Safer formulation concept for flame-generated engineered nanomaterials

Samuel Gass, Joel M. Cohen, Georgios Pyrgiotakis, Georgios A. Sotiriou, Sotiris E. Pratsinis, Philip Demokritou

Research output: Contribution to journalArticlepeer-review

55 Scopus citations


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 SiO2. Core-shell particles exhibit the surface properties of their amorphous SiO2 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 SiO2 encapsulation process, which was recently introduced by the authors as a means for a scalable manufacturing of SiO 2-coated ENMs. First, the versatility of the SiO2-coating process is demonstrated by applying it to four ENMs (CeO2, ZnO, Fe2O3, 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 SiO2-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 2 adsorption, TEM, XPS, isopropanol chemisorption). Finally, the biological interactions of SiO2-coated vs uncoated ENMs are evaluated using cellular bioassays, providing valuable evidence for reduced toxicity for the SiO2-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.

Original languageEnglish (US)
Pages (from-to)843-857
Number of pages15
JournalACS Sustainable Chemistry and Engineering
Issue number7
StatePublished - Jul 1 2013
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • Environmental Chemistry
  • General Chemical Engineering
  • Renewable Energy, Sustainability and the Environment


  • Core-shell particles
  • Flame-generated nanomaterials
  • Nanotechnology
  • Nanotoxicology
  • Safer nanoformulations


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