AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
A Safer Formulation Concept for Flame-Generated Engineered Nanomaterials (ENMs)
Samuel Gass, GEORGIOS PYRGIOTAKIS, Joel Cohen, Georgios A. Sotiriou, Sotiris E. Pratsinis, Philip Demokritou, Harvard University
Abstract Number: 515 Working Group: Nanoparticles and Materials Synthesis
Abstract Engineering less toxic nanomaterials that maintain valuable functional properties is crucial to the sustainability of the nanotech industry. We have therefore devised a safer formulation concept for flame-generated nanomaterials based on the encapsulation of potentially toxic nanomaterials by a biologically inert nanothin amorphous SiO2 layer. The core-shell particles maintain specific properties of their core material but exhibit surface properties of their SiO2 shell. The SiO2-coating process was performed using a modified flame spray pyrolysis (FSP)-based Versatile Engineered Nanomaterial Generation System (VENGES) in which core ENMs are coated in-flight by the swirl injection of hexamethyldisoloxane (HMDSO). We first demonstrate the versatility of the proposed SiO2-coating process by applying it to several ENMs (CeO2, Fe2O3, ZnO, Ag) marked by their prevalence in consumer products as well as their range in toxicity. We then investigate (1) the effect of the SiO2-coating on core material structure, composition and morphology (XRD, BET, and TEM), (2) the mobility and aggregation of SiO2-coated and uncoated ENMs in DI-water, biological media (DLS) and air (SMPS), and (3) the coating efficiency (XPS, Chemisorption) of the process for each ENM (XPS and Isopropanol Chemisorption). Finally, we provide valuable in-vitro toxicological evidence for the safety of this novel formulation concept by evaluating the relative toxicity of SiO2-coated vs. uncoated ENMs using a number of cellular assays (MTT, LDH, Live/Dead) and several cell-lines (A549 cancer alveolar epithelial cells and THP-1, macrophages). Our results show that the proposed method can be used to effectively coat flame generated ENMs with a nanothin layer of amorphous SiO2 thereby resulting in a significant reduction of their toxicological profile. Moreover, the proposed method can readily be scaled up and used by NT industry in the production of safer ENMs.