may assist to anticipate toxicity of nanomaterials of different structure and surface chemistry.
Environmental implications of nanotechnology throughout their life cycle.
Quantifying the risk: decoupling structure and surface chemistry in nanomaterial toxicity
Recently, we used dye-leakage assays to quantify the disruption of a model phospholipid bilayer membrane by emerging nanomaterials of different chemical composition, orientation, and morphology. Different levels of dye leakage from the vesicle inner solution, indicating a loss of membrane integrity, was observed for a set of two-dimensional nanomaterials while oxidative stress resulted in no loss of membrane integrity. These results suggest that chemical composition plays an important role during physical membrane–nanosheet interactions. We also observed an orientation-dependent interaction using aligned graphene oxide composite films, which was attributed to the density of edges with a preferential orientation for membrane disruption. In our on-going study, we complement these findings and assess the disruption of phospholipid bilayer membranes by manganese oxides of different morphologies.
A rapid nanomaterial toxicity sensor kit based on interactions of various lipid bilayers with nanomaterials
Interactions of various modified lipid vesicles (i.e., model-cell indicators) with engineered nanomaterials can be demonstrated simultaneously in real-time by a dye-leakage assay. We are working on the development of a soft-matter based sensing platform for engineered nanomaterials, which uses interactions of nanomaterials with a set of modified lipid bilayers designed to mimic specific cells of interest. By efficiently pinpointing toxicity in real-time, this kit will lessen release of toxic nanomaterials to the environment and drinking water, as well as inform the design of green, less-toxic nanomaterials.
(A) Schematic illustrating the experimental set-up, lipid vesicle structure encapsulating a fluorescent dye at high concentration, and possible mechanisms of interaction between nanosheets and vesicles.
(B) Kinetics of fluorescent dye leakage from vesicle inner solution to the extravesicular solution induced by two-dimensional nanomaterials.
Environmental behavior and toxicity of commonly-used micro- and nanoplastic
Plastic has become the largest pollutant in the aquatic environment, mainly due to its extensive use and slow degradation in the environment. Regulation for sustainable use and recycling of plastics is currently applied in most of the modern countries. However, only 14% of plastics are being recycled while the vast majority of plastics find their way to the landfills, seas, and oceans. We are interested in toxicity of micro- and nano-plastics towards human cells. plastic Degradation and adsorption-desorption processes occurring in the aquatic environment are key parameters which we account for during toxicity tests. Our hypothesis is that while pristine plastic particles might not have high toxicity toward cells, modified particles which absorbed organic/inorganic pollutants may have interact differently following cellular uptake.
Plastic pollution is everyone’s problem: (A) Human multiple exposure to micro-plastic from different sources and (B) representative scanning electron microscope image of polystyrene microplastic standard produced at the Zucker Lab
1. I. Zucker, J.R. Werber, Z.S. Fishman, S.M. Hashmi, U.R. Gabinet, X. Lu, C.O. Osuji, L.D. Pfefferle, M. Elimelech; Loss of phospholipid membrane integrity induced by two-dimensional nanomaterials – pp. 404–409, 2017, Environmental Science & Technology Letters.
2. X. Lu, X. Feng, J.R. Werber, C. Chu, I. Zucker, J. Kim, C. Osuji, M. Elimelech; Enhanced antimicrobial activity through the controlled alignment of graphene nanosheets – pp. E9793–E9801, 2017, Proceedings of the National Academy of Sciences.
Development of advanced water-treatment technologies which leverage the reactive and tunable properties of nanomaterials for selectivity toward priority pollutants, cost-efficiency and sustainability