Development and characterization of a quantitative method for respirable nanoparticle risk assessment
University of Vermont
The purpose of this research is to develop and characterize a novel method of respirable nanoparticle (NP) risk assessment that provides a quantitative and accurate in vitro cell culture model for the study of particle-cell interactions and NP toxicity in lung epithelial cells. The electrostatic particulate dosage and exposure system (EPDExS) is unique to the University of Vermont and functions on the principle of electrostatic precipitation, allowing for the delivery of NPs directly onto cells with 100% efficiency and real-time quantification of delivered dose. The central hypothesis is that the effective NP dose, and by extension NP cellular uptake, depends on the mode of cell exposure (i.e., through cell growth medium vs. at the air-liquid interface). This project aims to demonstrate that the agglomeration state of NPs is a function of mode of cell exposure and NP characteristics, and to evaluate total particle number vs. mass as the most appropriate dose-response metric. A major obstacle in current in vitro NP toxicology is the absence of quantifiable, reproducible, and accurate dose metrics for the exposure of cell cultures to NPs. Conventionally, NPs are either suspended in the cell growth media directly or extracted in solvent preceding addition, requiring extensive modeling of diffusion, agglomeration, and settling for accurate particle characterization and dosimetry. We have found that conventional methods lead to significant agglomeration of particles, effectively changing their surface area and size, whereas cell exposure at the air-liquid interface (ALI) using the EPDExS resulted in only singlets being deposited. Furthermore, agglomeration and effective particle deposition using conventional methods was strongly time-dependent, greatly hindering our ability to model and estimate effective NP doses to the cells. Ultimately, this project seeks to characterize the EPDExS as a more accurate, quantitative and efficient delivery method of respirable nanoparticulate to better assess NP toxicity in vitro.