AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
A Novel Method to Measure Effective Density of Engineered Nanomaterials in Liquid Suspensions: Implications for In Vitro Dosimetry and Nanotoxicology
Glen DeLoid, Joel Cohen, PHILIP DEMOKRITOU, Harvard University
Abstract Number: 83 Working Group: Nanoparticles and Materials Synthesis
Abstract With the ever-increasing number of engineered nanomaterials (ENMs) entering the consumer market, efficient and inexpensive in vitro toxicity assays are necessary tools for correlating ENM properties with biological activity. However, results from in vitro assays often vary substantially among different studies and from in vivo data. These discrepancies may be attributable to inadequate characterization of ENM transformations in suspension and the subsequent effects on particle delivery to cells in culture. ENM agglomeration influences in vitro dosimetry by reducing the effective density of ENMs, thereby limiting particle delivery to cells. In this study, we present a novel method for measuring the effective density of ENM agglomerates by volumetric centrifugation. Employing a standardized dispersion protocol recently developed in our group, a panel of well-characterized metal oxide ENMs was suspended in various cell culture media with and without serum proteins. ENM agglomerates were characterized for hydrodynamic diameter by dynamic light scattering. ENM suspensions were then centrifuged in packed cell volume (PCV) tubes equipped with volumetric pellet capturing capillaries. Effective densities were determined from the total volume of the ENM pellet, the known mass of suspended ENM, and the known densities of the ENM raw material and the suspension media. Empirically measured effective densities are reported for a large panel of ENMs dispersed in various media. Particle transport was modeled incorporating values for effective density, and demonstrates large discrepancies between administered and delivered doses. Our method allows for simple determination of effective density, an important step towards linking particle properties to bio-interactions in vitro.