Safer Formulation Concept for Flame-Generated Engineered
Nanomaterials
- Publication date
- Publisher
Abstract
The
likely success or failure of the nanotechnology industry depends
on the environmental health and safety of engineered nanomaterials
(ENMs). While efforts toward engineering safer ENMs are sparse, such
efforts are considered crucial to the sustainability of the nanotech
industry. A promising approach in this regard is to coat potentially
toxic nanomaterials with a biologically inert layer of amorphous SiO<sub>2</sub>. Core–shell particles exhibit the surface properties
of their amorphous SiO<sub>2</sub> shell while maintaining specific
functional properties of their core material. A major challenge in
the development of functional core–shell particles is the design
of scalable high-yield processes that can meet large-scale industrial
demand. Here, we present a safer formulation concept for flame-generated
ENMs based on a one-step, in flight SiO<sub>2</sub> encapsulation
process, which was recently introduced by the authors as a means for
a scalable manufacturing of SiO<sub>2</sub>-coated ENMs. First, the
versatility of the SiO<sub>2</sub>-coating process is demonstrated
by applying it to four ENMs (CeO<sub>2,</sub> ZnO, Fe<sub>2</sub>O<sub>3</sub>, Ag) marked by their prevalence in consumer products as well
as their range in toxicity. The ENM-dependent coating fundamentals
are assessed, and process parameters are optimized for each ENM investigated.
The effects of the SiO<sub>2</sub>-coating on core material structure,
composition, and morphology, as well as the coating efficiency on
each nanostructured material, are evaluated using state-of-the-art
analytical methods (XRD, N<sub>2</sub> adsorption, TEM, XPS, isopropanol
chemisorption). Finally, the biological interactions of SiO<sub>2</sub>-coated vs uncoated ENMs are evaluated using cellular bioassays,
providing valuable evidence for reduced toxicity for the SiO<sub>2</sub>-coated ENMs. Results indicate that the proposed “safer by
design” concept bears great promise for scaled-up application
in industry in order to reduce the toxicological profile of ENMs for
certain applications