Methods to Assess Presence and Biological Impact of Engineered Nanoparticles

Thesis (Ph.D.)--University of Washington, 2015-12During the past two decades, the rates of development and production of engineered nanoparticles (ENPs) have rapidly increased due to their potential applications in medicine, cosmetics, energy, manufacturing, catalysis, food preservation, etc. However, the environmental fate and transport of ENPs remains poorly understood. This is partly due to the lack of accurate, simple and affordable methodologies for ENP detection and characterization. Scientists developing the new generation of nanotech-enabled consumer products have little information on the potential life cycle implications of their designs, leading to critical data gaps regarding possible ENPs exposures and hazards (e.g., release rates, toxicity). The limitation in our current knowledge about the safety of ENPs creates tremendous uncertainty for industrial regulations and risk management. This dissertation presents a detailed description of methodologies aimed to (1) determine the biological impacts of ENPs on cell membranes, and (2) to screen for the presence of engineered nanoparticles in relevant complex biological and environmental samples. In the first method, we use electrophysiological measurements of ENPs in suspended lipid bilayers to provide insights into the interactions of nanoparticles with cell membranes. The platform probes the responses of the lipid bilayer membranes to functionalized multi-walled carbon nanotubes, quantum dots, and a control organic compound, melittin, and shows that ENPs disrupt lipid membranes, which induces significant transmembrane current fluxes. These findings suggest that ENPs can insert and traverse the lipid bilayer membrane, forming transmembrane channels that allow the transport of ions. In the second method, we demonstrate a colorimetric detection assay that assesses the surface reactivity of ENPs, which can be used to detect the presence of nanoparticles in complex matrices. Current detection techniques require expensive and complex analytical instrumentation and are challenging to implement in biological fluids and environmental samples. This work addresses an emerging need for methodologies to accurately and quickly assess the presence and reactivity of nanoparticles in commercial, environmental, and biological samples. Our colorimetric assay can detect ENPs at parts per billion concentration levels by a direct measure of the ENP surface reactivity. We show that we can detect particles extracted from commercial products and show that our measurements correlate well with cellular toxicity responses. The development of sensitive, simple, and affordable techniques to detect ENPs in environmental and biological samples will ultimately aid in understanding the health risk of ENPs exposure, design of safe nanoproducts, and advancement of nanomedicine